‘Personalised nutrition’ represents any attempt to provide tailor-made healthy eating advice based on the nutritional needs of an individual, as dictated by their behaviour, phenotype and/or genotype and their interactions. Increasing evidence has shown the potential for integrating lifestyle habits, physiology, nutraceuticals, the gut microbiome and genetics into nutritional solutions, specific to the needs of each individual, for maintaining health and preventing disease.
One area that has been gaining attention among both health professionals and the general public is nutrigenomics - the role of nutrients in gene expression. On a molecular level, nutrients work as messengers, transmitting signals that can be translated into changes in gene, protein, and metabolite expression and function, which may ultimately affect health outcomes. By employing molecular tools, nutrigenomics research identifies how nutrients and bioactive food compounds may alter gene expression, ultimately helping us to understand why people respond differently to the same diet and how genes and diet interact and predispose us to disease.
Advances in nutrigenetics - how genes impact nutrient metabolism - and nutrigenomics do seem to encourage more personalised advice when it comes to food intake and nutritional supplements.1
We are used to receiving generalized dietary guidelines and specific recommendations on food intake and nutrient supplements, based on age, gender and other requirements (e.g. during pregnancy or times of illness). For instance, many people will - at least intuitively - be familiar with some of the following daily nutritional recommendations for adults2:
- 200 µg folic acid
- 40 mg vitamin C
- No more than 6 g salt
- At least five portions of a variety of fruit and vegetables
- No more than 11% of energy from saturated fat
Deficiencies in calcium, potassium, dietary fibre and vitamin D are also generally considered a public health concern.3 Some supplementation can be recommended. For example, folic acid taken during pregnancy to reduce the risk of malformations developing in the brain and spinal cord of the unborn child.
By using information obtained from whole genome analysis, an individual’s genome can be scanned for polymorphisms (usually referred to as single nucleotide polymorphisms [SNPs]) in genes related to nutrient metabolism and disease development. For example, the methylenetetrahydrofolate reductase gene is associated with folate metabolism. If the common 677C-->T mutation (also known as the A222V mutation) is present in the methylenetetrahydrofolate reductase gene, it can result in an enzyme that has reduced activity. Should a person’s diet be low in folate, the presence of the 677C-->T mutation may lead to an increased risk of elevated homocysteine levels and a further moderate risk of cardiovascular disease.4,5 On a similar note, genetic variation may, at least in part, explain interindividual differences in plasma triacylglycerol concentrations on administration of polyunsatuared fatty acids, such as those found in fish oil,6 and it may also help explain why vitamin D might confer an increased risk of cancer development in some, while decreasing the risk in others.7
So, is the future of gut (and general) health in personalised nutrition? How can we test it? Evidence-based medicine (EBM) relies on findings from randomized controlled trials to identify whether or not a given treatment or behaviour leads to a certain outcome. We have become used to EBM being critical to medical decision-making. A one-size-fits-all approach may appear inherently incompatible with the concept of personalised nutrition, and challenges arise when agreeing on the extent, quality and interpretation of evidence and consequent implications for dietary recommendations, particularly within the nutrigenomics arena.
When will nutritional research be ready to be translated into public health action? Will personalized nutrition produce greater behaviour change and gains in health and wellbeing than can be achieved by conventional dietary advice?6 Although lowering the levels of dietary salt and saturated fats has had a positive effect on hypertension and lipid profiles, as demonstrated in clinical trials in healthy populations, limited trial data exist that prove a cause–effect relationship and a consequent reduction in disease by these dietary interventions.6 We also need to keep in mind that genes work together and not in isolation. This means that the presence of one SNP needs to be interpreted in the context of a person’s overall biochemistry, nutrition, and other lifestyle factors, such as activity, sleep and stress.
With advances in genetic testing, public awareness of personal genome testing and its potential is increasing. Companies are now offering affordable genetic testing options directly to the public. While there may be benefits to having your genetic information available, including the potential for personalised nutrition, there are also many risks and limitations that need to be highlighted and considered. These include, but are not limited to, whether there are sufficient regulations imposed on companies who perform genetic testing, interpretation and delivery of genetic information (via guidance of a health professional), ethical and social concerns, and privacy in terms of how DNA information is stored and used.
Nutrigenomics and nutrigenetics, albeit an exciting area, is still relatively young and has not advanced enough to allow us to develop a diet based on a person’s entire genome–much more work is required before this can happen. Nonetheless, these tools have developed enough to highlight some nutrient–gene (and environment) interactions. So, for now, our advice is to watch this space as the field of personalised nutrition research continues to develop - who knows where we will find ourselves in the years to come!
Before you go, we would also like to guide your attention to the nutrition guidelines that are available in the UEG Standards & Guidelines Repository, including many from ESPEN and ESPGHAN!
- Fenech M, El-Sohemy A, Cahill L, et al. Nutrigenetics and nutrigenomics: Viewpoints on the current status and applications in nutrition research and practice. J Nutrigenet Nutrigenom 2011; 4: 69–89.
- Food Standards Agency. Nutrient and food based guidelines for UK institutions. https://www.ptdirect.com/training-design/nutrition/national-nutrition-guidelines-united-kingdom. (2007, revised October 2007, accessed 11 May 2018).
- Blumeberg JF, Bailey RL, Sesso HD, et al. The evolving role of multivitamin/multimineral supplement use among adults in the age of personalized nutrition. Nutrients 2018; 10: 248.
- Kohlmeier M, De Caterina R, Ferguson LR, et al. Guide and position of the International Society of Nutrigenetics/Nutrigenomics on personalized nutrition: Part 2 – Ethics, challenges and endeavors of Precision Nutrition. J Nutrigenet Nutrigenom 2016; 9: 28–46.
- Liew SC and Gupta ED. Methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism: Epidemiology, metabolism and the associated diseases. Eur J Med Genet 2015; 58: 1–10.
- Görman U, Mathers JC, Grimaldi KA, et al. Do we know enough? A scientific and ethical analysis of the basis for genetic-based personalized nutrition. Genes Nutr 2013; 8: 373–381.
- Davis CD and Milner JA. Nutrigenomics, vitamin D and cancer prevention. J Nutrigenet Nutrigenom 2011; 4: 1–11.