Saturday, June 05, 2021

Follow the Science, At Least on Nutrition

If we’ve learned anything from the Covid-19 pandemic, it’s the make-or-break importance of solid, up-to-date scientific information – and the regulatory flexibility necessary to respond to new information quickly. At least with some aspects of Covid prevention and treatment, “follow the science” became the guiding mantra, as sustained inquiry into the coronavirus progressed at warp-speed, leading to scientific breakthroughs and three vaccines in only months, rather than the normal years or even decades.

However, related research also confirmed the truth that a healthy diet is key to preventing, managing and recovering from Covid-19 (and other diseases).

That’s why it’s surprising, and exasperating, that many suggestions in the 2020 Dietary Guidelines for Americans – the official government recommendations for a healthy diet – were based on outdated data. Rather than following the science, they have too often lagged behind recent findings or been subjected to apparently politicized science. That needs to change.

Dietary Guidelines are more than advice on how to eat. They form the basis of federal food policies and programs, nutrition education, and various public and private disease prevention initiatives. Formulated in consultation with the Dietary Guidelines Advisory Committee, the Guidelines serve as a reference tool, influence what’s on food labels, and dictate what foods are allowed in school lunch programs.

Just as important, health-care professionals and policy makers determine nutritional recommendations for especially vulnerable groups – such as pregnant women, young children and adolescents. All these people depend on (and assume there is) sound science behind the Guidelines.

Given the link between nutrition and health, one would think the congressionally required dietary Guidelines would be of high scholarly quality, accurate and scientifically up-to-date, particularly since they are published just once every five years. Indeed, the statute that mandates publication specifically requires that they be based on “the preponderance of current scientific and medical knowledge.”

Unfortunately, updates that include Recommended Dietary Allowance (RDA) values for various nutrients receive less attention.

Part of the science behind the guidelines is Dietary Reference Intakes (DRIs) that tell us how much of any given nutrient a healthy person needs, from macronutrients (proteins, fats and carbohydrates) to vitamins and minerals. Surprisingly, except for sodium and potassium, none of the DRIs have been updated in the last ten years; others, like magnesium and vitamin C, have had no updates since the 1990s.

So, on closer look, the “new” 2020 dietary guidelines turn out to be the fifth consecutive congressionally-mandated iteration of old, often outdated science, packaged in a new cover. Not surprisingly, the 2020 Advisory Committee recommended urgent extensive updates to existing DRIs, for most nutrients, for all age and sex groups and life stages, to better characterize potential risks of dietary inadequacy and excess.

If these official dietary recommendations are to mean anything, the underlying science must be current and the DRIs must be updated – right now, and more regularly in the future.

The 2020 Advisory Committee report on that point is clear: “The DRIs are essential resources for evaluating the nutritional quality of current dietary patterns for the American public, and the Committee has identified where updates are needed for the DRIs to be relevant in the Dietary Guidelines process.”

That’s why it should have been big news when former Deputy Undersecretary of Agriculture for Food Nutrition and Consumer Services Brandon Lipps’ team secured DRI research funding before leaving office. For some reason, though, there was hardly any media coverage.

Instead, ahead of the 2020 Guidelines’ publication, misguided news reports announced an expected reduction in RDAs for alcoholic drinks and added sugars – in the midst of the Covid lockdowns, when millions of Americans were increasing their intakes, as a way to cope with their isolation and boredom. But without new studies to justify them, USDA and HHS made no changes to the 2015 recommendations.

By contrast, a big change that was introduced in the 2020 Guidelines involved recommendations for young infants from birth to two years of age. For example, they suggested that babies and toddlers shouldn’t have any sweets in their first 24 months, even though there is no new science to support that new guideline. Making that change even more troubling, the very young are probably more vulnerable to the effects of using outdated DRIs than any other age group.

In another example, it’s been a long time since the last DRI update for choline, a nutrient that particularly affects infants. Certain animal source foods – such as eggs – provide sufficient amounts of choline, which appears to improve cognitive development that begins during infancy and lasts into school-age years.

Researchers at Cornell University recently discovered that women who consume twice the recommended intake of choline during their third trimester of pregnancy – a time of rapid brain development – deliver lasting neuro-protective benefits to their babies. Enhanced cognitive effects observed in the children (increased attention, memory and problem-solving skills) were still maintained at age 7.

Surprisingly though, since choline was first granted a DRI in 1998, the DRI for infants across all domestic food policy has not been based on even one actual clinical trial. It’s been based on the average level of choline in breast milk. That certainly appears to make the choline-intake recommendation entirely random and inadequate, especially for parents who follow vegan diets

DRIs have to be kept up-to-date, and ongoing, relevant research on any nutrition-health nexus must be incorporated into them.

In yet another example, the Guidelines also mention tooth cavities as a significant diet-related chronic disease.  And yet the Guidelines ignore the large body of evidence showing the role that chewing sugar-free gum can play in improving oral health by increasing saliva production and discouraging snacking.

In fact, the Guidelines almost entirely overlooked the importance of oral health to overall health, even though wider health benefits linked to a healthy oral biome include the prevention of heart disease, pre-eclampsia and eclampsia (a pregnancy complication characterized by high blood pressure), periodontitis (a serious gum infection that can destroy gums and even jawbones) and diabetes.

Chewing sugar-free gum has been associated with faster post cesarean recovery. Researchers have even suggested a link between oral health and Covid: coronavirus may spread into the bloodstream through infected gums, causing a more severe disease in people with poor oral hygiene.

To restate the obvious, if the government is going to publish Dietary Guidelines for Americans every five years, agencies need to follow the science. Rather than regurgitating and reprinting old information, and expecting us to follow it on faith, these highly influential Guidelines need to be based on current scientific knowledge. Our health and the health of our children are too important for anything less.

Whether it’s nutrition, Covid or climate change, the last thing we need is more sloppy politicized science, and more policies, laws and regulations dictated by “woke” or “cancel culture” agendas that put our well-being way down on the list of government priorities.

<i>Via email from Paul Driessen</i>

Tuesday, May 11, 2021

‘Potentially dangerous’ levels of microplastics found in rice: researchers

<i>Note that word "potentially".  A near synonym would be "unproven".  And even the chief researcher says: "I don’t think people should be concerned".

Note that most plastics are inert so any toxic level would be high</i>

A world first study has found rice contains a ‘potentially dangerous’ contaminating item, with levels highest in instant rice.

One of Australia’s most popular staple foods has been found to harbour “potentially dangerous” microplastics, a world-first Australian study has found.

University of Queensland researchers at the Queensland Alliance for Environmental Health Sciences identified 3-4mg of plastic in an average 100g single serve of uncooked rice.

The study, published today in the Journal of Hazardous Materials, also found instant or pre-cooked rice contained four times more plastic – averaging 13mg per 100g serve.

