The side effects of beta glucan can depend on the source from which it is obtained as well as the medical history of the individual taking it. In general, beta glucan is a dietary supplement that is extracted from the cell wall of a single-celled fungi, Saccharomyes cerevisae, which is more commonly known as baker's yeast. Types of beta glucan can also be derived from several other sources, however, including grains like oats and barley, some mushrooms, and even algae. In these cases, the side effects are directly related to any allergies or adverse reactions that individuals can have to these food substances. When beta glucan supplements are produced, they are largely nothing more than refined carbohydrate compounds, but their effects at stimulating the human immune system are well-known.
The benefits of beta glucan primarily involve its effects on the immune system, which often means that it is prescribed to people undergoing chemotherapy for cancer who have weakened immune systems from the treatment. The supplement is also known to have the ability to suppress tumor growth and act as an antioxidant compound in the blood. Because of these beneficial effects, the possibility of side effects from beta glucan are tied most directly to people with overly active immune systems who are fighting off infections such as lupus, or who have long-term conditions that heighten immune response like multiple sclerosis or inflammatory bowel disease. The side effects of beta glucan are also a concern for anyone who has undergone an organ transplant, as this requires taking immunosuppressant drugs, since beta glucan may minimize their effects, which could result in organ rejection.
Taking beta glucan can also lower cholesterol levels or enhance drugs designed to do so, as well as enhance the effects of antibiotics. These are beneficial effects that lead to beta glucan being prescribed for a wide range of conditions in pill form, from HIV/AIDS to diabetes and arthritis. It is used to treat the common cold as well as the flu, to alleviate the conditions of chronic fatigue, and treat common ailments like Lyme disease and hepatitis. The compound is also made into a cream that is applied to the skin to treat a variety of disorders from eczema to everyday wrinkles and dermatitis. As an intravenous fluid, it is also injected into muscle tissue for cancer patients. This array of uses and methods of use, as well as the fact that it is present in many food products like salad dressing, sour cream, and frozen desserts, means that the side effects of beta glucan have the potential to be widespread.
In the United States, beta glucan has earned a Generally Regarded As Safe (GRAS) rating by the Food and Drug Administration (FDA), which means that it has no known harmful effects. The beta glucan side effects can include an allergic response, however, as it contains a yeast cell wall component known as mannan that can trigger allergic responses in people who do not tolerate yeast well in general. These groups include people with inflammatory bowel disease and Crohn's disease. There is also anecdotal evidence as of 2011 of side effects of beta glucan in some HIV/AIDS patients who have developed dense areas of skin on the palms of their hands or soles of their feet while taking the supplement.
The substance has undergone extensive scientific testing, however, and its immune-boosting ability has led to it being recommended for treating the blood, preventing or treating infections of many types which leads to its use during surgeries, and for fighting cancer. Beta glucan has also been shown in research to stimulate the process of hematopoiesis, which is the creation of blood in the body, and which can be instrumental in recovery from exposure to radiation. Conditions involving the joints and blood supply that are common with aging are also believed to benefit from beta glucan, such as atherosclerosis and arthritis.