How to keep these nasty viruses at bay in winter
Most doctors and scientists agree that preventing colds and the flu is best done by avoiding exposure to the viruses that cause them. But as these are spread by droplets of body fluid sneezed, coughed or breathed out, and we come into contact with people daily and breathe the same air, it’s virtually impossible to avoid contact with viruses.
When a virus enters the body it meets specialised cells of the immune system that have been weakened or strengthened by factors such as diet, exercise and stress.
Antioxidants, vitamins and minerals are crucial to immune function. Antioxidant deficiencies impair immunity and supplementation could improve this. However, it’s highly unlikely that colds and flus are caused by a deficiency of a single nutrient or antioxidant.
Therefore it’s suprising (but not unexpected) to read that a recent SPARC research indicates that New Zealand athletes heavily rely on nutritional supplements. While nutrition experts agree that currently there is a lack of evidence to support high doses of anti-oxidant vitamins, glutamine supplementation or echinacea extracts in preventing immune suppression and protection from infection.
A healthy, regular diet can supply most daily requirements of nutrient based antioxidants. An adequate dietary intake of protein and specific micronutrients including vitamins A, C, E, B6 and B12 along with iron, zinc, copper and selenium are all critical factors for the maintenance of optimum immune function.
The “million dollar” question for athletes is whether or not supplemental forms or megadoses of these nutrients are beneficial. There is a growing list of research papers that report indifferent results on the effects of nutritional supplements on the acute immune response to exercise. Antioxidants (i.e. vitamins C and E) and glutamine have received considerable attention, but the data thus far does not support their role in negating immune function changes after exercise (Gleeson et al. 2004).
What should I eat?
Athletes should invest in nutrient-rich foods and fluids that provide sufficient energy and a wide range of vitamins, minerals and other important chemicals, such as phytochemicals, found naturally in foods. Dietary emphasis should be on a generous intake of plant foods. The New Zealand Food and Nutrition Guidelines (see below) suggest at least three servings of vegetables and two servings of fruit each day. If you take care to include some that are dark green or yellow in colour you should consume a complex mixture of antioxidants nutrients.
Food Group
Fruit and vegetables (incl. fresh, frozen, canned and dried).
Only one serving of vegetable of fruit juice of dried fruit counts.
If trying to contain energy content try not to eat too much dried fruit and drain syrup from canned fruit.
Advice
Eat at least 3 servings of vegetables per day and 2 serves of fruit per day
Nutrients Provided
Carbohydrates
Dietary fibre
Vitamins; especially A (yellow and green vegetables), C (dark green vegetables, most fruits and potatoes), and folate.
Minerals: magnesium, potassium
Food Group
Breads and cereals (incl. all bread, grains, rice and pasta)
Advice
Eat at least 6 servings per day (try to choose wholegrain)
Nutrients Provided
Protein
Carbohydrates
Dietary fibre
Vitamins: all B-group (except B12), E (rich in Wheatgerm),
Minerals: magnesium, calcium, iron, zinc and selenium (in wholegrain products)
Food Group
Milk and milk products (incl. cheese, yoghurt and ice cream)
Advice
Eat at least 2 servings per day (choose reduced of low fat options)
Nutrients Provided
Protein
Fats: higher portion of saturated fats rather than poly- or mono-unsaturated fats especially in full fat products
Vitamins: riboflavin, B12 and A
Minerals: especially calcium, phosphorous, zinc and iodine
Food Group
Lean meat, poultry, chicken, seafood, eggs, nuts and seeds and legumes
Advice
Eat at least 1 serving per day
Nutrients Provided
Protein
Fats: both visible and marbled in meat (mostly saturated and cholesterol). Mostly unsaturated in seafood nuts and seeds.
Carbohydrates: mainly legumes (dried peas and beans)
Vitamins: B12, thiamin and niacin
Minerals: zinc, iron, magnesium, copper, potassium, phosphorous and selenium.
- adjusted from the Ministry of Health
So what should I do?
To prevent cold and flu’s, walkers should eat a well-balanced diet high in fruit and vegetables, drink enough fluids, keep other life stresses to a minimum, avoid overtraining and chronic fatigue, get enough sleep, avoid contact with sick people before and after important events and space vigorous races and workouts.
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