Immune System Support Diet

All forms of sugar (including honey) interfere with the ability of white blood cells to destroy bacteria. Animal studies suggest diets high in sucrose (table sugar) impair some aspects of immune function. The importance of these effects in the prevention of infections in humans remains unclear.

Alcohol intake, including single episodes of moderate consumption, interferes with a wide variety of immune defenses. Alcohol’s immune-suppressive effect may be one mechanism for the association between alcohol intake and certain cancers and infections. However, moderate alcohol consumption (up to three to four drinks per day) has been associated in preliminary studies with either no risk or a decreased risk for upper respiratory infections in young nonsmokers.

The effect of fats on the immune system is complex and only partially understood. Excessive intake of total dietary fat impairs immune response, but some types of fat may be neutral or even beneficial. For example, monounsaturated fats, as found in olive oil, appear to have no detrimental effect on the immune system in humans at reasonable dietary levels.

Research on the effect of the omega-3 fatty acids that are abundant in some fish, fish oils, and flaxseed oil is conflicting. Liquid diets containing omega-3 fatty acids used in hospitals for critically ill people have been shown to improve immune function and reduce infections. However, in one controlled study in healthy people, a low-fat diet improved or maintained immune function, but when fish was added to increase omega-3 fatty acid intake, immune function was significantly inhibited...