Herbal remedies and other natural products were used by 19% of adults during the past 12 months according to a 2002 survey.(1) The ten most commonly used herbal remedies were echinacea, ginseng, ginkgo biloba, garlic supplements, glucosamine, St. John’s wort, peppermint, flax and fish oils, ginger, and soy.(1,13) Other commonly used herbal remedies include chamomile, bee pollen, kava kava, valerian, and saw palmetto.(1) Some common natural products are described below in relation to the conditions they are used to treat.
Ginkgo biloba is an extract from the leaves of the ginkgo tree that contains multiple natural products. It is used to treat Alzheimer’s dementia instead of or along with acetylcholinesterase inhibitors like donepezil. Studies have found that modest memory improvement can occur with use. The mechanism of action of ginkgo biloba is not known, but it is thought to be related to the extract’s anti-inflammatory properties. In addition, the flavonoid component of the extract is an antioxidant that scavenges the free radicals thought to be involved in the pathology of dementia. The most commonly reported side effect of ginkgo biloba is gastrointestinal symptoms. However, ginkgo biloba antagonizes anti-platelet factor, thereby inhibiting platelet aggregation. Thus, physicians should be aware of the potential for bleeding with ginkgo biloba use, especially if the patient is taking anticoagulants. In addition, gingko should be discontinued for several days before the patient undergoes elective surgery.(13)
Other natural products sometimes used for treatment of dementia include huperzine A and high dose vitamin E. Huperzine A is a natural acetylcholinesterase inhibitor that appears to be as effective in treating dementia as prescription acetylcholinesterase inhibitors. There is some evidence that high dose vitamin E may slow dementia progression. However, the doses required for this use are toxic. Thus, vitamin E should not be recommended to patients for the treatment of dementia.(13)
Glucosamine and chondroitin are the most popular natural products used to treat arthritis. Both are normal components of cartilage. Glucosamine may stimulate synthesis of proteoglycans and glycosaminoglycans by chondrocytes, as well as inhibit cartilage breakdown. Chondroitin also stimulates chondrocytes to synthesize cartilage components, as well as having anti-inflammatory properties. Not only do both supplements show efficacy against pain in clinical trials of moderate to severe osteoarthritis, but glucosamine may even retard progression of the disease. Since they have different mechanisms of action, glucosamine and chondroitin are often used together. The onset of action for both compounds requires several weeks, and patients should take other pain-relievers such as NSAIDs in the interim. In addition, diabetic patients taking glucosamine may have an increase in blood sugar levels. Chondroitin appears to have some anti-coagulant activity, and this should be considered in patients taking prescription anticoagulants. Chondroitin is contraindicated in men with prostate cancer since one of its components (versican) is overexpressed in prostate cancer.(13)
Other natural products used in the treatment of osteoarthritis include S-adenosylmethionine (SAMe), capsaicin, avocado/soybean oils, and omega-3 oils. SAMe appears to be effective for symptom reduction. However, it is expensive, and the quality of supplements is highly variable. In addition, SAMe should be avoided in patients who are taking other serotonergic drugs, as well as in patients with bipolar disease. Capsaicin is effective for relieving limb osteoarthritis and other musculoskeletal conditions. Its biggest advantage is that it is topically applied. Avocado/soybean oils appear to be beneficial for osteoarthritis, have no side effects, and can be used along with glucosamine/chondroitin.(13) Omega-3 fatty acids are found in fish and flaxseed oils. There is some evidence that they have anti-inflammatory effects. Although osteoarthritis is not initially an inflammatory disease, many patients do develop an inflammatory component as the disease progresses. Omega-3 fatty acids may have an anti-coagulant effect in high doses (over 3 grams), which should be considered in patients on prescription anti-coagulants.(13,14)
The most common supplements taking to prevent onset or progression of osteoporosis are calcium and vitamin D. However, natural products like soy and ipriflavone are also used. Ipriflavone has the strongest evidence in favor of its use, but its effects are significantly less than those of prescription drugs like bisphosphonates. In addition, ipriflavone may increase the concentration of other drugs by inhibiting cytochrome P450 enzymes, and it can cause lymphocytopenia in some patients.(13)
There is less evidence in favor of increased consumption of soy-based foods for decreasing the risk of osteoporosis. However, soy consumption has multiple other benefits. These include improvement of post-menopausal symptoms and a decreased cholesterol level. In addition, there are no side effects due to eating soy, with the possible exception of women with a history of breast cancer due to phytoestrogens present in soy. In general, natural products like ipriflavone and dietary supplements like soy can be used to help prevent development of osteoporosis. However, women who already have osteoporosis will almost certainly require a prescription drug like a bisphosphonate.(13)