Why are millions of dollars spent on shark cartilage supplements?
The Risks of Shark Cartilage Supplements
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.
An assessment of “websites on complementary and alternative medicine for cancer” found that “[m]any endorse unproven therapies and some that are outright dangerous,” potentially exploit[ing] highly vulnerable patients and enrich[ing] irresponsible snake oil peddlers”—or for that matter, shark-cartilage peddlers, accounting for millions of dollars of sales every year. Why shark cartilage, of all things?
“…[I]nterest in shark cartilage as an anticancer agent arose because many people believed that sharks did not get cancer.” Why would they think such a thing? Because some shark-cartilage supplement hawker wrote a book called Sharks Don’t Get Cancer. But that’s simply not true. “Sharks do get cancer.” “…[B]oth benign and cancerous…lesions have been reported in 21 species of sharks from [more than] 9 families.” For example, this oral tumor spilling out of the mouth of this great white.
Now, some “shark cartilage distributors insist [instead] that sharks [just] rarely get cancer,” [but] actual cancer rates in sharks have [never] been determined.” “[T]here [has simply] been no systematic tumor surveys of sharks” for them to make such a claim. But look, “even if sharks [were] less susceptible to cancer,” how can one logically jump from that to cancer patients benefiting from eating powdered cartilage from a shark?
“We know, for example, that there are [certain] proteins that allow [some bacteria to survive] in boiling hot [springs].” Uh, does that mean if we eat those bacteria we can survive boiling water, too? It doesn’t make any sense. “The illogic behind the pursuit of shark cartilage therapies has implications beyond the reduction of shark populations and the misdirection of patients to ineffective cancer therapies.” The stuff may be harmful, and I’m not just talking about the rare case of “shark cartilage-induced liver [inflammation].” Shark products can contain the neurotoxin BMAA, which I’ve talked about before. It’s been detected at elevated levels in the brains of Alzheimer’s disease and ALS patients, and may “play…a role in [the development of] neurodegenerative diseases.”
So, the “consumption of shark-fin soup may pose a significant health risk.” But what about shark-cartilage supplements? They tested 16 commercial shark-cartilage supplements, right off the shelves, and found BMAA “in fifteen out of sixteen.” But look, even if shark-cartilage supplements carry “pro-inflammatory properties, which could pose a potential health risk for consumers,” we’re talking about cancer. There are chemotherapy agents that are life-threateningly dangerous, but sometimes the benefits can outweigh the risks, when confronted with cancer. So, the question then becomes: are there any benefits to shark cartilage?
I mean, it’s not a completely wacky idea. “[C]artilage [in general] is highly resistant to invasion by tumor cells.” So, maybe there’s some “cartilage-derived anti-invasion factor.” “Less interesting alternative explanations…are” that it’s just hard for the cancer to penetrate the cartilage, or perhaps because of the poor blood supply in cartilage, cancer doesn’t consider it particularly fertile ground. But maybe that lack of blood vessels in cartilage can be exploited. The reason that no blood vessels end up in cartilage is because cartilage cells produce angiogenesis inhibitors, blood vessel-creation inhibitors. So, maybe we can starve tumor growth by infusing these cartilage factors. What scientists do is implant tumors into the eyeballs of rabbits, so they can visualize how many blood vessels the tumor is able to draw to itself.
And, indeed: “Shark cartilage contains inhibitors of tumor angiogenesis.” “Such findings made the sales [of shark cartilage sky]rocket, [driving]…two shark species…to the brink of extinction.” But, cow cartilage does the same thing. Here, they used bovine cartilage. And so does human cartilage, for that matter. So, why sell shark cartilage? Well, it does sound so much more exotic, and sharks have like 10 times more cartilage per animal. One 20-foot shark could net like 50 pounds of cartilage.
Just because cartilage has blood vessel-inhibiting chemicals in it, though, doesn’t mean if cancer patients eat it, it will help them. It’s kind of like magical thinking: shark cartilage stops blood-vessel growth. “Thus, by consuming shark cartilage, humans will [somehow] be…protected.” I mean, the “shark cartilage protein molecules [would seem to be] too large to be absorbed by the gut.” It’s not like you’re injecting shark cartilage into your bloodstream through an IV.
But there was this rat study that did find that just feeding shark cartilage to the animals, you could cut down on blood vessel growth within their bodies. Okay, but does that translate out to stopping the growth and spread of cancer? Apparently not, as “none of the shark cartilage doses tested had any retarding effect on [cancer growth]” or spread in tumor-bearing mice. But just because it doesn’t work in rodents doesn’t mean it doesn’t work in humans. To find that out, you need to put it to the test, evaluating shark cartilage in human cancer patients, which we’ll cover, next.
Please consider volunteering to help out on the site.