Lead author Dr Jake O’Brien said they found washing rice before cooking reduced plastics contamination by 20 to 40 per cent.

Dr O’Brien said they used everyday rice bought from a local store for the research. An average grain of rice was 8mm long, with microplastics defined as a plastic material measuring 5mm or less.

The researchers tested for seven different plastic types ranging from the most common plastic, Polyethylene to plastics used in clothing and food production, laminates, technical engineering, polystyrene, acrylics and tube piping.

The innovative method developed and used by the UQ research team is based on the plastic quantification technique used in their previous studies on plastics in seafood species and sewage sludge.

Dr O’Brien said the presence of microplastics was relatively low, but there was still much to be learned about their effects on human health.

“I don’t think people should be concerned, I think people should be aware,” he said.

“Currently there are many unknowns about how harmful consuming microplastics is to human health, but we do know exposure can cause an element of risk.”

He said it was still very early days in research to develop methods to measure plastic contamination in foods, and it was “really challenging to determine our exposure and exposure sources of these chemicals.”

“We hope this study encourages further research on where plastic contamination of rice is occurring, so we can reduce contamination and increase community awareness of where plastic exposure happens on a daily basis,” he said.

“In future studies, we aim to incorporate a measure of the plastic size, along with the concentration, because potential health impacts from microplastics are likely size dependent.”

Dr Thava Palanisami, a senior research fellow at The University of Newcastle, has been researching microplastics for many years.

In 2019 he co-led a project that combined data from more than 50 studies on the ingestion of microplastics by people.

The project led to a report that suggested people were consuming about 2000 tiny pieces of plastic every week. This was on average 5g – the size of a credit card.

Dr Palanisami said the presence of that quantity of microplastics in rice was a concern.

“Generally the smaller the size, the more potentially dangerous it can be to health,” he said. “It can get into the blood stream and the organs.”

Dr O’Brien said the research, while still in its very early days, showed washing rice before use was the best way to reduce risk. He said future research would examine other staple foods, including grains.

Saturday, April 03, 2021

Another attack on your bacon and sausages

The usual story: Tiny hazard ratios taken seriously. This is particularly unimpressive when one notes the international data sources -- very different countries and cultures. The opportunity for confounding variables was obviously large.

Maybe some people in some poor countries ate a lot of sausages and we know that poor people have worse health. So it was poverty that produced the effect, not sausages

Associations of unprocessed and processed meat intake with mortality and cardiovascular disease in 21


Dietary guidelines recommend limiting red meat intake because it is a major source of medium- and long-chain SFAs and is presumed to increase the risk of cardiovascular disease (CVD). Evidence of an association between unprocessed red meat intake and CVD is inconsistent.

The study aimed to assess the association of unprocessed red meat, poultry, and processed meat intake with mortality and major CVD.

The Prospective Urban Rural Epidemiology (PURE) Study is a cohort of 134,297 individuals enrolled from 21 low-, middle-, and high-income countries. Food intake was recorded using country-specific validated FFQs. The primary outcomes were total mortality and major CVD. HRs were estimated using multivariable Cox frailty models with random intercepts.

In the PURE study, during 9.5 y of follow-up, we recorded 7789 deaths and 6976 CVD events. Higher unprocessed red meat intake (≥250 g/wk vs. <50 g/wk) was not significantly associated with total mortality (HR: 0.93; 95% CI: 0.85, 1.02; P-trend = 0.14) or major CVD (HR: 1.01; 95% CI: 0.92, 1.11; P-trend = 0.72). Similarly, no association was observed between poultry intake and health outcomes. Higher intake of processed meat (≥150 g/wk vs. 0 g/wk) was associated with higher risk of total mortality (HR: 1.51; 95% CI: 1.08, 2.10; P-trend = 0.009) and major CVD (HR: 1.46; 95% CI: 1.08, 1.98; P-trend = 0.004).

In a large multinational prospective study, we did not find significant associations between unprocessed red meat and poultry intake and mortality or major CVD. Conversely, a higher intake of processed meat was associated with a higher risk of mortality and major CVD.

Saturday, March 27, 2021

Eating one rasher of bacon a day increases your chance of getting dementia by 44%, study into dangers of processed meats suggests

The heading above is misleading. The Hazard Ratios were all very low, indication a most tenous relationship between diet and dementia. The results allow for their being no real relationship at all

Eating processed meat such as sausages, bacon and burgers could dramatically increase the risk of getting dementia, new research shows.

The findings suggest that eating just one rasher of bacon a day could increase your chances of developing the disease by a staggering 44 per cent.

However meat-lovers need not despair, as scientists conducting the study also found that eating some unprocessed meat including beef, pork and veal can protect against dementia.

In the study, people who ate 50g a day of unprocessed meat were almost 20 per cent less likely to develop the condition.

The research, by Leeds University, explored a potential link between eating meat and developing dementia using data from 500,000 people.

Professor Janet Cade, who supervised the research, said: 'Anything we can do to explore potential risk factors for dementia may help us to reduce rates of this debilitating condition.

'This analysis is a first step towards understanding whether what we eat could influence that risk.'

Researchers investigated links between eating different types of meat and dementia risk.

The team studied data from the UK Biobank database containing genetic and health information from half a million Brits aged 40 to 69 between 2006 and 2010.

This included how often people snacked on different kinds of meat, with six options from never to once or more daily.

Vegetarian and vegan diets were not looked at specially but the study did include people who avoided red meat.

Over an average of eight years, almost 2,900 dementia cases emerged.

This was seen in people who were generally older, more economically deprived, less educated, more likely to smoke, less physically active, more likely to have stroke history and family dementia history, and more likely to carry a dementia-related gene.

More men than women were diagnosed with dementia in the study.

Professor Cade said: 'Some people were three to six times more likely to develop dementia due to well established genetic factors, but the findings suggest the risks from eating processed meat were the same whether or not a person was genetically predisposed to developing the disease.

'Those who consumed higher amounts of processed meat were more likely to be male, less educated, smokers, overweight or obese, had lower intakes of vegetables and fruits, and had higher intakes of energy, protein, and fat including saturated fat.'

Meat consumption has previously been associated with dementia risk, but this is believed to be the first large-scale study of participants over time to examine a link between specific meat types and amounts, and the risk of developing the disease.

Lead researcher Huifeng Zhang, a PhD student at the University of Leeds, said: 'Worldwide, the prevalence of dementia is increasing and diet as a modifiable factor could play a role.

'Our research adds to the growing body of evidence linking processed meat consumption to increased risk of a range of non-transmissible diseases.'

There are around 50 million dementia cases globally, with around ten million new cases diagnosed every year.

Alzheimer's Disease makes up 50 per cent to 70 per cent of cases, and vascular dementia around 25 per cent.

Its development and progression are associated with both genetic and environmental factors, including diet and lifestyle.

