Wednesday, September 05, 2012

Stanford Scientists Cast Doubt on Advantages of Organic Meat and Produce

The NYT below takes a very cautious approach to the findings and for once I agree with them.  Meta-analyses are sometimes just GIGO but, more importantly, what is termed organic is one huge fudge.  There are standards but very little enforcement.  You mainly just have the word of the grower that something is organic.  Still, it is clear that any health advantage of anything organic has yet to be demonstrated in any kind of scientific way.  Health nuts mostly seem to rely on intuition or an interpretation of some personal experience rather than science

Stanford University scientists have weighed in on the “maybe not” side of the debate after an extensive examination of four decades of research comparing organic and conventional foods.

They concluded that fruits and vegetables labeled organic were, on average, no more nutritious than their conventional counterparts, which tend to be far less expensive. Nor were they any less likely to be contaminated by dangerous bacteria like E. coli.

The researchers also found no obvious health advantages to organic meats.

Conventional fruits and vegetables did have more pesticide residue, but the levels were almost always under the allowed safety limits, the scientists said. The Environmental Protection Agency sets the limits at levels that it says do not harm humans.

“When we began this project, we thought that there would likely be some findings that would support the superiority of organics over conventional food,” said Dr. Dena Bravata, a senior affiliate with Stanford’s Center for Health Policy and the senior author of the paper, which appears in Tuesday’s issue of the Annals of Internal Medicine. “I think we were definitely surprised.”

The conclusions will almost certainly fuel the debate over whether organic foods are a smart choice for healthier living or a marketing tool that gulls people into overpaying. The production of organic food is governed by a raft of regulations that generally prohibit the use of synthetic pesticides, hormones and additives.

The organic produce market in the United States has grown quickly, up 12 percent last year, to $12.4 billion, compared with 2010, according to the Organic Trade Association. Organic meat has a smaller share of the American market, at $538 million last year, the trade group said.

The findings seem unlikely to sway many fans of organic food. Advocates for organic farming said the Stanford researchers failed to appreciate the differences they did find between the two types of food — differences that validated the reasons people usually cite for buying organic. Organic produce, as expected, was much less likely to retain traces of pesticides.

Organic chicken and pork were less likely to be contaminated by antibiotic-resistant bacteria.

“Those are the big motivators for the organic consumer,” said Christine Bushway, the executive director of the trade association.

The study also found that organic milk contained more omega-3 fatty acids, which are considered beneficial for the heart.

“We feel organic food is living up to its promise,” said Sonya Lunder, a senior analyst with the Environmental Working Group, which publishes lists highlighting the fruits and vegetables with the lowest and highest amounts of pesticide residues.

The Stanford researchers said that by providing an objective review of the current science of organic foods, their goal was to allow people to make informed choices.

In the study — known as a meta-analysis, in which previous findings are aggregated but no new laboratory work is conducted — researchers combined data from 237 studies, examining a wide variety of fruits, vegetables and meats. For four years, they performed statistical analyses looking for signs of health benefits from adding organic foods to the diet.

The researchers did not use any outside financing for their research. “I really wanted us to have no perception of bias,” Dr. Bravata said.

One finding of the study was that organic produce, over all, contained higher levels of phosphorus than conventional produce. But because almost everyone gets adequate phosphorus from a wide variety of foods, they said, the higher levels in the organic produce is unlikely to confer any health benefit.

The organic produce also contained more compounds known as phenols, believed to help prevent cancer, than conventional produce. While the difference was statistically significant, the size of the difference varied widely from study to study, and the data was based on the testing of small numbers of samples. “I interpret that result with caution,” Dr. Bravata said.

Other variables, like ripeness, had a greater influence on nutrient content. Thus, a lush peach grown with the use of pesticides could easily contain more vitamins than an unripe organic one.

The study’s conclusions about pesticides did seem likely to please organic food customers. Over all, the Stanford researchers concluded that 38 percent of conventional produce tested in the studies contained detectable residues, compared with 7 percent for the organic produce. (Even produce grown organically can be tainted by pesticides wafting over from a neighboring field or during processing and transport.) They also noted a couple of studies that showed that children who ate organic produce had fewer pesticide fragments in their urine.

