Saturday, March 17, 2007

The mega-vitamin mega-myth

This study was mentioned here on March 1st but it is discussed at greater length below by Steven Milloy

Another nutrition myth went down the drain this week. It seems that antioxidant vitamins don't quite live up to their hype. Researchers reviewing 68 studies on the effect of antioxidants on life span reported in the Journal of the American Medical Association this week that consumption of beta carotene, vitamin A, vitamin C, vitamin E and selenium, whether singly or combined, did not reduce the risk of premature death. If anything, the researchers concluded, there was actually a slight increase in risk of premature death among antioxidant supplement takers (with the exception of vitamin C and selenium).

Antioxidants have been hypothesized to reduce the oxidative damage to the body caused by so-called "free radicals." Some have suggested that antioxidant supplements may reduce the risk of cancer and heart disease. Such claims helped fuel the growth of the multi-billion dollar nutritional supplement industry.

The researchers didn't conduct new experimental research. Instead, they conducted a systematic review of the results of 68 studies involving 232,606 antioxidant supplement users, combing their results using a controversial statistical technique known as "meta-analysis." The conclusion that antioxidant supplements don't appear to help you live longer is likely on a sound footing. Even without statistically combining the studies through meta-analysis, it's fairly clear that antioxidant supplements are ineffective for increasing longevity. Of the 68 studies examined, 66 studies reported no statistically significant association between supplement use and longevity. The remaining two studies actually reported statistically weak increases in premature death with supplement use.

One strength of this analysis is that longevity is perhaps the most objective measure of health. A potential weakness of the study - at least in terms of putting the myth to bed - is that the researchers didn't examine whether supplement use reduced the risk of cancer or heart disease - two diseases often touted as preventable by antioxidant use. This shortcoming may enable the supplement industry to keep making unproven claims about antioxidants preventing those two diseases.

The study's other conclusion concerning the risk of antioxidant supplements increasing the risk of premature death rests on shaky ground, however. The researchers reported that beta-carotene supplements taken singly, vitamin A supplements taken singly or in combination with other antioxidant supplements; and vitamin E supplements taken singly or in combination with other antioxidant supplements were associated with 6 percent, 16 percent and 4 percent, respectively, increases in risk of premature death among the study group.

Although the three reported increases in risk were statistically significant, this is not likely a reason to fret about supplement use. All three results are relatively weak statistical correlations that would require large, well-designed, and carefully controlled clinical trials to confirm. But since there's no apparent health benefit from taking these supplements to begin with, there's probably little reason to take them or to study them further.

It will be interesting to see what impact this study has on the nutritional supplement industry. A Google search on "antioxidant" produced advertisements proclaiming, "Natural Antioxidant = Better Health"; and "Naturally Remove Free Radicals." A search on "beta-carotene" produced, "Reduce Cancer and Disease." A "vitamin E" search produced "Feel Strong. Be Healthy" and "You can look and feel 20 years younger than you actually are."

Then there's the vitamin C industry that's been built around double-Nobel Laureate Linus Pauling, perhaps the most prominent promoter of the notion that mega-doses of vitamin C improve health. In his highly publicized 1970 book "Vitamin C and the Common Cold," Pauling claimed that taking 10 times the recommended daily allowance of vitamin C reduced the incidence of colds by 45 percent. In his 1986 book, "How to Feel Better and Live Longer," Pauling claimed that mega-doses of vitamins "can improve your general health . increase your enjoyment of life and can help in controlling heart disease, cancer, and other diseases and in slowing down the process of aging."

As's Dr. Stephen Barrett points out, "Although Pauling's mega-vitamin claims lacked the evidence needed for acceptance by the scientific community, they have been accepted by large numbers of people who lack the scientific expertise to evaluate them. Thanks largely to Pauling's prestige, annual vitamin C sales in the United States have been in the hundreds of millions of dollars for many years."

While the jury is probably still out on whether typical use of antioxidant supplements pose any sort of long-term health risk, it is possible to overdose on antioxidants, particularly vitamin A. With respect to Pauling and mega-doses of vitamin C, Dr. Barrett says, "The physical damage to people he led astray cannot be measured."

None of this is to say that no nutritional supplement can have any value under any circumstances. But before falling blindly for claims made by the nutritional supplement industry, you should probably do your own research and check with your physician.


A demented approach to the ageing population

Scary headlines about a 'dementia timebomb' expose today's miserabilist view of the human success story that is longer life.

A report published last week by the UK Alzheimer’s Society, Dementia UK: a report into the prevalence and cost of dementia, confirmed what many people already knew: that dementia is one of the main causes of disability in later life. What was disappointing was the way the research was framed as another ‘ageing timebomb’.

Today, about one-in-five people over the age of 80 has a form of dementia. As a progressive disease, the impact on the individual ranges from mild to severe, so that only a small proportion lose most of their capacity for independent living. But for those worst affected it is extremely distressing for themselves and especially for their caring relatives.

