accurately determine that they are specifically supporting mitochondria, they are certainly beneficial to your body in many other ways.
However, diet related to immunity is a difficult topic to tackle. Unlike cardiovascular disease or diabetes, there aren’t many studies examining the effects on immunity nor biomarkers that we regularly test to check someone’s immune capacity.141 However, the suggestions below encompass the entire ethos of this book: to give you reasonable evidence-based suggestions, with a good dose of common sense, about how your lifestyle can enhance the functioning of your incredible body. These delicious ingredients will get you thinking about how nutrition is exceptionally important to building your immunity.
‘There are added benefits of obtaining vitamin C plus the abundance of other vital micronutrients from whole foods rather than supplements in isolation.’
+ Orange, yellow and green foods Bright orange and yellow-coloured foods, including winter squash and sweet potato as well as dark greens such as kale, contain vitamin A precursors called carotenoids. These plant chemicals are essential to our immune system and have a role in maintaining our gut barrier, the functioning of specialised immune cells as well as the cells involved in the immediate response to stressors.142 We also find different sources of vitamin A in animal products such as fatty fish and organ meats we don’t tend to consume much of, such as liver. Try the Fennel Sardines with Pine Nuts (see here) or the White Beans, Butternut Squash and Spicy Couscous (see here).
Along with vitamin A, brightly coloured foods also contain vitamin C, as do a number of green vegetables including broccoli, parsley, spring greens and Brussels sprouts, and by lightly steaming them (a technique I use regularly in my recipes) we can maintain this vitamin content. It’s long recognised that vitamin C is important for immune cells.143 It can aid your ‘first response’ immune system activity and vitamin C itself is a strong antioxidant which is important to protect your immune cells and limit the oxidative stress within your mitochondria.144, 145
For these reasons, many of my patients have bought into the advertising for vitamin C supplements. Although I believe these are fairly safe and well tolerated, there are added benefits of obtaining vitamin C plus the abundance of other vital micronutrients from whole foods rather than supplements in isolation. There are a huge range of other nutrients contained in dark leafy greens and citrus fruits beyond just vitamin C. For instance, a pile of steamed greens with olive oil, salt and lemon (like my Horta recipe here) would be a fantastic accompaniment to most meals as it doesn’t just offer vitamin C; it delivers sulforaphane, magnesium and added fibre to your diet. I encourage people to think of their food as a wonderful collection of thousands of micronutrients and plant chemicals rather than just one or two vitamins.
+ Nuts and seeds Nuts like cashews, almonds and Brazil nuts, as well as sunflower seeds and flaxseed, contain good sources of zinc, selenium and vitamin E. These three micronutrients have individually been studied in clinical trials using larger doses than found naturally with some positive results on immune health, which is why they’re labelled ‘immune boosting’ in many stores.146, 147, 148 However, I believe using supplements of individual micronutrients in large quantities is for the majority of people unjustified. Certain populations who may be at risk of deficiency and have lowered immune health, such as the elderly, may benefit from supplemental forms but we can obtain reasonable amounts of these essential nutrients from wholesome, delicious food. Not only do I use nuts and seeds to add texture to food, but they’re fantastic sources of protein and fibre that additionally contribute to immune health. Try the Herby Walnut and Cashew Roast (see here) for a great way of using more quality fats.
+ Fibre An effective strategy to improve our immune system would be anything that helps our gut environment; specialised prebiotic fibres including chicory, endive, Jerusalem artichoke and garlic provide your microbes with a source of food. When digested, they’re able to make a fatty acid chemical called butyrate which helps maintain the lining of the gut wall.149 A well-fed microbiota is better equipped to carry out its immune-modulating role of reducing inflammation and preventing pathogenic microbes from colonising in the gut, causing ill health.
+ Herbs and spices A variety of vegetables, like the colourful ingredients described above, also provide a fantastic food source for the microbes and there is also a rationale for using plentiful herbs and spices. Ginger, turmeric, fennel, and some botanicals like peppermint may have a role in immune support as they have been shown in some small studies to reduce gut inflammation.150 I think regularly including herbs and spices in our food for a culinary as well as functional purpose is an important aspect of our diets that we should embrace. Try the Ras el Hanout (see here) or the Laksa Paste (see here) for ideas.
There are some specific botanicals and herbs that have shown ‘immune modulating’ capacity, in that they may stimulate the production of cells of the immune system.151 There is also a tradition of using different herbs for immune support across many cultures, including elderberry, Echinacea, mushroom varieties and probiotics. However, I would rather we focus on accessible diet and lifestyle aspects that serve to build your immune reserve rather than relying on immune-modulating plants for general sustenance. Improving your lifestyle and diet are much more powerful strategies than relying on a special flower or fungi for support.
LIFESTYLE 360
Nutrition has a huge role in maintaining robust and balanced immunity, but if there was any system that exemplifies why total coordination of lifestyle factors, such as exercise and sleep, is necessary for universal functioning, your immune system is the poster boy. By harnessing the power of a variety of lifestyle factors, you can greatly enhance your metabolic energy and the ability of your immune system to perform at its peak. It will not only improve your resilience to common viruses and pathogens, but also aid inflammation balance under the control of immune cells.
+ Exercise For everyone there is an exercise sweet spot. Regular moderate exercise has been shown to universally benefit immunity. Aerobic exercise actually encourages your body to be more resilient to stressors and therefore has an overall benefit, despite the short-term effects of exercise being inflammatory.152 Aerobic exercise can actually improve your mitochondrial function which may also be why regular exercise builds a resilient immune system.153, 154
Persistent over-training, however, is associated with reduced immune reserve. There are recognised health risks of putting high amounts of strain on your body by over-exercising, that researchers have observed in endurance athletes like cyclists.155 A balance of training is what we should be aiming to achieve and there are specific types of exercises that may be particularly good for immune health.
+ Yoga Described as both a mindfulness technique as well as a form of exercise, recent studies on yoga have examined a fascinating effect on immune cells.156 Researchers have demonstrated that yoga practices can impact the expression of genes to one that positively improves immune cell function. Similar effects have been shown with other practices such as Qi Gong and Tai Chi.120 Combined with the physical benefits of the exercise, yoga could be one of the best all-round immune health promoting activities we know of. The best advice I have is to mix it up. I have developed my own yoga routine from watching online yoga sessions that are very accessible and easy to follow, as well as attending classes now and again to get some pointers. But I would also encourage HIIT (high intensity interval training) sessions, too, to improve aerobic capacity, as well as endurance training such as cycling and swimming for their additional benefits.
+ Meditation