Ms Zhang added: 'Further confirmation is needed, but the direction of effect is linked to current healthy eating guidelines suggesting lower intakes of unprocessed red meat could be beneficial for health.'

The findings were published in the American Journal of Clinical Nutrition Monday.

The abstract

Meat consumption and risk of incident dementia: cohort study of 493,888 UK Biobank participants

Huifeng Zhang


Worldwide, the prevalence of dementia is increasing and diet as a modifiable factor could play a role. Meat consumption has been cross-sectionally associated with dementia risk, but specific amounts and types related to risk of incident dementia remain poorly understood.

We aimed to investigate associations between meat consumption and risk of incident dementia in the UK Biobank cohort.

Meat consumption was estimated using a short dietary questionnaire at recruitment and repeated 24-h dietary assessments. Incident all-cause dementia comprising Alzheimer disease (AD) and vascular dementia (VD) was identified by electronic linkages to hospital and mortality records. HRs for each meat type in relation to each dementia outcome were estimated in Cox proportional hazard models. Interactions between meat consumption and the apolipoprotein E (APOE) ε4 allele were additionally explored.

Among 493,888 participants included, 2896 incident cases of all-cause dementia, 1006 cases of AD, and 490 cases of VD were identified, with mean ± SD follow-up of 8 ± 1.1 y. Each additional 25 g/day intake of processed meat was associated with increased risks of incident all-cause dementia (HR: 1.44; 95% CI: 1.24, 1.67; P-trend < 0.001) and AD (HR: 1.52; 95% CI: 1.18, 1.96; P-trend = 0.001). In contrast, a 50-g/d increment in unprocessed red meat intake was associated with reduced risks of all-cause dementia (HR: 0.81; 95% CI: 0.69, 0.95; P-trend = 0.011) and AD (HR: 0.70; 95% CI: 0.53, 0.92; P-trend = 0.009). The linear trend was not significant for unprocessed poultry and total meat. Regarding incident VD, there were no statistically significant linear trends identified, although for processed meat, higher consumption categories were associated with increased risks. The APOE ε4 allele increased dementia risk by 3 to 6 times but did not modify the associations with diet significantly.

These findings highlight processed-meat consumption as a potential risk factor for incident dementia, independent of the APOE ε4 allele.




Sunday, March 21, 2021

Vitamin D not helpful with COVID

There are a number of drug and supplement treatments that are said to help with COVID.  Vitamin D can now be crossed off the list

Effect of a Single High Dose of Vitamin D3 on Hospital Length of Stay in Patients With Moderate to Severe COVID-19, A Randomized Clinical Trial

Igor H. Murai et al.

Question  What is the effect of a single high dose of vitamin D3 on hospital length of stay among hospitalized patients with moderate to severe coronavirus disease 2019 (COVID-19)?

Findings  In this randomized clinical trial that involved 240 hospitalized patients with moderate to severe COVID-19, a single dose of 200 000 IU of vitamin D3, compared with placebo, did not significantly reduce hospital length of stay (median of 7.0 vs 7.0 days; unadjusted hazard ratio for hospital discharge, 1.07).

Meaning  The study does not support the use of a high dose of vitamin D3 for treatment of moderate to severe COVID-19 in hospitalized patients.


Importance  The efficacy of vitamin D3 supplementation in coronavirus disease 2019 (COVID-19) remains unclear.

Objective  To investigate the effect of a single high dose of vitamin D3 on hospital length of stay in patients with COVID-19.

Design, Setting, and Participants  This was a multicenter, double-blind, randomized, placebo-controlled trial conducted in 2 sites in Sao Paulo, Brazil. The study included 240 hospitalized patients with COVID-19 who were moderately to severely ill at the time of enrollment from June 2, 2020, to August 27, 2020. The final follow-up was on October 7, 2020.

Interventions  Patients were randomly assigned to receive a single oral dose of 200 000 IU of vitamin D3 (n = 120) or placebo (n = 120).

Main Outcomes and Measures  The primary outcome was length of stay, defined as the time from the date of randomization to hospital discharge. Prespecified secondary outcomes included mortality during hospitalization; the number of patients admitted to the intensive care unit; the number of patients who required mechanical ventilation and the duration of mechanical ventilation; and serum levels of 25-hydroxyvitamin D, total calcium, creatinine, and C-reactive protein.

Results  Of 240 randomized patients, 237 were included in the primary analysis (mean [SD] age, 56.2 [14.4] years; 104 [43.9%] women; mean [SD] baseline 25-hydroxyvitamin D level, 20.9 [9.2] ng/mL). Median (interquartile range) length of stay was not significantly different between the vitamin D3 (7.0 [4.0-10.0] days) and placebo groups (7.0 [5.0-13.0] days) (log-rank P = .59; unadjusted hazard ratio for hospital discharge, 1.07 [95% CI, 0.82-1.39]; P = .62). The difference between the vitamin D3 group and the placebo group was not significant for in-hospital mortality (7.6% vs 5.1%; difference, 2.5% [95% CI, –4.1% to 9.2%]; P = .43), admission to the intensive care unit (16.0% vs 21.2%; difference, –5.2% [95% CI, –15.1% to 4.7%]; P = .30), or need for mechanical ventilation (7.6% vs 14.4%; difference, –6.8% [95% CI, –15.1% to 1.2%]; P = .09). Mean serum levels of 25-hydroxyvitamin D significantly increased after a single dose of vitamin D3 vs placebo (44.4 ng/mL vs 19.8 ng/mL; difference, 24.1 ng/mL [95% CI, 19.5-28.7]; P < .001). There were no adverse events, but an episode of vomiting was associated with the intervention.

Conclusions and Relevance  Among hospitalized patients with COVID-19, a single high dose of vitamin D3, compared with placebo, did not significantly reduce hospital length of stay. The findings do not support the use of a high dose of vitamin D3 for treatment of moderate to severe COVID-19.

Sunday, March 14, 2021

Eat as much fish or as little fish as you like. No amount will protect you from heart disease

The journal article:

Associations of Fish Consumption With Risk of Cardiovascular Disease and Mortality Among Individuals With or Without Vascular Disease From 58 Countries

Deepa Mohan et al.

Question  Is there a difference in the association of fish consumption with risk of cardiovascular disease (CVD) or of mortality between individuals with and individuals without vascular disease?

Findings  In this analysis of 4 international cohort studies of 191 558 people from 58 countries on 6 continents, a lower risk of major CVD and total mortality was associated with higher fish intake of at least 175 g (2 servings) weekly among high-risk individuals or patients with vascular disease, but NOT in general populations without vascular disease; a similar pattern of results was observed for sudden cardiac death. Oily fish but not other types of fish were associated with greater benefits.

