Personalised nutrition: What makes you so special?

Personalised nutrition can be defined as developing unique nutrition guidelines for each individual; precision nutrition seeks to develop effective approaches based on the combination of an individual's genetic, environmental and lifestyle factors. The former infers variants that underlie traits are largely fixed (i.e. stable across time) and appeals to the notion that we are inherently different from one another. The latter opens up the possibility that what we do and where we are may be more important than what we are. While there are undoubtedly a specific minority of individuals who clearly require a more personalised approach to nutrition, several criteria must be fulfilled before we can justify or implement personalised nutrition for the general population. These would include identifying a desired health outcome and a valid predictor of how that outcome changes, which can be measured with sufficient accuracy and exhibit a robust correlation and/or causal relationship in the required direction (i.e. predictor-response). Many attempts to personalise nutrition, such as profiling the genome or microbiome, do not currently meet all these criteria. Therefore, we argue that there is presently insufficient rationale for truly personalised nutrition for the majority of people based on the inter-individual differences that separate them. Conversely, we propose that precision nutrition based on the environmental and/or behavioural 'lifestyle' variance within each person may provide a more effective basis for adjusting diet dynamically, with recognition of varying physiological demands and requirements over time.