As winter approaches and the coughing-and-sniffling orchestra starts to limber up on the trains and buses, it’s time to start boosting your body’s natural defenses against infection.

Which nutrients are important?

There are a whole host of nutrients that play crucial roles in the immune system:

Vitamin A plays an essential role in maintaining surfaces of the skin, respiratory passages, intestine which provide a barrier to infection.  It also has anti-viral activity.

Beta carotene can be converted to vitamin A and plays an immune-boosting role due to its anti-oxidant activity which protects the thymus gland where immune cells mature.

Vitamin C is anti-viral and anti-bacterial. It enhances the response of immune cells (white blood cells).  Levels are quickly depleted by infections.

Vitamin E enhances immune cells and antibody function.

B vitamins are important for a proper antibody response and white blood cell (immune cell) production.

Iron is crucial for effective immune system and even slight iron deficiency reduces immunity.

Zinc is also important for many aspects of immune function including white blood cell function.  It works together with vitamin A and is anti-viral.

Selenium is vital for the functioning of the anti-oxidant enzyme glutathione peroxidase which helps protect the body from harmful substances called free radicals which are produced as part of the immune response to kill invaders.  It is also important for white blood cell production.

Omega 3 good fats are important in helping to balance the immune system so different aspects of it don’t get over active.

Vitamin D is also recognized to play important roles in regulating the immune system.

Sterols are substances found in many plant foods such as beans and lentils which also help to balance the immune system.

10 immune ‘superfoods’ rich in immune-boosting nutrients

  1. Citrus fruits along with many other fruits, are a great source of vitamin C. Vitamin C can help to reduce symptoms of a cold so long as you get enough before the cold starts, so make sure you’re getting your 5-a-day.
  2. Chilli also contains vitamin C and other antioxidants. The heat comes from a substance called ‘capsicain’ which can make your nose run, so if you do succumb to a cold, it can be helpful in clearing nasal congestion by thinning the mucus in your sinuses.
  3. Mushrooms are rich in selenium and B vitamins. Studies in animals have shown mushrooms have antiviral and antibacterial effects so enjoy them in winter stews.
  4. Fish and shellfish provide zinc and vitamin B6. Seafood is also a good source of selenium,
  5. Garlic has been used traditionally for hundreds of years as a natural antibiotic, antifungal and anti-viral remedy. Its effects are though to be due to pungent sulphur compounds.  It also contains antioxidants.  Great roasted and mixed into mashed root veg, but unforuntately it’s most effective crushed and eaten raw! That’s because oxygen in the air activates immune boosing enzymes), so try it in dressings and uncooked sauces as well.
  6. Greens like broccoli are good for just about everything.  A good source of antioxidants and iron.   Animal studies suggest it can boost the immune system. Like spinach it also contains folate (a B vitamin), beta carotene and vitamin C.   Cabbage also is surprisingly high in vitamin C and makes a great accompaniment to a comforting winter stew, especially with a good knob of butter melted in.
  7. Sweet Potato, like carrots, a great source of the antioxidant beta-carotene.  Try mashing in some nori seaweed!  Sounds unlikely, but tastes great. Seaweed contains a multitude of natural trace minerals and vitamins important for a healthy immune system.  Also try nori sprinkled in soups and stews for an intensely savour flavour.
  8. Nuts and seeds are ultra-nutritious, with protein, zinc, B vitamins, vitamin E, selenium and essential fats. Pumpkin seeds are a good source of zinc.  Brazil nuts are high in selenium. Almonds, hazelnuts and sunflower seeds will provide plenty of vitamin E.
  9. Oysters - with the days getting shorter, it could be time for an early night.  Who knows whether oysters are an aphrodisiac, but certainly they contain plenty of zinc which boosts many aspects of immune function – and now is the time to eat them because we’re into the months with an ‘r’ in them, which signals they’re in season. Zinc lozenges may reduce the severity and duration of cold symptoms.
  10. Probiotic yogurt is a source of good bacteria which help to stimulate and regulate the immune system not only in the gut but throughout the whole body.

Sources:

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

Silvia Maggini1, Eva S. Wintergerst, Stephen Beveridge and Dietrich H. Hornig (2007) Selected vitamins and trace elements support immune function by strengthening epithelial barriers and cellular and humoral immune responses British Journal of Nutrition 98, Suppl. 1, S29–S35

Beisel William R (1996) Nutrition and Immune Function:  J. Nutr. 126: 2611S-2615S,

E. Weichselbaum (2010) Can supplements help prevent or treat a common cold? Nutrition Bulletin, 35, 26–29

 

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