The ANS proposes a call to action for development of systematic approaches to assess quality and relevance of mechanistic research in the development of nutrition policy.

Academy of Nutrition Sciences (ANS) warmly welcomed the BBSRC’s new response mode funding Spotlight initiative, which will focus on proposals which help to build a stronger understanding of the biological basis underlying effects of nutrition on human health (BBSRC launches new responsive mode spotlight pilot – UKRI).

This considers mechanistic research in nutrition to be vital in providing evidence of causal relationships between diet and health and central to the formulation of effective public health policy in nutrition..

However, the policy relevance of many cell and animal mechanistic studies is frequently questioned because of insufficient attention given to key aspects of study design. It is certainly the case that compliance to experimental diets can be more readily assured, and measured more accurately, in cell and animal models compared with humans. Nevertheless the literature includes many examples where extreme dietary exposures, which are unfeasible or potentially harmful in humans, are fed. Lack of relevance of the models themselves, or unfeasibility of the diets, means the data have limited applicability in making policy recommendations for human populations.

A challenge raised in this blog is whether such studies should continue to be funded where extrapolation of the data to humans, and consequent impact on human health, is known at the outset to be low? Is there opportunity to strengthen the value and impact of cell and animal research to human nutrition?

The first Academy paper in the Evidence-base series (Nature of the evidence base and frameworks underpinning dietary recommendations for prevention of non-communicable diseases: a position paper from the Academy of Nutrition Sciences | Semantic Scholar) emphasised how research in nutritional epidemiology has been strengthened by the development of methods and criteria for systematically selecting and assessing the quality, consistency and relevance of epidemiological findings to human diet-disease relationships. This approach has not only improved the quality and consistency of findings but is also widely used by groups working in nutrition policy.

Could similar approaches be used to enhance the relevance of mechanistic research? A recent review in the Proceedings of the Nutrition Society (https://www.doi.org/10.1017/S0029665122002750) emphasised the importance of mechanistic research in nutrition and its potential to confirm the causality of relationships shown in observational epidemiological studies. The review described early findings from a series of studies conducted by a group of diet and cancer researchers in Bristol and was funded by the World Cancer Research Fund. Their aim was to develop and validate a systematic framework for selecting, assessing and integrating data from cell, human and animal studies in the area of diet and cancer (https://www.semanticscholar.org/paper/Developing-the-WCRF-International%2FUniversity-of-for-Lewis-Gardner/a99c0eccea144e5b58a36df60055b6594e8bba35 ).

The proposed framework has demonstrated valuable early findings but also a number of significant challenges which include the heterogeneity of within and between species data and lack of agreed standards and criteria for cell and animal work involving diet.

As a nutrition community, should the challenge of defining agreed standards and criteria for cell, animal and human mechanistic research be a greater priority for us than has been the case to date?