The Doctor’s Kitchen - Eat to Beat Illness: A simple way to cook and live the healthiest, happiest life

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.

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.

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 (#litres_trial_promo)) or the White Beans, Butternut Squash and Spicy Couscous (see here (#litres_trial_promo)).

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.

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.

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 (#litres_trial_promo)) 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.

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 (#litres_trial_promo)) 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.

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.

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 (#litres_trial_promo)) or the Laksa Paste (see here (#litres_trial_promo)) 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.

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.

Aerobic exercise can actually improve your mitochondrial function which may also be why regular exercise builds a resilient immune system.

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.

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.

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.

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 The gradual deterioration of our immune capability as we age, known as immunosenescence, may be closely related to both psychological distress and stress hormones.

It would stand to reason that techniques to reduce stress effects may be beneficial from an immune perspective. Combined with the many positive effects of mind–body interventions, practices such as deep breathing, transcendental meditation or simple walks in nature are a no-brainer for me to advise. I was pleased to read a paper about the positive effect of walking in nature, specifically on cells of the immune system.

So perhaps the most immune-system-enhancing of activities could be a yoga session in a park followed by deep breathing in natural sunlight. And this brings me nicely onto the subject of vitamin D.

+ Vitamin D More than a vitamin, vitamin D acts as a master hormone that regulates a multitude of genes involved in a huge number of processes. Beyond its well-recognised involvement in bone health and calcium regulation, vitamin D has a very important role in immune health.

In both the initial ‘innate’ response to infections and the more specific ‘adaptive’ responses, scientists are researching the role of vitamin D and its importance to auto-immune conditions. There are very few sources of vitamin D in the diet and thus medical practitioners in the UK have taken to recommending vitamin D for the whole population during winter months and for those with darker skin colours. The best advice is to get adequate sun exposure outdoors, have regular tests by your GP if you’re at risk and take a supplement during the darker months of September to March in the UK.

+ Sleep deprivation It will come as no surprise to many people that sleep deprivation drastically lowers a person’s immunity. Your immune system is very likely to be regulated by routine and the sleep–wake cycles which influence all other cells in your body operating on a rough 24-hour cycle.

This is why sleep is integral to a healthy immune system. As a GP, I’ve lost count of the number of people turning up on a Monday suffering acute tonsillitis directly attributable to late nights at the weekend or travel. But this is just the tip of the iceberg. Persistent sleep loss significantly disrupts your immune system, increasing inflammation which drastically raises the risk of chronic illnesses like heart disease, Type 2 diabetes and even cancer. As you can probably appreciate by now, these are all conditions related to an ill-performing immune system. Achieving 7–9 hours of sleep a night could be considered one of the most potent therapies for improving ones’ immune system and it’s definitely on my prescription pad.

To sum up diet and lifestyle strategies to improve immune health we simply need to remember a few facts: gut health is exceptionally important; there are well-recognised detrimental effects of a western diet on immune health

(high in sugar, refined carbohydrates, low in fibre and lacking in micronutrients); certain micronutrients are critical for the adequate functioning of our immune cells; and the importance of supporting our mitochondria cannot be underestimated. Although this may sound complicated, the reality is that these additions to your diet and routine are accessible and straightforward. I’m confident that it is achievable for you as it is for many of my patients and my recipes will set you on the right path.

Eat to beat (#ulink_68e1639e-e971-5e02-a05f-d130ba362c28)

Cancer (#ulink_68e1639e-e971-5e02-a05f-d130ba362c28)

(https://open.spotify.com/episode/3R5jj4yKcCOAUUIJcw3h43)

This was by far the most difficult chapter to write. Not least because it is a complicated topic to tackle, but also because it is an emotive subject matter and therefore the most controversial. However, I believe it is our responsibility as medical professionals to educate ourselves, appreciate the wealth of literature surrounding this complicated topic and share it responsibly with the public.

Our understanding of cancer biology is continually evolving and the deeper one goes into the literature, the more complex the systems that underpin this life-changing disease appear to be. Cancer can be loosely defined as a series of mutations that have spun out of control, leading to uncontrollable growth of cells. It’s really an umbrella term to describe lots of different types of cancers that can be caused by different things (like bacteria, viruses or UV radiation) and affect different parts of the body. Some cancers are the result of inherited genes, but most of them occur as we age and acquire more mutations. The processes that prevent these mutations from developing into cancer become less reliable with age, which is why we see most cancers in patients over 50.

Apart from the classic ‘eat a balanced diet’ advice, we, the medical profession, have traditionally been reluctant to delve into meaningful discussions about the role of food and lifestyle as chemopreventative. A chemopreventative is a natural or synthetic substance that reduces the risk of cancer (examples included drugs like Tamoxifen to prevent certain types of breast cancer

), but food is generally not accepted as one. The argument against labelling food as potentially cancer protective is that there are simply not enough clinical trials yielding irrefutable, large-scale evidence. But considering how much we already know about the impact of diet and lifestyle, I sincerely hope this will change.

The lack of dialogue has created a vacuum of information that has, on occasion, been willingly filled by unqualified health commentators who have led people astray. It is this taint that continues to mark cancer and nutrition as a taboo subject. But it is time to redress the balance and normalise the conversation around food and cancer. In my opinion, it is simply inexcusable to say ‘nutrition has no role in cancer prevention or management’. This chapter is by no means comprehensive, but it should give you an idea of why I’m so passionate about this subject matter and the need for more robust nutrition and lifestyle advice within the field of oncology.