Shrimp is one of the lowest-mercury seafood options available. With an average mercury concentration of just 0.009 parts per million (ppm), shrimp contains roughly 100 times less mercury than high-mercury fish like swordfish. The FDA and EPA both place shrimp on their “Best Choices” list, meaning it’s safe to eat two to three servings per week, even for pregnant women and young children.
How Shrimp Compares to Other Seafood
To put 0.009 ppm in perspective, swordfish averages around 0.995 ppm and bigeye tuna around 0.689 ppm. Even moderately low-mercury fish like cod (0.111 ppm) contain more than ten times the mercury found in shrimp. Among all commercially sold seafood tested by the FDA, shrimp consistently lands near the very bottom of the mercury chart, alongside sardines, scallops, and salmon.
The EPA and FDA divide seafood into three tiers: “Best Choices,” “Good Choices,” and “Choices to Avoid.” Shrimp falls squarely in the “Best Choices” category. For adults, that means you can safely eat two to three servings (8 to 12 ounces) per week. Pregnant or breastfeeding women get the same 8-to-12-ounce weekly recommendation, and the guidelines specifically name shrimp as one of the lowest-mercury options suitable for children.
Why Shrimp Is So Low in Mercury
Mercury builds up as it moves through the food chain, a process called biomagnification. Large predatory fish like shark and swordfish sit at the top, eating smaller fish that have already accumulated mercury in their tissues over years. Each step up the chain concentrates the metal further.
Shrimp sit near the bottom. They’re small, short-lived, and feed primarily on algae, plankton, and organic debris rather than other fish. That means they have far less time and far fewer dietary sources to accumulate mercury. Shrimp also have a built-in detox mechanism: they shed mercury when they molt their exoskeletons, which happens repeatedly throughout their lives. This periodic shedding helps keep their mercury levels exceptionally low.
Selenium Offers Additional Protection
Shrimp contains selenium, a trace mineral that plays an antioxidant role and may help counteract mercury’s harmful effects in the body. Selenium binds to mercury and can reduce its toxicity, while also supporting enzyme systems that mercury would otherwise disrupt. The key metric researchers look at is the selenium-to-mercury ratio: a ratio above 1 suggests the selenium present is more than enough to offset the mercury.
In shrimp, that ratio is extraordinarily favorable. Small shrimp have a selenium-to-mercury ratio of roughly 28:1, and large shrimp come in even higher at about 58:1. For comparison, fish considered risky tend to have ratios near or below 1. So even the tiny amount of mercury in shrimp is effectively counterbalanced by the selenium present in the same bite.
What About Other Contaminants?
Mercury isn’t the only heavy metal found in seafood. Shrimp can also contain trace amounts of arsenic, cadmium, and lead. A 2024 study analyzing shrimp samples from coastal markets found detectable levels of all four metals, with concentrations varying by season. Winter-harvested shrimp tended to show slightly higher levels of certain metals than summer samples.
However, the amounts found in commercially sold shrimp generally fall within food safety limits set by international regulatory bodies. Arsenic in seafood is predominantly in its organic form, which is far less toxic than the inorganic arsenic found in some rice or groundwater. Cadmium levels in shrimp are typically quite low, well below the thresholds considered concerning for regular consumption. If you eat shrimp in normal quantities (a few servings per week), these trace contaminants are not a meaningful health concern.
Nutritional Tradeoffs Worth Knowing
Beyond being low in mercury, shrimp is a lean, high-protein food. A 4-ounce serving provides roughly 18 micrograms of iodine, a mineral many people don’t get enough of that’s essential for thyroid function. Shrimp also supplies omega-3 fatty acids, though in smaller amounts than oily fish like salmon or mackerel. It’s low in calories and fat, making it one of the more nutrient-dense ways to get the benefits of seafood without worrying about contaminant exposure.
For people trying to eat more seafood but nervous about mercury, shrimp is one of the safest starting points. You’d need to eat an almost absurd amount of it, far beyond any normal diet, before mercury became a concern. That’s true for the general population, for pregnant women, and for young children alike.