Studies cast new doubts on supplements

Research suggests that vitamin and mineral supplements simply don't bring the benefits we think they do

Three new studies query the health benefits of vitamin and mineral supplements. Photograph: Getty Images

Three new studies query the health benefits of vitamin and mineral supplements. Photograph: Getty Images


Stop wasting money on vitamin and mineral supplements is the strong advice from the American College of Physicians in a recent editorial in the Annals of Internal Medicine.

The editorial highlights three large reviews of vitamin and mineral use in different populations – none of which found benefit from taking the supplements.

The first study reviewed three trials of multivitamin supplements and 24 trials of single or paired vitamins in more than 400,000 participants. The authors concluded there was no clear evidence of beneficial effect on “all-cause mortality, cardiovascular disease or cancer”.

The second study looked at the value of a daily multivitamin supplement to prevent cognitive decline among almost 6,000 men aged 65 and over. After 12 years of follow-up, no differences were found between placebo and multivitamin groups in overall cognitive performance or verbal memory.

“The use of multivitamin supplement in a well-nourished elderly population did not prevent cognitive decline,” the authors concluded.

The third study looked at the benefits of high-dose multivitamin supplement in more than 1,700 men and women who had had a heart attack. After a 4½ year follow-up, there was no significant difference in recurrent cardiovascular events between those in the multivitamin group and the placebo group. However, the researchers noted that the trial was limited by “non adherence and dropouts”.

Adverse effects
Dr Mary Flynn, chief specialist in public health nutrition at the Food Safety Authority of Ireland (FSAI), said she was not surprised by the findings. “When you consider that one-third of Irish people take supplements, my concern is more about the adverse effects of high-dose supplements [than any suggested benefit] – some of which are 100-fold the recommended daily allowance.” Dr Flynn points to the fact that there are no EU-wide maximum safety limits for vitamins and minerals.

The FSAI, however, has two specific recommendations regarding vitamin and minerals in Ireland. “We recommend women take 400mg of folic acid daily before and during the first three months of pregnancy and we recommend that babies up to a year are given 5mg of vitamin D daily.” Otherwise, the FSAI doesn’t recommend vitamin and mineral supplements for maintaining health or preventing disease.

Responding to these studies, Olive Curran, nutritional therapist and chairwoman of the Irish Health Trade Association, said, “The intention of food supplements is to supplement the diet. They are not pharmaceutical and, therefore, there is no promise of cure.”

Poor health
Responding directly to the study of patients with pre-existing heart conditions, UK-based dietitian and nutritionist Dr Carrie Ruxton said: “All the people who entered the trial were in poor cardiovascular health. Vitamin and mineral supplements are intended for the maintenance of health rather than the management or treatment of pre-existing disease for which other treatments such as medicines or surgery are more usually employed.”

Dr Ruxton noted the third study used high-dose vitamins, including five times the US daily value of vitamin A, 20 times the daily value of vitamin C, 13 times the daily value of vitamin E, 25 times the daily value of vitamin B6 and 67 times of thiamin. “This was a very high-dose supplement designed to be used like medication – however, it is well accepted that vitamins are not intended to be used in this way so it is unsurprising that they do not have drug-like effects.”

Health + Family columnist Jacky Jones recently wrote that people with a healthy diet who get out and about and take enough exercise do not need any vitamin or mineral supplements. “They are a waste of money and can do a lot of harm. There is no getting away from fresh air, physical activity and a healthy diet, especially during the winter,” she said.

The question none of these experts addressed is whether vitamin and mineral supplements can help those who don’t have a good diet and don’t exercise enough.

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