First and foremost, follow national guidance for preventing COVID-19: avoid spreading the virus and cut your chances of catching it by regularly washing your hands, avoiding touching your face and reducing social contact. This is particularly important for protecting at-risk groups including people with existing health conditions, the elderly and pregnant women.
As well as protecting yourself from the virus on the outside, you can also build up your defences from the inside by strengthening your immune system.
One thing that you can control immediately is the health of the trillions of microbes living in your gut, collectively known as the microbiome. Recent research has shown that the gut microbiome plays an essential role in the body’s immune response to infection, and in maintaining overall health. As well as mounting a response to infectious pathogens like coronavirus, a healthy gut microbiome also helps to prevent potentially dangerous immune over-reactions that damage the lungs and other vital organs. These excessive immune responses can cause respiratory failure and death.
Healthy microbiome, healthy gut, healthy body
The food you eat has a big impact on the range and type of microbes in the gut. A diverse microbiome is a healthy microbiome, containing many different species that each play their part in immunity and health. Microbiome diversity declines as you get older, which may help to explain some of the age-related changes we see in immune responses, so it’s even more necessary to maintain a healthy microbiome throughout life.
The fine details of the interactions between the gut microbiome and the immune system are not fully understood. But there seems to be a link between the makeup of the microbiome and inflammation – one of the hallmarks of the immune response. Gut bacteria produce many beneficial chemicals and also activate vitamin A in food, which helps to regulate the immune system.
Eat to feed your microbiome
The best way to increase microbiome diversity is by eating a wide range of plant-based food, which are high in fibre, and limiting ultra-processed foods including junk food. Following a Mediterranean diet has also been shown to improving gut microbiome diversity and reduce inflammation: eating plenty of fruit, vegetables, nuts, seeds and whole grains; healthy fats like high-quality extra virgin olive oil; and lean meat or fish. Avoid alcohol, salt, sweets and sugary drinks, and artificial sweeteners or other additives.
If you are concerned about getting hold of fresh produce while self-isolating or quarantined, frozen fruit, berries and vegetables are just as healthy as fresh ones, and will last much longer than the currently recommended two-week isolation period. Canned fruit, beans and pulses are another long-lasting option.
You can also support your microbiome by regularly eating natural yoghurt and artisan cheeses, which contain live microbes (probiotics). Another source of natural probiotics are bacteria and yeast-rich drinks like kefir (fermented milk) or kombucha (fermented tea). Fermented vegetable-based foods, such as Korean kimchi (and German sauerkraut) are another good option.
Whether you’re shopping for yourself, your family or for elderly relatives or friends, choosing foods that support a healthy gut microbiome is very important. Managing your mental health, staying physically active and getting enough sleep will also help to keep your immune system in good shape.