Many people enjoy oysters, a bi-valve mollusk native to salt water, but you may experience side effects that can range from annoying to life-threatening. Understanding those risks can help you avoid reactions. Consider speaking to your health care provider or to a nutritionist to determine whether eating oysters is a good choice for you.
Bacterial Infection
It is best to determine where and when the shellfish were harvested -- oysters picked in certain locations and times of year are more prone to make you sick because they can contain potentially dangerous bacteria. The Vibrio vulnificus bacterium lives in naturally warm coastal waters, and the number of these bacteria increases during hot summer months. Side effects of consuming oysters infected with bacteria include chills and fever, vomiting, diarrhea and skin reactions. You may also go into shock and die if the infection is not treated. People with certain medical conditions are at greater risk from infected oysters. Heat destroys Vibrio vulnificus, so one way to avoid eating this bacterium is to only eat properly cooked oysters.
Allergic Reaction
About 3.5 to 4 percent of people worldwide suffer from food allergies, according to researchers at the University of Nebraska; a portion of these people have an allergy to shellfish, including oysters. Evidence presented in the 2008 issue of "Advances in Food and Nutrition Research" indicates that tropomyosin, a protein, is the allergen in oysters that triggers a reaction. Some side effects of eating oysters, both raw and cooked, when you have a sensitivity to tropomyosin include skin rashes and other skin problems, mouth or facial swelling and abdominal pain as well as more serious effects, such as anaphylactic shock that can lead to death.
Hemochromatosis
Oysters are quite high in iron -- a 3-oz. serving contains 57 percent of the daily recommended intake. While getting the iron you need is important for your red blood cell count, consistently eating getting too much iron in your diet may cause hemochromatosis. This condition triggers an over-absorption of iron in your digestive tract, which causes abdominal pain, lethargy, loss of body hair and a change in your skin color. If you eat an iron-rich diet, carefully monitor your meal plan -- you may have to limit your ingestion of oysters to avoid negative health impacts.
Gastrointestinal Problems
Eating oysters may cause stomach problems, and not just from allergies or bacterial infections. Three oz. of oysters contain 1,029 percent of the zinc your body requires each day. Even this quantity of oysters may be enough to trigger gastrointestinal reactions. These reactions include vomiting, diarrhea and abdominal cramps. The problems caused the zinc in oysters generally hit within three to ten hours of consumption and fade quickly after your zinc level returns to normal.
References
- U.S. Food and Drug Administration: Vibrio vulnificus Health Education Kit
- "Advances in Food and Nutrition Research"; Molluscan Shellfish Allergy; S.L. Taylor; 2008
- USDA National Nutrient Database: Mollusks, Oyster, Eastern, Wild, Cooked, Moist Heat
- PubMed Health: Hemochromatosis
- University of Maryland Medical Center: Iron
- University of Maryland Medical Center: Zinc in Diet -- Side Effects
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