Clam vs. Oyster — Health Impact and Nutrition Comparison

Summary

Oyster is richer in mineral content, especially in zinc and copper. In contrast, the clam is the winner in terms of vitamins, particularly with B group vitamins.

Both foods are widely consumed; moreover, oysters are used in pearl production.

Choosing the right places to enjoy these foods is very important to avoid fatal results. Besides, oysters and clams can be sources of allergy and intoxication for people with a weakened immune system, especially for children and pregnant women. Enjoy them, and don’t ignore the related health hazards.

Introduction

Are you a big fan of seafood? How about a bit of comparison between clams and oysters? Both clams and oysters are bivalve mollusks – shellfish with two-part shells and two muscles.  Although both belong to the phylum Mollusca and their texture is slimy, and they are similar in a variety of ways, there are plenty of differences between them as well.

Main Differences

Did you know that clams usually live in freshwater, are mobile, and move around on their muscle foot by burying themselves in the sand under the water? On the other hand, oysters live in saltwater. Except for the first weeks of their initial stages when oysters still have a muscle foot, they are mainly attached to the same spot, usually a hard surface such as a rock, their entire lives. They prefer to stay near the water’s surface, and we can easily notice them in the mud when it is low tide.

Their taste is different; clam is saltier and stronger, whereas oysters are buttery in taste. 

They are commonly used in soups and chowders. 

Clam has a shiny and smooth shell, whereas oyster shell is more calcified and rough. Both are used as a food in many countries, but clam is preferred due to its taste and tenderness.

Besides, oysters are known for producing pearls, while clams do not. A pearl is formed when an oyster produces nacre, the mix of calcium and protein, against the foreign matter trapped in the shell. The most common type of oyster is the Pacific oysters, Eastern oysters, European flats (European flat oysters), and Olympia oysters. 

Nutritional Content

In today’s competitive food market, shellfish play an important role due to their nutritional content. Although clam and oysters are both goldmines of various essential substances, we will look at the differences in their nutritional contents.

Minerals

You can easily notice from the charts below that oyster is enormously richer in copper, manganese, and zinc, considerably richer in iron, and magnesium, and lower in sodium. On the other hand, clam is richer in phosphorus, potassium, selenium, and calcium. Thus, oyster wins in this category.

Mineral Comparison

Mineral comparison score is based on the number of minerals by which one or the other food is richer. The "coverage" charts below show how much of the daily needs can be covered by 300 grams of the food.

Clam

4

:

6

Oyster

Contains more Calcium +48.4%

Contains more Phosphorus +112.6%

Contains more Potassium +157.4%

Contains more Manganese +104.1%

Contains more Iron +147.3%

Contains more Magnesium +222.2%

Contains less Sodium -65.3%

Contains more Zinc +3091.6%

Contains more Copper +524.1%

Equal in Selenium - 66.5

Clam

Oyster

Contains more Calcium +48.4%

Contains more Phosphorus +112.6%

Contains more Potassium +157.4%

Contains more Manganese +104.1%

Contains more Iron +147.3%

Contains more Magnesium +222.2%

Contains less Sodium -65.3%

Contains more Zinc +3091.6%

Contains more Copper +524.1%

Equal in Selenium - 66.5

Vitamins

From the viewpoint of vitamins, clam is undoubtedly the winner. It is drastically higher in vitamin B12 and vitamin C, fairly higher in vitamins B2 and B3, and somewhat higher in vitamins B5, B6, and vitamin A. However, oyster is slightly higher in folate.

The amount of vitamin B1 is equal in both foods.

Vitamin Comparison

Vitamin comparison score is based on the number of vitamins by which one or the other food is richer. The "coverage" charts below show how much of the daily needs can be covered by 300 grams of the food.

Clam

7

:

1

Oyster

Contains more Vitamin A +88.7%

Contains more Vitamin C +481.6%

Contains more Vitamin B2 +110.9%

Contains more Vitamin B3 +103.3%

Contains more Vitamin B5 +151.9%

Contains more Vitamin B6 +71.9%

Contains more Vitamin B12 +532.7%

Equal in Vitamin B1 - 0.15

Equal in Folate - 31

Clam

Oyster

Contains more Vitamin A +88.7%

Contains more Vitamin C +481.6%

Contains more Vitamin B2 +110.9%

Contains more Vitamin B3 +103.3%

Contains more Vitamin B5 +151.9%

Contains more Vitamin B6 +71.9%

Contains more Vitamin B12 +532.7%

Equal in Vitamin B1 - 0.15

Equal in Folate - 31

Macronutrients comparison

In this section, clam is a medal-holder again with its higher concentration of protein, fewer calories, and lower saturated fat, cholesterol, and carbohydrate content.