- Schmidt K, Ernst E. Assessing websites on complementary and alternative medicine for cancer. Ann Oncol. 2004;15(5):733-742.
- Wein S. Cancer, unproven therapies, and magic. Oncology (Williston Park). 2000;14(9):1345-1350.
- Cassileth BR. Evaluating complementary and alternative therapies for cancer patients. CA Cancer J Clin. 1999;49(6):362-375.
- Oikawa T, Ashino-Fuse H, Shimamura M, Koide U, Iwaguchi T. A novel angiogenic inhibitor derived from Japanese shark cartilage (I). Extraction and estimation of inhibitory activities toward tumor and embryonic angiogenesis. Cancer Lett. 1990;51(3):181-186.
- Penson RT, Castro CM, Seiden MV, Chabner BA, Lynch TJ. Complementary, alternative, integrative, or unconventional medicine?. Oncologist. 2001;6(5):463-473.
- Ernst E. Why there will never be an alternative cancer cure. Anticancer Drugs. 2006;17(9):1023-1024.
- Finkelstein JB. Sharks do get cancer: few surprises in cartilage research. J Natl Cancer Inst. 2005;97(21):1562-1563.
- Robbins R, Bruce B, Fox A. First reports of proliferative lesions in the great white shark, Carcharodon carcharias L., and bronze whaler shark, Carcharhinus brachyurus Günther. J Fish Dis. 2014;37(11):997-1000.
- Ashar B, Vargo E. Shark cartilage-induced hepatitis. Ann Intern Med. 1996;125(9):780-781.
- Ostrander GK, Cheng KC, Wolf JC, Wolfe MJ. Shark cartilage, cancer and the growing threat of pseudoscience. Cancer Res. 2004;64(23):8485-8491.
- Mondo K, Broc Glover W, Murch SJ, et al. Environmental neurotoxins β-N-methylamino-l-alanine (BMAA) and mercury in shark cartilage dietary supplements. Food Chem Toxicol. 2014;70:26-32.
- Holtcamp W. Shark fin consumption may expose people to neurotoxic BMAA. Environ Health Perspect. 2012;120(5):A191.
- Hammerschlag N, Davis DA, Mondo K, et al. Cyanobacterial neurotoxin BMAA and mercury in sharks. Toxins (Basel). 2016;8(8).
- Langer R, Conn H, Vacanti J, Haudenschild C, Folkman J. Control of tumor growth in animals by infusion of an angiogenesis inhibitor. Proc Natl Acad Sci USA. 1980;77(7):4331-4335.
- Ohba Y, Goto Y, Kimura Y, Suzuki F, Hisa T, Takahashi K, Takigawa M. Purification of an angiogenesis inhibitor from culture medium conditioned by a human chondrosarcoma-derived chondrocytic cell line, HCS-2/8. Biochim Biophys Acta. 1995;1245(1):1-8.
- Davis PF, He Y, Furneaux RH, Johnston PS, Rüger BM, Slim GC. Inhibition of angiogenesis by oral ingestion of powdered shark cartilage in a rat model. Microvasc Res. 1997;54(2):178-182.
- Horsman MR, Alsner J, Overgaard J. The effect of shark cartilage extracts on the growth and metastatic spread of the SCCVII carcinoma. Acta Oncol. 1998;37(5):441-445.
- Loprinzi CL, Levitt R, Barton DL, et al. Evaluation of shark cartilage in patients with advanced cancer: a North Central Cancer Treatment Group trial. Cancer. 2005;104(1):176-182.
- Merly L, Smith SL. Pro-inflammatory properties of shark cartilage supplement. Immunopharmacol Immunotoxicol. 2015;37(2):140-147.
- Lee A, Langer R. Shark cartilage contains inhibitors of tumor angiogenesis. Science. 1983;221(4616):1185-1187.
- Ross K. Crackdown on unproven cancer treatments focuses on internet marketers. J Natl Cancer Inst. 2008;100(17):1200-1202.
- Lane WI, Comac L. Sharks don't get cancer: how shark cartilage could save your life. Avery; 1992.
Image credit: Sandra Cohen-Rose via Flickr. 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.
An assessment of “websites on complementary and alternative medicine for cancer” found that “[m]any endorse unproven therapies and some that are outright dangerous,” potentially exploit[ing] highly vulnerable patients and enrich[ing] irresponsible snake oil peddlers”—or for that matter, shark-cartilage peddlers, accounting for millions of dollars of sales every year. Why shark cartilage, of all things?
“…[I]nterest in shark cartilage as an anticancer agent arose because many people believed that sharks did not get cancer.” Why would they think such a thing? Because some shark-cartilage supplement hawker wrote a book called Sharks Don’t Get Cancer. But that’s simply not true. “Sharks do get cancer.” “…[B]oth benign and cancerous…lesions have been reported in 21 species of sharks from [more than] 9 families.” For example, this oral tumor spilling out of the mouth of this great white.
