Oysters are one of the oldest living species and have been cultivated as food for more than 2,000 years. They are part of the mollusk family of shellfish that also includes mussels, clams and scallops.
Mollusks are bivalves, which means they are seafood species with two shells of equal size the protect a soft body. Oysters are one of the few species that are eaten both raw and cooked.
Oyster Nutrition Facts
Three ounces of raw oysters, which is about two medium oysters or three small oysters, is equal to a single serving. Three ounces of raw oysters contain:
- Calories: 69
- Total fat: 2 g
- Cholesterol: 42.5 mg
- Sodium: 90.1 mg
- Total carbs: 4.2 g
- Dietary fiber: 0 g
- Sugar: 0 g
- Added sugar: 0 g
- Protein: 8 g
- Total fat: One three-ounce serving of raw oysters has 2 grams of total fat, which includes 0.8 grams of polyunsaturated fat, 0.3 grams of monounsaturated fat, 0.4 grams saturated fat and 0 grams of trans fat.
- Carbohydrates: One three-ounce serving of raw oysters has 4.2 grams of carbohydrates, which includes 0 grams of fiber and 0 grams of natural sugar.
- Protein: One three-ounce serving of raw oysters has 8 grams of protein.
Vitamins, Minerals and Other Micronutrients
- Vitamin B12: 567% of your Daily Value (DV)
- Copper: 149% DV
- Zinc: 128% DV
- Selenium: 119% DV
- Manganese: 24% DV
- Iron: 24% DV
- Riboflavin (B2): 15% DV
- Phosphorous: 11% DV
- Niacin: 11% DV
- Vitamin A: 8% DV
- Vitamin C: 8% DV
- Magnesium: 4% DV
- Potassium: 3% DV
- One serving of oysters is not a significant source of calcium (1% DV).
Health Benefits of Oysters
Like other seafood, oysters have a rich and varied nutrient profile and contain a wide range of vitamins, minerals and healthy fats.
1. Oysters Are Linked to Good Brain Health
Oysters are like a multi-vitamin for your brain. They're packed with nutrients linked to brain and mental health, including vitamin B12 and omega-3 fatty acids.
Vitamin B12 is associated with better brain health and cognitive function, particularly as we age, according to the National Institutes of Health (NIH). B12 plays a role in the synthesis and metabolism of homocysteine, and a deficiency is associated with dementia and Alzheimer's disease. One three-ounce serving of oysters provides 567 percent of your DV for vitamin B12.
Omega-3 fatty acids have been shown to be vital to brain health. The two types that are found in oysters are EPA and DHA, which is the most abundant fat in our brains and helps to carry out many processes and functions.
Omega-3s can help protect cognitive function and research shows that people with Alzheimer's disease have lower serum levels of DHA compared to those who are cognitively healthy, per the NIH.
What's more, eating seafood regularly is tied to a 20-percent lower risk of depression, according to an article published in the November 2016 issue of the Journal of Affective Disorders.
2. Oysters Are Zinc Powerhouses
Oysters contain the highest concentration of zinc of any food with 128 percent of your daily dose in one three-ounce serving. Zinc is a trace mineral that is essential for our smell and taste senses to function properly, according to the NIH.
Zinc is also a vital part of other functions and processes in the body, including wound healing, immune response and male health.
One of the widely storied uses of oysters is as an aphrodisiac. This, in fact, may be true due to their high zinc content. Zinc is essential to the production of hormones such as testosterone and is a key nutrient in sperm production, per a 2018 article in the Journal of Reproduction and Infertility, which is why it's linked to improved fertility.
3. Oysters Are an Excellent Source of Iron
Iron is an integral part of your diet, helping red blood cells deliver oxygen throughout the body and supporting muscle metabolism, according to the NIH.
Low levels of iron can lead to iron deficiency or iron deficiency anemia, with symptoms such as fatigue, weakness, gastrointestinal distress, immunity issues and impaired cognitive function.
There are two main forms of iron: non-heme, which comes from iron-fortified foods or plant-based foods, and heme, which is found in animal products such as oysters. One three-ounce serving of oysters provides 24 percent of the DV for iron, making it an excellent way to reach your daily dose.
Oyster Health Risks
Shellfish is one of the more common food allergies. This includes two types of shellfish — crustacea, such as shrimp, crab or lobster and mollusks, such as oysters, clams, mussels and scallops, per the Food Allergy Research & Education.
Shellfish allergies most frequently occur in adults and older children but can appear at any age, according to the Cleveland Clinic. Shellfish allergy symptoms may range from mild to severe. Mild cases include oral allergy syndromes, such as swollen lips and an itchy mouth or tongue.
Moderate cases may include GI discomfort, nausea and diarrhea while severe cases could be life-threatening anaphylactic shock and require the use of an epi-pen.
Eating raw oysters may lead to vibriosis, an infection caused by the V. vulnificus bacteria that can make people ill. While most people who get it have mild symptoms (including diarrhea), as many as 1 in 5 people with the infection die, according to the CDC.
Bivalve mollusks, including oysters, filter 15 to 20 gallons of water per day. If the water itself is polluted, they can store toxins in their bodies for up to two years. When purchasing oysters, be sure to check where they come from.
Reputable markets are able to show tags certifying that the mollusks have been harvested from certified-as-clean waters.
If you're eating raw oysters in a restaurant, handling procedures may also lead to GI distress, such as cramps, nausea or diarrhea. These issues pose significant risks to those who are very young or old as well as immune-compromised groups, such as people with diabetes, cancer or autoimmune diseases. Opting for oysters from a reputable food-service establishment is a good way to avoid this.
