The effects of β-glucan on human immune and cancer cells

Abstract

Non-prescriptional use of medicinal herbs among cancer patients is common around the world. The alleged anti-cancer effects of most herbal extracts are mainly based on studies derived from in vitro or in vivo animal experiments. The current information suggests that these herbal extracts exert their biological effect either through cytotoxic or immunomodulatory mechanisms. One of the active compounds responsible for the immune effects of herbal products is in the form of complex polysaccharides known as β-glucans. β-glucans are ubiquitously found in both bacterial or fungal cell walls and have been implicated in the initiation of anti-microbial immune response. Based on in vitro studies, β-glucans act on several immune receptors including Dectin-1, complement receptor (CR3) and TLR-2/6 and trigger a group of immune cells including macrophages, neutrophils, monocytes, natural killer cells and dendritic cells. As a consequence, both innate and adaptive response can be modulated by β-glucans and they can also enhance opsonic and nonopsonic phagocytosis. In animal studies, after oral administration, the specific backbone 1→3 linear β-glycosidic chain of β-glucans cannot be digested. Most β-glucans enter the proximal small intestine and some are captured by the macrophages. They are internalized and fragmented within the cells, then transported by the macrophages to the marrow and endothelial reticular system. The small β-glucans fragments are eventually released by the macrophages and taken up by other immune cells leading to various immune responses. However, β-glucans of different sizes and branching patterns may have significantly variable immune potency. Careful selection of appropriate β-glucans is essential if we wish to investigate the effects of β-glucans clinically. So far, no good quality clinical trial data is available on assessing the effectiveness of purified β-glucans among cancer patients. Future effort should direct at performing well-designed clinical trials to verify the actual clinical efficacy of β-glucans or β-glucans containing compounds.

Nutritional advantages of oats and opportunities for its processing as value added foods - a review

“…These acids retard the growth of carcinoma cell lines and also induce apoptosis (programmed cell death) in carcinoma cells. Though limited data is available, some beneficial effects of β-glucan on carcinoma cells are reported (Murphy et al 2004). Fung Chan et al (2009 reported no direct cytotoxic reports of β-glucan on a panel of common cancer cell lines tested including carcinoma, sarcoma and blastoma.…”

Positive Effects of Oral β-Glucan on Mucositis and Leukopenia in Colorectal Cancer Patients Receiving Adjuvant FOLFOX-4 Combination Chemotherapy

“…Then, the small fragments of β-glucans are released by macrophages and are taken up by circulating granulocytes and monocytes, and dendritic cells. The immune response will then be revealed (Chan et al, 2009;Torello et al, 2012). There is little to no evidence for these hypothesized mechanisms of action in humans.…”

“…There is little to no evidence for these hypothesized mechanisms of action in humans. It is also suggested that β-glucans have no direct cytotoxic effects and do not trigger any apoptotic pathways in cancer cells (Chan et al, 2009); however, research has shown that β-glucans augmented antitumor monoclonal antibody-mediated efficacy via stimulation of the innate effector neutrophil complement receptor 3 (Zhong et al, 2009).…”

“…β-glucans are complex polysaccharides in the cell walls of yeasts, fungi, and pathogenic bacteria. β-glucans have been shown to act on several immune receptors, including Dectin-1, complement receptor 3 (CR3), and toll-like receptor (TLR)-2/6, and stimulated the production of macrophages, neutrophils, monocytes, natural killer cells, and dendritic cells in in-vitro studies (Chan et al, 2009). Thus, β-glucans may have antibacterial, immunomodulator, and anticancer effects.…”

The Bill Henderson Protocol

“…[21][22][23] Although there is some evidence to suggest that certain components of the protocol might be beneficial to those with cancer, the evidence is far from conclusive. [24][25][26][27][28][29][30][31] Possible risks associated with the protocol's use can be considered. It is known that in cancer patients, nutritional status interacts with disease factors, treatment factors, and resulting quality of life.…”