Now, some “shark cartilage distributors insist [instead] that sharks [just] rarely get cancer,” [but] actual cancer rates in sharks have [never] been determined.” “[T]here [has simply] been no systematic tumor surveys of sharks” for them to make such a claim. But look, “even if sharks [were] less susceptible to cancer,” how can one logically jump from that to cancer patients benefiting from eating powdered cartilage from a shark?
“We know, for example, that there are [certain] proteins that allow [some bacteria to survive] in boiling hot [springs].” Uh, does that mean if we eat those bacteria we can survive boiling water, too? It doesn’t make any sense. “The illogic behind the pursuit of shark cartilage therapies has implications beyond the reduction of shark populations and the misdirection of patients to ineffective cancer therapies.” The stuff may be harmful, and I’m not just talking about the rare case of “shark cartilage-induced liver [inflammation].” Shark products can contain the neurotoxin BMAA, which I’ve talked about before. It’s been detected at elevated levels in the brains of Alzheimer’s disease and ALS patients, and may “play…a role in [the development of] neurodegenerative diseases.”
So, the “consumption of shark-fin soup may pose a significant health risk.” But what about shark-cartilage supplements? They tested 16 commercial shark-cartilage supplements, right off the shelves, and found BMAA “in fifteen out of sixteen.” But look, even if shark-cartilage supplements carry “pro-inflammatory properties, which could pose a potential health risk for consumers,” we’re talking about cancer. There are chemotherapy agents that are life-threateningly dangerous, but sometimes the benefits can outweigh the risks, when confronted with cancer. So, the question then becomes: are there any benefits to shark cartilage?
I mean, it’s not a completely wacky idea. “[C]artilage [in general] is highly resistant to invasion by tumor cells.” So, maybe there’s some “cartilage-derived anti-invasion factor.” “Less interesting alternative explanations…are” that it’s just hard for the cancer to penetrate the cartilage, or perhaps because of the poor blood supply in cartilage, cancer doesn’t consider it particularly fertile ground. But maybe that lack of blood vessels in cartilage can be exploited. The reason that no blood vessels end up in cartilage is because cartilage cells produce angiogenesis inhibitors, blood vessel-creation inhibitors. So, maybe we can starve tumor growth by infusing these cartilage factors. What scientists do is implant tumors into the eyeballs of rabbits, so they can visualize how many blood vessels the tumor is able to draw to itself.
And, indeed: “Shark cartilage contains inhibitors of tumor angiogenesis.” “Such findings made the sales [of shark cartilage sky]rocket, [driving]…two shark species…to the brink of extinction.” But, cow cartilage does the same thing. Here, they used bovine cartilage. And so does human cartilage, for that matter. So, why sell shark cartilage? Well, it does sound so much more exotic, and sharks have like 10 times more cartilage per animal. One 20-foot shark could net like 50 pounds of cartilage.
Just because cartilage has blood vessel-inhibiting chemicals in it, though, doesn’t mean if cancer patients eat it, it will help them. It’s kind of like magical thinking: shark cartilage stops blood-vessel growth. “Thus, by consuming shark cartilage, humans will [somehow] be…protected.” I mean, the “shark cartilage protein molecules [would seem to be] too large to be absorbed by the gut.” It’s not like you’re injecting shark cartilage into your bloodstream through an IV.
But there was this rat study that did find that just feeding shark cartilage to the animals, you could cut down on blood vessel growth within their bodies. Okay, but does that translate out to stopping the growth and spread of cancer? Apparently not, as “none of the shark cartilage doses tested had any retarding effect on [cancer growth]” or spread in tumor-bearing mice. But just because it doesn’t work in rodents doesn’t mean it doesn’t work in humans. To find that out, you need to put it to the test, evaluating shark cartilage in human cancer patients, which we’ll cover, next.
Please consider volunteering to help out on the site.
- Schmidt K, Ernst E. Assessing websites on complementary and alternative medicine for cancer. Ann Oncol. 2004;15(5):733-742.
- Wein S. Cancer, unproven therapies, and magic. Oncology (Williston Park). 2000;14(9):1345-1350.
- Cassileth BR. Evaluating complementary and alternative therapies for cancer patients. CA Cancer J Clin. 1999;49(6):362-375.
- Oikawa T, Ashino-Fuse H, Shimamura M, Koide U, Iwaguchi T. A novel angiogenic inhibitor derived from Japanese shark cartilage (I). Extraction and estimation of inhibitory activities toward tumor and embryonic angiogenesis. Cancer Lett. 1990;51(3):181-186.
