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Limited evidenceGeneral health

Shark Cartilage

Shark cartilage is one of the clearest debunks in the supplement world: the premise that sharks don't get cancer is false, and two well-run randomized trials — including a 379-patient phase III — found no survival or quality-of-life benefit whatsoever.

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What the science says

  • Treats or slows cancer Limited evidence

    A randomized phase III trial in 379 patients with unresectable stage III non-small cell lung cancer added the standardized shark cartilage extract AE-941 (Neovastat) to chemoradiotherapy and found no survival benefit, with median overall survival essentially identical between arms. An earlier randomized trial in 83 patients with advanced breast or colorectal cancer found no difference in overall survival or quality of life versus placebo, with poor tolerability. Sharks do develop cancers, including tumors of cartilage, so the founding premise is factually wrong.

  • Inhibits angiogenesis in humans Limited evidence

    Cartilage contains anti-angiogenic proteins in vitro, which is where the idea came from. But these are large molecules digested to amino acids on oral ingestion, and the trials designed specifically to test the anti-angiogenic hypothesis with a standardized liquid extract — the strongest possible version of the product — were negative in both lung and renal cell carcinoma.

  • Relieves joint pain and osteoarthritis Limited evidence

    Shark cartilage contains chondroitin sulfate, but in variable and usually undisclosed amounts, typically far below the 800-1,200 mg/day of purified chondroitin used in osteoarthritis trials. No adequately powered trial has tested shark cartilage itself for joint pain. If chondroitin is what you want, buy chondroitin at a known dose.

Dosage & safety

Studied doseThere is no supported dose because there is no demonstrated benefit. Historical protocols used 60-100 g/day of powder, or the standardized liquid extract AE-941 at 240 mL/day in the phase III trials — both negative. Capsule products typically supply 750-2,000 mg with no defined active constituent.
SafetyReported adverse effects include nausea, vomiting, abdominal pain, constipation, an intensely unpleasant taste and odor, and hypercalcemia; hepatitis has been reported in case reports. Shark tissue accumulates methylmercury and the neurotoxin BMAA, both documented in commercial shark cartilage products. The most serious harm is indirect: using it in place of, or alongside, evidence-based oncology care — discuss any use with the treating oncologist. Not for children, pregnancy, or anyone recovering from surgery or a wound, given the anti-angiogenic premise. Also a conservation concern, as several shark species used are threatened.

How to take it

TimingNo timing is worth recommending — the standardized extract failed in phase III trials.
With food?Either way.
Worth knowingAvoid it around surgery or a healing wound: the whole anti-angiogenic premise works against wound repair, and shark tissue also concentrates methylmercury.

Interactions

With medications

  • cancer treatment (chemotherapy, radiotherapy, immunotherapy)

    Phase III trials were negative, and the documented harm is delaying or displacing treatment that works. tell your oncologist before taking it

With other supplements

  • calcium and vitamin D

    Shark cartilage is largely calcium salts and hypercalcaemia has been reported with it. do not stack it with high-dose calcium or vitamin D

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Does shark cartilage cure or treat cancer?

No: shark cartilage failed in well-run randomized trials, including a phase III trial of 379 lung cancer patients that found no survival benefit and a trial of 83 patients with advanced cancers that found no difference in survival or quality of life. The premise that sharks don't get cancer is also false.

Does shark cartilage help joint pain?

No adequately powered trial has tested shark cartilage for joint pain (limited evidence). Its chondroitin content is variable, usually undisclosed and typically far below the 800-1,200 mg/day of purified chondroitin used in osteoarthritis trials, so buy chondroitin at a known dose if that is what you want.

Is shark cartilage safe?

Shark cartilage can cause nausea, vomiting, abdominal pain and hypercalcemia, with hepatitis reported in case reports, and commercial products have contained methylmercury and the neurotoxin BMAA. The most serious harm is using it in place of evidence-based cancer care, so tell your oncologist before taking it.

Scientific references

Where to buy

NOW Foods, Shark Cartilage, 100 Capsules

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