Shark: little research on the meat, a lot on its mercury

The only randomized trial we found close to shark tested purified shark liver oil in capsules. In 10 overweight men, 4 g a day for 3 weeks lowered plasma free cholesterol, triglycerides and C-reactive protein against placebo, and the abstract gives no effect sizes. An uncontrolled 6-week study in 30 young Polish women taking 1500 mg of the oil a day saw LDL cholesterol rise from 76.6 to 86.7 mg/dL, with no control group to compare against. The trial oil was purified to remove contaminants and excess vitamin A and D, and its authors warn that non-purified oil could harm the liver. We found no source giving the vitamin A content of shark liver oil or a typical capsule, so how close these doses come to the adult upper limit of 3,000 mcg of preformed vitamin A a day is unknown. We found no trial or cohort of shark meat and any health outcome. The better documented side of the meat is mercury. In 5656 US children and teenagers, each step up in how often they ate high-mercury fish such as swordfish and shark was associated with 2.4 times higher blood mercury (95% CI 1.23 to 4.68), with the two fish counted together. Among 912 Korean adolescents, only 50 of whom ate shark, shark meat was associated with higher blood mercury, highest in those who had eaten it in the past 30 days. FDA testing of 356 shark samples from 1991 to 2007 found a mean of 0.979 ppm, among the highest of commercial fish.

The numbers, per 3.5 oz (100 g)

As people eat it, per 3.5 oz (100 g)

What a real portion looks like

• In the US dietary survey one shark fillet is counted as 140 g and one steak as 210 g. — USDA FNDDS food Fish, shark, WWEIA category Fish Evidence E source
  1 fillet 140 g; 1 steak 210 g; 1 cup 135 g; 1 oz yields 20 g

What your body absorbs

• Skinned shark tail carries 7.6 to 13.3 g of collagen per serving, but after eating cooked shark meat blood collagen peptides reached only about 30% of the level from an equal dose of collagen hydrolysate. — Japanese daily dishes analyzed for collagen; human volunteers after a cooked shark meat meal Evidence C source
  Collagen 7.6-13.3 g per serving of skinned shark tail vs 0.2-2.5 g in most dishes; peptide AUC about 30% of hydrolysate

What cooking and storage change

• By the USDA retention table for finfish, frying from frozen keeps 95% of vitamin B12 and baking lean fish keeps 90%, while minerals stay at 100%. — USDA retention factors for the group Finfish and Shellfish Products, which is shark's USDA group Evidence E source
  Vitamin B12 95% retained fried from frozen (Retn_Code 2601), 90% baked lean fish without drippings (2301); thiamin 90%

What it does to your health

• In a randomized crossover trial in 10 overweight men, 4 g a day of purified shark liver oil for 3 weeks lowered plasma free cholesterol, triglycerides and C-reactive protein against placebo. — 10 overweight or obese men aged 25 to 60, 3 weeks per arm with 3-week washout (n = 10) Evidence B source
  Significant decreases in free cholesterol, triglycerides and CRP; plasmalogens rose
• In an uncontrolled 6-week trial in 30 young women taking 1500 mg of shark liver oil a day, LDL cholesterol rose from 76.6 to 86.7 mg/dL. — 30 healthy non-smoking Polish women aged 20 to 27, 1500 mg shark liver oil daily for 6 weeks (n = 30) Evidence C source
  LDL-C 76.6 to 86.7 mg/dL, p = 0.003; omega-3 index 3.6% to 4.2%

