Antibodies (or immunoglobulins) are proteins produced by the immune system of the body in response to a foreign substance like infectious agents (bacteria, viruses etc.), drugs, foods, animal or plant protein or cancer cells. They are of five types and their level varies with age and each laboratory determines its own biological reference interval. They protect the body and play a role in allergic reactions. Immunoglobulin G (IgG) has the highest levels in blood followed by IgA and IgM. The levels of Ig D and IgE are very low. If the levels of immunoglobulin in the blood are reduced (hypogammaglobulinemia), a person is susceptible to infection. Food and exercise have no perceptible impact on immunoglobulin levels. You need to consult a doctor who can examine you and then advise you appropriately.