Home Lifestyle Food & Health Winter’s coming: Boost your immune system

Winter’s coming: Boost your immune system

Nutritionist advises on foods that can strengthen your body’s defence system

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Keeping your immune system working at its best is top of mind at the moment, due to the Covid-19 pandemic. Your body’s immune system is your best ally in fighting off diseases like the flu. And while it can’t stop you contracting the novel coronavirus, it might help your body put up a stronger fight when you do get it.

PLEASE follow the official medical advice on how to avoid getting the disease and how to help contain its spread. This includes regularly washing your hands thoroughly using soap or hand cleanser, keeping a distance of at least 1.5m from others and by self-isolating as much as you can.

While you are self-isolating and social distancing, however, here is some advice from Food For Mzansi’s resident nutritionist Andrea du Plessis on foods that will help support your immune system.

Natural Immune Boosters

Did you know that the key to a healthy immune system may be in your vegetable garden? With nature’s helpers on your side, you can be sure that your immune system will be on defence and help keep the flu at bay.

Fast Facts: The Immune System

  • The immune system is the body’s natural protection against harmful bacteria, fungi, viruses and other organisms that could cause infections.
  • The immune system involves a complex system of immune cells that are distributed throughout your body.
  • While immune cells generally circulate through the bloodstream, areas where harmful organisms are likely to enter the body, such as the respiratory and digestive systems, contain higher concentrations of certain immune cells, ready to fight invading organisms.
  • The following factors may impair the immune system’s function:
    • Inadequate or unhealthy diet – the immune system is dependent on a variety of nutrients for optimal functioning.
    • Lack of sleep – even losing 1 hour from your usual sleeping pattern can decrease the body’s defences that next day.
    • Stress – stress and the body’s hormonal response to pressure is known to break down the immune system’s defences.
    • Lack of exercise or excessive exercise – 30 minutes 3-5 times per week stimulates the immune system’s function. A lack of activity, as well as excessive high intensity exercise, are both known to impair the immune system’s function.
    • Chronic exposure to infectious diseases.
    • The use of certain medicines, such as antibiotics or immune-suppressive therapy, often typically to transplant patients.
    • Certain diseases including HIV infection and cystic fibrosis.

Vitamin C steals the show when one considers the immune support benefits of nutrients.

How does it work? 

Since our immune system is responsible for protecting our bodies against invading viruses and bacteria, it comes as no surprise that Vitamin C’s actions are directly focused on the immune cells.

  • According to test results published in Advances in Experimental Medicine and Biology, there is up to 100 times more Vitamin C in our white blood cells than in the plasma (the fluid component) of our blood.
  • Vitamin C has also been shown to increase the number and activity of our immune cells, as well as protecting our immune cells against premature degeneration.
  • At the onset of an infection, an increase in the usage of Vitamin C by our immune cells result in a decrease in Vitamin C levels. During this time, it seems that the body is able to retain dietary Vitamin C more effectively, as it is required to help fight the infection.

Can Vitamin C support the prevention and management of colds and flu?

  • Reduce severity of symptoms : A review published in the Cochrane Central Register of Controlled Trials revealed that a daily dose of 1000 mg of Vitamin C can reduce the severity of the symptoms of a cold.
  • Reduce the duration: This same report showed that Vitamin C supplementation showed a modest, but consistent reduction in duration of cold symptoms.

Contrary to the popular belief that oranges have the highest levels of Vitamin C, guavas, sweet red peppers and chillies contain between 3-6 times more Vitamin C than oranges (see table below).

With many vegetables listed as concentrated Vitamin C sources, it is important to consider the fact that heat exposure during cooking destroys up to 50% of the Vitamin C.  It is therefore important to find ways of ingesting vegetables such as red peppers in their raw state to get the desired immune boosting benefit.

Vitamin C content of well-known food sources

Food Source Vitamin C (per 100 g of item)
Guavas 347 mg
Red Peppers, uncooked 190 mg
Chillies, uncooked 132 mg
Lemons 77 mg
Cauliflower, uncooked 70 mg
Strawberries 58 mg
Oranges 53 mg
Grapefruit 34 mg
Blueberries 13 mg

(Source: Medical Research Council food composition tables)

Did you know? Signs of Vitamin C deficiency include: bleeding gums, poor healing of wounds and bruises, muscular atrophy, skin lesions, rheumatic pain in legs and depression.

Cod liver oil has a long history of protecting against colds and flu, strengthening the delicate mucus membranes in the eyes, nose and mouth, and generally boosting vitality. These days we know that its vitamin A and D content is partly responsible for a protective, strengthening effect on the mucus membranes. Cod liver oil naturally contains omega 3 fatty acids. We also know that it has a general anti-inflammatory effect on the body.

Zinc is a trace element (a mineral that you need in small quantities) which plays an important role in human health. Zinc supports the healthy functioning of the immune system.

Selenium is another trace element that supports immunity, mainly because it is an antioxidant. It has a powerful action against free radicals, which damage cells and are a primary cause of age-related degeneration.

Elderberry extract is derived from the berries of the Elder (Sambucus nigra), a large shrub. Elderberry also helps eliminate toxins via sweating. In addition to this, studies on elderberry extract show an antiviral activity on certain strains of influenza which could help reduce the duration and severity of flu symptoms. Elderberry also shows promise in reducing excess mucus production (catarrh). All these benefits led Hippocrates, regarded as the father of modern medicine, to regard elderberry as “an excellent remedy for a cold”.

RECIPE: Immune Boosting Snack:

Red Pepper Salsa, to have with multigrain crackers

Ingredient Benefit
1 large sweet red pepper, diced Rich source of immune boosting vitamin C
½ teaspoon freshly grated ginger root Natural expectorant, helping to expel mucus. Brilliant for relieving sore throats, due to its anti-inflammatory and anti-bacterial effects
1 fresh garlic clove, crushed Antibacterial and antiviral effects
1 tsp freshly chopped parsley Detoxifying action, helping to neutralise garlic odour
1 heaped tbs sunflower seeds Contains zinc, an immune support mineral
10 ml chilli-infused soy sauce Chilli thins mucous secretions, helping to relieve mucous congestion
  • In a pan over a medium heat, dry-roast sunflower seeds. Turn down heat when they start to turn light brown. Add chilli soy sauce and stir until all moisture is evaporated. Cool down.
  • Combine diced pepper, ginger, garlic and parsley. Transfer into a medium serving dish and sprinkle with sunflower seeds.
  • Scoop up salsa with multigrain corn cakes and enjoy as an immune boosting snack, or appetizer.
Andrea Du Plessis
Andrea Du Plessis
Andrea du Plessis is a well-known registered dietician with a passion for healthcare through nutrition, natural remedies and a healthy lifestyle. She regularly presents talks and educational workshops on nutrition throughout the country. Du Plessis is also known as the resident health and nutrition expert on SABC3’s Expresso breakfast TV show.
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