Safety, limits and interactions

• The authors of a shark liver oil trial note that their oil was purified to remove contaminants and excess vitamin A and D. They warn that non-purified oil could harm the liver and other organs and advise caution. — overweight or obese men given purified shark liver oil (Alkyrol) 4 g a day for 3 weeks (n = 10) Evidence D source
  The trial oil was purified to remove excess vitamin A and D and contaminants; authors warn non-purified oil could harm the liver; no measurement
• In a 6-week randomized trial in 60 healthy volunteers, a capsule of rosemary extract carried in shark liver oil caused no adverse change in liver tests or oxidation markers. — 60 healthy volunteers, mean age about 28, one capsule a day for 6 weeks (n = 60) Evidence B source
  No adverse effects on liver profile or oxidation markers versus control capsules
• FDA testing of 356 shark samples found a mean mercury level of 0.979 ppm, with a maximum of 4.54 ppm, close to swordfish and among the highest of commercial fish. — 356 shark samples tested by FDA, 1991 to 2007 (n = 356) Evidence E source
  Mercury mean 0.979 ppm, median 0.811, SD 0.626, max 4.54 ppm
• In 501 Korean adults, higher toenail mercury was associated with habitual eating of whale and shark meat, and toenail mercury was linked to metabolic syndrome more strongly when selenium was low. — 232 men and 269 women aged 35 and over, Yeungnam, Korea (n = 501) Evidence C source
  Shark and whale meat intake associated with higher toenail mercury; mercury-metabolic syndrome link weaker at higher selenium
• CDC reports that ciguatera toxin concentrations are highest in large predatory reef fish, shark among them. — 4 people poisoned in Texas and South Carolina, 1998 and 2004 (n = 4) Evidence D source
  Gastrointestinal and neurologic symptoms after eating large predatory fish
• In a 2026 study of 18 shark species from three oceans, 8 (44%) exceeded the EU mercury limit of 1 mg/kg, and deep-sea and large open-ocean sharks carried the most. — muscle of 18 shark species from Mediterranean, Indian and Atlantic Oceans (markets in Liguria and Djibouti, retail fillets in Milan) (n = 18 species) Evidence C source
  8/18 species above EU THg maximum (1 mg/kg ww); highest in deep-sea and large pelagic sharks (e.g. blue shark, shortfin mako)

What people believe that the data does not support

• In US Food Safety Surveys (4482 people in 2001, 2275 in 2006), women aged 18 to 45, the group the shark advisory targets, knew less about mercury in fish than other women. — nationally representative US Food Safety Surveys 2001 and 2006 (n = 6757) Evidence C source
  Awareness of mercury in fish rose from 69% to 80%; women of childbearing age less aware than other women
• The EU refused the claim that shark cartilage is good for joint health. — EU register of nutrition and health claims Evidence E source
  Claim status non-authorized
• The EU refused the claim that shark liver oil or its alkylglycerols strengthen immunity. — EU register of nutrition and health claims Evidence E source
  Claim status non-authorized

