Global Non-Communicable Diseases—The Nutrition Conundrum

Poor diets reduce our productivity and increase premature morbidity and mortality (1). Recent estimates suggest that ~45% of cardio-metabolic deaths in 2012 (318,000/702,000) were “associated with” top 10 dietary factors: fruits, vegetables, nuts/seeds, whole grains, unprocessed red meats, processed meats, sugar-sweetened beverages, polyunsaturated fats, seafood omega-3 fats, and sodium (2). Moreover, the health consequences of poor nutrition may be evident across the life-course and have intergenerational impacts (3–6). For example: pooled analyses from birth cohorts across several countries show that women with poor nutritional status give birth to babies which are disadvantaged in terms attaining their full cognitive potential and also have higher risk of developing chronic diseases in adult life (7–10). Thus, the scientific community has enthusiastically been pursuing several kinds of nutritional interventions across life span (in particular during early in utero life) to improve birth outcomes. However, nutrition science (especially nutritional epidemiology) poses particular challenges, for both science and communication of findings to the public. As our knowledge regarding nutrition advances, some long accepted theories are challenged (11, 12). For example, the much celebrated Diet-heart hypothesis by Prof Ancel Keys is now being questioned in the research community. Researchers have argued that the Ancel Keys theory that more saturated fat causes higher CVD was promoted and accepted by the research and policy communities in absence of any other data and stringent cross-examination. This is currently being contested by several groups that speculate/suggest simple sugars are the bigger demon in nutrition epidemiology (13). The purpose of this piece is to try and unpack some of the methodological challenges and obstacles that give rise to the confusion and contradictions in the evolving field of nutrition epidemiology. Below we describe some of the key challenges that underlie some of the contradictory findings and that need to be addressed to move the field forward: