A year-long investigation by Fusion’s Project Earth team has unearthed a trove of troubling evidence about the shark cartilage industry. Shark cartilage pills, which are taken as health supplements, have no known health benefits and research has shown that they may contain toxins and chemical properties that could be harmful to humans; and now, DNA testing has revealed that various brands of shark cartilage pills contained cartilage from an endangered species of shark, while other brands didn’t have shark cartilage at all, but rather DNA from other marine animals. After Fusion’s team shared their DNA evidence with the manufactures and retailers of shark cartilage products, two leading health stores in the U.S. announced that they had removed the product from their shelves and website.

Nope, cartilage doesn’t cure cancer.
Shark cartilage pills first became popular in the 1990’s, when William Lane a biochemist
turned cancer researcher, published a book called “Sharks Don’t Get Cancer. How Shark Cartilage Could Save Your Life.” In the book, Lane argued that as cartilage doesn’t have any blood vessels (tumors need blood vessels to grow) and sharks are made almost entirely out of cartilage, a concoction of shark cartilage could help human patients battle various forms of cancer. In 1993 Lane’s work got a publicity boost when 60 Minutes devoted an entire segment to his ideas, and by 1996 Lane decided to follow his first book with a similarly titled sequel: “Sharks Still Don’t Get Cancer: The Continuing Story of Shark Cartilage Therapy.” Conveniently, the cartilage concoction that Lane promoted as cancer cure was manufactured by Lane Labs, a company run by his son.
There was only one problem to Lane’s theory: there wasn’t any solid evidence that cartilage actually helped with cancer. In the years that followed, the National Cancer Institute called for research to investigate whether Lane’s cancer cure was as fishy as it sounded; a number of scientists conducted their own trials, but found no reliable evidence that shark cartilage cures cancer. Following these studies, the FDA pushed several injunctions against Lane Labs, and, in 2000, a number of cartilage manufacturers were made to pay restitution to customers because they had falsely claimed their product could help fight cancer.

It’s also been shown that sharks do in fact get cancer. But, as Mark Twain famously wrote: “How easy it is to make people believe a lie, and how hard it is to undo that work again!”
Cartilage pills are still sold in health stores across the country. Their labels now claim that cartilage can help treat joint pain and arthritis, among other things. But, just like the claim that shark cartilage cures cancer, researchers say there isn’t any medical backing here either. Moreover, recent research into cartilage products has found that at shark cartilage could be harmful to humans if consumed. All the while, shark numbers across the planet are plummeting at unsustainable levels.
The potential health hazards of shark cartilage pills.
“Shark, shark products, shark cartilage, it’s not medicine, no proven health benefits,” explained Deborah Mash, professor of Neurology and Pharmacology at the University of Miami. In 2014, Mash co-authored a study which examined shark products, including shark cartilage, for traces of toxic chemicals. Nearly all of the samples that Mash used in her study tested positive for both methylmercury and BMAA, a neurotoxin with links to degenerative diseases such as Parkinson’s and Alzheimer’s. “We already know that methylmercury is very bad, that’s why the EPA tells pregnant women and children not to eat shark, “explained Mash. “But [with BMAA] it gets worse.”

Both BMAA and methylmercury are toxins that biomagnify, which means that they get more concentrated the higher up the food chain you go. And so sharks, as apex predators, tend to have higher concentrations of both toxins then the little critters of the ocean. Mash explains that the presence of both toxins in cartilage products is especially troubling given that they have “synergistic toxicities.”

“Why would you ever supplement your diet with a purported health product that’s gonna potentially even a small risk, expose your brain to methylmercury and this neurotoxin BMAA?” said Mash. “I don’t get it.”
The year after Mash published her paper, researchers from the University of Miami released a study suggesting that shark cartilage supplements wouldn’t be helpful in treating the symptoms of arthritis and joint pain. In fact, by exposing human cells to shark cartilage, researchers found that shark cartilage might actually be harmful for those suffering from joint pain.


“Those [human] cells responded by producing a whole list of pro-inflammatory mediators, and our conclusion was that those would be exactly the kinds of mediators you would not want for most of the kinds of conditions for which shark cartilage is marketed,” explained Liza Merly, the study’s co-author and a senior lecturer at the University of Miami, where she focuses on Marine Immunology and Shark Conservation. “I think in a large part the scientific community has thought that the worst case scenario with these kinds of pills is that they have no effect and people are wasting their money, but the worst case scenario could in fact be that they’re sort of counter indicated for the kinds of things that people are taking them for.”

Merly pointed out that even though there is mounting evidence against the health benefits of cartilage pills, their status as supplements means that they lie outside the oversight of the FDA; “So there is no governmental body that oversees the production of these products… we don’t have a way of checking what the company is putting in the product.”