Who this works differently for

• NIH sets the upper limit for preformed vitamin A, the form found in fish liver oils, at 600 mcg a day up to age 3. It rises to 900 mcg at 4 to 8, 1,700 mcg at 9 to 13, 2,800 mcg at 14 to 18 and 3,000 mcg for adults, pregnancy included. The limits rest on liver damage, birth defects and toxic effects in children. — infants, children, adolescents and adults by age band, including pregnancy and lactation Evidence E source
  UL for preformed vitamin A: 600 mcg (birth to 3 years), 900 mcg (4-8 years), 1,700 mcg (9-13 years), 2,800 mcg (14-18 years), 3,000 mcg (19 years and older)
• NIH says intakes of preformed vitamin A above the upper limit can cause birth defects of the eye, skull, lungs and heart. Experts advise women who are or might be pregnant, or are breastfeeding, not to take more than 3,000 mcg RAE a day from supplements. — women who are or might be pregnant and women who are lactating; adults with acute or chronic excess Evidence E source
  Advice not to take vitamin A supplements above 3,000 mcg RAE (10,000 IU) a day in pregnancy or lactation; preformed vitamin A above the UL can cause birth defects
• A French case series describes three people poisoned by vitamin A after eating the liver of a large predatory fish. They had headache, nausea, vomiting and peeling skin, and the pregnant woman miscarried. — a 12-year-old girl, a 36-year-old pregnant woman and a 62-year-old man, Marseille poison control center, France (n = 3) Evidence D source
  Headache, nausea, vomiting and skin peeling after eating fish liver; high serum retinol in the girl; the pregnancy ended in miscarriage
• FDA and EPA place shark on the Choices to Avoid list for highest mercury in their fish advice for people who are or might become pregnant, who breastfeed, and children aged 1 to 11. — people who might become or are pregnant or breastfeeding, children aged 1 to 11 Evidence E source
  Shark listed under Choices to Avoid: highest mercury levels
• In US youth aged 1 to 19 (NHANES 2009-2012), each step up in how often they ate high-mercury fish such as swordfish and shark was associated with 2.4 times higher blood mercury. — 5656 US youth aged 1 to 19, NHANES 2009-2012 (n = 5656) Evidence C source
  Exp beta 2.40 (95% CI 1.23 to 4.68) per frequency of swordfish and shark intake
• Cleveland Clinic reported 8 cancer patients whose hypercalcemia may have been worsened by vitamin D, calcium or shark cartilage supplements. — 8 cancer patients with hypercalcemia (n = 8) Evidence D source
  Supplements possibly contributed to prevalence or severity of hypercalcemia
• In 912 Korean adolescents, eating shark meat was associated with higher blood mercury, most of all when it was eaten in the past 30 days. — 912 adolescents in the 3rd Korean National Environmental Health Survey, 50 of them shark meat eaters (n = 912) Evidence C source
  Log blood mercury beta 0.41 (95% CI 0.23 to 0.59) for shark meat eaters; beta 1.19 (0.30 to 2.08) if eaten within 30 days
• EFSA confirmed in 2026 that its tolerable weekly intake for methylmercury, 1.3 ug per kg body weight, remains valid after reviewing the stricter US ATSDR figure. — EU population; unborn child as the most sensitive (neurodevelopmental endpoint) Evidence E source
  MeHg TWI 1.3 ug/kg bw/week (as Hg) retained; ATSDR MRL 0.7 ug/kg bw/week not considered more robust

What is still unknown

• USDA lists 3.5 oz (100 g) of raw shark with 36.5 mcg selenium (66% DV), 1.49 mcg vitamin B12 and 21 g protein, while the UK table gives 23 g protein and 5 mcg B12, so the two disagree on B12 by about 70%. — USDA SR Legacy FDC 173697, Fish, shark, mixed species, raw; CoFID 16-142 Shark, raw Evidence E source
  Per 100 g raw: selenium 36.5 mcg, vitamin B12 1.49 mcg (CoFID 5), protein 20.98 g (CoFID 23); no Foundation samples

