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Celia Stewart Nutrition

To protect yourself from winter colds and flu pay attention to your diet to boost your immunity (Marcos et al 2003). Your immune system is composed of a delicately balanced system of tissues and cells designed to protect you from invading bacteria and viruses and allergens. Physical barriers such as the skin, and the mucous membranes of the respiratory and digestive tracts are your first line of defence. In the blood stream specialized white blood cells fight invading organisms. T lymphocytes seek out antigens and B lymphocytes create antibodies to destroy germs. Deficiency of one or more essential nutrients may prevent your immune system from performing at its best. Base your diet on whole, real foods and where possible choose organic animal and vegetable produce.

Increase you consumption of fruit and vegetables which contain valuable vitamins, minerals, and phytonutrients (WebMD 2012). These support immunity by having antioxidant, immune boosting and detoxification effects.

Aim to eat 5-7 portions of fruit and vegetables a day and try to eat a rainbow – this will provide you with a wide a variety of immune boosting phytonutrients Include berries, peppers, papaya, sweet potatoes, broccoli, cabbage, cauliflower, parsley, apples, dark green salad leaves, garlic and onions.

Eat more nuts and seeds and wholegrains which provide vitamin E, a potent antioxidant, which stimulates the production of immune cells known as killer cells. Sunflower seeds and pumpkin seeds are a good source of zinc which also increases these infection-fighting T cells.

Try to eat two portions of oily fish a week and a handful of nuts and seeds daily which provide essential fatty acids. Essential fatty acids play a role in modulating the immune system.

Include protein at every meal and choose lean options such as fish, chicken, eggs and pulses. Protein is digested into amino acids which are the building blocks of all bodily systems including the cells involved in immunity. Whey protein powder or pea or hemp protein powder helps to support immune function and can be added to smoothies. Add green super foods for extra antioxidants and phytonutrients.

Check your vitamin D levels Vitamin D has a crucial activating effect on infection fighting immune cells (Rode von Essen 2010). Sun exposure raises vitamin D levels and it is found in eggs and oily fish.

Support healthy digestion. Chew your food well which begins digestion and also stimulates your stomach to produce acid. Stomach acid along with digestive enzymes can inactivate bacteria and viruses. Stomach acid is required in the first step of protein digestion, which provides amino acids required as the building blocks for immune cells.

Seventy per cent of your immunity lies in your gut as a network of lymphatic tissue. As well as supporting digestion, healthy gut flora or probiotics – stimulate the lymph tissue in the gut to produce antibodies against disease-causing bacteria and viruses. These friendly bacteria also create a physical barrier against invading pathogens. To encourage the growth of healthy gut flora eat plenty of fruit and vegetables and fermented products such as yoghurt and kefir.

Avoid sugar and refined carbohydrates, such as white bread, pasta and rice, which are turned rapidly into sugar. This has been found to reduce the ability of immune white cells to engulf and destroy bacteria. Replace refined carbohydrates with wholegrains such as brown rice or quinoa.

Reduce saturated fats which can contribute to inflammation in the body. Avoid hydrogenated fats and trans fats, which are found in processed foods and are toxic to the body. Do not fry with sunflower or other vegetable oils as these oxidise, creating reactive free radicals which use up your antioxidant supply leaving fewer to support immunity. Free radicals can damage T cells as well. Use olive oil for cooking and raw as it contains antioxidants.

Reduce caffeine and alcohol which, as diuretics, deprive the body of immune boosting vitamins and minerals. Increase water and herbal teas such as ginger, green tea or pau d’arco.

More sleep is an obvious way to boost immune function. Aim for 7-8 hours per night.

Relax. Stress inhibits systems in the body which are not essential to immediate survival such as digestion and immunity. Instead focus is placed on increasing your heart rate and rushing blood to your muscles so that you can run from or fight your ‘attacker’. Prolonged stress can lead to continual immune suppression. Try to deal with the stress in your life with meditation or yoga or any activity which you find absorbing and enjoyable. Depression can also affect immunity so address this if you need to.

Regular moderate exercise supports good immunity but in excess can have the opposite effect.

If you find that despite following the above advice you are continually picking up infections a consultation with a nutritional therapist may give help to identify contributory factors such as intestinal dysbiosis, adrenal fatigue or vitamin D deficiency.


Marcos A Nova E Montero A (2003) Changes in the immune system are conditioned by nutrition European Journal of Clinical Nutrition 57(1):S66-S69

Rode von Essen M Kongsbak M Schjerling Olgaard K Odum N Geisler C (2010)
Vitamin D controls T cell antigen receptor signaling and activation of human T cells Nature Immunology 11:344-349

WebMD(2012) Healthy Eating and Diet Frequently asked questions about phytonutrients (online) Last accessed 23.02.2012 at

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