There’s a buzz-phrase used when learning about genes and nutrition,
“Genes load the gun, but environment pulls the trigger”.
What this means is that we may be predisposed to health challenges because of our gene variations (SNPs), but it’s what we do to ourselves that actually triggers a problem, or not. This is an important to remember. If we want to, we can always positively influence our health outcomes.
Environmental factors like exercise, stress, sleep, diet and pollution affect how our genes function. Cigarette smoke damages cellular DNA and causes mutations. Exercise has a positive effect on our health by optimising insulin and glucose levels. Some of the latest research into high intensity interval training is finding that this type of exercise triggers a release of anti-inflammatory chemicals from protein-encoding genes.
So, what about diet and gene interactions? There are two sides to this.
- Our genes affect how we respond to food (nutrigenetics)
- Food affects how our genes function (nutrigenomics)
Let’s work through a few examples of each.
Nutrigenetics (how genetic differences affect nutrients)
I am sure you know what micronutrient RDA’s are. They are the Recommended Daily Allowances for vitamins and minerals found in foods. You see them represented as percentages on food labels. It might say, “contains 30% of your RDA for iron”. These nutrient levels were calculated on what the acceptable level should be for an “average person” in “average health”. They give us general guidance. But these calculations are in no way matched to your genetic variations or to the levels of nutrients you currently have.
For example, 1 in 200 people in the UK and Ireland have a gene variation (a SNP) that predisposes them to absorb too much iron from their food. This means that over many years excess iron builds up in their body (it can’t be excreted). Men with this SNP who eat foods high in iron such as meat, liver, pate, shellfish, beans, lentils and spinach, risk liver, heart and pancreatic damage from the damaging effects of iron overload (Hemochromatosis). Women are less at risk because they lose iron through menstruation.
Here is another example. If you know what gene variation (SNP) you have on the BCO1 gene (Beta-Carotene Oxygenase gene 1), it will help you work out how much vitamin A you need to consume in your diet to keep your vision good, your immune system working well and your skin and mucus membranes healthy. Some people have a SNP on the BCO1 gene that reduces the production of the Beta-Carotene Oxygenase enzyme. This enzyme converts inactive beta-carotene (found in dark green leafy vegetables and orange coloured fruits and vegetables) into active Vitamin A for use in the body. If you know that you have that particular SNP on your BCO1 gene, then you might sensibly choose more animal foods over plant foods because they already contain active Vitamin A, while plant foods only contain inactive beta-carotene.
Nutrigenomics (how nutrients affect your genes)
Food metaphorically ‘speaks’ to our genes. Here’s a great health tip from the Institute of Functional Medicine, “brighter coloured whole foods, have the best language skills”. What it means is that if you eat a plate of rainbow-coloured fruits and vegetables every day, you are sending your genes all the right health messages.
You may be wondering how nutrients and food compounds influence this small but important proportion of protein-encoding genes? Well, they don’t actually change the order of the base nucleotides [Please read previous post], rather, they change the gene’s activity. They can activate it to make a protein, or they can de-activate it to stop making a protein. This is called gene “expression”. You may have heard such talk, of when a gene is “expressed” or not. It might be helpful to think of it this way. When a gene is in an active state, it is ‘expressed’, and then when a gene is ‘sleeping’, or inactive, it is ‘not expressing’.
A beneficial example is a compound in broccoli and other cruciferous vegetables (Brussel sprouts, cabbage, kale, cauliflower, Pak Choi) called sulphoraphane. Sulphoraphane can activate a gene which helps the body to detoxify harmful chemicals. Burnt or chargrilled meat, for example, contain harmful compounds called heterocyclic amines (HCAs) which can predispose us to colon cancer. So, it’s a smart move to eat your broccoli sprouts, cauliflower rice and coleslaw with your summer BBQ’s!
Plants make compounds, called phytochemicals, that protect them from attack. When we consume these phytochemicals, they help to protect us too. They help prevent DNA damage and they regulate inflammation. Some well researched phytochemicals are carotenoids, curcuminoids and flavonoids. You’ll find phytochemicals in brightly coloured fruits, vegetables, herbs and spices. For example, lycopene in tomatoes; lutein in leafy greens; beta-carotene in orange fruits and vegetables. Curcuminoids are found in turmeric root and flavonoids in green tea. So please, make your plate as colourful as you can and don’t underestimate the importance of these compounds for your genetic health.
The B group of vitamins are important for cell growth, energy production and DNA repair. Folate, or B9, is an important B vitamin which influences gene expression. The Latin name for Folate is “folium”, which means “leaf” and dark green leafy vegetables are high in folate. You may also know it as folic acid. Now, the MTHFR gene produces an enzyme responsible for converting inactive folate into active folate (I’ll spare you the technical names!). Once converted, the active folate is critical for making and repairing DNA and also for a multistep process that converts the amino acid homocysteine into methionine. Some people have SNPs on the MTHFR gene which slows folate enzyme activity, which when combined with low folate levels, can cause high levels of homocysteine. (MTHFR SNPs + low folate = high homocysteine). You don’t want too much homocysteine in your body because it has been associated with cardiovascular disease. People with the MTHFR SNPs would be well advised to test for their levels of folate and homocysteine. If needed, they can increase their intake of active methyl-folate from a supplement (not the commonly available synthetic folic acid).
When we know our nutrition-related SNPs and when we test our nutrient levels as well, we are in a good position to optimise our gene function and our long-term health. Thankfully testing our nutrient levels is now much easier and affordable. Although we can’t yet test for the level of every nutrient using a finger-prick blood sample, (compared to a full blood sample taken from a vein in your arm), we can take the following at-home test which we then send off in the post, for the following nutrients:
- Folate (B9)
- Vitamin D
- Omega 3 & 6 fats
Please get in contact if you want to have any of these tests done.
In the next blog we will look at some of my own personal SNPs. I will share with you what I’ve learnt using some interesting examples of how I have used this knowledge in practical ways to optimise my health.