The scientists sidestepped the debate over whether the current limits are too high. “Some of my patients take solace in knowing that the pesticide levels are below safety thresholds,” Dr. Bravata said. “Others have questioned whether these standards are sufficiently rigorous.”

Similarly, organic meat contained considerably lower levels of antibiotic-resistant bacteria than conventionally raised animals did, but bacteria, antibiotic-resistant or otherwise, would be killed during cooking.

Dr. Bravata agreed that people bought organic food for a variety of reasons — concerns about the effects of pesticides on young children, the environmental impact of large-scale conventional farming and the potential public health threat if antibiotic-resistant bacterial genes jumped to human pathogens. “Those are perfectly valid,” she said.

The analysis also did not take factors like taste into account.

But if the choice were based mainly on the hope that organic foods would provide more nutrients, “I would say there is not robust evidence to choose one or the other,” Dr. Bravata said.

The argument that organic produce is more nutritious “has never been major driver” in why people choose to pay more, said Ms. Lunder, the Environmental Working Group analyst.

Rather, the motivation is to reduce exposure to pesticides, especially for pregnant women and their young children. Organic food advocates point to, for example, three studies published last year, by scientists at Columbia University, the University of California, Berkeley, and Mount Sinai Hospital in Manhattan. The studies identified pregnant women exposed to higher amounts of pesticides known as organophosphates and then followed their children for years. In elementary school, those children had, on average, I.Q.’s several points lower than those of their peers.

Critics of the Stanford study also argue that lumping all organic foods into one analysis misses the greater benefits of certain foods. For example, a 2010 study by scientists at Washington State University did find that organic strawberries contained more vitamin C than conventional ones. [Big deal!  Lots of things have vitamin C.  Eat an orange if in doubt]

Dr. Crystal Smith-Spangler, another member of the Stanford team, said that the strawberry study was erroneously left out but that she doubted it would have changed the conclusions when combined with 31 other studies that also measured vitamin C.


How taking exercise can trigger a deadly food allergy

Eating vegetables and taking exercise are the cornerstones of healthy living advice.  But for Traton Steven, these two innocuous sounding activities have a far from positive effect.  In fact, he’s allergic to them.

Traton, 18, is one of half a million Britons who suffer from a condition called food-dependent exercise-induced anaphylaxis (FDEIA), where physical exercise sparks a severe and potentially fatal allergic reaction.

Indeed, it was only because of his father’s quick thinking that Traton survived his first attack at the age of 14.  He was helping out at his parents’ garden centre two hours after eating a meal of cannelloni.

‘I’d always had hay fever and allergies to horses, but I suddenly got what I can only describe as really bad hay fever, terrible stomach ache and, without being too dramatic, a sense of doom,’ says Traton.  ‘I went to wash my hands and change my clothes, which usually helps with my hay fever, but it got worse.’

Traton’s father put him in the car and rushed him to nearby Maidstone hospital.

By the time he arrived, 20 minutes after the reaction had started, the teenager’s face and eyes were so swollen he couldn’t see, his tongue was lolling out and he was having severe breathing problems.

He was suffering from anaphylaxis, a severe allergic reaction where the body’s immune system over-reacts to an allergen, triggering the release of the chemical histamine, which can affect the airways and mucous membranes (lips and eyes) and cardiovascular system.

The hospital administered adrenaline, steroids and oxygen, kept him in overnight and ran tests for peanut allergy, which came back clear.

Puzzled doctors released the teenager with an EpiPen — an adrenaline shot he can administer himself when the next reaction starts — and told him to be cautious.

Over the next three years, Traton had several more severe reactions, but allergy specialists could not explain why.

Finally, he was referred to Dr Stephen Till, a consultant in adult allergy at Guy’s and St Thomas’ NHS Foundation Trust in London, who diagnosed him as having FDEIA, brought on by a substance in green vegetables and salad called lipid-transfer protein.