The bottom line

Who should be careful. FDA and EPA put shark on their Choices to Avoid list, the highest-mercury group, for anyone who is or might become pregnant, anyone breastfeeding, and children aged 1 to 11. EFSA confirmed in 2026 that its tolerable weekly intake for methylmercury, 1.3 ug per kg of body weight, remains valid, with the unborn child as the most sensitive. In a 2026 study of muscle from 18 shark species from the Mediterranean, Indian and Atlantic Oceans, 8 exceeded the EU mercury limit of 1 mg/kg, highest in deep-sea and large open-ocean sharks such as blue shark and shortfin mako. Sample numbers differed by species, and some samples did not come from retail. US surveys in 2001 and 2006 found women aged 18 to 45, the group that advice is written for, less aware of mercury in fish than other women. In 501 Korean adults, habitual eating of whale and shark meat was associated with higher toenail mercury in a single cross-sectional study. CDC names shark among the large predatory reef fish in which ciguatera toxin concentrates, though the 4 poisonings in that report came from other fish. A Cleveland Clinic series of 8 cancer patients with high blood calcium suggests vitamin D, calcium or shark cartilage supplements may have added to it, with no test of cause and no way to separate the three. A 6-week trial in 60 healthy volunteers found no adverse change in liver tests from a capsule of rosemary extract carried in shark liver oil, a combined product tested for safety only. The shark liver oil trials on this page ran for 3 and 6 weeks, and none of our sources sets a safe upper intake for shark liver oil itself. Fish liver oils carry preformed vitamin A. NIH sets its upper limit at 600 mcg a day up to age 3, rising to 900 mcg at 4 to 8, 1,700 mcg at 9 to 13, 2,800 mcg at 14 to 18 and 3,000 mcg for adults, pregnancy included. The limits rest on liver damage, birth defects and toxic effects in children. Intakes above the limit can cause birth defects of the eye, skull, lungs and heart, and experts advise anyone who is or might be pregnant, or is breastfeeding, not to take more than 3,000 mcg a day of vitamin A from supplements. No source we found states how much vitamin A shark liver oil contains, and the oil in the 4 g trial had its excess vitamin A removed, so other products may carry more. A French case series describes three people poisoned by vitamin A after eating the liver of a large predatory fish, species not named. They had headache, nausea, vomiting and peeling skin, and the pregnant woman among them miscarried, which the report does not show vitamin A caused. The EU refused two claims: that shark cartilage is good for joint health and that shark liver oil or its alkylglycerols strengthen immunity. On the plate, USDA lists 3.5 oz (100 g) of raw shark with 36.5 mcg of selenium, 66 percent of the Daily Value, and 21 g of protein, from mixed species and a single record. The UK table gives 5 mcg of vitamin B12 per 3.5 oz (100 g) against 1.49 mcg in the USDA record, so the B12 figure is unsettled. The US dietary survey counts a shark steak as 210 g and a fillet as 140 g. By the USDA retention table for finfish, frying from frozen keeps 95 percent of vitamin B12 and baking lean fish keeps 90 percent. Skinned shark tail carries 7.6 to 13.3 g of collagen per serving in a Japanese analysis. After a cooked shark meal, blood collagen peptides reached only about 30 percent of the level from an equal dose of collagen hydrolysate, in a small non-randomized study that does not state how many people took part.

