Our immune system is a constellation of cells and molecules found in every corner of our body and interacting with every other system of our body. Our immune system protects us from infection and is at the core of our health and wellbeing. There is a prevailing idea that the immune system is some kind of internal force field. From vitamin C and Echinacea, to binging on ‘superfoods’ or using antibacterial hand gel, there’s no shortage of ideas flying about on how to ‘boost’ the immune system. However, the immune system is not just one single on-off switch, but a system with many parts in an exquisitely calibrated balance: robust defences to fight infection in times of need regulated by suppressive pro-resolvers that maintain the status quo. Most research either casts doubt on many ‘immune-boosting’ marketing claims or they are grounded in misunderstood science. You may think that you have low immune function, suffering from frequent infections but if at the same time you have allergies, caused by an overshooting of the immune system to something harmless, then it’s more likely you immune system isn’t balanced. But unfortunately, modern life is a bit of an immunological disaster. So if we can’t ‘boost‘ our immunity per say, what can we do to make sure our immune system is optimally functioning?
Like all body systems, there is a deeply entwined relationship between the immune system and nutrition. Immunity has its own nutritional and metabolic demands, so ultimately poor diet is an immunity impairing factor. Prioritising a balanced diet will provide the nutritional reserves to both effectively fight infection if we do get sick, while also quenching any unruly inflammation from the general daily grind of modern life.
There are a few key ingredients worth adding to create a truly immune nourishing diet:
Not only a great addition to many dishes, the research surrounding mushrooms and immunity is quite compelling. Beta-glucans are naturally occurring polysaccharides which double up as both a prebiotic (see above) and a molecular pattern that enhances the number and activity of our immune defence cells against infection. Beta-glucans are rich in some cereals too such as oats, and they act similarly to mushroom beta-glucans except less effective. But it’s not only beta-glucans that make mushrooms an immune nourishing powerhouse. They possess a wide array of nutrients including copper, potassium, B vitamins and vitamin D and are one of the highest source of two antioxidants called ergothioneine and glutathione that help fight unruly inflammation and bolster health. Get adventurous and try some of the more functional varieties such as shitake, miatake and rishi which appear to pack the biggest immunity punch.
IMMUNE VITAMIN TRIAD A/D/K
Vitamin D makes a well-established and important contribution to many aspects of our general health but plays a particularly key role in our immune system. We primarily obtain vitamin D through our skin in response to sunlight (which is why the Department of Health recommends taking a daily supplement in countries like the UK). The primary food sources of vitamin D are dairy products fortified with vitamin D, oily fish or mushrooms (pop them on a sunny windowsill to encourage them to churn out more vitamin D to protect themselves from UV radiation). Vitamin D cultivates adequate populations of ‘tolerant’ immune cells which patrol our gut and lung barriers, switching off unrequired inflammation and preventing unwanted allergic and autoimmune responses. But this isn’t the whole picture. Vitamin D can only do its job with the cooperation of vitamin A and, like a 3-legged stool, Vitamin K, which has somewhat languished in obscurity, works as a cofactor to maximise the effects of A & D. Vitamin A is supplied primarily by foods of animal origin such as dairy products, fish and liver, or plant-based beta-carotene rich fruits and vegetables, normally orange or dark green in colour (think carrots, pumpkin, winter squash, dark green leafy vegetables and apricots). Vitamin K is primarily found in dark leafy vegetables and is particularly enriched in Natto, a fermented Soy. Remember these vitamins are all fat soluble so eat them with a healthy fat such as extra virgin olive oil.
Magnesium is essential for over 300 reactions in the body, including many vital functions of the immune system. Green leafy veggies, nuts and seeds are our best dietary source, but multiple studies demonstrate that even a healthy modern diet can precipitate a magnesium deficiency exemplified by muscle cramping, excessive soreness after working out and disrupted sleep amongst other symptoms. Since magnesium plays a role in over 300 different chemical reactions in the body, including the general functioning of the immune system and protection from inflammatory stress, it is important to make sure we are getting enough. Oral magnesium supplements are available and helpful but not easily absorbed and at high doses can cause diarrhoea. A far better way is via transdermal route (through the skin). Epsom salt baths are one route to access transdermal magnesium and bypasses the potential digestive tract upset. Topical magnesium sprays are also available. Supplementing vitamin D without enough magnesium can induce further magnesium depletion, so magnesium should go hand-in-hand with vitamin D.
