Compiled by Initiative Team Member Mary Jo Feeney, MS, RD, FADA
Osteoporosis - an excessive decrease in bone mass - is a risk factor for fractures, which occur most commonly at the wrist, spine and hip. Osteoporosis and the fractures associated with it are a major public health concern, because of related morbidity and disability, diminished quality of life, and mortality. Measures to prevent osteoporosis usually focus on a healthy lifestyle, which includes being physically active, not smoking, and taking adequate amounts of calcium and vitamin D. Pharmaceutical treatment in high-risk groups (those with an elevated risk of fracture) and measures to prevent falls are also proposed as important interventions for preventing fractures. Screening for osteoporosis, by measuring bone density or other measures, is suggested to identify and treat people at risk for fracture. For more information, see http://www.sbu.se/en/Published/Yellow/Osteoporosis---preventiondiagnosis-and-treatment/.
Adequate calcium intake and vitamin D status have long been recognized as factors in maintaining bone health. Some research suggests a positive link between bone mineral density (BMD) and fruit and vegetable consumption in adults. The mechanism whereby fruit and vegetables affect bone is not clear and may be multifactorial (http://www.ajcn.org/cgi/content/full/83/6/1254). A higher intake of acid-forming foods (cereals and meats) rather than alkali-forming foods (fruits and vegetables) may result in bone mineral dissolution. A diet rich in fruit and vegetables which creates a more alkaline environment may reduce calcium excretion in the urine. In addition, fruits and vegetables are rich sources of antioxidant compounds which could combat oxidative stress, shown to be negatively associated with bone mineral density in adults. More research is needed linking fruit and vegetables to bone health.
From the Executive Summary
Osteoporosis/Bone Health: In vitro studies have reported positive effects of mushroom extracts on mineralisation of osteoblastic cell lines. Animal studies have reported increased bone density following consumption of mushroom extracts, while mice fed calcium plus vitamin D2-enhanced (UV irradiated) mushrooms showed improved bone mineralization through a direct effect on the bone, and by inducing the expression of calcium-absorbing genes in the duodenum and kidney.
In vitro studies (human cell lines)
The cultivation of human osteosarcoma cells HOS58 in the presence of an aqueous extract of Grifola frondosa has been shown to result in a significant elevation of alkaline phosphatase activity of the cells in comparison to untreated cells. In another osteoblastic cell line (SaOS-2) cells incubated with Grifola frondosa for 21 days, showed a nearly 2fold higher mineralization than cells cultured with a positive control, demonstrating the activity of Grifola frondosa extract as a bone-inducing agent (Saif et al., 2007).
The effects of Pleurotus eryngii extracts (PEX) on bone metabolism have been studied. PEX treatment showed an increase in the alkaline phosphatase activity of the osteoblasts and in the osteocalcin mRNA expression from primary osteoblasts. PEX also increased the expression of the Runx2 gene, and the secretion of osteoprotegerin from the osteoblasts showed marked increases after treatment with PEX. In vivo studies, using rats with ovariectomy-induced osteoporosis revealed that PEX alleviated the decrease in the trabecular bone mineral density (Kim et al., 2006b). An ethanol extract of Pleurotus eryngii has also been reported to help protect against bone loss caused by estrogen deficiency, without having a substantial effect on the uterus (Shimizu et al., 2006). Osteoclast forming suppressive compounds have been isolated from the mushroom Agrocybe chaxingu (Abel et al., 2007).
Animal model (mouse) studies
Lentinula edodes that are exposed to UV radiation contain enhanced vitamin D2 and have much higher calcium content than non-irradiated mushrooms. A recent study has evaluated whether irradiated Lentinula edodes could improve or prevent osteoporosis-like symptoms in 4-week old mice fed low calcium and a vitamin D deficient diet. Femur density and tibia thickness were significantly higher in mice fed calcium plus vitamin D2-enhanced mushrooms, and the expression of duodenal and renal calcium transport genes was significantly induced. The results indicated that in mice, vitamin D2 and/or calcium derived from irradiated Lentinula edodes may improve bone mineralization through a direct effect on the bone, and by inducing the expression of calcium-absorbing genes in the duodenum and kidney (Lee et al., 2009b).
Animal model (rat) studies
Ethanol extracts of Ganoderma lucidum have been evaluated against the ovariectomized (Ovx)-induced deterioration of bone density in 11-week-old female Sprague Dawley (SD) rats (Miyamoto et al., 2009). The results showed that the G. lucidum-treated Ovx rats showed improved bone density compared with the Ovx rats.
Effects on Rheumatoid Arthritis
Animal model (rat) studies
Non-steroidal anti-inflammatory drugs (NASIDs) are widely used clinically to treat inflammatory diseases and rheumatoid arthritis and free radicals have long been implicated in the change in connective tissues in inflammation and arthritis. Lipid-peroxide formation as well as altered levels of endogenous free-radical scavengers, such as superoxide dismutase, glutathione peroxidase, and reduced glutathione, have been considered as indirect in vivo evidence for the participation of free radicals in the progression of arthritis. A polysaccharide-protein complex (PPC-Pr) isolated from Phellinus rimosus (Berk.) Pilat administered to rats significantly increased lipid-peroxide levels in the plasma of adjuvant-induced arthritic rats. The antioxidant enzymes superoxide dismutase and glutathione peroxidase were elevated in adjuvant-induced rats, and reduced blood glutathione was decreased. Treatments with various concentrations of PPC-Pr modulated the above alterations produced in arthritic animals in a dose-dependent manner (Meera et al., 2009).
The anti-arthritic activity of glucomannan (GM) isolated from Candida utilis and of imunoglukan, a beta-(1,3/1,6)-D-glucan (IMG) isolated from Pleurotus ostreatus has been evaluated (Bauerova et al., 2009, Rovensky et al., 2009). Adjuvant arthritis (AA) was induced intradermally by the injection of Mycobacterium butyricum into Lewis rats. The experiments included healthy animals, arthritic animals without treatment, and arthritic animals with administration of glucomannan (GM-AA) in the oral daily dose of 15 mg/kg b.w. and of IMG (IMG-AA) in the oral daily dose of 2 mg/kg b.w. IMG administration had a positive immunomodulating effect on all cytokine plasma levels measured and changed markedly due to arthritis progression. Further studies are required to confirm any possible role in the treatment of rheumatoid arthritis.