We are bombarded with advice proclaiming the ‘best’ way to stay healthy, lose weight and improve our fitness. But despite the wealth of information available to us, in the UK, over 60% of adults and 30% of children are overweight or obese. Apart from the personal impact on individuals, the resource implications of this are staggering, with an estimated £7 billion spent in the NHS per annum treating ill health related to overweight and obesity. In a tempting environment of plentiful calories, and less physically demanding lifestyles, is there a different way of approaching the problem?
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In the past, nutrition and lifestyle advice has been based on large cohort studies so what seemed to be good for the population (e.g. cutting back on salt) was deemed good for you too. Whilst this is still likely to be true, you might be someone who is acutely affected by salt consumption, and the safe limit for you may be much lower than the ‘average’ person. Therefore nutritional advice could, in theory, work more effectively if it was carefully tailored to the individual.
What can nutrigenomics measure?
With the aim of finding clinical applications for personalised nutritional guidance, nutrigenomics research utilises an array of analytical techniques to measure a wide range of metrics, to drill down into the in vivo processes occurring when we (or rather our genes) interact with our nutritional environment, and the potential consequences for our health. The term ‘nutrigenomics’ has come to embrace a combination of assays including, but not confined to, genomic analysis, which attempt to correlate aspects of our metabolic phenotype with our genetic makeup. At the ‘top’ level food intake can be measured, with activity and exercise levels. At the ‘deepest’ level, genomic analysis can identify genetic variants which may have an influence on our nutritional response or our drive to eat. In between these two sets of metrics, nutrigenomics can examine in vivo processes at increasing level of depth, from the measurement of hormones, cytokine or metabolite levels in the blood or urine, through to gene activity and protein translation with the use of transcriptomics or proteomics.
Nutrigenomics research studies have measured levels of blood glucose or fatty acids following food intake looking for correlations with genetic markers or variants with the aim of linking this to disease phenotypes, for example diabetes or heart disease.
Differences in our gut microbiome, which are thought to have an important influence on our metabolism, can also be measured and factored in to nutrigenomic analyses. All of this data can be correlated with anthropometric and phenotypic data such as age, gender, weight and disease status, to highlight where differences between individuals or groups exist, and the consequences in terms of our health. For example, nutrigenomics research studies have measured levels of blood glucose or fatty acids following food intake looking for correlations with genetic markers or variants with the aim of linking this to disease phenotypes, for example diabetes or heart disease.
How could this be useful?
If individuals or groups of individuals with specific ‘metabotypes’ could be identified in this way, it may allow risk stratification, so that preventive strategies, for example, to prevent diabetes, could be delivered in a more targeted and effective way. Therapeutic strategies might be devised to work more synergistically with the individual, so that weight loss advice may take account of an individual’s biology and well as, say, their personal preferences for exercise, to increase the chances of success. Some studies have suggested greater success with weight loss programmes incorporating personalised advice, based on genetic variant information and psychosocial profiling, but there is some debate as to what extent this can be attributed to the science underpinning the advice, or whether there is to some degree a kind of ‘vanity placebo’ effect- perhaps people engage more enthusiastically with a method which claims to understand them and work with them, rather than a more utilitarian approach. Further work is needed to replicate findings, using larger cohorts and most importantly, to see if sustained benefits can be achieved over the longer term.
The science: what’s needed to build the evidence base for nutrigenomics?
Building the evidence base in nutrigenomics is vital, and there are some key areas where efforts could be concentrated:
- Establishing causality - practically all of the studies thus far involving genetic markers, have reported associations between genetic variants and phenotypes, therefore intervention studies are needed to establish causal links.
- Growing skills in novel analytical techniques- some of the analytical techniques which nutrigenomic analyses may draw on, such as proteomics and metabolomics, are technically challenging and at a relatively early stage of development.
- Data sharing initiatives- to provide suitably powered data sets, and bioinformatic systems and algorithms which are critical to building the evidence base and realising the potential of nutrigenomics research.
The applications: could this translate into better care and better outcomes?
Nutrigenomics represents a new way of looking at us as individuals in our nutritional environment. There are many potential applications but, to take weight management as a key example, I think there are two main challenges nutrigenomics faces on the path to the clinic.
The research must clearly demonstrate the magnitude of the benefits it can bring. For example, for weight loss programmes, greater evidence is needed to demonstrate a significant and sustained difference in outcome in larger cohorts, before investment in this as an alternative or adjunct to existing public health strategies.
Providing meaningful nutrigenomic data in a manner which is acceptable to people in real life settings. The technologies which nutrigenomics research uses, such as home-based sensors or personal sensors, can yield impressive data but any preventive or therapeutic strategy must be acceptable to patients to avoid non-adherence. Food is more than a biological fuel and there are many complex factors which come in to play at each individual food choice- emotional and social factors all play a part and intervening in this part of people’s lives is not an easy task.
Nutrigenomics research encompasses a broad range of technologies with potential applications in numerous clinical areas. In terms of its application in weight management, a multi-faceted approach to tackling the problem of obesity is likely to yield the greatest success, with ‘top-down’ external measures to help ‘clean up’ our nutritional environment, for example, less sugar in fizzy drinks, combined with scientifically valid nutrigenomics advice to empower individuals to best help themselves.