expert opinion

Consider dietary guidelines sufficiently micronutrient deficiencies?

March 5, 2015

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Balz Frei, PhD, Professor, Department of Biochemistry and Biophysics, Linus Pauling Institute, Oregon State University, USA

“Only a small proportion of people in the US actually follow the Dietary Guidelines for Americans. A lot of people are not meeting the recommended intake levels of vitamins AC,DE, and K, and for calciumpotassium, and magnesium. According to NHANES data, 50% of Americans are not making the Institute of Medicine’s recommendations for vitamin A, 40% for vitamin C, and over 90% for vitamins D and E. For potassium, 98% are not meeting the requirements (1). For calcium and magnesium it is 50% and 60%, respectively. As a result, there are quite significant micronutrient insufficiencies and deficiencies in the American population.

This data is not new, but this is information that is not getting enough attention. The focus of the US Dietary Guidelines Advisory Committee (DGAC), consisting of nationally recognized experts in the field of nutrition and health, on a healthy diet is causing a significant problem. The DGAC is turning a blind eye to this problem because it is preaching this ideal of a healthy diet. We should do something about this. The Dietary Guidelines for Americans think that a sufficient micronutrient intake can be achieved from a healthy diet. My point is that yes, put a healthy diet first, but next should be supplements. The committee behind the Dietary Guidelines thinks that if you do recommend supplements people will not eat a healthy diet. However, supplements are not a replacement, they supplement they diet.

Many randomized clinical trials (RCTs) involving vitamin and mineral supplementation have yielded disappointing results, with many experts in the nutrition science field questioning if RCTs are even a good model for assessing the effects of micronutrients (2). RCTs work very well for pharmaceuticals, but they have severe limitations when applied to micronutrients. Many do not consider the dose-response curve of the participants. If you do not know where your subject is on that curve, you do not know if you are capable of changing their status for that nutrient. Also, you never have a true placebo group: You’re just comparing a group with potentially lower levels with a group with higher levels. A third limitation is that vitamin and mineral trials often recruit people who are healthier than the average population because they are interested in participating. These people usually have a better health status to start with. To really see an effect of vitamin and mineral supplementation you really need to supplement for more than a decade. Very few health studies achieve that. 

The Physicians’ Health Study (PHS) II study from 2012 is the only large-scale, randomized, double-blind, placebo-controlled trial with almost 15,000 male physicians, which investigated the effects of a common multivitamin in the prevention of chronic disease for over a decade (3). The study showed that a daily multivitamin may reduce the risk of cancer by 8%. But even then the medical community turned around and questioned it! A daily multivitamin can help to fill nutrient gaps. Quite simply, at around a penny a day a multivitamin is the cheapest health insurance a person will ever buy.”

References

  1. Parker E. et al. America’s nutrition report card: Comparing WWEIA, NHANES 2007-2010 usual nutrient intakes to dietary reference values. FASEB J. 2014; 28(1):S384.2.
  2. Heaney R. P. Guidelines for optimizing design and analysis of clinical studies of nutrient effects. Nutrition Reviews. 2013; 72(1):48–54.
  3. Gaziano J. M. et al. Multivitamins in the prevention of cancer in men: the Physicians' Health Study II randomized controlled trial. JAMA. 2012; 308(18):1871–1880.