Like me, you were probably taught about Gregor Mendel’s pea experiments at some point during your education, and gained the impression that your genes are a sort of concrete code that dictates everything about you – including how long you will live and what you’ll die of.
However old you are now, it’s safe to assume that our understanding of genetics has changed a lot since you were at school. We now know for example that not everyone who gets breast cancer has the breast cancer gene – and not everyone with the breast cancer gene gets breast cancer. If you let that sentence sink in for a moment you’ll realise that other factors must be involved in the way your genes work, and those factors are diet, lifestyle and environment.
This article is intended as a sort of mini-masterclass to help you understand what we know, what we don’t know and how ‘getting into your genes’ can help you improve your health. It might help you to decide to investigate your own genes – or equally it might make you sure that you don’t. It’s important to make an informed choice, either way.
Your genes = My genes
The first popular misconception is that your genes are different to mine. We all have the same gene set containing around 20000 genes and we all have the same genes in the same place (locus) on the same chromosomes. (Well, OK, boys have a bit missing.) Differences between people occur not when they have different genes, but when they have a different version of the same gene. These variants are called alleles. Some alleles are definitely associated with longer life and better health than others which is one of the reasons they’re so interesting to study.
Most characteristics are controlled by a set of genes, not just one. For example, everyone’s eyes are different because a number of genes are involved in creating the colour. Cancer is similar – there isn’t one single gene for cancer, many genes are involved which makes it a complex disease to research.
Until recently it was thought that genetic instructions were fixed: that one gene = one protein. Now we know that your genes can work together to make different proteins at different times in response to varying environmental signals. And we can use that information to our advantage.
What do genes do?
Commonly, when we talk about genes, we mean the “protein-coding” genes that make the proteins that control your body. (There are lots of other genes, called non-coding genes, that we don’t understand quite so well so I’m not going to go there!) Strands of DNA carry messages that contain the instructions for making different proteins.
We tend to think of protein as something we eat but of course inside the body it’s a different matter. Proteins are what build us and manage us: there are proteins that dictate your eye colour; proteins that build your bone; proteins that carry hormones and nutrients in your blood; proteins that sit in cell membranes letting nutrients in and out; proteins that help you fight infection; and proteins that make you feel happy or sad. Almost everything your body does happens because your DNA makes a protein to set off a reaction. We call this ‘gene expression’.
If you have a ‘wild type’ (normal in the population) gene you will make the ‘normal’ protein for that gene, and if you have a gene mutation the product will be slightly different, or you may make more or less of it than normal. Sometimes that makes all the difference (good or bad) and sometimes it makes no observable difference at all.
What is an SNP?
If you are researching genetics to improve your health you will have come across the term Single Nucleotide Polymorphism, or SNP (pronounced ‘snip’), which refers to a gene mutation where just one nucleotide is copied wrongly, resulting in a change in gene expression. There is a lot of focus on SNPs right now as we discover that these tiny genetic glitches can make a big difference to health by changing the way we process nutrients, switching genes on or off, or cause bottlenecks in biochemical pathways that can increase the risk of health problems like inflammation, obesity, insomnia, hormonal imbalances and cancer.
Every single thing you think, do, breathe or eat acts as information to your genes, and carries the potential to change which proteins are made, and when. Understanding how your genes expression changes with changes to your diet and environment is often called epigenetics though, strictly speaking epigenetics refers to inheritable changes caused by lifestyle.
SNPs have been the focus of a lot of research because studying various gene mutations helps us to understand how genes work. Along the way we have learned a lot, including how you can use different approaches to manipulate gene expression – and that knowledge is very important for health.
How can we influence our genes?
For example, if you eat salmon and broccoli today on your yoga course your genes will be expressed in a different way than when you eat fish and chips tomorrow after a long, stressful day at work. Our increasing understanding of gene behaviour has led to a growing scientific interest in the relationship between genotype and the risk of developing diet-related diseases such as diabetes, obesity and cancer.
Nutrigenetics is the science of changing your health by making diet and lifestyle choices that influence gene expression. It sounds complicated but, in fact, you are already doing it. You know that if you eat some foods you feel better, and after others you feel bad. That’s genetic: the food you’ve just eaten is broken down by enzymes (produced by genes) and absorbed using transporters and hormones (produced by genes) and gets used or stored according to your metabolic response (mediated by genes) and makes you more or less healthy according to the genes it stimulates. An oversupply or deficiency of key nutrients can also speed up or slow down the conveyor belt or protein production with the result that we can get too much of something (e.g. LDL cholesterol) or too little of something (e.g. serotonin). From here it’s not such a big leap to see how and why continuously eating things that suit you will result in continuously good gene expression. And vice versa.
Is it too late for me?
Your gene expression is the sum of your lifetime exposures. It starts before you are born. Even before your mother was born, in fact: your grandmother made the egg cell that made you. And your father, well, he probably made the sperm that made you a couple of days before conception so you have to hope it wasn’t on his stag night! Then you spent nine months immersed in fluid inside your mother and everything that happened to her happened to you, in a diluted sort of way.