Meaning  Study findings suggest that fish intake of at least 175 g (2 servings) weekly is associated with lower risk of major CVD and mortality among patients with prior CVD, but not in the general population.


Importance:  Cohort studies report inconsistent associations between fish consumption, a major source of long-chain ω-3 fatty acids, and risk of cardiovascular disease (CVD) and mortality. Whether the associations vary between those with and those without vascular disease is unknown.

Objective:  To examine whether the associations of fish consumption with risk of CVD or of mortality differ between individuals with and individuals without vascular disease.

Design, Setting, and Participants:  This pooled analysis of individual participant data involved 191 558 individuals from 4 cohort studies—147 645 individuals (139 827 without CVD and 7818 with CVD) from 21 countries in the Prospective Urban Rural Epidemiology (PURE) study and 43 413 patients with vascular disease in 3 prospective studies from 40 countries. Adjusted hazard ratios (HRs) were calculated by multilevel Cox regression separately within each study and then pooled using random-effects meta-analysis. This analysis was conducted from January to June 2020.

Exposures:  Fish consumption was recorded using validated food frequency questionnaires. In 1 of the cohorts with vascular disease, a separate qualitative food frequency questionnaire was used to assess intake of individual types of fish.

Main Outcomes and Measures:  Mortality and major CVD events (including myocardial infarction, stroke, congestive heart failure, or sudden death).

Results:  Overall, 191 558 participants with a mean (SD) age of 54.1 (8.0) years (91 666 [47.9%] male) were included in the present analysis. During 9.1 years of follow-up in PURE, compared with little or no fish intake (≤50 g/mo), an intake of 350 g/wk or more was not associated with risk of major CVD (HR, 0.95; 95% CI, 0.86-1.04) or total mortality (HR, 0.96; 0.88-1.05). By contrast, in the 3 cohorts of patients with vascular disease, the HR for risk of major CVD (HR, 0.84; 95% CI, 0.73-0.96) and total mortality (HR, 0.82; 95% CI, 0.74-0.91) was lowest with intakes of at least 175 g/wk (or approximately 2 servings/wk) compared with 50 g/mo or lower, with no further apparent decrease in HR with consumption of 350 g/wk or higher. Fish with higher amounts of ω-3 fatty acids were strongly associated with a lower risk of CVD (HR, 0.94; 95% CI, 0.92-0.97 per 5-g increment of intake), whereas other fish were neutral (collected in 1 cohort of patients with vascular disease). The association between fish intake and each outcome varied by CVD status, with a lower risk found among patients with vascular disease but not in general populations (for major CVD, I2 = 82.6 [P = .02]; for death, I2 = 90.8 [P = .001]).

Conclusions and Relevance:  Findings of this pooled analysis of 4 cohort studies indicated that a minimal fish intake of 175 g (approximately 2 servings) weekly is associated with lower risk of major CVD and mortality among patients with prior CVD but not in general populations. The consumption of fish (especially oily fish) should be evaluated in randomized trials of clinical outcomes among people with vascular disease.

Saturday, March 06, 2021

An apple a day really DOES keep the doctor away! Chemicals in the fruit can boost brain function and reduce your risk of Alzheimer's disease, scientists say

<i>In mice</i>

Natural compounds found in apples can reduce the risk of developing Alzheimer's and other forms of dementia, scientists say.

High concentrations of compounds in apples and other plants, known as phytonutrients, stimulate the creation of neurons, in a process called neurogenesis.

Neurons are highly excitable cell that transmits information to parts of the body via electrical signals – and they boost our learning and memory abilities.  

Two compounds – quercetin in apple peel and dihydroxybezoic acid (DHBA) in apple flesh – generated neurons in the brains of mice in lab tests.

Interestingly, apple juice was not found to significantly contribute to neurogenesis, suggesting the benefits apply to eating the whole apple and not just a glass of juice.

The research was led by experts from the German Centre for Neurodegenerative Diseases (DZNE) in Bonn, Germany.  

'An apple a day keeps the doctor away – there may be some truth to this aphorism,' they say in their paper, published in Stem Cell Reports.

'In this study we demonstrate that apples contain pro-neurogenic compounds in both their peel and their flesh.'

The study showed that lab-grown stem cells from adult mouse brains generated more neurons and were protected from cell death when quercetin or DHBA were added to the cultures.  

Subsequent tests in mice showed that in distinct structures of the adult brain associated with learning and memory, stem cells multiplied and generated more neurons when the mice were given high doses of quercetin or DHBA.

The effects on neurogenesis were comparable to effects seen after physical exercise, which is a known stimulus for neurogenesis.

This suggested natural compounds in fruits, not just quercetin and DHBA but potentially others, may act in synergy to promote neurogenesis and brain function when given in high concentrations.

Given the wide consumption of apple juice, researchers also examined whether consumption of whole apple juice concentrate affected neurogenesis in the lab mice.

To eliminate any possible effect of the increased caloric intake of fruit sugar, a group of mice received a portion of sugar water with equal calories, as well as a control group that received normal drinking water.

Three weeks after being given apple juice, mice were trained to locate a submerged escape platform in a circular pool, known as the Morris water maze task.

This was designed to detect the contribution of adult-generated neurons to the overall performance in spatial navigation and cognitive flexibility.

However, apple juice supplementation was found to have no effect on adult neurogenesis or learning.   

'Given that the quercetin concentration in apple juice is very low (below 2 mg/litre) ... we conclude that this is likely an insufficient concentration of active phytochemical to modulate neurogenesis,' the team say.  

Researchers did point out that a 2010 study showed the consumption of apple juice improved behavioural symptoms in human patients with Alzheimer's.

Flavonoids, the abundant phytonutrients found in fruits and vegetables, can modulate molecular signalling pathways that influence cognitive abilities.

Dietary flavonoids are naturally occurring in fruit, vegetables, chocolate, and beverages like red wine and tea.

Although it's known an apple a day keeps the doctor away, two daily apples might be better to reduce the risk of suffering a heart attack or stroke, experts found in 2019.

When 40 people with slightly high cholesterol ate two large apples a day for eight weeks, it lowered their levels of 'bad' cholesterol by almost four per cent.

Two apples a day could help to reduce their risk of a stroke or heart attack, which can be caused by cholesterol hardening the arteries.

'It seems the old adage of an apple day was nearly right,' said study author Professor Julie Lovegrove, from the Hugh Sinclair Unit of Human Nutrition at the University of Reading, at the time.

'We believe the fibre and polyphenols in apples are important, and apples are a popular fruit among all ages, which are easy to eat and make great snack foods.'

