Shark Cartilage Supplements Put to the Test to Cure Cancer

Michael Greger M.D. FACLM · April 25, 2018 · Volume 41

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Shark cartilage supplements carry risks, but so do many cancer treatments. The question is, do they work?

Discuss

Transcript

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

When it comes to marketing “unproven cancer treatments,” “the Internet has become the Wild West. Fraudsters are…able…to take advantage of people” like never before. “Cancer Patients Find Quackery on The Web”, bemoaned the National Cancer Institute. Did you know there were “[m]ore than 200,000 documents about cancer…on the…Web”? What? When was this published? Oh, 1996. That’s just a few years after the web was born. Not to worry, though, said the author of Dr. Linden’s Guide to Online Medicine, “it takes a lot of time and money to maintain a Web page.” So, don’t worry, “the mass of information on the Internet will dwindle during the next few years as the Internet matures.”

Riiiiight. Yes, dwindling from 200,000 down to a mere, you know, nearly a quarter of a billion. And, one of the most commonly recommended quote-unquote “alternative cancer cures” on popular websites is shark cartilage.

“Much has been made in recent years of the mystical aura afforded [to the stuff]. Clearly, part of [it is the] visceral fear of cancer combined with a healthy respect for a creature [who] has survived [basically unchanged since] prehistoric times. It has been reported that sharks rarely get cancer,” and their skeleton is made out of cartilage, and so, “[l]ogic has led some to believe that this must be the reason for sharks’ relative health.” Not exactly sure that’s logical, but they do have a lot of cartilage. Cartilage, in general, has few blood vessels, and blood vessels are important for cancer growth, and all this “conspired to prime fraught [cancer] patients for shameful exploitation by pseudoscience and the supplement industry with the addition of just one myth”—that “sharks don’t get cancer.” But, they “do get cancer” after all. Just another “layer…of fallacious arguments,…successfully convinc[ing] desperate cancer patients to buy ineffective products.” But wait, you don’t know if it’s ineffective, until you put it to the test.

Sixty patients with a variety of advanced cancers were given like a dozen scoops a day of shark cartilage, and…not a single, even partial, response was noted in any of their tumors. Ineffective with “no salutary effect on [the] quality of life.” In fact, they suffered significant gastrointestinal toxicity from the stuff, all the while the tumors progressed in all the patients. But what’s missing from this survival graph? What happened in the control group? There was no control group. So, while this is what you’d expect to see in advanced cancer patients, how do we know the cancers wouldn’t have progressed even faster without the shark cartilage? That’s why we need randomized, controlled trials, but there weren’t any, until the Mayo Clinic stepped up. “[A]…randomized, placebo-controlled, double-blind, clinical trial [for] [p]atients with incurable breast or colorectal carcinoma.”

“Data on a total of 83…patients [was] analyzed. And? “There was no difference in…survival between patients [getting]…shark cartilage…versus [those getting] placebo”—nor any “suggestion of improvement in quality of life.” And, there was evidently a prostate cancer study, too. Only five patients were even able to complete the study, and, in all five, their cancers continued to progress unabated. So: “Unfortunately, the claims for the benefits of shark cartilage are completely unsubstantiated by any objective data from controlled clinical trials.”

Not so fast, said supplement manufacturers. Maybe these crude commercial shark cartilage powders just don’t have high enough levels of whatever active components there may be. So, cancer patients should instead be taking shark cartilage extract pills. So, the National Cancer Institute said fine, we’ll test that too, just to make absolutely sure. And so, they funded a randomized, double-blinded, placebo-controlled trial to put it to the test.

Unlike the other shark cartilage dietary supplement studies, they used the purified extract, and “the study outcome [was] unambiguous.” It failed. The shark cartilage group lived 14 months, and the placebo group lived 15 months. So, no significant difference in survival or time to progression or tumor response rate. So, “[t]hese clinical studies [suggest] shark cartilage is not just [an] unproven…cancer remedy, [but actually a] well disproven [one].” Yet, “[d]espite [the] overwhelming evidence to the contrary, such claims persisted. For example, the huckster who started it all wrote a sequel, Sharks Still Don’t Get Cancer. Perhaps “[t]he only cure for this myth is to spread the rumor that cartilage from the noses of [such] quacks [fights cancer too].”

Anyway, if you really wanted to eat angiogenesis inhibitors, why sit down to a bowl of cartilage powder, when you could just eat an apple, or drink green tea, or turmeric, or pomegranate berries and nuts, soybeans, flax seeds, or broccoli—all of which have been shown to have anti-angiogenic effects.

Please consider volunteering to help out on the site.

Sources

Acknowledgements

Image credit: David Clode via Unsplash. Image has been modified.