Sources

1. shk8-16 · food portion dataset
   Fish, shark | FNDDS code 26143110 | fdc_id 2706300 | 1 fillet, any size 64760 = 140 g | 1 steak 62898 = 210 g | 1 cup 10205 = 135 g | 1 oz yields 40016 = 20 g
   USDA FNDDS, Fish, shark, food code 26143110, fdc_id 2706300 · checked 2026-09-28
2. shk8-04 · feeding study
   The meat in one serving of most Japanese daily dishes contains 0.2-2.5 g of collagen, except for beef tendon, eel with skin, and skinned shark tail (7.6-13.3 g). After ingestion of cooked shark meat, nine collagen di- and tripeptides were detected in plasma and the area under the curve of most peptides, except for Hyp-Gly and Pro-Hyp-Gly, was ∼30% of that after ingestion of collagen hydrolysate containing an equivalent amount of collagen.
   J Agric Food Chem, 2019 · checked 2026-09-28
3. shk8-15 · USDA Table of Nutrient Retention Factors, dataset
   USDA-RETN-R6:2601 FINFISH(FROZEN),FRIED, group Finfish and Shellfish Products: vitamin_b12_ug 95% retained, riboflavin_mg 95%, thiamin_mg 90%, zinc_mg 100%; USDA-RETN-R6:2301 FINFISH,<5%FAT,BAKED,WO/DRIPPINGS: vitamin_b12_ug 90% retained, thiamin_mg 90%, vitamin_b6_mg 90%, niacin_mg 95%
   USDA Table of Nutrient Retention Factors, Release 6, 2007, Retn_Codes 2601 and 2301 · checked 2026-09-28
4. shk8-01 · randomized crossover trial
   In this randomized, double-blind, placebo-controlled cross-over study, the participants (10 overweight or obese males) received 4-g Alkyrol® (purified SLO) or placebo (methylcellulose) per day for 3 weeks followed by a 3-week washout phase and were then crossed over to 3 weeks of the alternate placebo/Alkyrol® treatment...In addition, SLO supplementation significantly decreased the plasma levels of total free cholesterol, triglycerides, and C-reactive protein.
   J Lipid Res, 2021 · checked 2026-09-28
5. shk8-03 · uncontrolled clinical trial
   Concerning LDL fraction of cholesterol (Table 1) in sera, we could observe a significant increase of its concentration after 6 weeks of supplementation (from 76.6 mg/dL to 86.7; p = 0.003).
   Nutrients, 2021 · checked 2026-09-28
6. hf2-shk-4 · randomized crossover trial
   The SLO that we used for this study (Alkyrol®) has been purified to enrich for alkylglycerols and to remove all contaminants and unwanted substances such as polychlorinated biphenyl, pesticides, heavy metals, fatty substances such as COH, squalene, and excessive amounts of vitamin A and D. However, nonpurified or semipurified SLO could have deleterious effects on the liver and other major organs because of the presence of substantial amount of squalene and other undesirable components. Therefore, SLO should be consumed with caution.
   J Lipid Res, 2021 · checked 2026-10-08
7. shk8-02 · randomized trial
   Sixty healthy volunteers participated in a six week, double-blind, randomized parallel pilot study with two study arms: RE-AKG capsules (CR) and control capsules (CC)...The lack of adverse effects on liver profile and oxidation markers, together with adequate tolerability and safe immunological adaptations, provide high-quality information for the potential use of CR as co-adjuvant of therapeutic strategies against colorectal cancer.
   Nutrients, 2019 · checked 2026-09-28
8. shk8-05 · FDA monitoring data
   SHARK | 0.979 | 0.811 | 0.626 | ND | 4.54 | 356 | FDA 1991-2007
   FDA, Mercury Levels in Commercial Fish and Shellfish (1990-2012), 2022 · checked 2026-09-28
9. shk8-08 · cross-sectional
   Higher toenail mercury levels were associated with habitual consumption of whale and shark meats, older age, obesity, smoking, alcohol drinking, and higher household income.
   Nutrients, 2016 · checked 2026-09-28
10. shk8-09 · case report
    Because these toxins are lipid soluble, they accumulate through the food chain as carnivorous fish consume contaminated herbivorous reef fish; toxin concentrations are highest in large, predatory fish such as barracuda, grouper, amberjack, snapper, and shark.
    MMWR Morb Mortal Wkly Rep, 2006 · checked 2026-09-28
11. shk8-18 · contaminant survey
    Eight out of 18 species (44.4%) exceeded the EU maximum THg concentration (1 mg kg–1), a threshold adopted internationally and provide a conservative benchmark for global consumer risk (Figure ).
    Environ Sci Technol, 2026 · checked 2026-09-29
12. shk8-11 · cross-sectional
    In 2001, the Food and Drug Administration (FDA) advised pregnant women, nursing mothers, young children, and women who may become pregnant not to consume shark, swordfish, king mackerel, and tilefish...In both 2001 and 2006, women of childbearing age (aged 18-45) were less aware and knowledgeable about this information than other women.