OMEGA 3 – 6 BALANCE
Essential fatty acids, omega 3 and omega 6 are so called because we can’t synthesise them and therefore must obtain them from our diet. Both these fatty acids work together to maintain the proper functioning of our immune system. Omega 6 is found naturally in nuts and plant-based oils and has an important role in the inflammatory responses which we need to help us recover from being sick or injured. Conversely, omega 3s are a family of fatty acids including ALA (found in flax oil, walnuts, and dark leafy greens), EPA & DHA (both rich in oily fish) that are particularly esteemed for their health-promoting anti-inflammatory powers. Remember plant-based ALA is a precursor to EPA and DHA but this conversion is done at extremely low rates, dropping significantly over the age of 40. While we do need both types, omega 6 has gained a negative reputation because it’s a common component of refined cooking oils and processed food which are easy to overconsume. Studies have shown that increased omega 6 to omega 3 ratio and an overall rise in omega 6 consumption damages important components of our immune response leading to an excess of inflammation in the body. Remember excess omega 6 blocks the effectiveness of anti-inflammatory omega 3’s so don’t take an omega 3 supplement and expect it to offset an inflammatory diet.
Phytochemicals are chemical compounds produced by plants which have anti-oxidant, anti-inflammatory, anti-carcinogenic and other biological properties which may prevent disease. There are literally thousands of phytochemicals and we are only just scratching the surface exploring their health benefits. Sulforaphane, part of the isothiocyanate family of phytochemicals, is found in cruciferous veggies such as broccoli, where it is stored in an inactive form, only activated by chewing or crushing and gentle heating. It helps our immune system to weed out the weak or damaged immune cells, reducing their chance of malfunctioning and causing allergic or autoimmune problems. Broccoli seeds and sprouts are one of the richest sources so get sprouting, throw some in your smoothies and sprinkle on your salads.
‘OLD FRIENDS’ & ORAL TOLERANCE
Microbes are no longer ‘just germs’ and the microbiome, the collection of microbes living on and in us, is fast becoming one of the hottest topics in health. The development of our immune system is inextricably entwined with the development of our microbiome. In short, we now know conclusively that without those bugs inside us, our immune system just doesn’t develop properly. Not only do we want plenty of gut bugs, but we can to cultivate a diverse array of different types. Since they eat what we eat, the best way to encourage diversity it to have a diverse diet including wide variety of prebiotic rich plant-based foods or using a good probiotic if you feel you need additional support. What’s more, our diet is only as good as our microbiome since we rely on these microbes in our digestive tract to liberate many of the nutrients stored in our foods. The microbiome also produces key immune-regulating metabolites known as ‘post-biotics’ which are literally our own personalised pharmacy for health. Part of the immune systems reliance on the microbiome comes from key postbiotics which encourage a phenomenon known as ‘oral tolerance’ which helps to prevent and minimise allergy.
Remember what we eat is only part of the picture, as how and when we eat is important too. Digestion in itself is actually a major source of collateral inflammation. Each time we eat, our gut becomes transiently ‘leaky’. Although it sounds alarming, this is a normal part of the digestive process, but it does have some implications for our immune system with small amounts of gut bacteria ending up in our bloodstream. The cell walls of these bacteria contain an immune activating barcode called LPS which switches on a transient inflammatory response termed ‘endotoxemia’. Constant grazing rather than eating at defined meal times therefore poses a larger inflammatory risk on the body and has been connected to metabolic and immune misfunctioning. Further research in this area has shown that eating meals at a similar time each day can also help to minimise the consequences of post-eating gut leakiness.