Like many people my age, I have fond memories of taking my daily vitamins as a child. The opportunity to eat a jelly sweet with a smiley face on it before breakfast was a welcome one, my favourite being Bassett’s soft and chewy in orange. It is still recommended by the NHS that children between the age of 6 months to 5 years should take supplements of vitamin A, C and D on a daily basis based on clinical evidence. The same recommendation however, is not made for adults. Despite the huge public interest in vitamin supplements (with an estimated public spend of £364 million in the UK each year), their supposed health benefits for the general public are somewhat dubious. While useful in some subgroups or for those with diagnosed deficiencies, many vitamin supplements consumed by the general public are at best a waste of money and at worst a risk to health.
A vitamin is defined as an organic compound essential to the diet that the body is incapable of synthesizing in sufficient quantities by itself. The word ‘vitamin’ is a shortened form of ‘vitamine’, a term coined by the Polish scientist Cashmir Funk in 1912. In the same year, English biochemist Sir Frederick Gowland Hopkins demonstrated in a series of animal feeding experiments that diets consisting purely of proteins, fats, carbohydrates or minerals were insufficient to allow normal growth. Together, Hopkins and Funk formulated the ‘vitamin hypothesis of deficiency disease’, suggesting that a lack of vitamins was harmful to health. Throughout the rest of the 20th century scientists gradually identified the various essential vitamins that are found in food and the symptoms related to their deficit. All of this work was highly valuable for those who could subsequently be diagnosed and treated with vitamins for a nutritional deficiency.
But this is precisely when they are needed: in cases where individuals are displaying symptoms of nutritional deficiency or if they belong to a certain subset of the population. Full NHS guidelines for taking vitamin supplements can be seen here 1 and the list may be surprisingly short to some. The truth is that the majority of the population will get all the necessary vitamins and minerals they require from their diet alone and supplements are often of no benefit to health. While many insist that taking vitamin C daily decreases their susceptibility to colds, a study conducted in 2005 found that ascorbic acid neither prevents nor treats the common cold (link to paper2). In fact, taking vitamins unnecessarily, particularly in large doses, could actually be detrimental to health. A meta-analysis in 2005 found that of the 136,000 people studied, those taking vitamin E supplements had an increased risk of death (link to paper3) and another study in 2011 found that in a group of 39,000 older women, those who took daily multivitamins has an increased risk of cancer and heart disease (link to paper4).
So why do so many people spend their money on vitamin supplements despite the lack of scientific evidence in their favour? Some blame may lie with the double Nobel prize winner Linus Pauling. Pauling was a brilliant chemist who produced invaluable work on the nature of chemical bonds but appeared to suffer from a phenomenon that some refer to as ‘the Nobel disease’. This refers to the strangely common instance of Nobel prize winners making claims outside of their fields of study after receiving their prize, possibly because their achievements have led them to believe that they can’t be wrong. A list of examples of this phenomenon can be found here 5. In Pauling’s case he became convinced that vitamin C had substantial health benefits, particular when taken in megadoses, such as preventing colds and cancer. He devoted a large part of his later life to promoting this idea, even writing several books on the subject. To accept claims made by Pauling at face value due to his scientific achievements would be to follow a logical fallacy (argument from authority). Studies released by Pauling and his collaborators promoting the benefits of vitamin C dosing have often been rife with experimental error while other sound studies frequently find no benefits (link to paper6). The ideas of Pauling however have undoubtedly penetrated the public consciousness more than his debunkers. Since these claims were spread, use of vitamin supplements of all kinds rocketed in the western world, also fuelled by huge marketing campaigns and celebrity endorsements. Last year, 5.8% of US households with an annual income of $125,000 or more spent $500 to $999 on vitamins and other nutritional supplements, most of which probably had no benefit.
Vitamins and dietary supplements are a massive industry and so long as people are willing to buy them, they will continue to be marketed with unsupported health claims. So if you feel like you could benefit from vitamin supplements, see your doctor before you shell out £53.99 on a bottle of ‘extra-potent’ vitamin B capsules or £119.95 on ‘healthy hair growth’ vitamin tablets from Holland and Barrett (Yes these are real prices). If you do go to Holland and Barrett they have some delicious vegetarian produce but I wouldn’t bother with the rest of it.
2. Douglas, R. M. & Hemilä, H. Vitamin C for preventing and treating the common cold. PLoS Med. 2, e168; quiz e217 (2005).
3. Miller, E. R. et al. Meta-analysis: high-dosage vitamin E supplementation may increase all-cause mortality. Ann. Intern. Med. 142, 37–46 (2005)
4. Mursu, J., Robien, K., Harnack, L. J., Park, K. & Jacobs, D. R. Dietary Supplements and Mortality Rate in Older Women. Arch. Intern. Med. 171, 1625 (2011).
6. Lee, B., Oh, S.-W. & Myung, S.-K. Efficacy of Vitamin C Supplements in Prevention of Cancer: A Meta-Analysis of Randomized Controlled Trials. Korean J. Fam. Med. 36, 278 (2015).