Cold and flu season bring many people to the drug store in search of ways to bolster their immune system. According to ConsumerReports.org, Americans spent $33.9 billion dollars in 2009 on complementary medicine. While the clinical science to date is equivocal, patients aren't waiting for the next clinical trial to tell them what they feel works. Some science indicates that certain vitamins help boost the immune system.
Vitamin C
The Linus Pauling Institute at Oregon State University focuses on the role of nutrition and vitamins in daily health. The institute notes that vitamin C plays a role in the production of white blood cells lines, including leukocytes, lymphocytes, phagocytes and neutrophils. Vitamin C seems to primarily work on neutrophils, the white blood cells that attack bacteria and viruses. The Institute notes that vitamin C may also protect white blood cells from free radical scavengers. Take 90 mg a day of Vitamin C for men and 75 mg a day for women, recommends the Institute. Their recommendations for those who smoke are somewhat higher, 125 mg and 110 mg respectively. The Institute notes that these recommendations are based on preventing deficiency only and may not be adequate to prevent disease.
Vitamin A
According to the Linus Pauling Institute, vitamin A is necessary for the body to generate an immune response. Vitamin A plays a role in the function of natural killer cells, macrophages and neutrophils. Vitamin A also plays a role in maintaining the structural integrity of the skin, eyes and mucus membranes.
The Institute notes that Vitamin A deficiency is common in third world countries where the availability of food is limited. Deficiency in vitamin A leads to immunodeficiency and vitamin A deficiency is in fact a leading cause of morbidity and mortality in infants, children and women in developing countries. Vitamin A enhances immunity and when given to hospitalized patients who are deficient, reduces morbidity and mortality. Because vitamin A can be toxic if too much is taken, the Linus Pauling Institute recommends getting vitamin A from a healthy diet instead of supplementation. Foods with vitamin A include many different fruits and vegetables such a mangoes, red peppers and carrots.
Vitamin D
The vitamin D metabolite, 1,25-dihydroxyvitamin D3, is recognized as a potent modulator of the immune system, according to the Linus Pauling Institute. The Institute notes that certain autoimmune diseases such as multiple sclerosis, rheumatoid arthritis and even diabetes may be associated with vitamin D deficiency. Supplementation with vitamin D in childhood showed a 29 percent decrease in the incidence of adult onset diabetes. The Harvard School of Public Health recommends taking 400 to 800 international units of vitamin D daily.
