It’s recognised that those who suffer from autoimmune conditions including psoriasis and rheumatoid arthritis tend to have imbalances in their gut populations.132 The research is still in its early stages but we also recognise that those who suffer from exaggerated immune responses, like in the case of asthma and eczema patients, may lack certain populations of gut bacteria that harmonise the body’s immune response.133, 134 This has led to the hypothesis that repopulating the gut microbiome with beneficial microbes may improve symptoms.
A theory gaining popularity to explain one of the causes of some autoimmune (AI) diseases is that the immune cells have been exposed to products that have entered directly into the bloodstream via ‘gaps’ in the lining of our digestive tract.135 These products have not been properly processed and identified by the immune system cells within the gut, and thus trigger an aggressive response that leads to harm of the normal tissue. It’s still under a lot of debate but it’s interesting to note that gut-focused treatments for AI disease, where potential triggers have been removed allowing the gut wall to repair itself, have led to some remarkable results.136, 137 I don’t have the space to dive into a full discussion of such a nuanced topic in this cookbook, but there is some interesting research on the horizon as well as a lot more we have to learn about process behind AI conditions and therapeutic dietary strategies. I suspect that it is more complicated than just nurturing the microbiome, but ensuring a healthy and thriving gut population using food could be a good starting point for helping with these illnesses and a lot of well-respected scientists in the field are in agreement on this.
ELIMINATION DIETS
It’s my responsibility to be honest about the validity of these interventions and assess whether you could benefit from them. There has been a lot of speculation regarding AIP (autoimmune protocol) diets and, although these appear to be restrictive and eliminate perfectly healthy items from your food, there have been some interesting and significant outcomes gained from their use. Depending on the condition, these short-term therapeutic dietary interventions may be beneficial, but I hasten to add that they should be actioned with the guidance of an experienced practitioner. I’m mindful of the scaremongering tactics surrounding components of food: gluten in flour, lectins in beans and other common ingredients. My advice is to maintain a high suspicion of anyone blatantly brandishing a single food as harmful for everybody and making outlandish and unhelpful claims. It makes no scientific sense to suggest gluten is bad for all citizens of the UK, for example, and I discussed the many reasons behind this in my first book. But I do believe there is a case for some patients to trial dietary strategies and many rheumatologist and immunologist colleagues are starting to use them carefully with interesting anecdotal successes.
MITOCHONDRIAL SUPPORT
In recent years, we’ve also begun to recognise the profound importance of a component of our cells called mitochondria. These are found in all of our cells and have been traditionally referred to as the ‘powerhouses’. These incredible batteries provide energy for all normal cell functions, but they’re also critical for recognising when an immune response is required.138, 139 Cutting a longwinded biology lesson short, we require healthy, functioning mitochondria for a robust immune system that can boost its metabolic activity to adapt to the increased demands of when your immune system needs to be more active. Whether it’s fighting an infection or balancing oxidative stress, your immune cells require more energy, and mitochondria are key to this. Supporting your mitochondria by preventing damage and providing them with fuel is therefore an essential immune-supporting strategy. Things that damage mitochondria include high-sugar diets and stress, and this gives us one explanation as to why poor diet and mental pressure appear to have detrimental impacts on our immunity.140
This is a very new area of research, so the evidence base behind what to eat for mitochondrial support is lacking, but that shouldn’t stop us from being able to make reasonable, educated adjustments to our lifestyles that we can be sure are safe. Even if we cannot 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