A recent report from the US Preventive Services Task Force in the Annals of Internal Medicine focused on the use of vitamin, mineral, or multivitamin supplements. Their conclusions are that the current evidence is insufficient to assess the benefits and harms of these supplements with respect to prevention of cardiovascular disease and cancer. However, they did issue caution for high doses of vitamin E and beta carotene supplements.
For the most part, experts at the Linus Pauling Institute agree with these findings, as they are supported by an evidence-based review of the scientific literature on vitamin and mineral supplements.
But LPI wants to make this clear: you shouldn’t stop taking your multivitamins.
One of the key words in the USPSTF report is “insufficient.” Although the report does not thoroughly examine the limitations prevalent in vitamin and mineral supplement trials, it is clear that large, clinical trials of vitamin supplements employ imperfect or inappropriate methodologies that render them largely useless in determining the real value of these micronutrients on supporting health.
LPI analysis of the literature also shows that the conventional trial design – although a “gold standard” for pharmaceutical drugs – is strongly biased against showing benefits of essential nutrients.
Unfortunately, the report combines a very diverse set of interventions together into their recommendations. While a review of the scientific literature can be very powerful, lumping studies together with completely different designs significantly weakens conclusions that can be made. So if the USPSTF statements sound weak, its likely due to these limitation.
However, the report acknowledges that limitations exist in the research conducted to date. Methods are not standardized, levels of insufficiency are not well defined, and the validity of current models is questionable. All of this “further hinders progress in understanding potential benefits of dietary supplements.” In general, this echoes the LPI message, and highlights all of the points that have limited micronutrient research.
Nevertheless, it is still worth noting that much of the US population does not meet intake recommendations for many vitamins and minerals, including the vitamins A, C, D, E, and K, and also calcium, magnesium, and potassium. These gaps can easily be addressed by the long-term use of multivitamin supplements, and when they are, some protection against diseases has been noted. The largest and longest trial on multivitamin use found a reduction in total cancer incidence and cataract incidence. This is nothing to be ignored.
The fact that these conclusions were reached in a health-conscious group (medical doctors) and conducted with the conventional study designs suggests that the results of these studies (and the effect of the multivitamin/mineral supplements) may be even greater when applied to general population.
LPI has been on the forefront of supporting the use of multivitamin/mineral supplements to support a normal diet. To quote Balz Frei, director and endowed chair of the LPI: “The persistence of poorly controlled studies within the field of micronutrient research undermines efforts to recommend multivitamins/minerals as a safe, economical, and effective means of promoting health.” Dr. Frei goes on to say that repeating poor studies “weakens efforts to fund additional, well-designed [trials]” and “serves to confuse and detract from the real issue of nutritional inadequacies”.
“Taking a daily multivitamin/mineral supplements is a safe, affordable, and simple way to help fill nutritional gaps and improve micronutrient status of Americans.”
Everyone needs vitamins and minerals to keep their bodies functioning properly. Multivitamins are a cheap and effective way to support good health.
