A Fishy Therapy
A thriving but controversial dietary supplement
By Janet Raloff
Shark cartilage is for sale all over the Web. Powders of it, packaged in jars and capsules, are among the products offered at sites specializing in herbal remedies, vitamins, health wares, and bodybuilding aids. These Internet sites claim that the cartilage skeletons of sharks and their close relatives—skates and rays—offer various health benefits. Inhibiting cancer is often at the top of the list. To support that contention, sellers point to studies indicating that something in shark cartilage can inhibit the blood vessel growth that tumors rely on for access to nutrients.
The idea that cancer patients who aren’t helped by conventional medicine might benefit from ground-up shark skeletons was the central thesis of two books coauthored in the 1990s by nutritionist I. William Lane. Their titles argue that “sharks don’t get cancer.”