Ask the doctor.(immune system )

I'm interested in what role the immune system plays with regard to anti-aging and what I can do to maintain my immune system in this respect.

--A.E., Buffalo, New York

Aging is accelerated--or even caused--by the accumulation of waste products in the body or by cellular damage to various parts of the body. Alzheimer's disease, for instance, is caused by damage to the brain; multiple sclerosis is caused by damage to the nervous system; and emphysema is caused by damage to the lungs.

Of these three conditions, multiple sclerosis and emphysema are commonly caused by immune system reactions. That is, the tissues affected by these conditions were damaged not by an outside invader but by one's own immune system.

The bottom line is that the immune system must be kept in balance. An overactive immune system can cause allergies and autoimmune reactions, while an underactive one can allow diseases that drain the body of its strength and accelerate aging.

How do you achieve a balanced immune system? Here are some ideas to help you get started.

To maintain healthy natural killer (NK) cell activity, which protects the body against outside invaders and internal problems, I recommend mushroom products. The immunopolysaccharide complexes found in mushrooms have been shown to enhance NK cell activity and "modulate" the immune system. Modulation in herbal medicine means to counteract the effects of stress and bring a process back to normal levels.