Reflections on Workshops and Opportunities to Influence Nutrition Policy and Health
This week Canadian and American federal agencies hosted a workshop Options for Consideration of Chronic Disease Endpoints for Dietary Reference Intakes (DRIs) at the NIH campus in Bethesda, MD. The purpose was to bring a panel of experts together to consider chronic disease endpoints (or surrogates) to set future nutrient DRIs. The meeting opened with welcoming comments from representatives of NIH-ODS (Dr Paul Coates) and Health Canada (Dr Amanda MacFarlane). In reviewing the workshop focus and charge, four nutrients deserving of review were identified: omega-3 fatty acids, sodium, magnesium, and vitamin E.
These 4 nutrients were chosen based on public health and/or policy importance. Much to my chagrin, the experts took a much broader approach. More time was spent discussing evidence linking macronutrients with chronic disease, the validity of using dietary intake to assess nutrient status, and the lack of mechanistic evidence associating nutrient intake with chronic disease outcomes than was needed. The experience was similar to serving on a jury. Like jurors, the attendees [ Scientists involved in DRI reviews, individuals from agencies and other groups that sponsor and/or fund DRI reviews, and users of DRI’s (e.g., researchers, policy and program leaders, and health professionals involved in clinical and educational activities)] were voiceless. The audience sat silently, waiting for panelists to share their opinions on different aspects of DRIs. When would the experts discuss the 4 priority nutrients? They didn’t really. Here are my thoughts.
To derive a DRI, an appropriate criterion of adequacy is needed. For example, the folate DRI based on red blood cell folate concentrations. The DRI for vitamin D which is based on maintaining a serum 25-hydroxyvitamin D3 concentration of at least 50 nmol/L. The observation that individuals with serum 25(OH)D3 concentrations between 50-70nmol/L have the lowest risk of mortality from cardiovascular disease, stroke and acute myocardial infarction validates the IOM criterion of adequacy for vitamin D.
It is premature for the workshop participants to debate the impact of dietary patterns. We need experts identifying potential biomarkers of nutrient status and evaluating their usefulness in assessing nutrient-outcome relationships. Using criterion of adequacy, then one can determine amounts and sources to maintain these healthy ranges.
There is precedent. Red blood cell fatty acid concentrations are known to be better indicators of long-chain fatty acid status than blood or serum fatty acids. So, what omega-3 index is optimal for cognitive function or cardiovascular health? Knowing this, one can establish dietary recommendations to maintain such levels.
What serum α-tocopherol concentration helps maintain healthy liver function? Should serum α-tocopherol concentrations be adjusted for cholesterol status? Does this change the optimal serum vitamin E status different for someone who is overweight and at risk of nonalcoholic fatty liver disease? I hoped the moderator and panelists would discuss such points. It takes more than placebo vs supplement randomized controlled trials without nutrient status indicators to elucidate nutrient-health outcomes.
Unfortunately, the workshop wasn’t interactive and didn’t build upon the knowledge of those in the room. Fortunately, agencies create opportunities for oral comments, e.g. the March 24, 2015 public meeting in response to the “Scientific Report of the 2015 Dietary Guidelines Advisory Committee. These are important forums to go on record. Submitting written comments can also have a powerful, lasting impact on policy.
Don’t be a silent bystander. When there are opportunities to shape governance and policy, become involved.
Durup D, Jorgensen HL, Christensen J, Tjonneland A, Olsen A, Halkjaer J, Lind B, Heegaard A-M, Schwarz P. A reverse J-shaped association between serum 25-hydroxyvitamin D and cardiovascular disease mortality-the CopD-Study. 2015 JCEM doi: 10.1210/jc.2014.4551
Harris WS, Thomas RM. Biological variability of blood omega-3 biomarkers. 2010 Clin Biochem doi: 10.1016/j.clinbiochem.2009.08.016
Tan ZS, Harris WS, Beiser AS, Himali JJ, Debette S, Pikula A, DeCarli C, Wolf PA, Vasan RS, Robins SJ, Seshadri S. Red blood cell omega-3 fatty acid levels and markers of accelerated brain aging. 2012 Neurology doi: 10.1212/WNL.0b013e318249f6a9
Von Schacky C. Omega-3 index and cardiovascular health. 2014 Nutr doi: 10.33990/nj6020799
Lavine JE, Schwimmer JB, Van Natta ML, Molleston JP, Murray KF, Rosenthal P, Abrams SH, Scheimann AO, Sanyal AJ, Chalasani N, Tonascia J, Unalp A, Clark JM, Brunt EM, Kleiner DE, Hoofnagle JH, Robuck PR, for the Nonalcoholic Steatohepatitis Clinical Research Network. 2011 JAMA doi: 10.1001/jama.2011.520
Pacana T, Sanyal AJ. Vitamin E and nonalcoholic fatty liver disease. 2012 Curr Opin Clin Nutr Metab Care doi: 10.1097/MCO.0b013e328357f747