Lessons on Nutrition Consensus from Goldilocks
Nutrition is complex. After decades of observation and experimentation, vitamins were discovered (over 100 years ago) to be essential for life. When vitamin intakes are too low, deficiency diseases become prevalent. When vitamin intakes are inadequate and status is suboptimal, health is compromised. Just like “The Story of the Three Bears”, researchers continue efforts to determine the amount of dietary X that is “just right”.
Semba and colleagues hypothesized that resveratrol might be the elixir of life – the single entity explaining longevity. Twenty-four hour urinary resveratrol metabolite concentrations were measured from a sample of 783 community-dwelling adults living in 2 villages in Chianti, Italy. These individuals were participating in a prospective cohort study, the Invecchiare in Chianti (InCHIANTI) Study (“Aging in the Chianti Region”) conducted between 1998 to 2009. Total urinary resveratrol metabolites were not associated with markers of inflammation (serum C-reactive protein, IL-6, IL-1β, TNF) or prevalent and incident cardiovascular disease or cancer.
Read the title of the paper. Why do researchers try to distill longevity to a single dietary entity? Health isn’t a monogamous relationship. Longevity isn’t exclusive to nutrition. Throughout life, we dance (dally) with many partners - nutrition, physical activity and lifestyle behaviors, e.g. smoking. Researchers regularly use statistics to ferret out confounders. Having done the necessary statistical contortions, is it reasonable to conclude that “dietary substance X does not have a substantial influence on inflammation, cardiovascular disease, cancer or longevity”?
With respect to essential, nutrients with an impressive body of research, such as vitamin A, zinc, iron, iodine, and omega-3 fatty acids, a consensus statement by leading experts nicely summarized the field:
“Interventions focused on supplying single nutrients are unlikely to contribute significantly to optimizing the complex processes that maintain health and decrease or delay disease.”
Resveratrol, like any dietary constituent, is not the elixir of life even though it has several established metabolic effects. Short-term resveratrol interventions have statistically significant effects on glucose metabolism in older individuals with moderate glucose intolerance. 250 mg resveratrol daily for 3 weeks reduced glycosylated hemoglobin (HbA1C) concentrations in individuals with type 2 diabetes. Placebo-controlled intervention trials found that resveratrol for 6 weeks improved flow mediated dilation by 23% in hypertensive individuals. Resveratrol supplementation decreased fat cell size and altered lipid catabolism pathways in obese, healthy men.
It is accepted that childhood stunting is rarely resolved by a single micronutrient intervention. Many nutrients, many factors interact to affect childhood mortality and growth. Longevity is an even more protracted process. A lifetime in fact. Age of death is unlikely to be extended by a single dietary constituent.
Researchers should continue to ask questions. Journal editors should publish studies. Consensus does not dismiss nutrients based on a single study.
Semba RD, Ferrucci L, Bartali B, Urpi-Sarda M, Zamora-Ros R, Sun K, Cherubini A, Bandinelli S, Andrs-Lacueva C. Resveratrol levels and all-cause mortality in older community-dwelling adults. 2014 JAMA Intern Med doi: 10.1001/jamainternmed.2014.1582
Kaput J, van Ommen B, Kremer B, Priami C, Pontes Monteiro J, Morine M, Pepping F, Diaz Z, Fenech M, He Y, Albers R, Drevon CA, Evelo CT, Hancock REW, Ijsselmuiden C, Lumey LH, Minihane A-M, Muller M, Murgia C, Radonjic M, Sobral B, West Jr, KP. Consensus statement understanding health and malnutrition through a systems approach: the ENOUGH program for early life. 2014 Genes Nutr doi: 10.1007/s12263-013-0378-y
Crandall JP, Oram V, Trandafirescu G, Reid M, Kishore P, Hawkins M, Cohen HW, Barzilai N. Pilot study of resveratrol in older adults with impaired glucose tolerance. 2012 J Gerontol doi: 10.1093/Gerona/glr235
Bhatt JK, Thomas S, Nanjan MJ. Resveratrol supplementation improves glycemic control in diabetes mellitus. 2012 Nutr Res doi: 10.1016/j.nutres.2012.06.003
Konings E, Timmers S, Boekschoten MV, Goossens GH, Jocken JW, Afman LA, Muller M, Schrauwen P, Mariman EC, Blaak EE. The effects of 30 days resveratrol supplementation on adipose tissue morphology and gene expression patterns in obese men. 2014 Int J Obesity doi:10.1038/ijo.2013.155