Saturday, February 27, 2021

Street lamps can increase your risk of CANCER: People who live near artificial neon lights are up to 55% more likely to be diagnosed with thyroid cancer

The journal article:

Good that the authors made no causal inferences. It is for starters a study of retired people so should not be generalized to other age cohorts.  There was also no way they could control for income so we may be looking at a poverty effect only

The study also used extreme quintiles, which suggests that there was no overall effect in the data

One also wonders why thyroid cancer was singled out.  Was it the only one showing any effect?  Very bad methodology if so

Living in an area with high levels of outdoor artificial light can increase the chance of developing thyroid cancer - with neon lights increasing the risk by 55 per cent, study shows.

Researchers from the University of Texas Health Science Center looked for a link between people developing thyroid cancer and levels of artificial outdoor light.

They looked at data from a cohort of 464,371 participants followed for about 13 years as part of the NIH-AARP diet and health study - then analysed satellite imagery to estimate levels of light in the areas where the people involved in the study lived.   

They found that those in areas with the highest level of night light pollution had a 55 per cent higher risk of developing thyroid cancer than those in low-light areas. 

They believe that one reason for the link is that light at night suppresses melatonin, a modulator of oestrogen activity - which may have an anti-tumour effect.  

Light pollution, also known as photopollution, is the presence of anthropogenic light in the night environment. 

Artificial light that’s excessive, obtrusive and ultimately wasteful is called light pollution, and it directly influences how bright our night skies appear. 

With more than nine million streetlamps and 27 million offices, factories, warehouses and homes in the UK, the quantity of light we cast into the sky is vast. 

While some light escapes into space, the rest is scattered by molecules in the atmosphere making it difficult to see the stars against the night sky. What you see instead is ‘Skyglow’. 

Over the past century, night scapes - particularly in cities - have changed dramatically due to the rapid growth of electric light, study authors said.

Studies have also reported an association between higher satellite-measured levels of nighttime light and elevated breast cancer risk.  

As some breast cancers could share a common link to thyroid cancer, lead author Qian Xiao and colleagues decided to hunt for an association between night light and later development of thyroid cancer.

They used the NIH-AARP Diet and Health Study - featuring data on hundreds of thousands of people aged 50 to 71 - recorded in 1995 and 1996.

Xiao then looked at satellite imagery of each of their homes to determine whether those living in high-light areas were more likely to develop thyroid cancer.

The team then examined state cancer registry databases to identify thyroid cancer diagnoses through 2011 and found 856 cases among the 464,371 volunteers.

'When compared with the lowest quintile of light at night, the highest quintile was associated with a 55 percent higher risk of developing thyroid cancer,' said Xiao.

'The association was primarily driven by the most common form of thyroid cancer, called papillary thyroid cancer, and it was stronger in women than in men,' he found.

In women, the association was stronger for localised cancer with no sign of spread to other parts of the body, while in men the association was stronger for more advanced stages of cancer, the team discovered. 

The association appeared to be similar for different tumour sizes and across participants with different demographic characteristics and body mass index. 

The researchers noted that additional studies are needed to confirm their findings. 

If confirmed, it will be important to understand the mechanisms underlying the relationship between light at night and thyroid cancer, Xiao said. 

The scientists noted that light at night suppresses melatonin, a modulator of oestrogen activity that may have important anti-tumour effects. 

Also, light at night may lead to disruption of the body's internal clock (or circadian rhythms), which is a risk factor for various types of cancer.

'As an observational study, our study is not designed to establish causality,' said Xiao, adding 'we don't know if higher levels of outdoor light at night lead to an elevated risk for thyroid cancer.' 

'However, given the well-established evidence supporting a role of light exposure at night and circadian disruption, we hope our study will motivate researchers to further examine the relationship between light at night and cancer, ' said Dr. Xiao. 

'Recently, there have been efforts in some cities to reduce light pollution, and we believe future studies should evaluate if and to what degree such efforts impact human health.'

The findings have been published in the journal Cancer.

Wednesday, February 24, 2021

Ditch the white bread! Eating more than seven portions of refined grains a day can increase your risk of early DEATH by 27%

Journal reference:

This study is nonsense on stilts.  What they actually found was that people in countries where they ate little white bread had fewer heart attacks and related problems. So Chinese people live longer than Americans?  Problem:  They don't.  Americans live a couple of years longer.

So what is  going on?  All the effects were tiny and hence likely to be unstable.  Most of the hazard ratios were just above 1.00 whereas a figure of over 2.00 would normally be needed to support policy prescriptions.  So ignoring the study would be wisest

From a delicious piece of white toast to a bowl of pasta, many of us enjoy consuming refined grains.

But a new study has warned that eating too many of them can have serious consequences, including an increased risk of heart disease, stroke and even early death.

Refined carbohydrates, including croissants, white bread and pasta, have had the high fibre parts removed, meaning they get broken down faster and lead to rapid spikes in blood sugar levels when consumed.

Based on the findings, the researchers are urging people to consider replacing their favourite refined grains with wholegrain options, such as brown rice and barley.

The Wholegrains Council explained: 'White flour and white rice are refined grains, for instance, because both have had their bran and germ removed, leaving only the endosperm. 

'Refining a grain removes about a quarter of the protein in a grain, and half to two thirds or more of a score of nutrients, leaving the grain a mere shadow of its original self.'

In the study, researchers from Simon Fraser University looked at the effects of following a diet high in refined grains.

Their analysis included 137,130 participants from 21 countries, including those from low-, middle- and high-income areas.

Grains in the participants' diets were categorised into three groups – refined grains, whole grains and white rice.

Refined grains included goods made with white flour, including white bread, pasta, noodles, breakfast cereals, crackers and baked goods.

Meanwhile, whole grains included any foods made with wholegrain flours, or intact or cracked whole grains.

The analysis revealed that participants who consumed more than seven servings of refined grains per day were at a 27 per cent greater risk for early death.

This group was also found to be at a 33 per cent higher risk for heart disease, and a 47 per cent higher risk for stroke.

Professor Scott Lear, who led the study, said: 'This study re-affirms previous work indicating a healthy diet includes limiting overly processed and refined foods.'

Sunday, February 14, 2021

Step away from the omelette: Eating just half an egg a day increases your risk of DEATH by 7%

This finding is from a very carefully analysed study with good controls.  It even allowed for household income, which is unusual.

The analyses were however of quintiles, with most comparisons being with the lowest quintile.  Quintile analyses are always suspicious.  They suggest that there was no overall significance in the data. What would a simple correlation between egg consumption and lifespan show after partialling out confounders?  We are not told.  My guess that it would be so low as to be of no concern.  Complex statistics can conceal as much as they reveal

Boiled, fried, scrambled or in an omelette, whole eggs pose a threat to health and eating more of them increases your risk of death, a study claims.

Researchers found eating just half a whole egg — which includes the yolk and the white — increases the likelihood of dying by seven per cent.

Risk of death increases by a further seven per cent for every half an egg on top of this, so a person eating one egg a day has at 14 per cent greater chance of death than someone who avoids the food.

