COULD KNOWING YOUR GENES HELP YOU LOSE WEIGHT?
You are unique. Yes, you really are! What’s good for you isn’t necessarily good for me. Your carb tolerance is my muffin top (and it goes far further than that.) Here’s a new approach to health that starts with you.
ITwas a mammoth project. Over the 10 years leading up to the millennium, scientists from around the world worked together on the Human Genome Project to identify and sequence the chemical components of the human genome (the complete set of our DNA, including all our genes). Their goal was to identify all 3.3 billion of the base pairs (adenine, cytosine, guanine and thymine, abbreviated to A, C, G, and T) that comprise that genome. We said it was mammoth! The reason? The sequencing of the bases of the DNA molecule determines what controls our growth, development, functioning and reproduction. So it’s the key that unlocks (some of) the mysteries of life, really. And they did it!
Sequencing the genome means we can see which genetic variants
Sequencing the genome means we can see which genetic variants up the risk of diseases like diabetes and cancer, and we will also be able to custom-design medications for someone’s specific genome.
up the risk of diseases like diabetes and cancer, and we will also be able to custom-design medications for someone’s specific genome, making the medication more effective and potentially reducing side effects.
OF COURSE, IT’S NOT THAT SIMPLE…
We may have sequenced the genome, but nothing is written in stone: genes react to their environment – to things like the food we eat, who we interact with, when and how much we sleep, and how we exercise. Genes can be turned off and on. If you think of the human lifespan as a very long movie, says What is Epigenetics? (a great online resource), ‘the cells are the actors and actresses, essential units that make up the movie. DNA is the script – instructions for all the participants of the movie to perform their roles. The DNA sequence is the words in the script, and certain blocks of these words that instruct key actions or events to take place are the genes. The concept of genetics is like screenwriting. The concept of epigenetics [biological mechanisms that switch genes on and off] is like directing. The script can be the same, but the director can choose to eliminate or tweak certain scenes or dialogue, altering the movie for better or worse’.
IT’S A SNIP!
The way the food we eat interacts with our genes to affect our health is an exciting new area of study called nutrigenomics, which is a nutritional guide to preventing and managing diseases associated with obesity. A lengthy list of genetic variants called ‘snips’ (single nucleotide polymorphisms, or SNPs) are associated with common chronic diseases, especially in tandem with particular diets or foods. ‘We have loads of gene variants, and it’s perfectly normal,’ Rochez O’Grady explains.
‘You get 50% of your genes from your mum and 50% from your dad, and in that replication process, the amino acid or base pair often differs from the original, and that “spelling mistake” is called an SNP or gene variant. Your DNA is a double helix strand. Two base pairs connect the helix, and there are four letters in the DNA ‘alphabet’. So a different amino acid is the gene variant.’
For example, Dr Ahmed ElSohemy, associate professor at the University of Toronto, and Canada Research Chair in Nutrigenomics, says a study they published in the Journal of the American Medical
Association showed that in some people, caffeinated coffee intake lowered the risk of heart attacks. But in others, the same amount increased the risk of heart attacks: it came down to whether they had the ‘slow’ or ‘fast’ version of the gene CYP1A2 (which breaks down caffeine in the liver).
These findings suggest that caffeinated coffee increases heart disease only in those who have a limited capacity to break down caffeine, says Dr El-Sohemy. And it’s probably because those with the ‘fast’ version of the gene quickly get rid of the caffeine while preserving the antioxidants in the coffee. He reckons ‘it’s these antioxidants, not the caffeine, that might offer protection for the heart’. My coffee is your poison, then. Or your coffee is my poison. Everyone really is different.
In one type of snip, a diet high in protein is linked with greater weight loss, but in someone with another snip, there’s higher weight regain! Similarly, in the presence of one snip, you see less weight loss with a high-fat diet, and someone with yet another snip sees greater weight loss on a low-fat diet. As
Dr El-Sohemy says, ‘This area of research explains why some people can eat a high-fat diet and have no problem with their cholesterol levels while others experience the exact opposite response.’
