It is a triumph of marketing over evidence that millions take supplements every day. There is no question we need vitamins in our diet to live. But do we need vitamin supplements? It’s not so clear. There is evidence that our diets, even in developed countries, can be deficient in some micronutrients. But there’s also a lack of evidence to demonstrate that routine supplementation is beneficial. And there’s no convincing evidence that supplementing vitamins in the absence of deficiency is beneficial. Studies of supplements suggest that most vitamins are useless at best and harmful at worst. Yet the sales of vitamins seem completely immune to negative publicity. One negative clinical trial can kill a drug, but vitamins retain an aura of wellness, even as the evidence accumulates that they may not offer any meaningful health benefits. So why do so many buy supplements? As I’ve said before, vitamins are magic. Or more accurately, we believe this to be the case.
There can be many reasons for taking vitamins but one of the most popular I hear is “insurance” which is effectively primary prevention – taking a supplement in the absence of a confirmed deficiency or medical need with the belief we’re better off for taking it. A survey backs this up – 48% reported “to improve overall health” as the primary reason for taking vitamins. Yes, there is some vitamin and supplement use that is appropriate and science-based: Vitamin D deficiencies can occur, particularly in northern climates. Folic acid supplements during pregnancy can reduce the risk of neural tube defects. Vitamin B12 supplementation is often justified in the elderly. But what about in the absence of any clear medical need? (more…)
If you’re a regular reader of this blog, I’ll bet you’re not a regular consumer of vitamins or supplements. I’m in that group. Aside from sporadic vitamin D in winter, I don’t take any vitamins or supplements routinely, nor do I give any to my children. Your reasons may be close to mine: There is little to no evidence suggesting that dietary deficiencies are widespread, nor is there good evidence to suggest that vitamin supplements are beneficial in the absence of deficiency. I don’t have any need for an other supplements, nor am I confident in the scientific evidence for many of them.This position of “no supplements” is a cautious and conservative one, but is based on a consideration of the scientific evidence. I view decisions about healthcare as evaluations of risk and benefit, and then cost if necessary. Given supplementation (with some exceptions) has no demonstrable benefits and, in some cases, a little risk, the odds favour not supplementing in most cases. Add in costs, and it’s even less attractive as a routine health strategy.
Yet a decision not to take vitamins or supplements regularly is becoming a minority position. Supplement use has grown over the past 40 years among Americans, with the National Health and Nutrition Examination Survey (NHANES) showing steadily increasing utilization among younger and older adults:
I was asked to write an article for Slate, the on-line magazine, about Andrew Weil’s selection as the keynote speaker for the 2012 AAFP annual scientific assembly. The science and health editor, Laura Helmuth, was initially enthusiastic about what I wrote, but eventually decided not to publish it. Here is the initial draft of my article. My comments follow.
Original Draft of Article for Slate
The American Academy of Family Physicians picked Andrew Weil to be the keynote speaker at its annual scientific assembly October 16-20 in Philadelphia. What were they thinking? That’s like having an astrologer give the keynote speech at an astronomy meeting.
The AAFP stands for the best in conventional medicine, for the standard of care as determined by physicians and scientists. Weil doesn’t. The AAFP stands for evidence-based medicine. Weil doesn’t. (more…)
Multivitamin supplementation has been getting a rough ride in the literature, as evidence emerges that routine supplementation for most is, at best, unnecessary. Some individual vitamins are earning their own unattractive risk/benefit profiles: Products like folic acid, calcium, and beta-carotene all seem inadvisable for routine supplementation in the absence of deficiency or medical indication. Vitamin E, already on the watch list, looks increasingly problematic, with data recently published confirming the suspected association of supplementation with an elevated risk of prostate cancer.
Reading through the vitamin posts here at SBM, one issue comes through repeatedly: The danger of assuming therapeutic benefits in the absence of confirmatory evidence. Vitamin supplement have the patina of safety and of health, a feature that’s reinforced when you purchase them: You don’t need a prescription, you don’t get counseled on their use, and there isn’t a long list of frightening potential side effects to accompany the product. You can pull a bottle off the shelf, and take any dose you want. After all, how harmful can vitamins be when you can buy 5 pounds of vitamin C at a time, or vitamin E capsules in a 1000-pack? But the research signals seem to be getting stronger, and most are pointing in the same direction: what we though we knew about antioxidants was based on simplistic hypotheses about nutrition and health. And while we thought we were doing ourselves good with antioxidant supplements, we may have been doing harm. (more…)
The discovery of various vitamins – essential micronutrients that cause disease when deficient – was one of the great advances of modern scientific medicine. This knowledge also led to several highly successful public health campaigns, such as vitamin-D supplementation to prevent rickets.
Today vitamins have a deserved reputation for being an important part of overall health. However, their reputation has gone beyond the science and taken on almost mythical proportions. Perhaps it is due to aggressive marketing from the supplement industry, perhaps recent generations have grown up being told by their parents thousands of times how important it is to take their vitamins, or eat vitamin-rich food. Culture also plays a role – Popeye eating spinach to make himself super strong is an example this pervasive message.
