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Quest Vitamins LTD,
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Issue # 61: Nutritional Influences on the Immune System

The human immune system is a complex combination of many different types of specialist cells which have all been designed to help protect the body from invading organisms including bacteria, viruses and parasites. As with most systems in the body, this also needs a regular supply of nutrients in order for it to function effectively.

A recent study investigated the effects of various nutritional and lifestyle factors on immune function. Factors such as age, obesity, eating disorders, physical exercise, food hypersensitivity and gastrointestinal disorders were assessed. In the introduction, the study stated that:

"The adequate functioning of this defensive system is critically determined by nutrition, and as a consequence, so is the risk of illness".

Regarding nutrients, it was discovered that daily intake of vitamin A, beta-carotene, folic acid, vitamin B6, vitamin B12, vitamin C, vitamin E, riboflavin, iron, zinc and selenium were essential for optimum immune responses and antioxidant nutrients have a role in protecting the immune cells from oxidative stress and preserving their adequate function.

Dietary lipids were also deemed vital as an alteration in consumption of these nutrients may alter the fatty acid composition of the immune cells thus impairing their function.

Obesity has been linked to poor immune responses and it is thought to be due to the increased release of leptin and tumour necrosis factor from the adipose tissue. Therefore, simply losing weight may increase the effectiveness of the immune system.

This study also investigated the effects of regular exercise on the immune system. The evidence seems to support moderate exercise ahead of high intensity exercise, as the latter is actually associated with a decrease in immune function. If high intensity exercise is combined with improper nutrition and psychological stress, then the negative effects are worsened. Therefore, if high intensity exercise is a regular occurrence, then sound nutritional practises are essential.

Gastrointestinal disorders also exert a negative effect on the immune system at gut level as they will upset the balance of 'probiotic' bacteria which have been shown to increase immunity.

In conclusion it should be noted that many different aspects of lifestyle contribute to a healthy immune system. If any of the above mentioned factors are neglected then an infection could result. This in turn may further deplete nutritional and psychological status which may cause additional infections.

European Journal of Clinical Nutrition (2003) 57, Suppl, S66-S69

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