Oysters are saltwater bivalve mollusks that live in marine habitats such as bays and oceans.
They’re a vital part of the ecosystem, filtering pollutants out of the water and providing habitats for other species, such as barnacles and mussels.
There are many different types of oysters — their briny, flavorful meat is considered a delicacy around the world.
Though well known for their purported aphrodisiac qualities, these mollusks have a lot to offer in terms of health benefits.
This article reviews the impressive health benefits — but also risks — of eating oysters and explains the best ways to prepare them.
Oysters have a hard, irregularly shaped shell that protects a gray-colored, plump inner body.
This inner body — known as the meat — is highly nutritious.
In fact, a 3.5-ounce (100-gram) serving of wild eastern oysters provides the following nutrients ():
- Calories: 68
- Protein: 7 grams
- Fat: 3 grams
- Vitamin D: 80% of the Reference Daily Intake (RDI)
- Thiamine (vitamin B1): 7% of the RDI
- Niacin (vitamin B3): 7% of the RDI
- Vitamin B12: 324% of the RDI
- Iron: 37% of the RDI
- Magnesium: 12% of the RDI
- Phosphorus: 14% of the RDI
- Zinc: 605% of the RDI
- Copper: 223% of the RDI
- Manganese: 18% of the RDI
- Selenium: 91% of the RDI
Oysters are low in calories yet loaded with nutrients, including protein, healthy fats, vitamins, and minerals.
For example, a 3.5-ounce (100-gram) serving provides over 100% of the RDI for vitamin B12, zinc, and copper, and over 75% of your daily needs for selenium and vitamin D.
These tasty mollusks are also a good source of omega-3 fatty acids, a family of polyunsaturated fats that play important roles in your body, such as regulating inflammation and keeping your heart and brain healthy ().
People who eat diets high in omega-3 fats have a lower risk of developing conditions like heart disease and type 2 diabetes (, ).
Summary Oysters are packed with essential nutrients, such as protein, vitamins, minerals, and omega-3 fatty acids. They’re particularly high in vitamin B12, zinc, and copper.
Oysters are packed with nutrients. They’re especially high in the following vitamins and minerals:
- Vitamin B12. This nutrient is critical for nervous system maintenance, metabolism, and blood cell formation. Many people, especially older adults, are deficient in this vitamin ().
- Zinc. This mineral plays a vital role in immune system health, metabolism, and cell growth. A 3.5-ounce (100-gram) serving of oysters provides over 600% of the RDI ().
- Selenium. This mineral maintains proper thyroid function and metabolism. It also acts as a powerful antioxidant, helping prevent damage to cells caused by free radicals ().
- Vitamin D. Vitamin D is essential to immune health, cellular growth, and bone health. Many people are deficient in this vitamin, especially those living in colder climates ().
- Iron. Your body needs iron to make hemoglobin and myoglobin, proteins that carry oxygen throughout your body. Many people don’t get enough iron through their diet ().
Aside from their other various roles in health, many of these nutrients offer antioxidant protection as well.
For example, selenium is a powerful antioxidant that helps protect your body against oxidative stress, an imbalance that occurs when excessive amounts of free radicals are produced.
Oxidative stress has been linked to an array of chronic conditions, such as cancer, heart disease, and mental decline ().
What’s more, zinc and vitamins B12 and D also have antioxidant effects, boosting the protective benefits of oysters even higher (, ).
Research shows that people who eat diets rich in antioxidants lower their risk of heart disease, diabetes, certain cancers, and all-cause mortality (, , ).
Summary Oysters are rich in zinc, iron, selenium, and vitamins B12 and D. Some of these nutrients have antioxidant properties and help promote overall health.
Oysters are an excellent source of high-quality protein, with a 3.5-ounce (100-gram) serving packing in 7 grams of this filling nutrient.
They’re also a complete protein source, meaning they contain all nine essential amino acids your body needs.
Adding protein sources to meals and snacks can help promote feelings of fullness and encourage weight loss.
Protein-rich foods stabilize hunger by increasing levels of fullness-promoting hormones like peptide YY and cholecystokinin (CCK) (, ).
Higher-protein diets have been proven effective in boosting weight loss and lead to greater weight loss than low-fat diets or higher-carb diets (, , ).
Following a high-protein diet may also benefit blood sugar control, particularly in people with diabetes.
For example, a review of nine studies demonstrated that high-protein diets significantly reduced levels of hemoglobin A1c — a marker of long-term blood sugar control — in adults with type 2 diabetes ().
What’s more, high-protein diets may reduce heart disease risk factors in those with type 2 diabetes.