Chinese researchers who led the study believe high fat and cholesterol levels in eggs are to blame.

They warned that people should use only the whites or switch to healthier egg substitutes, which lower the risk of dying.

Substituting an equivalent amount of nuts or legumes for half a whole egg reduced death rates by up to a third. Poultry, dish or dairy products had a similar effect.

Researchers gave a questionnaire to more than half a million Americans  between 1995 and 1996 and followed them for 16 years.

Data from this study, published in PLOS ONE, shows 129,328 people who filled out the original form died.

Co-author Professor Yu Zhang, of Zhejiang University said: 'In this study, intakes of eggs and cholesterol were associated with higher all cause, cardiovascular disease and cancer mortality.'

Professor Zhang said: 'The increased mortality associated with egg consumption was largely influenced by cholesterol intake.'

The link between eggs and health has been debated for years. They have long been thought of as a healthy dietary addition.

They are included in many country's national dietary guidelines. But the food, specifically the yolk, is high in cholesterol - which is known to be harmful.

Researchers asked the participants about how much cholesterol they had as part of their diet on top of eggs and found an additional 300 milligrams of cholesterol a day were 19 per cent more likely to die over the next 16 years.

Deaths specifically from cancer and cardiovascular disease rose by 24 and 16 per cent, respectively.

There is no cholesterol in the white of a medium-large chicken egg, and around 186 mg in the yolk.

'Our findings suggest limiting cholesterol intake and replacing whole eggs with egg whites/substitutes or other alternative protein sources for facilitating cardiovascular health and long-term survival,' the authors say.  

The NHS says eggs are a good choice as part of a healthy, balanced diet. As well as being a source of protein, they also contain vitamins and minerals.

It says there is no recommended limit on how many eggs people should eat, but advises cooking them without adding salt or fat. Frying can increase their fat content by around 50 per cent.

'This research makes it possible to look at relationships between what people ate in the past and whether that could be related to disease or death in the future,' says Dr Ada Garcia, a senior lecturer in Public Health Nutrition at the University of Glasgow who was not involved in the research, saus.

'The authors took a very careful approach to analysed the data and consider many aspects that could distort the findings.

'The study concluded that retired people who ate more whole eggs seven per cent higher risk to develop cardiovascular disease. The highest consumption of eggs was about half a small egg in 2000 Kcal per day.'

However, she criticises the methodology and conclusions of the Chinese team, saying: 'Being overweight or obese, smoking or consuming too much alcohol and not being physically active are much more important factors to consider for prevention of chronic diseases and related death.

'The conclusions of this study are overblown. Blaming eggs alone for an increased risk of cardiovascular disease is a simplistic and reductionist approach to the concept of diet and disease prevention.'

Saturday, February 06, 2021

Association Between County-Level Change in Economic Prosperity and Change in Cardiovascular Mortality Among Middle-aged US Adults

This is not a particuarly strong study methodologically but  I am putting it up as an all-too-rare study where the effect of poverty is examined  -- with the expected results

Sameed Ahmed M. Khatana et al.


Importance:  After a decline in cardiovascular mortality for nonelderly US adults, recent stagnation has occurred alongside rising income inequality. Whether this is associated with underlying economic trends is unclear.

Objective:  To assess the association between changes in economic prosperity and trends in cardiovascular mortality in middle-aged US adults.

Design, Setting, and Participants:  Retrospective analysis of the association between change in 7 markers of economic prosperity in 3123 US counties and county-level cardiovascular mortality among 40- to 64-year-old adults (102 660 852 individuals in 2010).

Exposures:  Mean rank for change in 7 markers of economic prosperity between 2 time periods (baseline: 2007-2011 and follow-up: 2012-2016). A higher mean rank indicates a greater relative increase or lower relative decrease in prosperity (range, 5 to 92; mean [SD], 50 [14]).

Main Outcomes and Measures:  Mean annual percentage change (APC) in age-adjusted cardiovascular mortality rates. Generalized linear mixed-effects models were used to estimate the additional APC associated with a change in prosperity.

Results:  Among 102 660 852 residents aged 40 to 64 years living in these counties in 2010 (51% women), 979 228 cardiovascular deaths occurred between 2010 and 2017. Age-adjusted cardiovascular mortality rates did not change significantly between 2010 and 2017 in counties in the lowest tertile for change in economic prosperity (mean [SD], 114.1 [47.9] to 116.1 [52.7] deaths per 100 000 individuals; APC, 0.2% [95% CI, −0.3% to 0.7%]). Mortality decreased significantly in the intermediate tertile (mean [SD], 104.7 [38.8] to 101.9 [41.5] deaths per 100 000 individuals; APC, −0.4% [95% CI, −0.8% to −0.1%]) and highest tertile for change in prosperity (100.0 [37.9] to 95.1 [39.1] deaths per 100 000 individuals; APC, −0.5% [95% CI, −0.9% to −0.1%]). After accounting for baseline prosperity and demographic and health care–related variables, a 10-point higher mean rank for change in economic prosperity was associated with 0.4% (95% CI, 0.2% to 0.6%) additional decrease in mortality per year.

Conclusions and Relevance:  In this retrospective study of US county-level mortality data from 2010 to 2017, a relative increase in county-level economic prosperity was significantly associated with a small relative decrease in cardiovascular mortality among middle-aged adults. Individual-level inferences are limited by the ecological nature of the study.

Saturday, January 30, 2021

Being fat can PROTECT you from certain diseases: People who eat foods high in saturated fats including bacon and cheese are less likely to develop acute pancreatitis

We're regularly told to minimise the amount of saturated fats we consume, but a new study suggests that eating foods rich in these fats could actually offer some protection against certain diseases.

Researchers have revealed that eating foods rich in saturated fats, including cakes, bacon and cheese, may reduce your risk of acute pancreatitis.

The US team analysed data from people in 11 countries on how different fats consumed by different nations – either unsaturated or saturated – are linked with the serious condition, where the pancreas becomes inflamed.  

Saturated fat is found in butter, lard, fatty meats and cheese – foods heavily consumed in western societies – while unsaturated fats are mostly found in oils from plants and fish and are prevalent in Asian and some South American diets.

The scientists found that high levels of unsaturated fat stored around the abdominal organs generates more of a certain type of molecule that triggers cell injury, inflammation and even organ failure.   

Official advice from the NHS is to swap saturated fats for unsaturated fats in our diet to reduce the risk of heart disease.

While this study does not challenge this advice, it does suggest obesity can sometimes protect patients during certain types of acute illnesses.

This 'obesity paradox' has already been controversially suggested in previous studies, but not without backlash from other experts.

