Oysters 101: A Complete Guide

Oyster Nutrition Facts

A 3-ounce (oz) serving of raw oysters (the equivalent of two medium oysters or three small oysters) provides 69 calories, with 8 grams (g) of protein, 2g of fat, and 4.2g of carbohydrates. They also contain about 90 milligrams (mg) of sodium and 43 mg of cholesterol.

People often order a dozen oysters at a time. There are about 413 calories in a dozen raw oysters, depending on the oyster size.

In terms of vitamins, oysters are an excellent source of Vitamin B-12, with one serving providing 567 percent of your daily value (DV). They’re also an excellent source of key minerals such as copper (149 percent of your DV), zinc (128 percent of your DV), and selenium (119 percent of your DV).

Health Benefits of Oysters

Like other seafood, oysters have a rich and varied nutrient profile that can help support overall health, with a few standout benefits.

Cognitive Support

Oysters are packed with nutrients linked to brain health, including Vitamin B-12 and omega-3 fatty acids.

Vitamin B-12 is associated with better brain health and cognitive function, particularly as we age, according to the Office of Dietary Supplements. It plays a role in the synthesis and metabolism of homocysteine, a deficiency that is associated with dementia and Alzheimer's disease.

Omega-3 fatty acids are also vital to brain health, according to the Office of Dietary Supplements. Oysters contain both eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), the most abundant fats in our brains that help carry out a number of processes and functions. Research shows that people with Alzheimer's disease have lower serum levels of DHA compared to those who are cognitively healthy.

Immune Support

Raw oysters contain the highest concentration of zinc of any food, according to the Office of Dietary Supplements. Zinc is a trace mineral that’s essential for a number of functions and processes in the body, including DNA synthesis, wound healing, and the immune response. Zinc supplements consumed within 24 hours of experiencing common cold symptoms may help shorten the length of the illness, according to Mayo Clinic.

Energy Support

Iron is an integral part of your diet, helping red blood cells deliver oxygen throughout the body and supporting muscle metabolism, according to the Office of Dietary Supplements. Low levels of iron can lead to iron deficiency or iron deficiency anemia, with symptoms including 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-based foods like oysters. One standard serving of oysters is a great source of iron, providing nearly 25 percent of your DV.

Oyster Health Risks

Despite their benefits, oysters may present a few health risks as well.

Food Allergies

Shellfish is one of the more common food allergies, including crustaceans (shrimp, crab, or lobster) and mollusks (oysters, clams, mussels, and scallops), according to the Food Allergy Research and Education.

Shellfish allergies most frequently occur in adults and older children, but they can appear at any age, according to Cleveland Clinic. Shellfish allergy symptoms may range from mild to severe. Mild cases may include swollen lips and an itchy mouth or tongue. Moderate cases may include gastrointestinal discomfort, nausea, and diarrhea. Severe cases could lead to life-threatening anaphylactic shock.

Vibriosis

Eating raw oysters may lead to vibriosis, an infection caused by Vibrio bacteria that can make people ill. While most people experience mild symptoms including diarrhea, the infection can be life threatening for some, according to the Centers for Disease Control and Prevention.

Opting for raw oysters from a reputable food service establishment is a good way to avoid this illness.

Drug Interactions

Zinc can reduce the absorption and potency of quinolone antibiotics (Cipro) and tetracycline antibiotics (Achromycin), according to Mayo Clinic. Because oysters have such high zinc content, the Office of Dietary Supplements recommends eating them at least two hours before or four to six hours after taking antibiotics.

Zinc can also interfere with the drug penicillamine (Cuprimine, Depen), which is used to treat rheumatoid arthritis. To avoid the interaction, eat oysters and other zinc-rich foods at least one hour before or after taking the medication.

Oyster Preparation and Storage Tips

If you’re eating oysters at home, you must clean them before you shuck them. Discard any oysters with broken or gaping open shells, as they 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 1/4 cup salt for every 4 cups of cold water. Refrigerate and allow them to soak for at least an hour, which helps them purge any grit they’ve accumulated.

How to Shuck Oysters

To shuck oysters (split them open without cooking them), you will need an oyster knife, which has a short, round, and strong blade with a guard to protect your fingers. It's recommended you wear work gloves to protect your hands.

1. Hold the oyster firmly in your palm or on a counter on top of a folded kitchen towel, with the deeper-cupped shell side facing down and the hinge toward you. Place the knife blade between the halves of the shell near the hinge and twist until it gives way.
2. Carefully slide the knife along the top shell to sever the hinge muscle and remove the top shell.
3. Pick out any remaining grit or broken shell, then slide the knife along the inside of the cupped shell to release the oyster meat.

How to Steam Oysters

If you prefer to eat your oysters cooked, try steaming them:

1. Place scrubbed oysters flat-side up in a single layer in a large steamer basket,
2. Bring a pot of water to a boil and place the steamer basket on top of the pot (without the water touching the oysters).
3. Reduce the heat, cover with a lid, and steam the oysters until their shells open.
4. Discard any oysters that remain shut.

Storing Oysters Safely

If you're planning to eat oysters at home, keep the following tips in mind:

• Handle fresh oysters carefully. If an oyster's shell is chipped or the shell doesn’t close when you tap it, remove and dispose of it immediately.
• To store fresh live oysters in the shell, put them in a bowl covered with a damp kitchen towel and place them in the refrigerator. Oysters are highly perishable, so eat them within a couple days.
• Live oysters may also be frozen in the shell and kept for 3–6 months. Place the oysters in vapor-resistant freezer bags, press out all the excess air, and freeze.
• Shucked oysters should be refrigerated in an airtight container covered by their own liquor. You can freeze shucked oysters this way, too.