Beta Glucans and Enhanced Immunity
Beta glucans are naturally occurring complex sugars known as polysaccharides. The simplest sugar is glucose, and polysaccharides consist of hundreds of glucose units linked together to form chain-like molecular structures. The chemical structure and effects within the human body of beta glucans vary according to their source.
Beta glucans obtained from cereals such as oats or barley, known as beta 1.3/1.4 glucans, form long unbranched molecular chains, and may have beneficial effects on blood cholesterol levels, but have little effect on the immune system. Beta glucans obtained from certain types of fungi, known as beta 1.3/1.6 glucans, form characteristic branched chain molecules, and have a stimulatory effect on the immune system.
The immunostimulating effect of specific types of mushrooms has been known in the Far East for many hundreds of years; more recently baker's yeast has been identified as the best source of beta 1.3/1.6 glucans in terms of immunostimulating power. The specific type of branched chain beta 1.3/1.6 glucan molecules produced only in bakers yeast are thought to be of particular importance for stimulation of the immune system.
Beta glucans and the immune system
The immune system is comprised of two parts, namely innate immunity and acquired immunity. As the name indicates, the innate immune system is inborn, and serves as the body's first line of defence against infections organisms. Acquired immunity, with which many people will be more familiar, involves the development of antibodies (either by exposure to infection or via immunisation) to foreign organisms, as a second line of defence against infection.
The importance of the innate immune system is highlighted by the fact that many (particularly less developed) species are unable to develop antibodies via acquired immunity, yet are still able to withstand exposure to infectious organisms. Beta 1.3/1.6 glucans provide a stimulus to activate neutrophils, macrophages, and natural killer (NK) cells of the innate immune system, thereby enabling the body to defend itself against the possible presence of infectious organisms.
It is thought that in the ultra-clean modern environment in which most people live in industrialised societies, there is insufficient exposure to the microbial products that in the past would have acted to provide natural stimulation of the innate immune system. The importance of the latter has been highlighted in research by Dr Paul Clayton, recently featured in the Daily Mail, which demonstrated the high level of exposure to beta glucans in the Victorian diet and environment, and the health benefits that this subsequently conferred on their immune function.
Because of the widespread problems of resistance to antibiotics, and the development of vaccine resistant genetically variable organisms such as those responsible for avian flu, the importance of the innate immune system (and potential methods for its activation) have been increasingly recognised.
Evidence for efficacy and safety of beta 1.3/1.6 glucans
Numerous studies on beta 1.3/1.6 glucans have been carried out in experimental animals. Of particular notes are the protection of mice against infection with normally lethal doses of anthrax (vetvicka et al 2002), enhanced survival of mice receiving normally lethal doses of radiation (Patchen & MacVittie, 1986), and reduced mortality of mice with certain types of cancer (Thompson et al, 1987).
A number of randomised controlled clinical trials have been carried out to investigate the efficacy and safety of supplementation with beta 1.3/1.6 glucans. Examples include the reduction in risk of infection in patients with multiple trauma and head injury (Felippe et al, 1993), patients undergoing gastrointestinal surgery (Dellinger et al, 1999).
In the study by Felippe et al, administration of beta 1.3/1.6 glucans (30mg per 24hrs) to hospitalised patients suffering multiple trauma with head injury, resulted in an approximate three to five-fold reduction in risk of pneumonia, sepsis and mortality due to infection, compared to placebo. In the study by Babineau et al, patients at high risk of post-operative infection undergoing thoracic or abdominal surgery were treated with beta 1.3/1.6 glucans (1-2mg/kg) or saline placebo pre and post-surgery.
Patients receiving beta 1.3/1.6 glucans had their risk of post-operative infection significantly reduced by approximately 60 per cent. In the study by Dellinger et al, pre and post operative administration of beta 1.3/1.6 glucans (1mg/kg) reduced the risk of serious infection of death by 39 per cent in patients undergoing non-colorectal gastrointestinal surgery, compared to placebo.
With regard to safety, in general clinical trial studies such as those above have shown the incidence of adverse effects to be similar in beta 1.3/1.6 treated and placebo groups. Studies in healthy volunteers have demonstrated iv administration of beta 1.3/1.6 glucans (0.05-2.25mg/kg) to be safe and well tolerated (James et al, 1992). Thus beta 1.3/1.6 glucans are generally recognised to be non-toxic, non-allergenic and generally well tolerated.
Comparison of commercially available beta glucan supplements
A wide range of supplements containing beta glucans is commercially available. These supplements contain beta glucan from various sources, which have differing chemical structures and actions within the body. As noted above, the type of beta glucans obtained from cereals such as oats or barley (beta 1.3/1.6 glucans) are not effective in stimulating immune function. Whilst certain species of mushrooms contain beta 1.3/1.6 glucans with immunostimulatory action, it is now recognised that the best source of these compounds is baker's yeast, Saccharomyces cerevisiae.
Even within this specific category of yeast derived beta glucans, the effectiveness of different commercial preparations may vary widely. Key determinants of effective immune response activation by beta 1.3/1.6 glucans include the number and length of processing and uniformity of molecular size. The best characterised commercially available beta 1.3/1.6 glucan supplement, in terms of control of production and clinical effectiveness, is Wellmune WGP.
Wellmune WGP is manufactured to ISO 9002 standards via a patented process by the Biothera Corporation, USA. A particular feature of this process is the removal of unwanted contaminants from the active compound. Recent clinical trial studies specifically using Wellmune WGP include reduced infections and improved health in stressed individuals, reduced immune suppression in marathon runners, increased resistance to the effects of colds and flu, and reduced respiratory tract infections in fire fighters. Details of these and other studies relating to Wellmune WGP are listed on the website www.wellmune.com.
References
- Babineau Tj et al (1994) Randomised phase I/II trial of a macrophage specific imununomodulator (PGG glucan) in high risk surgical patients. Ann Surg: 220(5): 601-609
- Dellinger EP et al (1999) Effect of PGG glucan on the rate of serious post-operative infection or death observed after high risk gastrointestinal operations. Arch Surg: 134(9): 977-983
- Felippe JD (1993) Infection prevention in patients with severe multiple trauma with the immunomodulator beta 1-3 polyglucose (glucan). Surg Gynecol Obstet; 177: 383-387
- James S et al (1992) Phase 1 clinical study with Betafectin. Proc Int Congr Immunol, (Budapest) 739-740
- Patchen ML, MacVittie TJ (1986) Comparative effects of soluble and particulate glucans on survival in irradiated mice. J Biol Response Modifiers: 5(1): 45-60
- Thompson IM et al (1987) Immunochemotherpy of bladder carcinoma with glycan and cyclophosphamide. Am J Med Sci: 294)5): 294-300
- Vetvicka V et al (2002) Orally administered yeast beta 1.3 glucan prophylactically protects against anthrax infection and cancer in mice. J Am Nutr Assoc, 5(2): 5-9
