Our immune system is our bodies’ defence against infections. Without it, even the mildest of infections might make us seriously unwell. We can take action to help to boost our own immune systems through healthy diet and exercise.
A good starting point is trying to prevent chronic inflammation. I liken chronic inflammation to a city where many small fires are repeatedly breaking out in different locations. The fire service is stretched. If a large fire breaks out, (representing Covid-19) the fire service will struggle to put it out. If the background inflammation is controlled there is more ability to stage a good immune response.
Your blood results can indicate if you have chronic inflammation, such as an increase in what are called ‘inflammatory markers’ (ESR or cRP). These may be raised if you have various health conditions such as rheumatoid arthritis or inflammatory bowel disease, but even being significantly overweight can be a cause of inflammation.
Your diet can help to reduce chronic inflammation and may even help to improve or prevent these kinds of conditions, especially obesity. Good foods to start with are fruits and vegetables, which are loaded with vitamins, especially A, C and E and folic acid. The cabbage family, or brassicas, are exceptional and include cabbage, kale, cauliflower and broccoli.
Vitamin D supplement is helpful if you might have low levels and in a UK Winter and especially in women who dress modestly, this is likely to be the case. It has been shown that replacing vitamin D can help to reduce chest infections and flu. The data on Covid is a little more unclear, however there are many good reasons to take vitamin D supplements, including reducing the risk of depression and aches and pains. You get vitamin D in eggs, oily fish and ‘fortified foods’ including some drinks but this is one vitamin where it is advisable to take a supplement as you often don’t get enough in the diet. The recommended dose varies but is usually around 400-1000 units daily (10-25micrograms).
You also want antioxidants in your diet, which can help to reduce inflammation. Purple fruits and vegetables like berries, red onions and aubergines provide antioxidants as do olives, olive oil, green tea, very strong dark chocolate and herbs and spices.
Next in line are the B vitamins and these can be provided by meat, fish, beans, lentils and wholegrains such as quinoa. Vitamin B12 is important and is mostly found in meat, milk and yeast extract (e.g. Marmite). Some older people don’t absorb B12 well and vegetarians and vegans are often lacking in this important vitamin. A yearly blood test for your B12 level can be helpful.
Oily fish, like salmon, herring, sardines and mackerel are sources of omega-3, which is a powerful anti-inflammatory. It has been shown in early research by Prof Philip Calder, of the University of Southampton, that omega-3 may help to prevent the cytokine storm, which can be a feature of a severe Covid-19 infection. (Losing weight if you are overweight can also help to prevent this.)
Minerals are important for our immune system, especially selenium, iron and zinc. You get selenium in fish, eggs, mushrooms and nuts, especially Brazil nuts. Iron is in meat and fish and also spinach, watercress, lentils and dried beans. Zinc is in meat, nuts, seeds and root ginger.
So far, we’ve noted that a mixture of fruit and vegetables, especially cabbage and kale, mushrooms, eggs, meat, fish, beans, nuts, seeds and green tea will go a long way towards having a healthy immune system. You now need to look inside, to the gut bacteria, which live in harmony with us in their trillions. These are also vital in helping to support our immune system. But we need to support them by having plenty of fibre in our diets and fermented foods like natural yoghurt, kefir, sauerkraut and miso paste (which is made from fermented soya beans.) Chicken soup (or other bone broths) may help the gut lining and in this way may boost the immune system.
In contrast, there are foods and drinks which are more likely to worsen inflammation and to reduce your immune response. Sugar is one of the biggest culprits, whether this is added to your tea or coffee, used in your baking, present in fizzy drinks or even natural sugar in fruit juices. A surprisingly high offender is grape juice, popular on Shabbos. There can be 3.5 teaspoons per 100ml. ‘Light’ grape juice is less sweet and a much healthier choice.
Starchy foods are also an issue because they can raise your blood sugar. It has been shown that a frequently high blood sugar can seem to ‘stun’ the immune system. Even people who don’t have diabetes may have some spikes in their blood sugar if they have a lot of sugar and starches in their diet. The main starches are flour, bread, rice, pasta and potatoes. Ideally try not to have bread with all your meals and reduce the portion sizes of ‘fillers’ like rice, potato and pasta and always prefer wholemeal or wholewheat varieties. (If you take medication for diabetes, don’t make big changes to the amount of bread etc. that you eat, without discussing this with your doctor first, as your medication dose may need to be dropped before you do so.)
Other things to ideally cut down on are alcohol and processed foods, including ‘nosh’. Many people are now becoming aware of the names of some of our immune cells. The all-important T cells can be reduced in number by bouts of drinking alcohol.
Moving away from the diet, regular exercise, which can just be walking or even housework, can help your immune system. Drink plenty of water to prevent dehydration and try to get about 7-8 hours sleep a night, if possible. The herbal treatment, echinacea, may be useful if you feel as though you might be starting to get viral symptoms or you have been exposed to the virus.
All the above advice can have a good effect at improving your immunity, helping you to feel generally healthier and more energetic and even helping you to lose weight but very importantly, such measures are not advised to replace keeping a safe distance from others, wearing a face mask and washing your hands and accepting the vaccine when it is made available to you. This is how we might best emerge from the Coronavirus epidemic with good health and vitality.
Dr Jackie Rose (Lewis) is co-author of ‘To Life! Healthy Jewish Food’ together with Judi Rose, daughter of the late Evelyn Rose. She also works voluntarily as co-chair of Salford Healthy Communities and as a GP/ nutritionist for Private GP Extra.