An overview of genetics
Our genes continually build and maintain our bodies. Each gene essentially encodes the instructions for making a single protein. Each of us has an estimated 20,000 genes within our DNA strands, which are packaged into larger units called chromosomes. Each human cell contains two sets of chromosomes - one set of 23 chromosomes inherited from the mother and one set of 23 chromosomes from the father.1
These instructions are found in almost every cell, but different genes are turned on or off, depending on what a particular cell needs. Brain cells act differently to gut cells, so different instructions are used to create the structures and functions needed. There are many factors that influence whether a gene is turned on or off and the study of changes in gene expression (rather than changes in the genetic code itself) is known as epigenetics.1
Genetic makeup doesn't just stay the same throughout the family tree. Significant changes in the DNA, or mutations, can directly cause disease. But there are also smaller variations known as polymorphisms, which can increase or decrease the risk of developing a particular disease. These variations are where the genetic link to autoimmune disorders comes into play.1
Genetic predispositions to autoimmune disorders
One way that your genes influence your health is by making you more susceptible to certain health conditions, including autoimmune conditions. Some genes are linked to specific autoimmune diseases, but there are also genetic dispositions for general autoimmunity.
One condition with a strong genetic component is systematic lupus erythematosus (SLE). The condition itself is fairly rare, with a rate of around 65 in 100,000 people. But research shows that 24-59% of identical twins will develop SLE if their sibling is affected. Among non-identical siblings, including fraternal twins, the chance of developing SLE if a brother or sister is affected is estimated at 2% to 5%.2 Women are also six times more likely to develop SLE than men.3
There is also a link known as familial autoimmunity. This means that if one family member has one autoimmune condition, you may be at risk of developing another autoimmune condition.4
Although these links have been made, there are only a handful of genes that are directly linked to autoimmunity. The Coeliac HLA gene has variants that are associated with a higher risk of developing coeliac disease. For those who test negative to those variants, their risk of ever developing coeliac is estimated at less than 1%.5
Triggers for genetic predispositions
When it comes to autoimmune disease, inheriting a particular gene is not a guarantee you will develop the condition - it simply means that you are particularly susceptible to that disease. But when you combine a genetic predisposition with other triggers, your risk may increase.
Stress - particularly chronic stress - is a recognised trigger for both autoimmunity and genetic predispositions. Ongoing stress is now known to alter the expression of genes that are associated with autoimmune disease. Physical stress in early life such as a difficult birth experience can also play a role. In fact, gene expressions seen in people with autoimmune diseases are, in some cases, linked all the way back to a difficult pregnancy for their mother.6
Diet is another factor that can influence the expression of genes. Some dietary habits can have a positive effect on health, whereas others can make harmful changes to gene expression. Some of the dietary issues for genes include alcohol, low intake of B vitamins and a low protein intake. Each of these has a different impact on DNA methylation, which is the main process for switching a gene on or off in a cell.7
How to minimise the risk of triggering genes for autoimmunity
Whether autoimmunity is a known condition in your family, or you just want to reduce your risk, there are steps you can take. Although you can't guarantee you won't develop an autoimmune condition, these tips may help minimise the chance.
If stress is a trigger, then relaxation is key. This doesn't mean eliminating all sources of stress - after all, some stress is inevitable. But you can start to incorporate strategies to manage your stress levels.
How you reduce stress is a personal choice. If you prefer a calming approach, you could try meditation or deep breathing exercises. If you aren't good at sitting still, you might prefer a more active form of stress relief such as walking or yoga.
If you are overwhelmed by stress, however, it may be best to seek help from a professional.
Know your food choices
There is no one 'perfect' diet for minimising autoimmune risk. Everyone has different trigger foods and different genes that might play a role, but there are a few ways to work your food choices in your favour:
- Keep alcohol reserved for special occasions, rather than having a glass of wine every night
- Include a portion of protein at each meal
- Eat a variety of brightly coloured vegetables daily to ensure you consume a variety of antioxidants, vitamins and minerals
- Include sources of vitamin B12 such as eggs, fish, red meat and poultry
- Explore whether you have any food intolerances that need addressing
Supplements might also be worth looking at, as they can help bridge the gap if your diet needs some tweaking, or if you follow a plant-based diet. For example, taking a vitamin B supplement daily can help.
If you're not sure what foods are right for you, consider speaking to a nutritionist for tailored advice.
Reduce your toxin exposure
Like stress, it's impossible to avoid exposure to environmental toxins completely, but there are some ways you can try to limit your exposure.
To reduce exposure to mercury, for instance, you can choose low-mercury fish options and discuss mercury-free options for fillings with your dentist.
Arsenic is found in high levels in rice, so make sure you thoroughly rinse rice before cooking which can reduce its arsenic content by around 30%. Alternatively, switch rice for low-arsenic options such as buckwheat or quinoa.8
Lead is often hiding in locations you might not see. If you live in an older home, it's best to have it assessed before renovating, as many older paints contain lead. Some houses may still have lead pipes or water tanks that leach into the water.9 If you suspect you have lead pipes, contact your water company for advice. To minimise your exposure, make sure you flush a tap for a minute or so before using it for cooking or drinking. It's also best to only use water from the cold tap for cooking or drinking.10
If you're interested in learning more about how to keep your immune system healthy, head over to our Immunity Advice Centre.