Nutritional Assessment and Nutrient Guidance: Omega-3 Case Study
In nutrition, there are 2 frequent means to link nutrients with health outcomes. 1) Measure food intake, usually with dietary records or food frequency questionnaires of food intake which are coupled with food databases. 2) Analyze a biomarker present in blood, urine, or tissue of individuals. Historically, the greatest emphasis has been on the former because nutritional biomarker analysis has been time-consuming and expensive. The problem is that people aren’t very accurate in reporting what and how much is eaten. The errors in estimating nutrient intakes are compounded by the changing composition of foods as consumers and the food industry attempt to follow nutrition guidance.
With the elucidation of the human genome and advances in analytical techniques and instrumentation, cost effective rapid tools are becoming available to assess genomic and nutritional biomarkers. Intervention trials demonstrate that omega-3 fatty acid levels in the blood by be increased by changing dietary fat intake (Wood et al, 2014). In 2014, I think scientists should measuring actual nutrient status rather than attempting to record dietary intakes of individuals.
The field of nutrition and food science needs to transition from food record to biomarker analysis. The food and supplement choices of consumers, and the guidance issued by nutrition policymakers, need to be guided by studies (and headlines) assessing biomarkers of nutritional status. It is time to reallocate resources from nutrient intake estimates to assessments of nutrition biomarker and genomics. As Dr Steven Zeisel, University of North Carolina Chapel Hill and Kannapolis (see link to International Life Sciences Institute annual meeting), “nutrition studies should be required to collect samples for nutrient biomarker and genomic evaluation”.
Blood and tissue samples, analyzed using validated analytical standards and methods, are indisputable, objective measures of individual nutrient exposure. These findings expand understanding of individual and population nutrient status. Biomarker values can be correlated with functional measures of health and biomarkers of disease. As genetic polymorphisms are identified, study samples can be re-examined to determine if a nutrient-gene interaction exists.
From studies associating levels of omega-3 fatty acids (EPA+DHA) in red blood cells, we learn that n-3 fatty acid status is associated with a larger brain volume (Pottala et al, 2014). We gain important insights into the role of fatty acid type and amount with cognitive function and healthy aging. Cross-sectional studies assessing the relationship between plasma nutrient biomarkers and imaging/cognitive indices in dementia-free older adults find correlations between fatty acid status and brain health (Bowman et al, 2014). Observations that men in the highest quintile of serum EPA+DHA have a 33% lower risk of type 2 diabetes (Virtanen et al, 2014) should be the basis of further research evaluating the impact of suboptimal omega-3 status on individual risk and health care costs.
The World Economic Forum is meeting this week to develop insights, initiatives and actions to address current challenges, one of which is malnutrition. As Marc Bellemare wrote in Foreign Affairs, the primary needs of the poor are clean water, plentiful and nutritious food, and a steady source of income. Just as he hopes to avoid mission creep, is it too idealistic to hope that nutrition guidance be based on nutritional biomarkers rather than food and supplement records?
Pottala JV, Yaffe K, Robinson JG, Espeland MA, Wallace R, Harris WS. Higher RBC EPA+DHA corresponds with larger total brain and hippocampal volumes: WHIMS-MRI study. 2014 Neurol doi: 10.1212/WNL.0000000000000080
Wood KE, Lau A, Mantzioris E, Gibson RA, Ramsden CE, Muhlhausler BS. A low omega-6 polyunsaturated fatty acid (n-6 PUFA) diet increases omega-3 (n-3) long chain PUFA status in plasma phospholipids in humans. 2014 PLEFA doi: 10.1016/j.plefa.2013.12.010
Bowman GL, Silbert LC, Howieson D, Dodge HH, Traber MG, Frei B, Kaye JA, Shannon J, Quinn JF. Nutrient biomarker patterns, cognitive function, and MRI measures of brain aging. 2012 Neurol doi: 10.1212/WNL.0b013e3182436598
Virtanen JK, Mursu J, Voutilainen S, Uusitupa M, Tuomainen T-P. Serum omega-3 polyunsaturated fatty acids and risk of incident type 2 diabetes in men : The Kuopio Ischemic Heart Disease Risk Factor Study. 2014 Diabetes Care doi: 10.2337/dc13-1504