There are also links between specific vitamin and mineral deficiencies and disease – when certain genes are ‘switched on’: low vitamin D is linked with type 2 diabetes, and low selenium, with cardiovascular disease. So that’s where the science is. But…
CAN ANYBODY BE TESTED?
Yes, they can – but it’s still extremely expensive. Rochez uses genetic testing in her practice, as do some local dieticians and healthcare practitioners. No needles necessary – just a swab from inside your cheek. The sample is sent to the DNAlysis Biotechnology labs to identify the range of genes depending on your needs.
‘I usually ask a client about their goals. The foundation range of tests is DNA Health, which tests for 36 gene variants involved in cholesterol metabolism and risk for heart disease; bone health and osteoporosis risk; vitamin B metabolism and cancer risk; inflammation and oxidative stress, detoxification; insulin sensitivity and diabetes risk; food responsiveness including lactose intolerance, caffeine processing, salt sensitivity and blood pressure.
‘If they’re looking for weight loss, I add on DNA Diet, which looks at genetic variations that impact metabolism, and absorption and storage of fats and carbs. It also identifies the genes linked to binge-eating, a sweet tooth, a larger appetite or reduced satiety.
Then, I check whether there are oestrogen issues, like endometriosis or polycystic ovary syndrome. If there’s a build-up of oestrogen, you have an increased risk of breast or ovarian cancer. I can get enough information from those two tests to see if we need oestrogen support, through the DNA Oestrogen test. If you group the tests together, it’s more affordable – it costs about R3 000-R4 000.’
There’s also the DNA Sport test, which looks at injury risk, recovery and athletic potential.
‘But remember, this is about predisposition,’ says Rochez. ‘It doesn’t look at what’s going on in the body now. A blood test or a urine test will show you that.’
CAN YOU NUKE A GENE?
Rochez explains that the tests she uses are for low penetrance genes – genes you can influence. ‘It doesn’t mean you can change the gene itself, but you can turn it on (up-regulate) or turn it off (down-regulate). You could have a higher risk of developing cancer if you have issues with your detoxification process. But that doesn’t mean you’re going to get cancer. We up-regulate those detoxification genes with nutrition and lifestyle to lower the risk of cancer.’
On the other hand, she explains, high penetrance genes aren’t as readily influenced.
‘An example is BRCA, the gene Angelina Jolie has. The solution was a mastectomy.’
Rochez opens her own report, skimming through the various genes: ‘Here’s TAS1R2, the sweet tooth gene. FTO is about appetite and regulation, but that’s just one part of what it affects. PPARG, that’s in your insulin sensitivity.’ She stops at the GST gene.
‘Detoxification happens in the liver, in two phases. The GST genes are responsible for the second phase, and you either have it or you don’t. I don’t have it, and this deletion is associated with increased risk of lung, larynx and bladder cancers as well as basal carcinomas of the skin.’ Sounds scary. But is there a dietary intervention that might help?
‘I have these other two GST genes, so my phase two isn’t terrible, but it does mean I have to up-regulate my other GST genes. To aid detoxification, I have to eat cruciferous vegetables as the bioactive component in them, sulforaphane, up-regulates your GST.’
She also points out the gene linked to carbohydrate responsiveness.
‘Potatoes and pasta trigger the reward centres in your brain. This gene has been linked to other addictive behaviour patterns too.’
And if you have the MC4R and FTO genes, which are linked to increased appetite and reduced satiety, you have to make sure you eat plenty of protein, and you shouldn’t skip meals, says Rochez.
NATURE & NURTURE
The potential to improve your health by knowing your genome is exciting. But, says Rochez, there are other things besides diet that can influence these genes, like environmental factors.
‘You also have to find out what’s happening in the body right now. If someone comes to me with gut issues, you have to address that. You’ve got your kitbag with all your tools, and genetic testing is a great extra tool. The more information you have, the more you can help.’