Foods high in saturated fat include:

Fatty red meats like pork and beef
Butter and products made of butter, including pastries and pies
Cakes and biscuits
Cheese, cream and ice cream

Unsaturated fats are those found in:

Nuts and seeds
Fish such as salmon and mackerel
Vegetable oils, including olive oil
Peanut butter

'Here, we find that a higher proportion of dietary unsaturated fat can worsen AP [acute pancreatitis] outcomes at a lower adiposity than seen in individuals with a higher proportion of saturated fats in their diet,' say the researchers in their paper, published today in Science Advances.

Draft guidelines from the World Health Organisation recommend people get fewer than 10 per cent of their daily calories (150kcal-250kcal) from saturated fat and instead try to replace them with unsaturated.

Previous reports have observed that obesity appears to protect patients with acute medical issues such as burns, trauma and cardiovascular surgery.  

'Obesity sometimes seems protective in disease,' say the study authors, who are from the Mayo Clinic in Arizona and the Washington University School of Medicine in Missouri.

'This obesity paradox is predominantly described in reports from the Western Hemisphere during acute illnesses.'

However, the impact of fat composition on disease severity has remained unclear.

To better understand 'the obesity paradox', researchers assessed how the type of fats populations consume influence body fat composition and correlate with acute pancreatitis severity.

The team used 20 clinical reports from 11 countries that associated pancreatitis severity with a cutoff body mass index (BMI) of 30 – the point at which someone is officially classified as obese.

They also used seven clinical reports with a cutoff BMI of 25, and dietary fat data from the Food and Agriculture Organisation.

The researchers found a moderate correlation between the percentage of patients with severe acute pancreatitis and their unsaturated fat intake.

But they also observed that a severe form of this disease occurred in individuals with lower BMIs in countries that consumed food with fewer saturated fatty acids.

According to the team, visceral fat (stored around the abdominal organs) with a high unsaturated fat content leads to the generation of more non-esterified fatty acids (NEFAs).

These NEFAs trigger cell injury, systemic inflammation, and organ failure even in individuals with comparatively low body mass indexes (BMIs).

In contrast, visceral fat with a higher saturated fat content interferes with the production of these fatty acids, resulting in milder pancreatitis.

Researchers then conducted further experiments with mice in the lab.  

To test how fat composition affects pancreatitis outcomes, researchers fed mice either a diet enriched with linoleic acid (an unsaturated fatty acid) or palmitic acid (a saturated fatty acid).

When the researchers induced pancreatitis in the mice, only 10 per cent of those on the linoleic acid diet survived after three days.

This compared with 90 per cent of those on the palmitic acid diet.

By comparing the mice’s fat pads and fatty acid serum levels, the researchers found that saturated fats do not interact favourably with the enzyme pancreatic triglyceride lipase.

This leads to lower production of damaging long-chain NEFAs.  

'Therefore, visceral triglyceride saturation reduces the ensuing lipotoxicity despite higher adiposity, thus explaining the obesity paradox,' the researchers say.

The authors note that other factors they did not study, such as sex, genetic background, and the presence of other diseases, may also contribute to severe acute pancreatitis rates in humans.

In 2019, a team of scientists challenged the World Health Organisation's recommendation for people to cut down on saturated fats.

In their article published in the British Medical Journal, they argued that avoiding saturated fats entirely instead of considering the more general health impact of foods may mean important nutrients are missed.

Eggs, dark chocolate, meat and cheese, for example, are high in saturated but also contain a lot of vital nutrients and vitamins.

Researchers criticised the World Health Organisation for recommending that people cut down on saturated fats instead of being more specific.

In their report they said: 'Scientific and policy missteps may have led to many unnecessary deaths globally, and lessons should be learned.'

Saturday, January 23, 2021

Effect of Vitamin B12 Injection on the Vocal Performance of Professional Singers

Hagit Shoffel-Havakuk et al.


Importance  One-third of singers and vocal professionals report experiencing a benefit from empirical vitamin B12 injections for improvement of mild singing-related symptoms (eg, reduced stamina, vocal fatigue, and effort). However, there is no objective evidence to support or refute these claims.

Objective  To assess the presence and magnitude of the effect of empirical vitamin B12 injection on the vocal performance of singers.

Design, Setting, and Participants  A randomized, double-blind, placebo-controlled, crossover trial was conducted from November 7, 2017, to November 30, 2018, at an academic voice center among 20 active adult singers without dysphonia but with mild vocal symptoms. Individuals with known or suspected vitamin B12 deficiency or active or recent vitamin B12 treatment were excluded. Analysis was on a per-protocol basis.

Interventions  Participants were randomized to receive an intramuscular (deltoid) injection of either vitamin B12 (1000 μg of cyanocobalmin) or placebo (0.9% sodium chloride). After a washout period of at least 4 weeks, participants were crossed over to receive the opposite injection. Both the investigators and participants were blinded to the order of injections.

Main Outcomes and Measures  The participants completed the Singing Voice Handicap Index–10 (SVHI-10), the Voice Fatigue Index (VFI), and the Evaluation of the Ability to Sing Easily (EASE) before each injection and at intervals of 1 hour, 3 hours, 24 hours, 72 hours, and 1 week after the injection. The primary time point assessment was 72 hours after injection, and the SVHI-10 score was the primary outcome measure.

Results  Twenty singers (10 men; median age, 22 years [range, 19-42 years]) were enrolled. The improvements after either placebo or vitamin B12 injections were comparable to each other. At 72 hours after the vitamin B12 injection, the median difference in the SVHI-10 score was 1 (95% CI, –1 to 2) compared with 3 (95% CI, 0-4) after placebo. The median difference between differences at 72 hours between placebo and vitamin B12 injections were 1.5 (95% CI, –2 to 5) for the SVHI-10, 1 (95% CI, –9 to 9) for the VFI, and –1 (95% CI, –3 to 2) for the EASE. The improvements after both injections failed to reach the estimated minimal clinically important difference. Of the 20 participants, 4 (20%) reached the estimated minimal clinically important difference in their SVHI-10 score after 72 hours for both vitamin B12 and placebo injections.

Conclusions and Relevance  This randomized, double-blind, placebo-controlled, crossover trial found that after empirical vitamin B12 injection to improve mild voice-related symptoms, the improvement in self-reported voice measures in singers shows no meaningful difference compared with placebo.

Saturday, January 16, 2021

This'll shake you... too LITTLE salt can be bad for us

Health chiefs constantly tell us to slash our salt intake, but new research suggests that having too little also carries health risks.

Doctors at the Royal Free Hospital in London found that too little salt in the body, over a long period of time, weakens the immune system, increasing the risk of infections.

Patients with Gitelman syndrome and Bartter syndrome, which cause an excessive loss of salt through the kidneys, were more likely than others to suffer from recurrent fungal and urinary infections.

The authors of the study, published in the medical journal Nature Communications, explain that a lack of salt halts the production of a type of white blood cell called interleukin 17, which detects and destroys infections.

