Research suggests that some of the decline in immune function seen as people age may be preventable with good nutrition. The Penn State study, published in the British journal Mechanisms for Aging and Development, found that women aged 60 to 80 who were well nourished maintained comparable immune function to women aged 20 to 40. Several past studies also suggest that nutrition may have significant effects on aging immune systems, though some researchers contend that a partial decline may be unavoidable.

Our immune systems fight off invaders like viruses, bacteria and abnormal cells. For years, research has shown immune function weakening with age. Such weakening increases our susceptibility to infections and allows tumours to emerge.

Published research suggests that at least some portion of the age-related weakening of the immune system could be due to diet.

A French review reported in the American Journal of Clinical Nutrition suggests that protein-calorie malnutrition, a condition unfortunately common in the aged, may play a large role in immune changes. Levels of several types of immune-related cells go down in individuals suffering from diets lacking protein. Deficiencies of zinc, selenium and vitamin B-6 may also contribute to a weakening of the immune system. Meat, poultry, seafood and whole grains are good sources of all these nutrients.

Research at Tufts University in Boston shows that antioxidants may also play an important part in immune function. Some studies show vitamin E or beta-carotene helping to boost levels of certain immune system cells. Exercise is another recognized factor in maintaining a healthy immune system.

For now, the research in this field stresses what sound nutrition has been telling us for years: as people age, poor nutrition takes a toll on the immune system. The evidence doesn’t indicate that very high doses of nutrients are required to combat the aging effect. Instead, it stresses that inadequate or poorly balanced diets are detrimental to the health of the elderly.

Nutritional status may not influence immune function in young adults as directly as in elderly individuals. Yet many of our chronic diseases — cancer, heart disease, osteoporosis — begin developing many years before problems surface. A balanced, plant-based diet for preventive health is important for the young-in-body as well as the young-at-heart.

“Nutrition Notes” is provided as a public service by the American Institute for Cancer Research, 1759 R Street, NW, Washington, DC 20009