Health Impact

Health benefits

Nervous system benefits

Clams have neuroprotective functions on the nervous system, specifically in Parkinson's disease. Clam extracts are being researched into treatment methods for different neurodegenerative diseases. This benefit was not found in oysters (1). 

Anti-oxidant, anti-fatigue, and muscle wasting 

Oysters contain compounds called oyster hydrosylates that have been shown to have anti-oxidative, anti-fatigue, and anti-muscle wasting effects. a
These extracts have beneficial effects on reducing oxidative stress and fatigue. In addition, as we grow older by age and adopt a more sedentary lifestyle, muscle mass starts to decrease, which in turn increases the risks of different diseases such as diabetes. It would be beneficial to add oysters to a diet (2)(3).  

Sleep and reproductive health

Oysters are richer in zinc compared to clams, and this provides healthy sleep as it reduces the duration of falling to asleep. In addition, it is important to maintain normal levels of zinc for reproductive health (4)(5). 

Risks

Cardiovascular health

oysters are lower in proteins and higher in total fats and specifically saturated fats. This can increase the risks of cardiovascular diseases and mortality (6). 

Public and environmental health

From the very start, it is necessary to point out that clams and oysters are filter feeders, which means they use their gills to filter water and collect nutrients. So depending on where they have been harvested, there is a risk of picking up bacteria and viruses. In this connection, it should be noted that eating raw or undercooked clams and oysters can put us at risk for such serious states as paralytic, neurotoxic, diarrheic, and amnesic shellfish poisoning caused by several strains of Vibrio bacteria and Norovirus.

According to the USA Centers for Disease Control and Prevention (CDC), in the United States, Norovirus is the leading cause of gastroenteritis outbreaks; it is estimated to cause 19–21 million illnesses a year, and approximately 50% of all food-borne disease outbreaks (7).

According to the CDC report, in the United States, Vibrio parahaemolyticus is the cause of about 35000 domestically acquired food-borne infections annually, most of which are associated with the consumption of raw or undercooked shellfish (8).

According to a study published in 2013, pre-birth maternal shellfish consumption at least once a month is associated with a higher risk of food allergy (9).

Cooking and Storing

It follows logically from what has been said that proper harvesting, cooking, and storing of clams and oysters are crucial; otherwise, we run the risk of serious health threats.

It must be pointed out that both clam and oyster should be harvested alive. Clams and oysters are both eaten in a variety of ways. Although clams can be eaten raw or steamed as a half shell, they are most often eaten as a component of a more complex dish. The most popular clam dishes are New England clam chowder, linguine with clam sauce, and Spanish paella. On the other hand, eating raw oysters in the shell at many fine restaurants is a great joy for gourmets. Despite this, oysters may be used in their cooked, smoked, frozen, or canned forms.

The important point in storing clams and oysters is, once again, storing them alive. The storing conditions of clam and oyster are similar. According to the Washington State Department of Health, both should be stored in the refrigerator in an open container to ensure air circulation (10). They must be covered with a damp towel to maintain humidity. In order to avoid their death or spoiling, it is not allowed to store them in water. Shells must be closed; if they are open and don’t close after tapping, the shellfish are dead and should be discarded. In this way, clams can be stored alive for up to 7 days outside of water and oysters for up to 2-3 weeks. However, it is highly recommended to eat them as fresh as possible. The cooked shellfish can be kept for two days in the refrigerator and up to 3 months in the freezer.

You can also read about mussels vs oyster. 

References

1. https://pubmed.ncbi.nlm.nih.gov/35160004/ 
2. https://pubmed.ncbi.nlm.nih.gov/30488053/
3. https://pubmed.ncbi.nlm.nih.gov/34959937/
4. https://pubmed.ncbi.nlm.nih.gov/15041778/
5. https://pubmed.ncbi.nlm.nih.gov/28019085/ 
6. https://pubmed.ncbi.nlm.nih.gov/19631050/ 
7. Travel-Related Infectious Diseases
8. https://www.cdc.gov/mmwr/preview/mmwrhtml/mm6315ahtm
9. https://www.ncbi.nlm.nih.gov/pubmed/24295221
10. Shellfish Handling, Storing, and Cooking