Foods boosting the immune system

The immune system is marvellous in defending against many disease-causing microorganisms. But sometimes they manage to sneak through despite all efforts as we all have experienced some time or other during each year’s feared cold and flu season. It’s now that time in the Southern Hemisphere and we are all hoping that the immune system will provide adequate protection. Question is, can something be done to boost the immune system? Maybe an improved diet could help? Or certain vitamins or herbal preparations? Maybe a complete lifestyle change will be necessary?

Boosting the immune system is an enticing but elusive idea for many reasons. It is not a single entity but a complex and interrelated system that requires balance and harmony to function well. There is still much to learn about the intricacies and interconnectedness of the immune response to be able to actively push it in the right direction. Disappointingly I have to tell you that there are no scientifically proven direct links between specific lifestyle changes and enhanced immune function. But don’t give up so easily, general healthy-living strategies are certainly a good way to give your immune system a boost.

The impact of exercise, stress and diet

Exercise to relieve stress and improve immune response (Photo Sangudo)

Exercise to relieve stress and improve immune response (Photo Sangudo)

Regular exercise is a good start. It improves cardiovascular health, lowers blood pressure, helps control body weight, and protects against a variety of diseases. Exercise can contribute to general good health and therefore to a healthy immune system. It may contribute even more directly by promoting good circulation, which allows the cells and substances of the immune system to move through the body freely and do their job efficiently.

Stressful situations might damage various aspects of our immune response. Social stress can be even more damaging than physical stress. Stress can disrupt communication between the nervous system, the hormone system, and the immune system. These three systems communicate using natural chemical messages, and must work in close coordination to be effective. Long-term stress releases stress hormones that affect the thymus, where lymphocytes are produced, and inhibit the production of cytokines and interleukins, which stimulate and coordinate white blood cell activity. However, the exact impact of stress on the immune system and overall health is still unclear. And it might not be easy to deliberately reduce stressors anyway.

But what about the impact of diet, this is by all means a blog about food. Many food products and supplements on store shelves claim to boost or support immunity. The first advice I can give is to be skeptical of any such health claim. The European Food Safety Authority has evaluated a range of claims of foods that will boost the immune system, but failed to find proof for most of them. However, EFSA produced favourable opinions for a range of individual micronutrients. These include beta-carotene as a precursor of vitamin A and vitamin A itself, vitamin B6, B12, folate, vitamin C and D, and a range of minerals including zinc, copper, selenium and iron.

So what can you do?

If you suspect that your diet is not providing you with all your micronutrient needs you should seek out foods rich in the above micronutrient. Beta-carotene and other carotenoids can be found in apricots, asparagus, beets, broccoli, cantaloupe, carrots, corn, green peppers, kale, mangoes, turnip and collard greens, nectarines, peaches, pink grapefruit, pumpkin, squash, spinach, sweet potato, tangerines, tomatoes, and watermelon. Vitamin C can be found in berries, broccoli, Brussels sprouts, cantaloupe, cauliflower, grapefruit, honeydew, kale, kiwi, mangoes, nectarines, orange, papaya, red, green or yellow peppers, snow peas, sweet potato, strawberries, and tomatoes. Zinc can be found in oysters, red meat, poultry, beans, nuts, other seafood, whole grains, fortified cereals, and dairy products. Selenium can be found in Brazil nuts, tuna, beef, poultry and fortified breads, and other grain products.

So the choice of food is great. And most people eating a varied diet would satisfy the demand for the above micronutrients without much problem. However, should you have a skewed diet, taking a daily multivitamin and mineral supplement in moderation might help in further boosting the immune system.

Leaving science aside for a moment

Chicken soup as a folk remedy (Photo: Wendy Cooper)

Chicken soup as a folk remedy boosting the immune system (Photo: Wendy Cooper)

But you want more you say. Don’t despair, the internet is full of advice on foods that are proposed to improve the immune response. And here you have to rely on your beliefs.

The not-so-skeptic could try chicken soup for fending off sniffles. It is supposed to provide the fluids needed to help fight off viruses, to be a powerful mucus stimulant to help clear nasal congestion as well as thin mucus. It’s also thought to have a mild anti-inflammatory effect than can help ease cold symptoms.

Onion and garlic are both old folk remedies. In combination these flavourful healers are claimed to contain numerous antiseptic and immunity boosting compounds and, as an added plus, garlic might help to open clogged sinuses.

Mushrooms have been claimed to increase the production of cytokines, which help fight off infection. They contain polysaccharides that might support the immune system. The most potent cold- and flu-fighting mushrooms are supposed to be shiitake, maitake and reishi, should you believe in their healing power.

There are no arguments about citrus fruits that clearly contain large doses of vitamin C that can reduce cold symptoms. This trick should not be dismissed.

Less clear are findings that eating a cup of low-fat yoghurt each day would reduce your susceptibility to colds by 25 percent. The claimed beneficial component is the Lactobacillus reuteri bacteria that might block the replication of viruses invading the body when we get sick.

A cup of hot tea is always nice. It doesn’t hurt that it is claimed to be soothing and a great home remedy, helping to thin mucus and ensure proper hydration. For added health benefit, sips of green or black tea are both filled with flavonoids, which are potent antioxidants.

And what about ginger that can soothe a scratchy throat, while containing chemicals called sesquiterpenes that might target rhinoviruses causing the common cold. Ginger is also supposed to be a natural pain and fever reducer and a mild sedative. You could add a couple of tablespoons of shredded ginger root to your tea, or why not make ginger tea.

Honey is supposed to have numerous medicinal properties and because it coats your throat it is a natural way to soothe sore throats. It also has antioxidant and antimicrobial properties to help fight infections from viruses, bacteria, and fungi.

Make recipes more flavourful with spices like black, pepper, garlic, thyme, rosemary, sage and oregano. This might give you an added immune-system boost.

But back to science

The choice is yours. But by all means don’t smoke, maintain a healthy weight, drink alcohol only in moderation and get adequate sleep. And why not take steps to avoid infection, such as washing your hands frequently and cooking meats thoroughly. And maybe add a bit of ginger and chicken soup for good measure.

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