Sunday, January 10, 2021

Is eating fish healthy?

We know of fish as a healthy food, but pregnant women are told to limit consumption. Do the health benefits of eating fish outweigh the risks, particularly as stocks grow more depleted?

In recent decades, one of the biggest concerns about fish has been its potentially harmful levels of pollutants and metals.

One concern is polychlorinated biphenyls (PCBs). Although they were banned by the 1980s, these industrial chemicals were used worldwide in huge quantities and still linger in our soil and our water. They’ve been associated with a range of negative health effects on everything from the immune system to the brain. While PCBs are present in everything from dairy products to drinking water, the highest levels tend to be found in fish.

The solution for limiting your intake of PCBs from fish may be counterintuitive, says Johnathan Napier, science director at Rothamsted Research in Hertfordshire, England.

“The possible problem of the accumulation of toxic compounds is likely to be more of concern for wild species that are caught for direct human consumption,” he says. Because the marine-derived ingredients that farmed fish are fed are cleaned or scrubbed to remove toxins, farmed fish is often safer than wild.

That isn't always the case, however, and PCB content also fluctuates seasonally.

While they are generally viewed as better for our health and the environment, large-scale aquaculture has its own problems, such as polluting the oceans with waste and becoming breeding grounds for diseases that can spill over into the wild.

Another worry is mercury, a neurotoxin that could pass through the placenta and affect child development. There are numerous links between mercury ingestion and cancer, diabetes and heart disease. While mercury can be found in other foods, such as vegetables, one study found that 78% of participants' mercury intake came from fish and seafood.

In fish, mercury levels are high enough for the US Food and Drug Administration (FDA) to recommend that pregnant people limit their intake of some popular fish, including halibut and tuna, to one serving a week.

But concerns around the accumulation of heavy metals in fish has been overexaggerated, says Napier. He says it’s only a problem when it comes to species that live a particularly long time – like swordfish, which can live for 15 to 20 years. Swordfish has a mercury concentration of 0.995 PPM, while salmon, which lives on average for four to five years, has around 0.014. While research is still ongoing, the US's Environmental Protection Agency currently states that for pregnant women, the highest allowable average mercury concentration per serving, if eating one serving a week, is 0.46 PPM.

But the issue is set to worsen, as there’s evidence to suggest that levels of mercury found in the ocean may rise as the planet warms. Research has found that as Arctic permafrost melts, it releases mercury that was trapped in frozen ground into waterways.

While mercury poses a small risk, Napier says there stands to be much more to gain from fish – particularly marine omega 3.

Consumption of oily fish, including salmon, tuna, sardines and mackerel, has been linked to a lower risk of cardiovascular disease, thanks to its marine omega 3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

“Both EPA and DHA play a plethora of important roles in human metabolism, but we can’t make them very effectively in our bodies, so it’s really important to have them as part of our diet,” Napier says.

“Population data looking at the effects of marine omega 3 on health is consistent and strong, and shows that people with a higher intake of EPA and DHA have a lower risk of developing common diseases, particularly heart disease, and dying from them,” says Philip Calder, head of human development and health at England’s University of Southampton.

One way to avoid potential damage from mercury exposure while still getting omega 3 is to take fish oil supplements. However, research recently carried out on behalf of the World Health Organization (WHO) looking at omega-3 supplements across range of health outcomes found they don’t have the same effect as eating oily fish.

“Our findings suggest a very small beneficial effect [in terms of lowering the risk] of dying of coronary heart disease,” adds Lee Hooper, a reader at the University East Anglia and one of the WHO study’s researchers.  

Around 334 people would have to take omega-3 supplements for four or five years for one person not to die from coronary heart disease, she says.

But there’s an issue with population studies like Hooper’s. While some oily fish, such as sardines, aren’t relatively expensive, fish is generally associated with a more expensive diet. It’s widely accepted that socioeconomic status affects health outcomes – so it’s possible that families who eat more fish also have higher incomes and healthier lifestyles in general.

Normally, researchers will take into account such confounding factors, Calder says, but they might not think of everything that could skew a study’s results. The WHO report was a review of 79 studies, which each will have differed in how they controlled for participants' socioeconomic status.

But intervention trials, where people are randomly assigned to a group and an intervention such as taking omega-3 supplements is measured, have problems, too. Analysing potential health impacts of EPA and DHA deficiency, for example, is difficult, Calder says, because people start trials with varying levels of omega-3 in their systems.

In addition, research shows that fish might impact everyone’s health to varying degrees, depending on how well they can convert precursor forms of EPA and DHA. This difference could come down to a person’s overall diet and lifestyle, Calder says, but genetic differences could also play a role.

Another reason the health benefits of fish may vary is because of how fish are raised.

Marine ecosystems are full of omega-3: little fish eat marine plankton, and get eaten by bigger fish, and the whole food chain passes on omega-3 to humans. But the system is different for farmed fish, which is what most of us eat. “In a fish farm, it’s just thousands of fish in a cage. They eat what they’re given by the fish farmer,” Napier says.

As they would in the wild, farmed fish normally are fed smaller fish species. In the wild, however, fish would eat a variety of smaller fish. In farms, fish are often fed fish meal made from Peruvian anchovies.

But these anchovies are already being fished at the maximum level at which the industry can be sustained, Napier says – even as global aquaculture is expected to keep growing. According to the UN’s Food and Agricultural Organization, growing demand for fish oil supplements means that the fish oil contained in the fish meal fed to farmed fish is diminishing. That means the amount of omega-3 in the fish we consume is declining, too.

“There are finite levels of omega fish oils that come out of the ocean each year – that’s all we’ve got,” he says. “If aquaculture is expanding but the most important input you need to put into people’s diets, the fish oil, is completely static, you’re diluting how much is fed to the fish.”

Research from 2016 found that levels of EPA and DHA in farmed salmon decreased by half over a decade. Even so farmed salmon still has more omega-3 than wild salmon, Napier says.

“Wild salmon swims back forth across the Atlantic; it’s a lean animal. It’s not laying down fat because it’s burning everything it consumes,” he says.

Still, because there isn’t robust research suggesting major health inadequacies for people who don’t eat fish, Calder says it’s difficult to definitively say that fish is essential to overall human health. However, he adds, it is clear that omega-3 promotes health and reduces the risk of disease.

But getting to the bottom of how healthy fish really is may be a moot point after long. “Since fish isn’t a sustainable food source, research now will probably focus on solutions to that – such as how to grow algae and harvest omega-3 oil, instead of more studies into fish,” Calder says.

Individuals can help by choosing the most sustainable fish species available. Guides like the one by the Marine Conservation Society show which fish are the best, with 50 of the 133 species listed coming up as mostly sustainable, “good” choices – including, fortunately, popular favourites like farmed salmon, prawns, cod, mackerel, mussels, oysters and farmed halibut.