The Ache: Nearly half of Americans in their lifetimes will suffer from knee osteoarthritis, a disease that causes pain and stiffness; hip osteoarthritis will affect about a quarter of the population, according to the Centers for Disease Control and Prevention. 

The Claim: Dietary supplements made from avocado and soybean oils can relieve hip and knee osteoarthritis pain without side effects, some clinicians say.

The Verdict: Several studies found a French company’s avocado-soy-oil blend can help pain for a period of three to six months. But two long-term studies have found it no better for relieving pain than a placebo.

Osteoarthritis involves the breakdown over time of cartilage, needed to cushion joints and help them move smoothly. Medications commonly used to relieve arthritis pain have been shown to cause ulcers and, in high doses, increase the risk of heart attack or stroke. Although avocado-soy supplements don’t appear to cause any serious side effects, “there’s not enough evidence that they are effective,” says David Felson, a senior arthritis researcher at Boston University School of Medicine.

The supplements, sold under a variety of brand names, go by the unwieldy name of avocado-soybean unsaponifiables, or ASU. In the laboratory, ASU have shown anti-inflammatory activity and also appear to help build joint cartilage and slow its destruction over time, says Jason Theodosakis, a physician and chief executive of Supplement Testing Institute Inc., in Tucson, Ariz., which sells the Dr. Theo’s Official Avosoy brand supplement. Eating avocados or soybeans won’t have the same effect as taking a supplement, which concentrates the beneficial portion, says Dr. Theodosakis, who is also a clinical associate professor at the University of Arizona College of Medicine-Tucson.

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