Asking the Right Question – Role of Nutritional Status rather than Value of Supplementation
Eating right and being physically active aren’t just a “diet” or a “program” – they are keys to a healthy lifestyle. With healthy habits, you may reduce your risk of many chronic diseases such as heart disease, diabetes, osteoporosis, and certain cancers, and increase your chances for a longer life. So it was written in Nutrition and Your Health: Dietary Guidelines for Americans, 1980. Thirty-four years later, the same words ring true. Maintaining optimal concentrations of essential vitamins, minerals, amino acids, and long-chain polyunsaturated fatty acids are critical for longevity.
We don’t need evidence that supplements can be a source of nutrients. Just like we don’t need proof that foods provide energy and micronutrients. We don’t need to judge the choices others make to ensure nutrient adequacy – natural/organic/fortified foods and beverages and/or dietary supplements. The choices people make to obtain their nutrition are personal.
The merits of scientific research can be evaluated however. It isn’t enough to statistically evaluate the role of supplementation with a placebo vs intervention mentality. Systematic reviews on the benefits and harms of vitamin and mineral supplements on the prevention of cardiovascular disease and cancer are trying to answer the wrong question. It is not whether supplementation benefits (or not) that it important.
Nutrition research needs to shift from a one-size-fits-all mentality to understand the impact of suboptimal nutrient status on disease outcomes. Using guidelines on experimental design, analytical methods and evaluation of nutrient status outlined by Dr Robert Heaney, researchers need to evaluate if people with suboptimal nutrient status at the beginning of an intervention (baseline) have a reduced risk of cancer or cardiovascular disease when (if) their nutritional status is improved. This hypothesis can be tested with foods or supplements and biological samples. Both approaches have helped generate nutrient-health outcome claims in the US and EU.
Case-cohort studies where participants are retrospectively stratified by baseline data (toenail selenium in this case) without subsequent measures of nutrient status shouldn’t be used to make strong recommendations on the benefits/harms of supplementation (Krystal et al, 2014). Nutritional interactions are complex. Supplementation is not expected to benefit individuals with optimal nutrient status. It is also important to understand the reasons that people use dietary supplements.
Simplified generalizations that ‘…supplementation isn’t a good idea. The best way to stay healthy is to eat healthy’ are not constructive. It is not a question of where we obtain our nutrients. The question is, have we consumed enough to maintain normal nutrient levels.
The best way to stay healthy is to maintain optimal micronutrient status. Dietary supplementation is an option.
Kristal AR, Darke AK, Morris JS, Tangen CM, Goodman PJ, Thompson IM, Meyskens Jr FL, Goodman GE, Minasian LM, Parnes HL, Lippman SM, Klein EA. Baseline selenium status and effects of selenium and vitamin E supplementation on prostate cancer risk. 2014 JNCI doi: 10/1093/jnci/djt456
Heaney RP. Guidelines for optimizing design and analysis of clinical studies of nutrient effects. 2013 Nutr Rev doi: 10.1111/nure.12090
Dickinson A, MacKay D. Health habits and other characteristics of dietary supplement users: a review. 2014. Nutr J doi:10.1186/1475-2891-13-14