Oyster Nutrition Facts

Calories, Carbs, and Health Benefits of Oysters

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When it comes to oysters, you either love them, or you hate them, or won't even try them. But did you know that oysters are good for you?

It's hard to imagine that these small, tasty morsels that don't require any chewing and easily slide down your throat are high in several important minerals and protein. Scan these oyster nutrition facts to inspire you to add them to your diet.

Nutrition Facts

The following nutrition information is provided by the USDA for one medium (50g) raw Pacific oyster.

  • Calories: 40
  • Fat: 1.1g
  • Sodium: 53mg
  • Carbohydrates: 2.5g
  • Fiber: 0g
  • Sugars: 0g
  • Protein: 4.7g

A single oyster doesn't have many calories or grams of fat. Although size matters substantially. Oysters vary in size and can weigh an ounce (about 28 grams) up to three ounces (over 75 grams). But with only about 50 calories and 1.1 gram of fat per serving, oysters are an excellent appetizer for those who are watching their weight.

Carbs in Oysters

There are very few carbohydrates in oysters. A single large oyster provides about two grams of carbohydrate. This food is not a significant source of fiber, sugar, or starch.'

The estimated glycemic load of an oyster is two, making it a low-glycemic food.

Fats in Oysters

Oysters do add to your daily fat intake, although not substantially if you only eat one or two. A single medium-sized oyster provides just over one gram of fat. You'll increase your saturated fat intake minimally (saturated fat is considered to be a less healthy form of fat). But you will also minimally increase your healthy (polyunsaturated and monounsaturated) fat intake.

Protein in Oysters

Oysters are packed with protein. Just one medium oyster provides almost five grams of this vital macronutrient. If you eat two or three oysters, you'll get as much protein as a small serving of chicken breast and more protein than an egg.

Micronutrients in Oysters

Oysters provide several important vitamins and minerals. 

A single oyster provides a whopping 8 mcg of vitamin B12. That's 133 percent of your recommended daily intake for the day. You'll also gain small amounts of vitamin A, vitamin C, thiamin, riboflavin, niacin, folate, and pantothenic acid.

Minerals in oysters include iron (14 percent of your daily needs), zinc (55 percent of your daily needs), copper (39 percent of your daily needs), selenium (55 percent), manganese (16 percent), and smaller amounts of phosphorus, potassium and sodium.

Health Benefits

For such an unassuming food, the oyster is packed with nutrition and health benefits. Protein helps your body build and maintain muscle and oysters provide this important macronutrient with very little fat and zero carbohydrate.

The micronutrients in oysters also provide health benefits. Zinc is a mineral your body needs for many different biochemical processes to occur and is crucial to the immune system. It assists in cell growth and division, the healing of wounds, and breaking down carbohydrates. 

The vitamin B12 in oysters helps your body to preserve healthy nerves and cells. There may be other benefits provided by vitamin B12, including boosted heart health, dementia prevention and increased athletic performance, but research has not been able to confirm these benefits yet, according to the Centers for Disease Control.

Oysters also high in iron, key in producing hemoglobin, which your body needs to transport oxygen to all of your organs and tissues. An iron deficiency also causes fatigue and could lead to anemia.

Lastly, just about every list of aphrodisiacs includes oysters and while there's no evidence to support the idea that any foods will increase your sexual attraction, it is interesting to note that zinc is essential for men's sexual health, testosterone levels, and sperm production.

Oyster Safety

Oysters can be eaten raw, cooked, or used in dishes such as oyster stew. Generally, raw oysters are safe to eat, but just as with the consumption of any raw fish or seafood, there is a possibility of food-borne illness. Raw oysters may be contaminated with Vibrio vulnificus, which is a bacteria related to cholera. Oysters harvested in warm water are more likely to be infected than oysters collected from colder water.

Which is why there is the saying that you should only eat oysters in months that have the letter "r" in them—the months that don't have an "r" include May, June, July, and August, the warm months when Vibrio contamination is more likely. That was a problem many years ago when oysters weren't tested properly, but today the oysters you buy are safe year round and you can confidently buy and eat oysters any time of the year.

Eating raw shellfish, oysters in particular, can put you at risk of contracting hepatitis A, a disorder that affects your liver. That's because oysters filter a substantial amount of water, and if that water is contaminated with stool containing the hepatitis A virus, the oyster can become contaminated. But because oysters for purchase are tested, the risk is minimal. 

A healthy person who ingests the bacteria may suffer from abdominal pain, vomiting, and diarrhea. However, the infection can be severe in a person who has liver disease or is immunocompromised because the bacteria can get into the bloodstream and cause septicemia, which is fatal about 50 percent of the time.

If you've been told not the consume raw oysters, you must avoid them. The only way to kill the bacteria is through cooking. There are myths that adding lots of hot sauce or drinking alcohol while you eat raw oysters will kill the bacteria, but that is not true.

Common Questions

Is there a nutritional difference between East coast and West coast oysters?

Oysters are available either farmed or wild and are harvested in both the Pacific and Atlantic Oceans. Since farmed oysters are grown in living conditions that are similar to wild oysters, there doesn't appear to be any difference as far as nutrition goes. 

How do I buy oysters?

When buying oysters, choose fresh oysters that have been harvested and processed according to safety guidelines. (Look for a tag on containers or sacks of oysters.) Throw away any oysters that have broken shells, and tap any open shells with your finger—a live oyster should close its shell when you tap it. If it doesn't close, then throw it away.

How do I store raw oysters?

Fresh oysters should be refrigerated at 40 F or lower until you serve them or use them in a recipe. When you cook fresh oysters, the shells should open up. Discard any oysters that remain closed.

Recipes and Preparation Tips

Oysters are often served raw, usually sitting on its shell. To prepare raw oysters, you'll need to open them up by shucking them (use a thick towel and an oyster shucking knife), or you can buy them already shucked. Oysters can also be smoked, baked, fried (as in crispy "oysters Rockefeller"), grilled, or used as the featured ingredient in dishes such as oyster stew or oyster-stuffed artichokes.

Allergies and Interactions

According to the American Academy of Asthma, Allergy and Immunology people with a shellfish allergy should be very careful to avoid even a small exposure to oysters. Symptoms may be mild to severe, ranging from hives or eczema to anaphylaxis.

Be careful when eating out to avoid any contact with oysters if you have ever been diagnosed with a shellfish allergy and avoid other types of seafood including clams and calamari.

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