The study could have been greeted simply as a rational contribution to helping society adjust its priorities to an ageing population. With demographic shifts, the types of illnesses that society should focus on change. With substantially reduced infant mortality and more people living to an old age compared to 100 and even 25 years ago, less medical research can be devoted to defeated or contained diseases such as polio, smallpox, tuberculosis, scarlet fever, measles or typhoid, and more can be devoted to heart disease, stroke, cancer and dementia. That’s rational social adaptation.

Unfortunately, a review of the media headlines illustrates a much more alarmist and miserabilist message: ‘Dementia timebomb warning’, ‘The country’s looming dementia crisis’, ‘Dementia timebomb will cost NHS millions’. Such a reaction to the underlying research in this report is not only unjustified but also counter-productive. The Alzheimer’s Society itself warns that such alarmist talk is misleading. It argues with reason that: ‘The use of phrases such as the demographic timebomb, or the view that older people are a burden on our society, does not encourage the view that a sustainable system can be developed.’ (2)

There is nothing new here. The threat of a ‘timebomb’ is frequently invoked in relation to ageing - just look at the debate about pensions. But this fear and anxiety is not a good way to plan transformation and progressive adaptation. Instead, fear-mongering today tends to reinforce a fatalist resignation to the future, epitomised by a naturalist view of ageing: we’re ageing, old age historically brings negative consequences, so we have to put up with it.

Knee-jerk responses in the face of an ‘emerging crisis’ make things worse, more often than not. (That’s also the story of the perverse, counter-productive impact of pension reforms over the past 20 years.) For example, the report draws attention to the ‘starkly different ordering of [research] priorities: cancer 23.5 per cent, cardiovascular disease 17.6 per cent, musculoskeletal disorders 6.9 per cent, stroke 3.1 per cent and dementia 1.4 per cent’. I’m sure it is not the authors’ intention but when legitimate calls for more specific research funding are made in the hyperbolic context of a perceived looming ‘cost crisis’, one can easily imagine the response will be ‘okay, let’s cut funding to these other areas and reallocate to dementia instead’. In the short term, this might seem to support the prospects for potential dementia sufferers, but overall could produce a worse future for old people if other age-related chronic disorders lose funding as a result.

These anxieties about the social and economic impact of ageing are unjustified. We need to challenge an intensifying paradox of our times: that even though we are living longer, healthier and more prosperous lives than ever in human history, we are also more negative about ageing and old age. In the past, old age had both positive and negative connotations – experience and wisdom, not just decrepitude. Today, we only seem to recognise the negative: a timebomb bringing about an intolerable economic and social strain based on millions more dependent people.

Whatever the specific issue, there are always three ways to expose this paradox of ageing.

Firstly, society is getting wealthier all the time. Whatever the extra costs associated with an older population, the trend of rising productivity means that we will have even more resources in the future, so we can bear these costs easily.

History justifies that perspective. There is nothing new or unprecedented about ageing. Developed countries will age over the next half-century at much the same rate that they have for the last hundred years. In contrast to the warnings today that ‘ageing will slow down future economic growth’, this demographic shift hasn’t stopped us from getting more prosperous as a society and older people have benefited from this greater social wealth.

Secondly, a narrow ‘telescope’ view of the future tends to mislead when broader social consequences are drawn. Focusing on one particular feature of the future can fail to incorporate offsetting factors.

The most obvious example as it applies to ageing is that fewer young people necessarily offset more old people. Hence, more absolute spending on old age-related costs is offset by less on younger sections of the population - for example, on education and the specific health costs of the young.

Even in the narrow area of health within wider social spending there are inevitable offsets. Some forms of morbidity rise with age, so more old people mean more illness to be treated. But we are living not just longer lives but longer healthier lives. This trend counteracts the impact of increased health spending related to old age.

This is even more the case when the main influence on the ageing of society is no longer falling birth rates but longer life. For most of the twentieth century, ageing populations mostly represented a changed ratio between young and old people – falling fertility reduced the size of younger cohorts producing an automatic increase in the average age and in the proportion of old people in the population. More recently, since about the 1960s, greater longevity has become a bigger influence on the age structure. The fact that we are living longer is partly attributable to the defeat, or better treatment, of diseases that used to debilitate or kill off younger people. People, including those who are already old, are living to a greater age. Postponed death of this sort tends to go along with people being fitter and healthier during their lives because they are both reflections of social progress and higher living standards.

Most of us are getting through youth and middle age without requiring much medical support, and much less than our parents and grandparents needed. Lower health costs earlier in life means a healthier society, which is good, and which brings about an inevitable concentration of health resources on the older segment of the population because of the higher probability of disease and death with advancing age. 

