No single vitamin alone is responsible for boosting your immune system, but adequate nutrition is necessary for ensuring the body has enough nutrients and fuels to fight infection and disease. Eating a healthy and varied diet that contains sources rich in the following vitamins are crucial to reducing your chances of illness.
1. Vitamin C
Vitamin C has been long recognized as an important nutrient for the immune system. Vitamin C is vital in the production of white blood cells that defend the body against both infection and toxins. Vitamin C also plays a role in a protein called interferon, which is released from cells in response to the presence of a pathogen, such as a virus or bacteria, and activates the immune cells to fight the invader.
Although the official Recommended Dietary Intake for vitamin C for adults is 60-75 mg per day, many health experts feel this may be set too low for optimal immune system function. 200 milligrams per day is a safe level and easy to achieve with a diet that includes at least six servings of fruits and vegetables each day.
2. Vitamin E
Vitamin E is another important nutrient that stimulates the production of B-cells, which are a type of lymphocyte that produce antibodies to destroy bacteria in the body.
Foods rich in vitamin E include nuts, seeds, vegetable oils and whole grains. The recommended daily intake for adults is 15 milligrams, or approximately 22 IU a day. Most supplements contain significantly more than this, because people need about 50% more of the synthetic form to obtain the same amount of the nutrient than from foods.
3. Vitamin A
Vitamin A is important for the regeneration of the mucosal barrier in the intestine that keep infection out of the body. It also regulates the immune system through its role in the production of white blood cells. Beta-carotene is a precursor to vitamin A, which means that the body uses the nutrient and transforms it into the vitamin form. Beta-carotene belongs to a group of antioxidants called carotenoids, which increase the number of infection-fighting cells in the body, including T-cells, a type of lymphocyte similar to B-cells that fight antigens or infections.
Although vitamin A is necessary for immune function, excess vitamin A may actually hinder immunity. Foods are recommended over supplements to ensure an adequate level of the vitamin. Foods high in vitamin A include liver, whole milk, whole eggs and fortified foods. Foods high in beta-carotene are orange-colored fruits and vegetables, such as mango, carrots and sweet potatoes.
4. Vitamin B6
Pyridoxine, the chemical name for vitamin B6, is not as well known for its immune system contribution. The body needs B6 to make hemoglobin, a component of the red blood cell that carries oxygen to the body tissue. B6 is also needed in protein metabolism and cell growth. Some animal studies have shown a link between vitamin B6 deficiency and decreased antibody production.
Vitamin B6 is found in many foods, such as fortified cereals, beans, meat and some fruits and vegetables. Adults need between 1.3 and 1.7 milligrams per day.
Other Important Nutrients
As mentioned, vitamins work in concert with other dietary nutrients to keep the immune system in working order. Zinc, for example, is a mineral that works with beta-carotene in increasing the number of T-cells to fight infection. Ensuring an appropriate intake of protein and essential fatty acids, such as omega-3's from fish or flax, is necessary for cell and tissue building. And foods that contain allicin, such as garlic and onions, may help with antibody production.