Shark cartilage is a dietary supplement derived from the tough, flexible skeletal structure of sharks (cartilaginous fish). This substance is harvested, dried, and powdered, then sold commercially in capsule or powder form. Commercialization began in the late 20th century, fueled by the misconception that sharks do not develop cancer. Although this myth has been scientifically debunked—sharks do get cancer—the supplement remains popular among consumers seeking alternative treatments. Scientific investigation continues into the components of this marine product and their effects on human health.
Primary Health Claims and Traditional Uses
Shark cartilage is marketed to treat various chronic conditions, stemming from the initial anti-cancer premise. The most prominent claims center on its ability to combat cancer by causing tumor regression or preventing growth. Proponents also suggest its use for various inflammatory and degenerative conditions.
The supplement is frequently promoted for managing joint disorders, including osteoarthritis and rheumatoid arthritis. Other claims include benefits for chronic inflammation, such as psoriasis, chronic intestinal inflammation, wound healing, and certain degenerative eye conditions.
Scientific Review of Anti-Angiogenesis
The primary scientific hypothesis behind the anti-cancer claims is anti-angiogenesis, the inhibition of new blood vessel formation. Since cartilage is naturally devoid of blood vessels, researchers theorized that shark cartilage contains molecules capable of suppressing this process. Blocking new blood vessel growth could theoretically “starve” tumors, which rely on this process for oxygen and nutrients.
Initial laboratory research supported this idea, showing that certain extracts exhibited anti-angiogenic and anti-tumor activity in petri dishes and animal models. For example, a purified extract called AE-941 (Neovastat) reduced tumor size in some animal tests. This promising early data led to large-scale human clinical trials.
However, controlled human studies have been largely disappointing, failing to demonstrate the efficacy observed in lab settings. Trials involving patients with advanced breast, colorectal, or non-small cell lung cancer showed no difference in overall survival or quality of life compared to placebo. The consensus is that crude shark cartilage is ineffective as a cancer treatment because the active proteins are likely digested and not absorbed intact when taken orally.
Evidence for Joint Health and Inflammation
Shark cartilage contains natural components relevant to joint structure, specifically the glycosaminoglycans chondroitin sulfate and glucosamine. These compounds help maintain cartilage integrity and are commonly sold as standalone supplements for joint relief. Proponents suggest the whole cartilage may offer a comprehensive benefit for conditions like osteoarthritis.
However, the efficacy of the whole, powdered shark cartilage complex for joint pain is inconsistent and less established than purified supplements. While studies on purified chondroitin and glucosamine show mixed results, evidence for the raw, dried product is weaker. Some in vitro studies even suggest components may induce a pro-inflammatory response, counterintuitive to anti-inflammatory claims. Professional medical organizations often recommend against using shark cartilage for conditions like hip and knee osteoarthritis due to the lack of consistent, reliable evidence.
Safety Considerations and Adverse Effects
Taking shark cartilage orally carries a risk of minor adverse effects. These frequently include gastrointestinal complaints such as nausea, vomiting, constipation, and an unpleasant taste in the mouth. Some reports have also noted reversible hepatic dysfunction, or liver issues.
A significant safety concern is contamination with heavy metals. As apex predators, sharks accumulate environmental toxins like mercury, which has been found in commercial products. The neurotoxin BMAA, linked to degenerative diseases, has also been detected in many brands. Use is advised against during pregnancy or breastfeeding, as its anti-angiogenic properties could interfere with fetal development. It is also contraindicated for individuals recovering from surgery, where new blood vessel growth is necessary for healing. Ethical and environmental issues are also a consideration, as demand contributes to the unsustainable harvesting of endangered shark species.