- Penson RT, Castro CM, Seiden MV, Chabner BA, Lynch TJ. Complementary, alternative, integrative, or unconventional medicine?. Oncologist. 2001;6(5):463-473.
- Ernst E. Why there will never be an alternative cancer cure. Anticancer Drugs. 2006;17(9):1023-1024.
- Finkelstein JB. Sharks do get cancer: few surprises in cartilage research. J Natl Cancer Inst. 2005;97(21):1562-1563.
- Robbins R, Bruce B, Fox A. First reports of proliferative lesions in the great white shark, Carcharodon carcharias L., and bronze whaler shark, Carcharhinus brachyurus Günther. J Fish Dis. 2014;37(11):997-1000.
- Ashar B, Vargo E. Shark cartilage-induced hepatitis. Ann Intern Med. 1996;125(9):780-781.
- Ostrander GK, Cheng KC, Wolf JC, Wolfe MJ. Shark cartilage, cancer and the growing threat of pseudoscience. Cancer Res. 2004;64(23):8485-8491.
- Mondo K, Broc Glover W, Murch SJ, et al. Environmental neurotoxins β-N-methylamino-l-alanine (BMAA) and mercury in shark cartilage dietary supplements. Food Chem Toxicol. 2014;70:26-32.
- Holtcamp W. Shark fin consumption may expose people to neurotoxic BMAA. Environ Health Perspect. 2012;120(5):A191.
- Hammerschlag N, Davis DA, Mondo K, et al. Cyanobacterial neurotoxin BMAA and mercury in sharks. Toxins (Basel). 2016;8(8).
- Langer R, Conn H, Vacanti J, Haudenschild C, Folkman J. Control of tumor growth in animals by infusion of an angiogenesis inhibitor. Proc Natl Acad Sci USA. 1980;77(7):4331-4335.
- Ohba Y, Goto Y, Kimura Y, Suzuki F, Hisa T, Takahashi K, Takigawa M. Purification of an angiogenesis inhibitor from culture medium conditioned by a human chondrosarcoma-derived chondrocytic cell line, HCS-2/8. Biochim Biophys Acta. 1995;1245(1):1-8.
- Davis PF, He Y, Furneaux RH, Johnston PS, Rüger BM, Slim GC. Inhibition of angiogenesis by oral ingestion of powdered shark cartilage in a rat model. Microvasc Res. 1997;54(2):178-182.
- Horsman MR, Alsner J, Overgaard J. The effect of shark cartilage extracts on the growth and metastatic spread of the SCCVII carcinoma. Acta Oncol. 1998;37(5):441-445.
- Loprinzi CL, Levitt R, Barton DL, et al. Evaluation of shark cartilage in patients with advanced cancer: a North Central Cancer Treatment Group trial. Cancer. 2005;104(1):176-182.
- Merly L, Smith SL. Pro-inflammatory properties of shark cartilage supplement. Immunopharmacol Immunotoxicol. 2015;37(2):140-147.
- Lee A, Langer R. Shark cartilage contains inhibitors of tumor angiogenesis. Science. 1983;221(4616):1185-1187.
- Ross K. Crackdown on unproven cancer treatments focuses on internet marketers. J Natl Cancer Inst. 2008;100(17):1200-1202.
- Lane WI, Comac L. Sharks don't get cancer: how shark cartilage could save your life. Avery; 1992.
Image credit: Sandra Cohen-Rose via Flickr. Image has been modified.
Motion graphics by Avocado Video.
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The Risks of Shark Cartilage Supplements
LicenseCreative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)
Content URLDoctor's Note
Aren’t there any benefits to outweigh the risks? Find out in my video Shark Cartilage Supplements Put to the Test to Cure Cancer.
Intravenous vitamin C is another popular alternative attempt at cancer treatment. What does the science say? SeeVitamin C Supplements for Terminal Cancer Patients.
If the BMAA concept was unfamiliar to you, check out ALS (Lou Gehrig’s Disease): Fishing for Answers and Diet and Amyotrophic Lateral Sclerosis (ALS).
For other cautionary tales about supplements, see:
- Dietary Supplement Snake Oil
- Some Dietary Supplements May Be More Than a Waste of Money
- Risk Associated with Iron Supplements
- Diet Pills Do Fat a Lot of Good
- Should We Take a Multivitamin?
- Treating Asthma with Plants vs. Supplements?
- Are Calcium Supplements Safe?
- Are Calcium Supplements Effective?
- Industry Response to Plants Not Pills
- Resveratrol Impairs Exercise Benefits
- Black Raspberry Supplements Put to the Test
- Dangers of Dietary Supplement Deregulation
- Do Vitamin C Supplements Prevent Colds But Cause Kidney Stones?
- Lycopene Supplements vs. Prostate Cancer
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