Clams vs oysters: nutrition compared

Full comparison · Protein · Calories · Healthier

Per 3.5 oz (100 g), clams has 86 calories and 14.7 g of protein; oysters has 51 calories and 5.7 g. Fiber: 0 g vs 0 g.

Where each one is ahead

Clams has clearly more protein (29% DV vs 11%), vitamin a (10% DV vs 1%).
Oysters has clearly more iron (26% DV vs 9%).

Side by side, per 3.5 oz (100 g)

	Clams	Oysters
Calories	86 calories	51 calories
Protein	14.7 g (29% DV)	5.7 g (11% DV)
Fat	0.96 g (1% DV)	1.7 g (2% DV)
Saturated fat	0.19 g (1% DV)	0.47 g (2% DV)
Carbohydrate	3.6 g (1% DV)	2.7 g (1% DV)
Fiber	0 g	0 g
Total sugars	0 g	0.62 g
Sodium	601 mg (26% DV)	85 mg (4% DV)
Potassium	46 mg (1% DV)	156 mg (3% DV)
Calcium	39 mg (3% DV)	59 mg (5% DV)
Iron	1.6 mg (9% DV)	4.6 mg (26% DV)
Magnesium	19 mg (5% DV)	18 mg (4% DV)
Vitamin A	90 mcg (10% DV)	13 mcg (1% DV)
Vitamin C	0 mg	0 mg
Vitamin D	0 mcg	0 mcg
Vitamin K	0.2 mcg (0% DV)	1 mcg (1% DV)
Folate	5 mcg (1% DV)	7 mcg (2% DV)
Vitamin B12	11 mcg (470% DV)	8.8 mcg (365% DV)
Cholesterol	30 mg (10% DV)	40 mg (13% DV)

— not reported by USDA for this food.

Per typical serving

Servings differ: 4 oz (113 g) of clams and 4 oz (113 g) of oysters, the serving sizes we use for each (USDA household measures; 4 oz for meat and fish).

	Clams	Oysters
Calories	98 calories	58 calories
Protein	16.6 g (33% DV)	6.5 g (13% DV)
Fat	1.1 g (1% DV)	1.9 g (2% DV)
Saturated fat	0.21 g (1% DV)	0.54 g (3% DV)
Carbohydrate	4 g (1% DV)	3.1 g (1% DV)
Fiber	0 g	0 g
Total sugars	0 g	0.7 g
Sodium	682 mg (30% DV)	96 mg (4% DV)
Potassium	52 mg (1% DV)	177 mg (4% DV)

— not reported by USDA for this food.

What the numbers don't tell you

Zinc is the clearest nutrition gap, and NIH says oysters hold more per serving than any other food. In USDA survey data one raw oyster (15 g) carries about 5.9 mg, so six carry about 35 mg, near the adult upper limit of 40 mg a day, and a cup (225 g) carries 88.4 mg. For children the limit is 4 to 34 mg by age. NIH says 50 mg or more over weeks can inhibit copper absorption, and that food alone is unlikely to supply that much.

CDC says most Vibrio infections come from raw or undercooked shellfish, especially oysters. Hot sauce, lemon juice and alcohol do not kill Vibrio, and a contaminated oyster looks, smells and tastes normal. In the 1988 Shanghai hepatitis A epidemic, only 3.5% of people who fell ill had cooked their clams, against 18.1% of those who stayed well.

FDA lists raw oysters, even ones treated after harvest, among foods to avoid in pregnancy, for young children, older adults and people with weakened immunity. CDC adds liver disease, diabetes, cancer, immune-suppressing treatment and stomach acid medicines to the higher-risk list. A shrimp allergy puts both in question, because the main shellfish allergen cross-reacts between crustaceans and molluscs.

In those groups, eat them cooked. CDC advises boiling shucked oysters for at least 3 minutes.

Evidence behind this note

Level E NIH says oysters contain more zinc per serving than any other food. Its upper limit for zinc is 40 mg a day for adults and 4 to 34 mg for children and teens by age. Taking 50 mg or more for weeks can inhibit copper absorption, though food alone rarely supplies that much. NIH Office of Dietary Supplements, Zinc Fact Sheet for Health Professionals
Level E Three oysters cover the whole daily zinc reference value, and a cup of them carries more than twice the tolerable upper limit. USDA FNDDS 2021-2023 and 21 CFR 101.9(c)(8)(iv)
Level E CDC says most vibriosis comes from raw or undercooked shellfish, particularly oysters, and that people with liver disease, diabetes or cancer, or taking stomach acid reducers, face a higher risk of severe complications. About Vibrio Infection, US Centers for Disease Control and Prevention, People at risk
Level E CDC states that hot sauce, lemon juice and alcohol do not kill Vibrio in raw oysters and that a contaminated oyster does not look, smell or taste different, so neither the condiment nor an experienced palate makes a raw oyster safe. CDC, Vibrio and Oysters
Level C In the 1988 Shanghai hepatitis A epidemic only 3.5 percent of people who fell ill had cooked their clams, against 18.1 percent of those who stayed well. J Infect Dis, 1991
Level E FDA lists raw oysters, even if treated after harvest, among foods that at-risk groups should avoid, and says post-harvest treatment eliminates some naturally occurring pathogens but does not remove all pathogens that can cause illness. US FDA, Selecting and Serving Fresh and Frozen Seafood Safely
Level E CDC says most vibriosis comes from eating raw or undercooked shellfish, and that liver disease, cancer, diabetes, HIV, immune-suppressing therapy or stomach acid reducers raise the risk of infection and severe complications. About Vibrio Infection, US Centers for Disease Control and Prevention, People at risk
Level C Tropomyosin is the major shellfish allergen and it cross-reacts between crustaceans and molluscs, which is why a shrimp allergy puts clams and mussels in question rather than in the clear. Immunol Invest, 2016
Level E CDC says most people get a Vibrio infection by eating raw or undercooked shellfish, especially oysters. For shucked oysters it advises boiling for at least 3 minutes or frying in oil for at least 3 minutes at 375 °F. CDC, Vibrio Infection: Prevention

Written from the studies and agency guidance we hold for both foods, reviewed by the Bioma editorial system. How we verify.

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Where the numbers come from

Clams: USDA FoodData Central, Mollusks, clam, mixed species, raw, FDC ID 174214 · all forms of clams
Oysters: USDA FoodData Central, Mollusks, oyster, eastern, wild, raw, FDC ID 171978 · full profile · all forms of oysters

Each food is one USDA entry, chosen as it is usually eaten. Other cuts, brands and preparations differ; the links show them. % DV uses FDA Daily Values for adults. How we verify.