    Environ Res, 2011 · checked 2026-09-28
13. shk8-12 · EU claim register entry
    POL-HC-7920 Shark cartilage For joint health. For supportive tissue health. Non-authorised
    EU Register on nutrition and health claims, claim POL-HC-7920, snapshot 2026-09-21 · checked 2026-09-28
14. shk8-13 · EU claim register entry
    POL-HC-7924 Shark liver oil/alkylglycerol Strengthens immunity Non-authorised
    EU Register on nutrition and health claims, claim POL-HC-7924, snapshot 2026-09-21 · checked 2026-09-28
15. hf2-shk-1 · agency advice
    The FNB has established ULs for preformed vitamin A that apply to both food and supplement intakes [5]. The FNB based these ULs on the amounts associated with an increased risk of liver abnormalities in men and women, teratogenic effects, and several toxic effects in infants and children. ... Birth to 12 months 600 mcg 600 mcg 1–3 years 600 mcg 600 mcg 4–8 years 900 mcg 900 mcg 9–13 years 1,700 mcg 1,700 mcg 14–18 years 2,800 mcg 2,800 mcg 2,800 mcg 2,800 mcg 19+ years 3,000 mcg 3,000 mcg 3,000 mcg 3,000 mcg
    NIH Office of Dietary Supplements, Vitamin A Fact Sheet for Health Professionals · checked 2026-10-08
16. hf2-shk-2 · agency advice
    Total intakes of preformed vitamin A that exceed the UL as well as some retinoid medications used as topical therapies (such as isotretinoin, used to treat severe acne, and etretinate, a treatment for severe psoriasis) can cause congenital birth defects [1]. These birth defects can include malformations of the eye, skull, lungs, and heart [14]. Experts advise women who are or might be pregnant and those who are lactating not to take high doses (more than 3,000 mcg RAE [10,000 IU] daily) of vitamin A supplements [1].
    NIH Office of Dietary Supplements, Vitamin A Fact Sheet for Health Professionals · checked 2026-10-08
17. hf2-shk-3 · case series
    In European countries, vitamin A toxicity is most often the result of an excessive intake of vitamin supplements and rarely the consequence of the ingestion of a large carnivorous fish liver. We report 3 cases of vitamin A poisoning after fish liver ingestion in mainland and overseas France. The patients were a 12-y-old girl, a 36-y-old pregnant woman, and a 62-y-old man. They experienced headache, nausea, emesis, and desquamation. Laboratory examination showed a high serum retinol level in the girl. The woman's pregnancy progressed to a miscarriage.
    Wilderness Environ Med, 2020 · checked 2026-10-08
18. shk8-06 · FDA and EPA fish advice
    For Those Who Might Become or Are Pregnant or Breastfeeding and Children Ages 1 - 11 Years...King mackerel, Marlin, Orange roughy, Shark, Swordfish, Tilefish (Gulf of Mexico), Tuna, bigeye
    FDA and EPA, Advice about Eating Fish, 2024 · checked 2026-09-28
19. shk8-07 · cross-sectional
    frequency of consuming certain seafood types had significant positive association with blood mercury concentrations: high-mercury fish (swordfish and shark) [exponentiated β coefficient (expβ): 2.40; 95% CI: 1.23, 4.68]
    J Nutr, 2015 · checked 2026-09-28
20. shk8-10 · case report
    We report eight cases of hypercalcemia in cancer patients seen at the Cleveland Clinic Foundation in whom these nutritional supplements may have contributed to the prevalence or severity of hypercalcemia.
    Support Care Cancer, 2003 · checked 2026-09-28
21. shk8-17 · cross-sectional
    Of the 912 participants, 50 (5.5%) were identified as shark meat consumption group...Shark meat consumption was associated with higher blood mercury concentrations (β = 0.41; 95% confidence interval [CI]: 0.23-0.59), with the highest levels observed among those who consumed shark meat within the past 30 days (β = 1.19; 95% CI: 0.30-2.08)
    Ann Occup Environ Med, 2026 · checked 2026-09-28
22. shk8-19 · agency risk assessment (TWI)
    Consequently, the current EFSA TWI for methylmercury of 1.3 μg/kg bw, expressed as mercury, remains valid.
    EFSA Journal, 2026 · checked 2026-09-29
23. shk8-14 · USDA FoodData Central and CoFID datasets
    Fish, shark, mixed species, raw (FDC 173697, SR Legacy, Finfish and Shellfish Products): selenium 36.5 ug per 100 g = 66% DV; vitamin B12 1.49 ug = 62% DV; protein 20.98 g = 42% DV; CoFID 2021 16-142 Shark, raw: vitamin B12 5 ug, protein 23 g; Foundation samples 0
    USDA FoodData Central, SR Legacy, FDC 173697; CoFID 2021, code 16-142 · checked 2026-09-28