We consider it quite a feat to escape winter without a single cold. However, research is beginning to indicate that a healthy diet may help strengthen the immune system and give your body the best chance of fighting colds.

To date, the only specific cold treatments available from your doctor or pharmacist are designed to deal with symptoms such as sore throats, runny or stuffy noses, coughing, sneezing and sleeplessness. Very little advice is given on diet for the simple reason that there is little research-based evidence to suggest that what you eat has much effect once the virus has taken hold.

One possible exception to this rule is increasing intakes of vitamin C.

Although not yet conclusive, the indications are that giving people large quantities of this nutrient the moment that cold symptoms appear may be of some benefit. It has been found that for some people, taking between 500 –1000mg of vitamin C a day could help to lessen the severity and possibly the duration of a cold. Researchers feel that these effects could be due to the vitamin C in the blood boosting interferon levels thus helping to protect cells from viral attack.

Vitamin C intakes can be increased through foods and drinks such as citrus fruits and juices, kiwi fruit, sweet potatoes, peppers, blackcurrants, green leafy vegetables and exotic fruits, such as guava, or certain foods fortified with vitamin C. Supplements of vitamin C may also be considered.

Other work indicates that prevention could well be better than cure. When elderly people in long-term care were given a multi-micronutrient supplement including 20mg of zinc, 100µg of selenium, 15mg of vitamin E and 6mg of beta carotene, scientists discovered that they caught fewer respiratory infections. It is possible that diets supplying good and regular amounts of these vitamins and minerals could help to protect the population at large.

It is not just vitamins and minerals that are potentially important infection fighters. Herbalists have long promoted the benefits of garlic for its antiviral effects; a property that could be due to a natural constituent it supplies. Extracts from Echinacea, (the purple cornflower), as drops or capsules are also valued for their antiviral effects.

Just as certain nutrients seem to help strengthen the immune system, stress appears to deplete some vitamins and minerals. Combining a healthy varied diet containing a lot of fruits and vegetables with a good balance of exercise and sleep would seem to be a good strategy to start this winter’s battle against the common cold.

References

• Paul Knipschild: Systemic Reviews: Vitamin C and the common cold. BMJ; 309:719-21, 1994 .
• Carr AB et al: Vitamin C and the common cold: Using identical twins as controls. Med J Aust 2:411-12, 1981.
• Gerber WF et al: Effect of ascorbic acid, sodium salicylate, and caffeine on the serum interferon level in response to viral infection. Pharmacology 13 (3): 228-33, 1975.
• Mary Ann Johnson et al: Micronutrient Supplementation and Infection in Institutionalized Elders, Nutr Re, vol. 55, No. 11, 400 – 404.
• Berdanier CD: The many faces of stress, Nutr. Today 22 (2): 12, 1987.
• Ross AC: Vitamin A and protective immunity, Nutr Today 27 (4):18, 1992

FOODS SUPPLYING VITAMIN C, VITAMIN E, BETA CAROTENE, ZINC AND SELENIUM

NUTRIENT	FOODS TO EAT
Vitamin C	Citrus fruits, kiwi, guava, peppers, blackcurrants, strawberries
Vitamin E	Almonds, hazelnuts, sunflower seeds, sweet potatoes, sunflower oil, wheat germ and wheat germ oil, avocado pears
Beta carotene	Carrots, sweet potatoes, pumpkin, guava, mangoes, apricots, red peppers tomatoes, dark green vegetables
Zinc	Shellfish, red meat, wheat germ, whole grain cereals like wholemeal bread and whole grain breakfast cereals
Selenium	Brazil nuts, sunflower seeds, mussels, tuna canned in oil, haddock, kidneys

FOOD TODAY 11/1999