Even though demand for cartilage pills may be quite small (in 2011, the total U.S. market was about $3 million, according to the Nutrition Business Journal), it’s still another stressor for global shark populations. Merly explained that the cartilage industry adds value to shark carcasses, which, no matter how small the market may be, further incentives shark fishermen to increase their catch.


Moreover, Merly believed that because the manufacturers of cartilage pills have little oversight and provide almost no information about the sharks used for their products, it’s possible that sharks are being sourced unsustainable. “When you call these companies to find out what the geographic location [of the shark] is, what species they use, what age the sharks were, how they were harvested, they do not provide any information,” said Merly. “It could absolutely be any species of shark.”

Shark cartilage: as fishy as it sounds.

In order to understand how the cartilage industry affects the conservation of wild sharks, Fusion’s team reached out to the manufactures and retailers of shark cartilage products, which include large stores like GNC, the Vitamin Shoppe, Walgreens and CVS. However, the companies declined to comment or provide information as to where and how the sharks for cartilage products are sourced.
Fusion’s team then sent a batch of cartilage pills for DNA testing to Laragen Inc., a private sequencing and genotyping lab. The DNA results showed that pills marketed as GNC’s Natural Brand Shark Cartilage didn’t contain shark at all, but rather DNA from manta rays and other unidentified marine animals (not sharks); pills marketed as Vitamin Shoppe Shark Cartilage also didn’t contain shark, but rather DNA from Aleutian Skates. This sort of bait and switch in seafood is relatively common, with about 1/3rd of all seafood products in the U.S. having some degree of mislabeling, according to Oceana.


Two brands of pills sold by CVS (Cartilade-Pure Shark Cartilage and Vida Mia Shark Cartilage) contained DNA from scalloped hammerhead, which is an endangered species. International trade in scalloped hammerhead is highly regulated, due to its protected status under CITES appendix two, and certain regional populations of scalloped hammerheads are also protected under the Endangered Species Act. But, and here’s the catch, there are several regions where fishing for scalloped hammerheads is allowed, including many areas off the coast of the U.S.
“It does matter where those animals were captured, in terms of the legalities involved, and where the parts are being sent to,” explained Neil Hammerschlag, the director of the Shark Research and Conservation Program at the University of Miami. “For example, in Florida in our waters…. Scalloped Hammerheads are prohibited, meaning you cannot target them… However, just outside of those waters… within U.S. Federal waters they can be harvested.” Hammerschlag explained that without knowing where and how these companies are sourcing their catch, it’s very hard to know whether they’re breaking both international and domestic conservation laws.
Fusion’s team reached out again to the sellers and manufacturers of cartilage products, hoping that the existence of DNA evidence might encourage companies to share information about their shark sources. However, most companies, including GNC and the Vitamin Shoppe, still declined to comment. The owner of Cartilade declined to be interviewed, but claimed in an email that his product was “Blue [shark], Made In The USA”. However, the DNA results showed that the Cartilade brand of pills contained scalloped hammerhead sharks.

CVS and Walgreens, which at the time of the investigation had been selling cartilage pills that had DNA from endangered and vulnerable species of shark, respectively, also declined to comment. However, shortly after the DNA results were shared with them, both CVS and Walgreens sent emails explaining that they had pulled all of the shark cartilage products off their shelves and website; the companies cited “business decisions” and “overall assortment decisions,” as the reasons for removing cartilage products.

“The potential health hazard of consuming shark and shark cartilage products can bring about something very bad for human health,” said Mash. “[But] if we can inform the public about this potential danger, then the research we do here has meaning.”
As of the publishing of this article, cartilage pills remain on the shelves in many health stores across the U.S.


Nicolás Ibargüen is an environmentalist and director of the Planet Initiative of the Americas Business Council Foundation, an organization that supports innovative social and environmental impact projects.

He is the environmental Correspondent for Fusion and Univision.

Nicolás organizes expeditions and events with world leaders to raise awareness about our relationship with the planet. He produced the award-winning documentary “Amazon Gold” and he is a board member of NRDC’s Voces Verdes and the Humane Society International. He was the Editor and Publisher of Poder Magazine.


Born and raised in Spain, Lara is a digital producer and writer for Fusion — covering stories in culture and technology as well as in-depth environmental issues across the globe.

Lucas Isakowitz is a contributing author for Fusion’s Project Earth vertical.

Madison Stewart, AKA ‘Shark Girl’, is Fusion’s shark correspondent. She’s a dive master, shark conservationist, and underwater filmmaker. She was born and raised in Australia where she started diving with sharks at age 12.