A review of 18 studies in people with type 2 diabetes found that high-protein diets significantly reduced triglyceride levels — a major risk factor for heart disease ().
Summary High-protein diets that include oysters may promote weight loss, improve blood sugar control, and reduce heart disease risk factors in people with type 2 diabetes.
Aside from being packed with beneficial nutrients like vitamins, oysters also contain a recently discovered, unique antioxidant called 3,5-Dihydroxy-4-methoxybenzyl alcohol (DHMBA).
DHMBA is a phenolic compound that exhibits powerful antioxidant effects.
In fact, a test-tube study showed that it was 15 times more powerful in fighting oxidative stress than Trolox, a synthetic form of vitamin E commonly used to prevent damage caused by oxidative stress ().
Some test-tube studies indicate that DHMBA from oysters may be of particular benefit to liver health.
For example, one test-tube study demonstrated that it protected human liver cells from damage and cell death caused by induced oxidative stress ().
Scientists are hopeful that DHMBA may be useful in preventing or treating liver diseases in the future, but research is limited to test-tube studies at this time ().
Another test-tube study found that DHMBA reduced oxidation of LDL (bad) cholesterol. Oxidation of cholesterol is a chemical reaction linked to atherosclerosis (plaque buildup in your arteries), a major risk factor for heart disease (26, ).
Though these results are promising, more research is needed to determine whether DHMBA would be effective in fighting oxidative stress in humans.
Summary DHMBA is a powerful antioxidant in oysters. It may help fight oxidative damage, benefiting liver and heart health. Still, research is currently limited to test-tube studies.
Though it’s clear that oysters offer impressive health benefits, some potential concerns exist — especially when consuming them raw.
May Contain Bacteria
Eating raw oyster meat poses a greater risk of bacterial infection.
Vibrio bacteria — including Vibrio vulnificus and Vibrio parahaemolyticus — can be concentrated in filter-feeding shellfish. Eating them raw can increase your risk of exposure.
Infections by these bacteria can lead to symptoms like diarrhea, vomiting, fever, and even more serious conditions, such as septicaemia — a serious blood infection that can cause death ().
According to the Centers for Disease Control and Prevention (CDC), 100 of the 80,000 people who get sick from vibrio bacteria in the United States every year die from the infection ().
Oysters can also carry Norwalk-type viruses and enteroviruses that can pose health risks ().
Additionally, these mollusks may contain chemical contaminants, including heavy metals like lead, cadmium, and mercury ().
Those who choose to eat raw oysters should be aware of these potential risks. At this time, there is no way to ensure that they’re safe to consume in their raw form, despite rigorous monitoring by both state and federal authorities.
This is why major health organizations like the CDC recommend that they only be eaten cooked ().
Oysters contain an exceptionally high amount of zinc. While this mineral is important for health, consuming too much can be harmful.
Though zinc toxicity is most often associated with supplements, eating too many oysters too frequently can lead to negative health effects, such as reduced levels of the minerals copper and iron that zinc competes with for absorption.
Additionally, those who are allergic to seafood should avoid eating them.
Summary Raw oysters can carry potentially harmful bacteria and viruses. Health organizations recommend that they be cooked before eating to avoid dangerous infections.
Because they can pose a health risk, eat raw oysters with caution. Always buy them from a reputable establishment — though this doesn’t guarantee safety (36).
Eating them cooked is much safer since cooking destroys harmful bacteria.
Here are some delicious and easy ways to add oysters to your diet:
- Add cooked oyster meat to pasta dishes.
- Coat whole oysters in bread crumbs and broil.
- Serve them cooked in their shell and topped with fresh herbs.
- Add them to seafood soups and stews.
- Fry panko-crusted oyster meat in coconut oil.
- Steam them and top with lemon juice and butter.
- Coat oyster halves in a marinade of your choice and roast them on the grill.
Here are some safety tips to consider when shopping for oysters:
- Only choose oysters with closed shells. Discard those with open shells.
- According to the Food and Drug Administration (FDA), oysters that don’t open during cooking should be discarded as well (37).
- Don’t cook too many at once in a single pot, such as when boiling, as overcrowding can lead to some being undercooked.
Summary To avoid infection, consume thoroughly cooked oysters. Choose those with closed shells and discard any that don’t open during cooking.
Oysters are highly nutritious shellfish that offer a wide array of health benefits.
They’re packed with high-quality protein, vitamins, minerals, and antioxidants — all of which benefit health.
Still, raw oysters can contain potentially harmful bacteria, so enjoy them cooked to avoid infection.
If you’re a seafood lover, try adding these tasty, nutrient-dense mollusks to your diet.