Nutrigenomics, the study of how genes, nutrients and lifestyle factors interact, is no longer the future of medicine. It’s here today, and this exciting new field of medicine is already being practised by forward thinking nutritionists, doctors and health professionals throughout the world. Clinical nutritionist and accredited nutrigenomics practitioner, Sheena Hendon provides insight into how the exciting world of human genome discovery and the latest nutritional science is set to change medicine, nutrition and even the food industry forever.

Two guys of the same age eat a diet low in fruit and veggies and high in sodium and saturated fat. One develops hypertension, hypercholesterolemia, and eventually atherosclerosis, while the other lives a long life without chronic disease. Two women consume similar diets low in essential fatty acids and high in refined carbohydrates and are equally active. One puts on weight, and the other is as skinny as a bean pole.

Why individuals experience different health outcomes even though they eat similar diets and practice comparable lifestyles is an important question asked for decades. While it’s long been suspected that genetics play a critical role in determining how a person responds to dietary intake, as well as environmental and lifestyle factors, it is only in recent years this has been proven.

How it all began

It all started in the 1950’s when Watson and Crick proposed the double helix structure of DNA (short for deoxyribonucleic acid). Although DNA was discovered over a century ago, this finding enabled researchers to make great strides in understanding genetics especially after the completion of the Human Genome Project (HGP); an international scientific research project mapping and sequencing the entire human genome (the complete, unique blueprint of every person). Scientists then discovered nutrition and lifestyle choices such as smoking and alcohol consumption could influence gene expression and our health and wellbeing.

Genetics 101

Here’s a quick overview of genetics

• DNA is the hereditary material in humans and almost all other organisms.
• A gene is a segment of DNA that contains information on hereditary characteristics such as hair colour as well as predisposition to specific health risks. Genes provide the instruction manual for how, when and where we make each of the many thousands of proteins required for life.
• Each gene comprises of thousands of nucleotides; combinations of four “genetic” letters: A, T, C and G, for adenine, thymine, cytosine and guanine.
• Every person has two copies of each gene, one inherited from each parent. People have 99.9% identity between their However, it’s the 0.1% genetic variation which can change the way our body responds to different foods, bioactive compounds and environmental exposures.
• There are two types of genetic variation among individuals, SNP (single nucleotide polymorphism, pronounced “snip”) or lifestyle (copy number variation).

• A SNP may or may not have an effect on an individual’s health. In rare cases, a SNP can cause a disease, such as sickle cell anaemia. More often, SNPs affect health by increasing or decreasing chronic disease risk.
• CNV are genes, where at some point in evolutionary history, communities have developed additional copies of genes that assist in adapting to their particular environment. The number of copies can vary enormously. For example, the gene coding for amylase, AMY1, can have anywhere from 1 to 20 copies.

Every time we come to the dinner table, we bring not only our appetite but also our genes.

Our genes are not our destiny

While you can’t change your inherited genes, you can compensate for their influence by choosing better nutritional matches for your genes. DNA damage can be repaired, and gene expression can be ‘dialled up or down’ to significantly improve the functioning of our genes. The effect can start in the earliest stages of embryo development or even before conception to effect the sperm and egg and continues throughout our lifetime.

Many of our genes are essentially like a “dimmer switch” for a light; They can be ‘dialled up’ or ‘dialled down’ depending on what foods we eat and other lifestyle choices

Nutrigenomics in action

• Developing individual nutritional and lifestyle plans

There are a number of accredited nutrigenomic, gene profiling practitioners in NZ – all of whom are qualified health professionals including dietitians, doctors and nutritionists. All you need for gene profiling is for the patient to provide a single saliva sample which is sent off to a lab and used to detect gene variants.

Given that there are thousands of genes how do we know which genes to profile?

Fitgenes, one of the most experienced genetic profiling organisations in Australasia, applies rigorous selection criteria to determine genes that are suitable; these genes must:

• influence the physiological functioning of our body at the cellular level;
• have been researched and supported by solid peer reviewed scientific research;
• have variations greater than approximately 10% in different ethnic populations; and,
• have nutrition, exercise and lifestyle interventions that can change the gene expression and influence health and wellbeing.

For example, in the case of obesity, we would examine genes that express for fat absorption, metabolism and transport, thermogenesis, inflammation and appetite control. Genes such as the AMY1 gene, which determines the amount of alpha-amylase enzyme within saliva, can determine how well our body metabolises starch carbohydrates, and influence such health issues as food intolerances, weight gain, insulin resistance or Type 2 Diabetes. Or Leptin gene polymorphisms LEPR-1 and LEPR-2 may lead to poor appetite control and increased food intake.

A genetic profile report identifies the individual’s gene activity, such as how well the patient is likely to metabolise starch carbohydrates, controlling food intake or likelihood of inflammation. Then the practitioner will design a customised dietary and lifestyle intervention strategies to recover normal homeostasis and to prevent diseases.

What about the food industry?

There are already products available: ‘functional’ foods enriched with various nutrients and non-nutrients such as omega-3 fatty acids or folic acid to prevent or treat diseases and specific foods and already diets are used for coeliac disease patients and other single gene diseases. So we can predict the future development of beverages and foods as preventive agents or for the treatment for individuals, families or subgroups with certain gene profiles predisposed to a particular disease. For example, diets balanced in the essential fatty acids are paramount for patients with chronic inflammatory diseases, such as arthritis, asthma, or ulcerative colitis, as well patients with coronary artery disease and hypertension.

What is the downside to nutrigenomics?

People may be reluctant towards genetic testing because they fear misuse of information generated. Additionally, insurance brokers, who already have the right to demand disclosure of factors affecting health may ask to include genetic information which may have a direct effect on life insurance.

In summary

The era of personalised medicine has arrived, no longer do we need a one size fits all approach to our health. Nutrigenomics research is still in its infancy, and more research necessary to understand the mechanism and overcome the limitations or hurdles entirely.

Find out more about testing for you and your family by checking out Genetic profiling and booking in for a session.

Written by Sheena Hendon, BSc Honours (Nutrition & Dietetics), BHSc (Natural Medicine with distinction). www.sheenahendonhealth.co.NZ

Sources:

Amin, Tawheed, et al. Application of nutrigenomics in food industry: A review. Indian Horticulture Journal 2.3and4 (2012): 54-59.

BBC Knowledge (2017) DNA. Understanding the basics. Retrieved from  https://vimeo.com/60747882#sthash.jnYeGZfu.dpuf

Fenech, Michael. “Nutrigenomics and Nutrigenetics: the New Paradigm for Optimising Health and Preventing Disease.” Journal of nutritional science and vitaminology 61.Supplement (2015): S209-S209.

Fitgenes. (2017). Practitioner FAQ. Retrieved from http://www.fitgenes.com/about_fitgenes/practitioners/practitioner-faq

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Home page: National Library of Medicine (US). Genetics Home Reference [Internet]. Bethesda (MD): The Library; 2013 Sep 16 [cited 2013 Sep 19]. Available from: https://ghr.nlm.nih.gov/.

Nutrigenomics NZ (2017) Retrieved from http://www.nutrigenomics.org.nz/our-science

Ronteltap, J. C. M. van Trijp, and R. J. Renes, “Consumer acceptance of nutrigenomics-based personalised nutrition,” British Journal of Nutrition, vol. 101, no. 1, pp. 132–144, 2009.

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Salem, Rany M., and Laura Rodriguez-Murillo. “Human Genome Project.” Encyclopedia of Behavioral Medicine. Springer New York, 2013. 1003-1004.