Beta-glucan is not an essential nutrient. It is found in whole grains (especially oats, wheat, and barley) and fungi such as baker’s yeast, Coriolus versicolor , and the medicinal mushrooms maitake and reishi .
Different food sources contain differing amounts of the various chemical constituents collectively called beta-glucan. Grains primarily contain beta-1,3-glucan and beta-1,4-glucan. Fungal sources contain a mixture of beta-1,3-glucan and beta-1,6-glucan. Purified products containing only the 1,3 form are also available.
The other primary proposed use of beta-glucan products involves effects on the immune system. Test-tube , animal , and a few controlled studies in humans suggest that beta-glucans can alter various measurements of immune function. In the alternative medicine literature, these effects are commonly summarized as indicating that beta-glucan is an “immune stimulant.” This description, however, is an oversimplification. The immune system is extraordinarily complicated and, as yet, incompletely understood. At the current level of scientific understanding it is not possible to characterize the effects of beta-glucan more specifically than to say that it has “immunomodulatory” actions, or that it is a “biological response modifier.” These intentionally unsensational terms indicate that we merely know beta-glucan affects (modulates) immune function, not that it improves immune function.
Some of the immune-related effects seen in studies include alterations in the activity of certain white blood cells and changes in the levels or actions of substances, called cytokines, that modulate immune function.
Beta-glucan, as a substance widely present in foods, is thought to have a high margin of safety. However, if it really does activate the immune system, harmful effects are at least theoretically possible in people with conditions where the immune system is overactive. These include multiple sclerosis , lupus , rheumatoid arthritis , asthma , inflammatory bowel disease , and hundreds of others conditions. In addition, people taking immunosuppressant drugs following organ transplantation surgery could, in theory, increase their risk of organ rejection. However, there are no reports as yet to indicate that any of these hypothetical problems have actually occurred. Maximum safe doses in young children, pregnant or nursing women, or people with severe liver or kidney disease have not been established.
- Reviewer: EBSCO CAM Review Board
- Review Date: 08/2013 -
- Update Date: 08/22/2013 -