Can what you eat have an effect on your genes?

Can what you eat have an effect on your genes?

Can what you eat have an effect on your genes

The future of nutrition

The science is out – what you eat has an effect on your genes, and consequently on your jeans too!

More and more we’re coming to realise that one-size-fits-all health and dieting strategies don’t work. It explains why your two colleagues have lost a ton of weight banting, while you’ve struggled through, tearfully turning away that comforting bowl of pasta in the hopes it’ll eventually start to work for you. It’s why someone can smoke for their whole
life and die of natural causes, while a young 40-year-old who never smoked succumbs to lung cancer. It’s all to do with your unique, genetic coding.


During the 1990s, a team of international researchers undertook the mapping of human DNA in the hopes of unravelling its secrets and what lies behind the human genome. Finally completed in 2003, the Human Genome Project revealed the full sequence of the human genome. This scientific breakthrough revolutionised many
medical and biological fields, even laying the ground for new ones such as nutrigenomics, a branch of nutritional science that focuses on the molecular-level interaction between nutrients and other dietary bioactives with the genome. While still a relatively new area, nutrigenomics is a rapidly expanding field that may hold the key to
humanity’s increasingly dangerous dance with the likes of obesity, diabetes, and cardiovascular disease. It looks closely at how an individual’s cells react when they eat or don’t eat, eat too much, or what happens when they eat a particular food.

Words to know

  • Genome: Your DNA, or more specifically the genetic material you’re born with and that makes you you.
  • Epigenome: The network of chemical compounds that interacts with your genome by directing which
    gene to activate or which to leave inactive. It’s affected by your health, diet, nutrition, exercise, and other lifestyle choices.
  • Penetrance: In genetics, penetrance refers to the proportion of people with a particular genetic variant, such as a mutation in a specific gene, who exhibit signs and symptoms caused by the mutation.
  • Bioactive components: A compound that has an effect on a living organism’s cells. These compounds
    are found in both plants, such as carotenoids and polyphenols, and animal products, like fatty acids in
    fish, or they can be synthetically produced. Bioactive compounds also include flavonoids, caffeine,
    creatine, and polysaccharides.

Rochez O’Grady, a registered dietitian at in Cape Town, explains the field of nutrigenomics as ‘the study of how nutrition, especially the bioactive components in food, has an impact on our genes’. The bioactive components found in food can regulate your genes – either upregulating (turning them on) or downregulating
(turning them off). In other words, what you eat influences how your genes behave and respond.

‘Let’s give a practical example,’ says Rochez. ‘The bioactive phytochemical sulphoraphane, found in broccoli and other cruciferous vegetables, is essential in assisting your body’s detoxification process. Sulphoraphane also upregulates, or turns on, over 2 000 other genes in your DNA. Your detoxification process takes place in your liver.
During phase two of detoxification there are gene variants that can impair this process. These genetic variants increase the risk of developing certain cancers. By including more cruciferous vegetables in your diet, you can assist your body with the detoxification process and promote disease prevention.’

In another example, certain genes can be upregulated by polycyclic aromatic hydrocarbons (PAHs), chemicals released from burning coal, oil, gasoline, tobacco or charcoal. ‘This would be a case where gene expression can increase the risk for certain diseases through nutrition. The aim here is to decrease exposure to environmental
pro-carcinogens such as cigarette smoke, smoked and chargrilled foods,’ adds Rochez.

Key nutrients and foods that support detoxification

If you have a diagnosed problem with detoxification, try the following foods. They contain sulphoraphane, which activates genes that protect against inflammation.

  • Cruciferous vegetables: rocket, bok choy, broccoli, broccoli sprouts, Brussels sprouts, cabbage,
    cauliflower, collard greens, horseradish, radish, kale, turnips, watercress.
  • Allium vegetables: onion, garlic, leeks, chives, spring onions.
  • Beetroot
  • Turmeric


But what are they testing?

‘Your DNA is made up of a double strand helix joined by complementary base pairs. You receive 50% of your genes from each parent and when your DNA is replicated, variants occur,’ explains Rochez. ‘This means there is a different single base pair than originally. These are called Single Nucleotide Polymorphisms (SNPs) or gene variants. These SNPs are the low penetrance genes that affect the cellular defence pathways.’ These remarkable variants in our DNA also underlie differences in an individual’s susceptibility to certain diseases.

‘The genes we test are low penetrance genes,’ adds Rochez, ‘which means that nutrition and lifestyle factors can influence them.’ Genes also influence how you metabolise and store fats, your response to exercise, your ‘sweet
tooth’ tendencies, or addictive behaviour towards carbohydrates, including your appetite and satiety, all of which have a direct influence over your weight and eating behaviour. ‘Because your genes are responsible for every cellular
process within the body, gene expression influences our cellular defence processes. These are methylation (DNA repair process), detoxification, energy production, redox status (of which oxidation is a part) and inflammation. And in
turn these processes control your disease risk for things like diabetes mellitus, heart disease, certain cancers, high cholesterol, high blood pressure and much more,’ she explains.

What you eat directly determines the genetic messages your body receives. These messages, in turn, control all the molecules that constitute your metabolism: the molecules that tell your body to burn calories or store them. If you can learn the language of your genes and control the messages and instructions they give your body and your metabolism, you can radically alter how food interacts with your body, lose weight, and optimise your health. — Dr Mark Hyman

Genetic testing and your unique results allow a dietician to design and prescribe a nutritional diet based on your genome and your genetic variations. Testing is a simple and painless process where a quick cheek swab sample
is sent to a genetic laboratory to be analysed. ‘The analysis of your genes usually takes 2-3 weeks, says Rochez. ‘Once the report is received, an appointment is made for the interpretation of the results, and based on those results we would recommend clear dietary and lifestyle changes.’ If your genetic results indicate you’re at higher risk for certain cancers or perhaps heart disease, it doesn’t necessarily mean you will succumb to cancer or heart disease. It rather indicates that you’re at higher risk.

‘We’ll then work on necessary dietary interventions and lifestyle changes you can implement to ensure prevention,’ adds Rochez. That’s where the brilliance of nutrigenomics comes in. ‘The DNA test shows which defence processes need extra support and how these needs can be addressed nutritionally. It shows us exactly which areas to focus on to prevent disease and optimise your health!’ Should you choose to look into your genes to improve your overall nutritional health, make sure that whoever is doing the DNA test and interpretation of the results is reputable.
‘Nutrigenomics is an exciting and dynamic new tool and it’s great using it to help personalise nutrition,’ says Rochez.


Joni van der Merwe

About Joni van der Merwe

Digital editor I’m getting married in 2018 and I think it’s the perfect time to focus on my relationship with not only my fiance but my friends, family and colleagues too. I want to nurture and cherish the people I love by being more understanding and present in their lives.


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