 An assessment of websites on complementary and alternative medicine for cancer found that many endorse unproven therapies in some that are outright dangerous, potentially exploiting highly vulnerable patients and enriching irresponsible sneak oil peddlers, or for that matter, shark cartilage peddlers. Accounting for millions of dollars of sales every year, why shark cartilage of all things? One shark cartilage as an anti-cancer agent arose because many people believe 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. Both benign and cancerous lesions have been reported in 21 species of sharks, more than 9 families. For example, this oral tumor spilling out of the mouth of 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. There's 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 and like boiling hot springs. Does that mean if we eat those bacteria, we can survive boiling water too? It doesn't make any sense. The ill logic behind the pursuit of shark cartilage therapies have 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 disease. So like the consumption of shark fin soup or something 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 15 out of 16. 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. Cartilage in general is highly resistant to invasion by tumor cells. So maybe there's some cartilage-derived anti-invasion factor? Less interesting alternative explanation is 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 a 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. And 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 skyrocket, 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, it 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 animals, you could cut down a blood vessel growth within their body. OK, but does that translate out to stopping the growth in 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.