Would Nutritional Status Maps Influence where you Choose to Live?
In an extremely insightful article in Scientific American, Melinda Wenner Moyer identifies the challenges in getting a clear, cohesive picture on the role nutrients play in maintaining health. Within the article she cites Dr Robert Heaney’s guidelines on study design.
1. Measure baseline nutrient status, use status as an inclusion criterion, and in reporting results.
2. Interventions must provide sufficient nutrient to change status which needs to be quantified by a suitable analysis.
3. The hypothesis must test the effect of a change in nutrient status not just a change in dietary intake.
4. Other nutrients must be optimized to ensure that the test nutrient is the only limiting nutritional factor.
With a population of more than 318 million, the US cannot afford to have >30 million people deficient in vitamin B6, >24 million with vitamin D levels they could diagnosed with rickets, and >15 million who technically have scurvy (Figure 1, Second National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 2012). Federal nutrition goals should be more aspirational than preventing deficiency.
Nutritional deficiencies have been defined for decades, eg. serum 25-hydroxyvitamin D < 30 nmol/L. In 2010, the Institute of Medicine described vitamin D levels below 50 nmol/L as ‘insufficient’. It is time to define optimal nutrient levels and set milestones when the majority of the population will be ‘optimally nourished’.
Just as per capita food availability does not explain food insecurity, dietary intakes with incomplete and out-of-date food databases are not good assessments of nutrient intake or status. Accept that dietary records and food frequency questionnaires are not ideal nutrient assessment tools. Don’t let food beliefs about the value of supplements or certain food sources derail us from nutritional status measurements. Research does not support recommendations to increase fruit and vegetable intake to lose weight (Kaiser et al, 2014) yet we continue to advocate these foods as important sources of micronutrients (including antioxidants) and dietary fiber.
Nutrition is at a tipping point when it should transition from a preoccupation (obsession) with estimating nutrient intake to assessing nutritional status. Regardless of whether nutrients are ingested as foods or dietary supplements, human health is a reflection of nutrient concentrations and actions within the body. It is the plasma vitamin E (α-tocopherol) concentrations which are inversely associated with incidence of prostate cancer (Albanes et al, 2014). Don’t get sidetracked by placebo vs treatment interventions. Without consideration of nutrient status, simple treatment vs placebo statistical analyses of randomized, controlled trials are not constructive.
The time has come to measure nutritional biomarkers and map nutritional status just as is done for obesity and prevalence of food insecurity. By visualizing nutritional status of Americans by region across the country, educators, legislators, and industry can partner to remedy nutritional insufficiency.
Wenner Moyer M. Health impact of vitamin pills remains uncertain in developed world. 2014 Scientific American
Heaney RP. Guidelines for optimizing design and analysis of clinical studies of nutrient effects. 2014 Nutr Rev doi: 10.1111/nure.12090
Kaiser KA, Brown AW, Bohan Brown MM, Shikany JM, Mattes RD, Allison DB. Increased fruit and vegetable intake has no discernible effect on weight loss: a systematic review and meta-analysis. 2014 AJCN doi: 10.3945/ajcn.114.090548
Albanes D, Till C, Klein EA, Goodman PJ, Mondul AM, Weinstein SJ, Taylor PR, Parnes HL, Gaziano JM, Song X, Fleshner N, Brown PH, Meyskens FL, Thompson IM. Plasma tocopherols and risk of prostate cancer in the Selenium and Vitamin E cancer prevention trial (SELECT). 2014 Cancer Prev Res doi: 10.1158/1940-6207.CAPR-14-0058