27 August 2020
Questions of the best diet to promote health and prevent disease are never far from the headlines; this is an area enthusiastically embraced by all manner of people keen to sell prescriptions (and frequently accompanying products) for a healthier life. One of the latest is the ‘DNA diet’, that tells you how you should eat based on analysis of your genetic factors related to nutrition-linked health traits such as metabolism and cholesterol processing, it joins similar offerings that will prescribe personalised fitness regimes or even skincare products based on genetic analysis - for a price.
However, behind all the hype there lie some undoubted truths: what and how we eat definitely does have relevance to our health, and different people vary both in propensity to disease and responses to food. Can science such as the study of nutrigenomics and the microbiome shine a genuine light on these issues?
The influential US National Institutes of Health (NIH) has a strategic plan for nutrition research, outlined in a recent JAMA article; it defines precision nutrition as efforts to ‘understand the health effects of the complex interplay among genetics, microbiome, antibiotic and probiotic use, metabolism, food environment, and physical activity, as well as economic, social, and other behavioral characteristics’.
Precision nutrition might therefore be considered a subset of or specialism within precision medicine, and indeed a potentially important element in personalised prevention of disease: in particular, a host of common conditions such as obesity and diabetes, cardiovascular disease and cancer that represent a huge burden on health systems, and for individuals. Poor nutrition is known to be a significant risk factor for many such diseases; finding public health solutions definitely necessitates a holistic approach addressing social and economic factors as well as diet – but science could also play a vital role.
Though a nascent field where the unknowns definitely outweigh the knowns, the potential importance of understanding these critical and undeniably complex interactions is vast. So it is good to see the NIH blazing a trail in research to address fundamental questions: how nutrition affects health and disease, how it interacts with the genome and other significant (and potentially modifiable) elements such as the human microbiome, and how this knowledge could be used to prevent disease and promote health. As the authors note, only ‘with a firm grasp of the contributions and interrelationships among these factors will it be possible to develop targeted nutrition guidance for diverse individuals in a highly diverse world’.
To consider one issue alone, obesity – for which poor nutrition increases risk, though it is possible to be well nourished and also obese – is a clear goal for public health gains: reducing obesity improves health. But the causes of obesity are both complex and varied, and include not only environmental and social issues but also undoubtedly psychological and genetic factors. Still, a better understanding of precision nutrition might help unravel the biological aspects and enable more effective and personalised interventions to prevent or manage overweight and obesity at the individual level, as well as informing population level strategies.
It could also inform wider health challenges; for example, people living with obesity and other chronic diseases with dietary influences are known to be at greater risk from COVID-19, and it has been suggested that the increased risks in these groups may be in part due to impaired immune responses related to nutritional status; and this could also increase risk for other people without the diseases.
There is much to admire in the new NIH strategy, not least the commitment to innovative research approaches drawing on diverse experience, and the application of multidisciplinary expertise. It also sees a big role for wearable and point of care devices in research – which will begin with a major cohort study - to examine the genomes, microbiomes and dietary intakes of participants.
Overall, the programme seeks to address four fundamental questions:
Many already purport to have the answers to these questions, but the truth is we are only at the beginning of a mission to mobilise new and emerging science and technology to help us understand the true roots of health and wellbeing. Nutrition is undoubtedly one , and should play an important role in wider efforts to develop personalised and population approaches to disease prevention.