Benefits
Chondroitin sulfate from shark cartilage reaches the blood
In two absorption studies in healthy volunteers, purified chondroitin sulfate made from shark cartilage was partly absorbed after a single oral dose of 1.2 g or 4 g. Plasma levels peaked after about 4 to 9 hours. These studies measured blood levels only, and used a purified extract rather than whole cartilage powder.
Joint support claims rest on chondroitin, not shark cartilage trials
Shark cartilage is often sold for joints because it contains chondroitin. No randomized trial has tested shark cartilage powder itself for joint comfort. The joint evidence comes from purified chondroitin sulfate products, covered in the separate chondroitin entry.
No added benefit in two large placebo-controlled trials
Large trials found no benefit as an add-on to standard care. In 83 people with advanced breast or colorectal cancer, a shark cartilage product did not change survival or quality of life versus placebo. In 379 people with stage III lung cancer, the extract AE-941 added to chemoradiotherapy did not improve survival (median 14.4 vs 15.6 months).
High-dose powder in a 60-person open study
In an open study without a control group, 60 adults with advanced cancer took shark cartilage powder at 1 g per kg of body weight a day. No tumor responded, quality of life did not improve, and 5 of 47 fully assessed people stopped because of stomach side effects or intolerance. The authors judged the rate of stable disease similar to what is seen with supportive care alone.
Blood-vessel growth in a wound model in healthy men
In 29 healthy men, a liquid shark cartilage extract taken daily for 23 days lowered the density of blood-vessel cells growing into a small sponge implanted under the skin, compared with placebo. This is a lab marker of new vessel growth in a wound, not a health outcome.
Mechanism of action
The blood-vessel growth idea (lab and animal work)
Cartilage has no blood vessels, which led to the idea that it holds substances that block new vessel growth. Laboratory work found that extracts such as AE-941 interfere with a vessel growth signal (VEGF) and with tissue-degrading enzymes. That active components reach target tissues after eating crude cartilage has not been shown, and placebo-controlled trials in people found no clinical benefit.
A source of chondroitin and collagen
Shark cartilage supplies chondroitin sulfate and type II collagen. In volunteers, part of a purified shark chondroitin dose was absorbed: in one study about 10% as large chains and about 20% as smaller fragments.
Immune-cell activation in lab tests
In test-tube studies with human white blood cells, extracts of a commercial shark cartilage supplement triggered inflammatory signals (interferon gamma and chemokines), with a type II collagen protein identified as one active component. Effects of eating the product on inflammation in people are unknown.
Clinical trials
Randomized, double-blind, placebo-controlled trial of a shark cartilage product (BeneFin, per ClinicalTrials.gov record NCT00026117, with the National Cancer Institute as collaborator) taken 3 to 4 times a day alongside standard care. Primary outcome: overall survival. (Loprinzi et al. 2005, Cancer)
83 evaluable adults with incurable breast or colorectal cancer and good performance status; chemotherapy was allowed.
Overall survival did not differ between shark cartilage and placebo, and there was no suggestion of better quality of life. The authors concluded the trial could not show any suggestion of efficacy for the product.
Randomized, double-blind, placebo-controlled phase III trial at US and Canadian centers with the US National Cancer Institute as lead sponsor (NCT00005838); oral AE-941, a standardized liquid shark cartilage extract, 120 mL twice daily. Closed early in 2006 for slow enrollment. (Lu et al. 2010, J Natl Cancer Inst)
379 eligible patients with unresectable stage III non-small cell lung cancer receiving chemotherapy and chest radiotherapy (188 AE-941, 191 placebo).
Median overall survival was 14.4 months with AE-941 and 15.6 months with placebo (P = .73). Time to progression, progression-free survival and tumor response also did not differ. The authors concluded the study does not support shark cartilage-derived products as therapy for lung cancer.
Single-arm phase I/II study of oral shark cartilage powder at 1 g/kg a day in three divided doses, with no other anticancer therapy, assessed at 6 and 12 weeks. (Miller et al. 1998, J Clin Oncol)
60 adults with advanced, previously treated cancer of various types; 47 were fully assessable.
No complete or partial tumor responses occurred and quality of life did not improve. Ten of 50 assessable patients (16.7% of all 60 enrolled) had stable disease for 12 weeks or more, a rate the authors judged similar to supportive care alone. Five people stopped because of stomach side effects or intolerance; 14 of 21 recorded adverse events were digestive (nausea, vomiting, constipation).
Randomized, placebo-controlled study of a liquid shark cartilage extract (7 or 21 mL a day) taken for 23 days, with a small sponge implanted under the arm skin from day 12 to day 23 to measure new vessel growth. (Berbari et al. 1999, J Surg Res)
29 healthy male volunteers in three groups.
Endothelial cell density in the sponge was lower with the extract (grades 2.24 and 2.47 for 7 and 21 mL) than with placebo (3.15; P < 0.01). Collagen content of the sponge (hydroxyproline) did not differ. This is a lab marker of wound vessel growth, not a health outcome.
Randomized phase I/II dose-comparison trial of oral AE-941 at 30, 60, 120 or 240 mL a day for 12 weeks, with 12 weeks of follow-up. (Sauder et al. 2002, J Am Acad Dermatol)
49 adults with plaque psoriasis.
PASI scores improved in 50%, 41.7% and 30.8% of patients on 240, 120 and 60 mL a day, and in none at 30 mL, a significant dose trend. With no placebo arm, the size of any true effect is unknown. Digestive side effects (mainly nausea, diarrhea, vomiting, gas and constipation) occurred in 12 of 49 patients. AE-941 was an investigational drug, not a supplement.
Single-dose absorption study of 4 g of chondroitin sulfate from shark cartilage, with plasma sampling over 48 hours. (Volpi 2003, Osteoarthritis Cartilage)
20 healthy male volunteers.
Plasma chondroitin sulfate rose by more than 120%, peaking at about 8.7 hours (average peak 4.87 micrograms per mL), with the rise significant from 4 to 16 hours. Absorption was slow. No joint or symptom outcomes were measured.
Pharmacokinetic study of partially depolymerized shark chondroitin sulfate given as single doses of 0.2 g by injection and 1.2 g by mouth. (Ronca et al. 1993, Int J Clin Pharmacol Res)
10 healthy volunteers (5 men, 5 women) aged 25 to 53.
After the oral dose, plasma levels peaked at 240 minutes (4.6 micrograms per mL). About 10% of the oral dose was absorbed as high-molecular-weight and about 20% as low-molecular-weight derivatives. No clinical outcomes were measured.