Motion graphics by Avocado Video.

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

When it comes to marketing “unproven cancer treatments,” “the Internet has become the Wild West. Fraudsters are…able…to take advantage of people” like never before. “Cancer Patients Find Quackery on The Web”, bemoaned the National Cancer Institute. Did you know there were “[m]ore than 200,000 documents about cancer…on the…Web”? What? When was this published? Oh, 1996. That’s just a few years after the web was born. Not to worry, though, said the author of Dr. Linden’s Guide to Online Medicine, “it takes a lot of time and money to maintain a Web page.” So, don’t worry, “the mass of information on the Internet will dwindle during the next few years as the Internet matures.”

Riiiiight. Yes, dwindling from 200,000 down to a mere, you know, nearly a quarter of a billion. And, one of the most commonly recommended quote-unquote “alternative cancer cures” on popular websites is shark cartilage.

“Much has been made in recent years of the mystical aura afforded [to the stuff]. Clearly, part of [it is the] visceral fear of cancer combined with a healthy respect for a creature [who] has survived [basically unchanged since] prehistoric times. It has been reported that sharks rarely get cancer,” and their skeleton is made out of cartilage, and so, “[l]ogic has led some to believe that this must be the reason for sharks’ relative health.” Not exactly sure that’s logical, but they do have a lot of cartilage. Cartilage, in general, has few blood vessels, and blood vessels are important for cancer growth, and all this “conspired to prime fraught [cancer] patients for shameful exploitation by pseudoscience and the supplement industry with the addition of just one myth”—that “sharks don’t get cancer.” But, they “do get cancer” after all. Just another “layer…of fallacious arguments,…successfully convinc[ing] desperate cancer patients to buy ineffective products.” But wait, you don’t know if it’s ineffective, until you put it to the test.

Sixty patients with a variety of advanced cancers were given like a dozen scoops a day of shark cartilage, and…not a single, even partial, response was noted in any of their tumors. Ineffective with “no salutary effect on [the] quality of life.” In fact, they suffered significant gastrointestinal toxicity from the stuff, all the while the tumors progressed in all the patients. But what’s missing from this survival graph? What happened in the control group? There was no control group. So, while this is what you’d expect to see in advanced cancer patients, how do we know the cancers wouldn’t have progressed even faster without the shark cartilage? That’s why we need randomized, controlled trials, but there weren’t any, until the Mayo Clinic stepped up. “[A]…randomized, placebo-controlled, double-blind, clinical trial [for] [p]atients with incurable breast or colorectal carcinoma.”

“Data on a total of 83…patients [was] analyzed. And? “There was no difference in…survival between patients [getting]…shark cartilage…versus [those getting] placebo”—nor any “suggestion of improvement in quality of life.” And, there was evidently a prostate cancer study, too. Only five patients were even able to complete the study, and, in all five, their cancers continued to progress unabated. So: “Unfortunately, the claims for the benefits of shark cartilage are completely unsubstantiated by any objective data from controlled clinical trials.”

Not so fast, said supplement manufacturers. Maybe these crude commercial shark cartilage powders just don’t have high enough levels of whatever active components there may be. So, cancer patients should instead be taking shark cartilage extract pills. So, the National Cancer Institute said fine, we’ll test that too, just to make absolutely sure. And so, they funded a randomized, double-blinded, placebo-controlled trial to put it to the test.

Unlike the other shark cartilage dietary supplement studies, they used the purified extract, and “the study outcome [was] unambiguous.” It failed. The shark cartilage group lived 14 months, and the placebo group lived 15 months. So, no significant difference in survival or time to progression or tumor response rate. So, “[t]hese clinical studies [suggest] shark cartilage is not just [an] unproven…cancer remedy, [but actually a] well disproven [one].” Yet, “[d]espite [the] overwhelming evidence to the contrary, such claims persisted. For example, the huckster who started it all wrote a sequel, Sharks Still Don’t Get Cancer. Perhaps “[t]he only cure for this myth is to spread the rumor that cartilage from the noses of [such] quacks [fights cancer too].”

Anyway, if you really wanted to eat angiogenesis inhibitors, why sit down to a bowl of cartilage powder, when you could just eat an apple, or drink green tea, or turmeric, or pomegranate berries and nuts, soybeans, flax seeds, or broccoli—all of which have been shown to have anti-angiogenic effects.

Please consider volunteering to help out on the site.

Image credit: David Clode via Unsplash. Image has been modified.

Motion graphics by Avocado Video.

Doctor's Note

What are the other risks? I cover them in The Risks of Shark Cartilage Supplements.

For other cautionary tales about supplements, check out:

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