As you grew up and were probably dosed with antibiotics, like most kids, and suffered toxic exposure from pesticides and exhaust fumes, solvents and radiation. Most of which you couldn’t control. You probably behaved pretty badly as a teenager from time to time (at least I hope you did) which created a few more hiccups. So, eventually, you arrived at the ripe old age you are now and, luckily, you have a chance to make amends.
Of course, most of the health problems you have experienced to date have happened as a direct result of your diet and lifestyle choices interacting with your genes. When you look at it like this you can see that making different choices get different results. We know for sure that diseases, especially the big ones, develop over decades. But we’re also learning that lifestyle changes can stop them in their tracks. For example removing sugar and starches from your diet can reverse diabetes. Adding coconut oil to the diet of an Alzheimer’s patient can improve cognitive function. Changing eating patterns for Parkinsons patients can help control tremors. Diseases that we think of as ‘genetic’ are nevertheless responsive to nutritional interventions.
I’m hoping that helps you to feel a lot less afraid if you know you have a genetic predisposition to disease – and a lot less negligent if you don’t.
Forewarned is forearmed
So although genes affect your health, they rarely cause disease – that’s why we normally say that genes are ‘associated’ with a disease. In simple terms it means that having a gene might increase the likelihood of you getting a disease but even if you have ‘the Alzheimer’s gene’ or the ‘breast cancer gene’ you only have a predisposition: the outcome is very much in your hands. We all know that lifestyle has a huge role to play, but many of us don’t realise just how powerful it can be.
This gives us a critical advantage in health management. Nutrigenetic counselling can help you understand your individual risk factors and focus on the things that are important for you. So instead of feeling powerless when we learn we have the BRCA gene, we can protect ourselves by understanding the way it works and making diet and lifestyle choices that reduce its effect.
Why are genes such a problem?
When gene mutations occur one of two things happens: either the organism becomes better suited to the environment it lives in and becomes stronger, or the organism is worse off, and becomes weaker. If it dies, it doesn’t get to pass on the mutation to the next generation. Hence, mutations passed from one generation to the next tend to confer advantage on the carrier and offspring – rather than disadvantage. Which is all a bit confusing since we tend to think of genetic mutations as something to worry about.
The problem is that we have become maladapted to our environment. Genetic mutations take many generations to appear but during the last couple of generations the environment has changed faster than our genes can. So, for example, one of your great-great-great-great-grandparents may have benefited from a gene that allowed her to harvest more calories from her diet than the person in the mud hut next door. When food was scarce that gave here a survival advantage. A couple of centuries later, that same gene is making you much more likely to put on weight than the lady next to you on the cross-trainer, leading to obesity and inflammation. Your genes haven’t changed but the environment has. Scarcity has been replaced by abundance and many of us are not handling that too well.
It’s all about your environment
At best, your particular genome is probably suited for life 100 years ago; I think mine would probably be happier back in Georgian times! Dr Paul Clayton wrote a fascinating paper in which he concluded that the Victorians were healthier than we are.
Few people are suited to the 21st century environment: the survival of the fittest for the coming generation will be those who can get away with eating sugar all day long while sitting on a chair staring at a screen. Anyone whose genes are ideally adapted to those conditions has a rosy future ahead. The rest of us have a problem.
Understanding how your particular SNPs interact with your diet and lifestyle is one of the cornerstones of personalised nutrition. We still have a lot to learn about how our genes work but there’s plenty that we do know that can help to improve your risk for disease. What we do know keeps confirming that good lifestyle choices result in better gene expression.
Who needs genetic testing?
It’s fair to say that some of the things we think we know now about genes will be overturned by future research and that means we need to be cautious in our use of genetic tests. I tend to focus on very well researched gene pathways and only when there’s a good reason to do so: for example if there’s an obvious nutrient deficiency that can’t be explained by diet, or a persistent health problem that isn’t responding to other interventions. Also, it must be said that genetic testing isn’t for everyone. Although I’ve explained here how your genes don’t necessarily dictate your health, and they don’t accurately predict what you’ll die of, some people just can’t get that idea out of their head. So if you’re someone who suffers from anxiety and insomnia I recommend that you think twice before delving into this area. You might be better off not knowing.
My personal interest in nutrigenetics was sparked when I learned that I don’t have the breast cancer gene, despite having had the disease. I used my own genetic data to study the relationship between breast cancer and ‘non-classic’ gene mutations as part of my post-graduate study. It’s a fascinating field that can really help to target individual health concerns. I went on to become a BANT registered nutrigenetic counsellor in order to be able to help other people with what I had learned.
I don’t offer genetic evaluation as part of my Three Steps to Health programme, and for a very good reason. So much of the research I did simply confirmed the things we already know: that good gene expression is about healthy lifestyle choices – good diet, plenty of exercise, manageable stress levels and good quality sleep. For the vast majority of people sorting the lifestyle issues resolves the genetic problems too. Of course there are a few people for whom that’s not true and for them I offer the opportunity to dig a bit deeper.