Regardless of the cause, the general feeling is that vitamins are all good – they are not only important for health, they promote health. Many people take vitamin supplements on the idea that more is better, or for nutritional “insurance” to make sure they are getting enough of every vitamin.
Science has found no evidence that vaccines cause autism; but the true cause(s) of autism have not yet been determined. So far the available evidence has pointed towards a largely genetic cause with possible interaction with environmental factors. A new study supports that interpretation. It also supports previous evidence that autism is triggered prior to birth, rather than at the time of vaccinations.
Schmidt et al. published a study in Epidemiology on May 23, 2011, entitled “Prenatal Vitamins, One-carbon Metabolism Gene Variants, and Risk for Autism.” It was a population-based case control study of 566 subjects comparing a group of autistic children to a matched control group of children with normal development. They looked at maternal intake of prenatal vitamins in the 3 months before conception and the first month of pregnancy, and they looked for genotypes associated with autism. They found that mothers who didn’t take prenatal vitamins were at greater risk of having an autistic child, and certain genetic markers markedly increased the risk. There was a dose/response relationship: the more prenatal vitamins a woman took, the less likely she would have an autistic child. There was no association with other types of multivitamins, and no association with prenatal vitamin intake during months 2-9 of pregnancy. (more…)
Age-related macular degeneration (AMD) is one of the major causes of visual impairment in the elderly: it affects central vision, impairing the ability to read and recognize faces while preserving some peripheral vision. It comes in two forms: wet and dry. Dry macular degeneration is by far more common, but wet macular degeneration, involving the proliferation of blood vessels, is more severe.
There is evidence that antioxidant vitamin supplementation may slow the progression of the dry type when it is already established and moderately severe, but the published evidence does not support the use of these supplements for prevention or for patients with early stages of the disease. Some people are using it for prevention, but there is concern that the risks might exceed any benefit. Of more concern, it appears that a manufacturer’s (Bausch & Lomb’s) advertising has gone way beyond the available evidence. (more…)
In the interests of fairness and intellectual honesty, I’ve forced myself to read a lot of really bad books. The True Believer tells me his guru’s book is the Real Stuff. He tells me I have a closed mind and won’t look at anything outside establishment dogma, and if I only read the book and understood Dr. Quack’s evidence and arguments, I would be a True Believer too. I have tried, really I have. I’ve given the Dr. Quacks every chance to convert me, and I’ve hoped to learn something new, but I’m always disappointed. I’ve come to the point that I feel like I’m reading the same book over and over: it is always a mixture of real science, pseudoscience, and speculation, based on cherry-picked evidence and argued with the same logical fallacies.
I recently got hooked into reading another one by a correspondent who had called me an “ignorant relic” for writing a “grossly ignorant article” about alternative medicine. I suggested he read R. Barker Bausell’s book Snake Oil Science and a couple of others, which he promised to do. Then he said, “If I am willing to buy three books that you have suggested and read them and you are not willing to read what I have suggested, then that pretty much says all that needs to be said.”
I was willing, even though the very title of the book suggested that its message was incompatible with the scientific evidence as I know it: How to Prevent and Treat Cancer with Natural Medicine. The authors are big names in naturopathic and herbal medicine: Michael Murray, Tim Birdsall, Joseph Pizzorno, and Paul Riley. It’s nowhere near as bad as some of the bad books I’ve read, but it is a good example of the genre and I’ll use it to illustrate why I call them bad.
It offers “an arsenal of disease-fighting tools for prevention, treatment, and coping with side effects” (Yes, it offers tools; but do those tools work?) And it promises to “change your internal environment so cancer can’t survive.” (Wow! If it could really do that, every oncologist in the world would enthusiastically adopt these methods and the authors would be eligible for a Nobel prize.)
I’ll start with a confession. I used to do something irrational. I used to take a daily multivitamin, not because I thought there was good scientific evidence to support the practice, but for psychotherapy. I tried to eat a healthy diet and worried about it. By taking a pill, I could stop worrying.
Then I found out that higher intake of vitamin A was associated with an increased risk of hip fractures in postmenopausal women like me, and I stopped. (High doses of vitamin A also cause births defects and are contraindicated in pregnancy.) Now I only take supplemental calcium and vitamin D, not on general principles but because of personal risk factors.
We’re being bombarded by advice to take vitamins and various other supplements. Health gurus like Andrew Weil recommend that everyone take vitamins (which they just happen to sell). The orthomolecular followers of Linus Pauling want us to take megadoses of vitamins. Ray Kurzweil tells us we should take vitamins to make us live longer; he takes 250 vitamin and supplement pills a day and thinks he will live forever. (You can read about his ideas in his book Fantastic Voyage: Live Long Enough to Live Forever.) Who should we believe? (more…)