A related factor that is often downplayed in discussions of age-related health costs is that the cost of dying is more relevant than the cost of ageing. The highest costs arise in the final six-to-18 months prior to death, whatever the age of death. Focusing on the costs of people with dementia in their final years forgets that this means we are paying the cost of these final months for fewer younger people - and in the context of dementia, ‘younger’ means people below the age of 80. 

In other words, just because there will be more people with dementia in an ageing population doesn’t tell us anything about total social expenditures in the future.

Thirdly, the future is one of transformation and adaptation, not extrapolation. This is the statistical distinction between ‘projections’ and ‘forecasts’, which invariably get mixed up in everyday discussion. This confusion is a boon to those who make fearful speculations about the future. A statistician can make a projection about the future based on certain present-day assumptions and extrapolating from them. But every serious professional statistician will add the warning that this is not a forecast of the future, because things will change - society progresses - and therefore the assumptions made for the projection will become invalid.

This misleading shorthand applies to the dementia study itself. It claims: ‘The total number of people with dementia in the UK is forecast to increase to 940,110 by 2021 and 1,735,087 by 2051, an increase of 38 per cent over the next 15 years and 154 per cent over the next 45 years.’ Hence the alarmist BBC News headline: ‘1.7m “will have dementia by 2051“‘. (3) These figures are really projections, not forecasts, based on the researchers’ assumptions about the numbers of elderly people, the incidence of conditions such as high cholesterol and blood pressure, and levels of exercise. Many of these assumptions will not work out exactly.

More importantly, the prevalence of dementia could fall if some means of preventing or, in the shorter term, postponing dementia were discovered. This is the message of the report that should be heeded – more research can accelerate building upon the existing indications of scientific and medical progress in this area. But this gets a little lost in the hyperbole. 

More broadly we can reasonably expect further improvements in standards of health in the future. The general trend is that in most countries a symptom of living longer healthier lives is that the age of onset of particular illnesses is postponed. The average 65-year-old today is much healthier than one in 1950 due to a combination of improvements in living standards and medical progress; healthy life expectancy is growing with increases in overall life expectancy.

The only uncertainties are the pace of improvements in healthy life expectancy and total life expectancy - and the relation between them. In general, morbidity is being postponed. There are indications for some illnesses, though not yet dementia, of tendencies to their compression as well as postponement. This means that some chronic disorders might be concentrated into a smaller proportion, and even a shorter absolute period, at the end of a person’s life. That’s because the older you are when you become ill, the quicker you may finally succumb to that illness.

This report on dementia is one more example of the unjustified negativity with which an ageing population is perceived these days, alongside the ongoing fears and panics about the cost of pensions and other age-related phenomena such as the cost of long-term care. All this pessimism about the human success story of people living longer older tells us more about society’s collective sense of uncertainty and anxieties about where we are heading, than it does about a rational understanding of any of these age-related issues.



Just some problems with the "Obesity" war:

1). It tries to impose behavior change on everybody -- when most of those targeted are not obese and hence have no reason to change their behaviour. It is a form of punishing the innocent and the guilty alike. (It is also typical of Leftist thinking: Scorning the individual and capable of dealing with large groups only).

2). The longevity research all leads to the conclusion that it is people of MIDDLING weight who live longest -- not slim people. So the "epidemic" of obesity is in fact largely an "epidemic" of living longer.

3). It is total calorie intake that makes you fat -- not where you get your calories. Policies that attack only the source of the calories (e.g. "junk food") without addressing total calorie intake are hence pissing into the wind. People involuntarily deprived of their preferred calorie intake from one source are highly likely to seek and find their calories elsewhere.

4). So-called junk food is perfectly nutritious. A big Mac meal comprises meat, bread, salad and potatoes -- which is a mainstream Western diet. If that is bad then we are all in big trouble.

5). Food warriors demonize salt and fat. But we need a daily salt intake to counter salt-loss through perspiration and the research shows that people on salt-restricted diets die SOONER. And Eskimos eat huge amounts of fat with no apparent ill-effects. And the average home-cooked roast dinner has LOTS of fat. Will we ban roast dinners?

6). The foods restricted are often no more calorific than those permitted -- such as milk and fruit-juice drinks.

7). Tendency to weight is mostly genetic and is therefore not readily susceptible to voluntary behaviour change.

8). And when are we going to ban cheese? Cheese is a concentrated calorie bomb and has lots of that wicked animal fat in it too. Wouldn't we all be better off without it? And what about butter and margarine? They are just about pure fat. Surely they should be treated as contraband in kids' lunchboxes! [/sarcasm].

Trans fats:

For one summary of the weak science behind the "trans-fat" hysteria, see here. Trans fats have only a temporary effect on blood chemistry and the evidence of lasting harm from them is dubious. By taking extreme groups in trans fats intake, some weak association with coronary heart disease has at times been shown in some sub-populations but extreme group studies are inherently at risk of confounding with other factors and are intrinsically of little interest to the average person.