Around 750,000 Britons are thought to have suffered an anaphylactic reaction — and a food allergy is one of the most common causes.

But in an estimated ten to 20 per cent of people with a food allergy, the reaction is only sparked when they exercise.

It typically occurs two to four hours after ingesting food, but in some people it can be as much as 12 hours later.  Wheat and prawns are the most common culprits, but fruit, vegetables and nuts can also cause anaphylaxis.

The patient may go through life eating the food they are allergic to without any reaction, and it’s only when they exercise afterwards that the anaphylaxis strikes.

‘The exercise involved can be moderate — one patient suffered anaphylaxis when pushing her baby’s pram up a hill — and in many different forms, from labouring on a building site or dancing in a nightclub to taking a walk or going for a run,’ says Dr Till.

But it’s thought that the more the person exerts themselves, the stronger the reaction.

Diagnosis is based on a patient’s history, what they ate and when they ate it before exercise, plus blood tests commonly used to detect food allergies.

‘Classically, anaphylaxis will occur if the patient exercises two hours after eating the food, but sometimes it can be much longer,’ he says.  ‘One patient, a triathlete, reacted to something she had eaten the night before a race.’

Allergy consultants estimate they see one or two patients with FDEIA a month, but all agree the number of undiagnosed sufferers is likely to be much higher.

Why exercise should spark anaphylaxis is unknown, but there are theories that it increases the permeability of the gut, changes the way the blood vessels react to allergens or has an effect on the body’s neuroendocrine cells (specialised nerve cells that produce hormones such as adrenaline).

Heat, alcohol, anxiety and mental stress are also thought to exacerbate the problem.

The first case of FDEIA was recorded in a marathon runner in 1979, who collapsed when he ran after eating prawns.

However, there has been no other research into the condition — due, in part, to the danger of inducing a potentially fatal condition.

But this year, doctors will begin a three-year study, funded by the Food Standards Agency, looking at the effects of exercise on food allergies.

Dr Andrew Clark, a consultant in paediatric allergy at Addenbrooke’s hospital in Cambridge, is leading the study that will involve 100 people with a peanut allergy.  ‘Each will eat peanuts on four occasions and, under strictly controlled conditions, exercise on a static bike,’ he says. The researchers expect exercise to lower the threshold at which patients can tolerate peanuts before suffering a reaction.

They think that even people with a food allergy who do not have full-blown FDEIA, exercise may make reactions worse.

‘We will take blood tests to see if there are changes in the blood vessels, gut or allergy cells during exercise,’ says Dr Clark.

Whatever the causes, once a diagnosis is made, avoiding the food causing the reaction is often all that’s necessary for cure.

Alastair Lockhart, 70, from Oban, avoids wheat after an attack earlier this year.   ‘For many years I would sometimes get “the itches” — hives and red blotches around my mouth — but thought nothing of it, until the day I walked a mile to the nearby village in the sunshine after a meal,’ he says.

‘I started to get itchy, so I stopped at the local shop to buy antihistamine.  'But soon I was shaking and shivering and couldn’t keep still. I felt as if I was losing consciousness.’

Luckily, a builder in the shop spotted the signs of anaphylaxis and called the local GP, who administered adrenaline.

Alastair was referred to Professor Jonathan Brostoff at King’s College London, and was diagnosed with FDEIA with an allergy to wheat.  ‘Working out what foods contain wheat has been tricky — even some whiskies do,’ he says.

As well as food avoidance, patients must have adrenaline with them at all times.  If anaphylaxis strikes, Professor Brostoff advises them to lie down and raise their legs so blood goes back to the heart.

‘Take an antihistamine or adrenaline as soon as possible, call the doctor and, when you are better, ask your GP for a referral to an allergist,’ he says.

Some patients also need to work with a dietitian so they can identify the culprit food.

Since Traton was diagnosed, he avoids greens and salad. He feels healthy and works at the family garden centre part-time. ‘I can eat cauliflower, carrots and red cabbage as well as fruit,’ he says.  ‘Luckily for me, I’m a meat and potatoes person, so I don’t mind.’


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