Shark Cartilage No Good for Cancer
Shark cartilage does not appear to be beneficial for the treatment of advanced cancer, reports a study in Cancer (2005;104:176–82). Cancer is generally regarded as advanced or incurable once it has spread (metastasized) beyond the site of the original tumor.
An interest in shark cartilage as a treatment for cancer arose from the observation that sharks rarely get the disease themselves. It has been thought that constituents in shark cartilage may have the ability to block the formation of new blood vessels that cancer cells need to survive. Previous studies have yielded conflicting results regarding its efficacy in battling cancer. Some trials have suggested that shark cartilage may inhibit tumor growth and extend life expectancy in animals. In a study of 47 people with advanced cancers, however, there was no apparent benefit of shark cartilage supplementation.
Treatment strategies for people with advanced cancer are usually aimed at reducing the size of the tumor and controlling pain and other symptoms. Radiation or chemotherapy may help shrink the tumor and possibly extend life expectancy in people with terminal cancer. These treatments are often associated with serious side effects, however, such as blood cell abnormalities (anemia), local tissue damage, fatigue, nausea, vomiting, diarrhea, and increased tendency to develop infections.
The new study was designed to determine if taking shark cartilage could improve overall survival in 83 people with advanced breast or colon cancer. The participants received either powdered shark cartilage three to four times per day or a placebo, for as long as they could continue the treatment. Each group began by taking 4 scoops (24 grams) of shark cartilage or placebo, gradually increasing to 16 scoops (96 grams) per day, as tolerated. The powder was mixed in water or juice and consumed 30 minutes before meals. Participants continued their usual care, including cancer medications, for the duration of the trial.
The participants recorded the presence of symptoms such as nausea, vomiting, constipation, fatigue, and mouth and rectal sores. They were also monitored for problems related to blood, kidney, lung, cardiovascular, and neurological function. Quality of life was assessed using several different rating scales; the participants rated their mood, appearance, ability to get around, sleep quality, and emotional, physical, and spiritual well-being.
Overall survival time did not differ significantly between participants receiving shark cartilage and those taking placebo. Quality of life also did not appear to differ between the groups. In fact, the results of one rating scale indicated that participants in the shark cartilage group experienced a significantly decreased feeling of overall well-being after one month of supplementation.
Most of the side effects experienced were of mild to moderate intensity, and the percentage of participants who experienced adverse events was similar between the two groups. Serious adverse side effects in the shark cartilage group included dizziness, bone pain, diarrhea, and blood cell abnormalities. None of these side effects were noted in the placebo group.
From the time of the inception of the study until its completion, interest in shark cartilage as a treatment for cancer had decreased considerably. Because of this, the number of participants was much smaller than originally anticipated, making it more difficult to draw reliable conclusions from the study. Based on the results of this study and others, however, it does not seem that shark cartilage is useful for the treatment of cancer, and it may in fact cause considerable adverse effects.
Kimberly Beauchamp, ND, earned her bachelor’s degree from the University of Rhode Island and her Doctorate of Naturopathic Medicine from Bastyr University in Kenmore, WA. She cofounded South County Naturopaths in Wakefield, RI. Dr. Beauchamp practices as a birth doula and lectures on topics including whole-foods nutrition, detoxification, and women’s health.
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