Zinc can reduce the absorption and potency of quinolone antibiotics (such as Cipro) and tetracycline antibiotics (such as Achromycin). Because of oysters' high zinc content, eat them at least 2 hours before or 4 to 6 hours after taking antibiotics, per the NIH.
Zinc can also interfere with the drug penicillamine, which is used to treat rheumatoid arthritis. To avoid the interaction, have oysters and other zinc-rich foods at least 2 hours before or after taking the medication.
Oyster Preparation and Useful Tips
If you're looking to use oysters at home, follow these storage tips:
- Handle fresh oysters carefully. If an oyster's shell is chipped or the shell does not close when you tap it, remove and dispose of these oysters immediately.
- To store fresh live oysters in the shell, place them in a bowl covered with a damp kitchen towel and place them in the refrigerator. Oysters are highly perishable, so eat them within three days.
- Live oysters may also be frozen in the shell and kept up to three months. To do this, place the oysters in vapor-resistant freezer bags, press out all the excess air, and freeze.
- Fresh-shucked oysters should be submerged in their own juices, should appear plump, uniform in size and should smell fresh like clean salt water. Shucked oysters should be refrigerated in an airtight container covered by their own liquor. If more is needed, dissolve one-half teaspoon of salt into one cup of water and add to the container. They should stay fresh for up to two days but are best eaten immediately.
- To freeze shucked oysters, clean and wash the meat then pack in resealable freezer bags and use within three months. To thaw, place freezer bag in the refrigerator for approximately six to seven hours.
Now that you've purchased oysters and brought them home, you'll have to clean them before shucking. Here's how to do it:
- Discard any oysters with broken or gaping open shells; those have died and are unsafe to eat.
- Scrub the outside of each oyster with a brush and then place them into a large bowl with the following: 1 gallon cold water with 1/4 cup of cornmeal and 2 tablespoons of salt per quart of oysters. Allow them to soak for two to three hours, which helps purge any grit accumulated by the oysters.
- Rinse well, then cover oysters with cold water. Discard any that are floating after five minutes.
- Scrub oysters with a brush once again under cold running water. Prior to shucking, you can place the oysters in the freezer for 10 to 20 minutes, which may help them open more easily.
How to Shuck Oysters
To shuck oysters, you will need an oyster knife ($9.99 on Amazon), which has a short, round and strong blade with a guard to protect your fingers.
If you do not have one, try using a short screwdriver or beer can opener instead. It's recommended to wear work gloves to protect your hands.
- Hold the oyster with the deeper-cupped shell side facing down and the hinge toward you, firmly in your palm or on a counter on top of a folded kitchen towel. Place the knife blade between the halves of the shell near the hinge and twist until it gives way.
- Carefully slide the knife along the top shell to sever the hinge muscle and remove the top shell.
- Pick out any remaining grit or broken shell then slide the knife along the inside of the cupped shell to release the oyster meat.
Not Into Raw Oysters?
Try this easy and delicious recipe for Grilled Oysters.
How to Steam Oysters
- Place scrubbed oysters flat-side up in a large pot, fill with a few inches of water or broth and bring to a boil.
- Reduce heat to low then cover the pot and steam until the shells open, about six to eight minutes.
- Discard any oysters that are remain shut.
Now that you have your oysters, here are some quick serving ideas.
- Fresh or frozen oysters work well in soups and stews. Canned oysters are already cooked, so add them to soups, stews and other dishes last minute to retain their texture.
- Serve freshly shucked oysters raw on the half shell with a vinaigrette and horseradish.
- Cook oysters in their shells on the grill until they pop open, about three minutes.
- Bake shucked oysters in their shells topped with bread crumbs, chopped spinach and butter for a classic Oysters Rockefeller dish.
- Add a cup of cooked oysters to stuffing.
- Place shucked oysters in a large square of aluminum foil with chopped tomatoes, fennel, herbs, salt, crushed red pepper flakes and olive oil. Close foil to make a pouch and grill or bake for about 20 minutes.
- Pan-fry shucked oysters by heating a pan over medium-high heat, adding oil, dredging the oysters in flour then placing them in the pan. Cook for about five minutes, flipping over occasionally. Serve with lemon wedges.
Alternatives to Oysters
Other shellfish like clams, mussels and scallops are good swap-outs. Depending on the dish, other seafood like fish, shrimp or lobster can be used as well.
- Encyclopedia Britannica: “Oysters”
- My Food Data: “Raw Oysters”
- NIH: “Fact Sheet for Health Professionals: Vitamin B12”
- NIH: “Fact Sheet for Health Professionals: Omega-3 Fatty Acids”
- Journal of Affective Disorders: “Dietary n-3 PUFA, fish consumption and depression: A systematic review and meta-analysis of observational studies”
- NIH: “Fact Sheet for Health Professionals: Zinc”
- NIH: "Fact Sheet for Health Professionals: Iron”
- The Cleveland Clinic: “Allergies: Shellfish”
- CDC: “Oysters and Vibriosis”
- Seafood Source: "American seafood consumption up in 2015, landing volumes even"
- FARE: "The Food Allergy Epidemic"
- Journal of Reproduction and Infertility: "Zinc is an Essential Element for Male Fertility: A Review of Zn Roles in Men’s Health, Germination, Sperm Quality, and Fertilization"