Seafood is one of the most nutrient-dense foods you can eat. It delivers high-quality protein, omega-3 fatty acids that your body can’t make on its own, and minerals that are hard to get from other sources. Eating it regularly, even just once a week, is linked to a 15% lower risk of dying from heart disease. The U.S. Dietary Guidelines recommend 8 to 10 ounces per week for adults, and most Americans fall short of that.
Why Omega-3s Matter So Much
The omega-3 fats in seafood, specifically EPA and DHA, are the main reason fish gets singled out as a health food. Your body uses these fats to build cell membranes, reduce inflammation, and regulate heart rhythm. Plants like flaxseed contain a different form of omega-3 that your body converts to EPA and DHA very inefficiently, which is why seafood remains the most reliable dietary source.
Not all fish deliver the same amount. Atlantic mackerel is one of the richest options, packing 2.5 grams of combined EPA and DHA per 100-gram serving (roughly 3.5 ounces). Farmed Atlantic salmon comes in at about 1.8 grams. Sardines and sockeye salmon each provide around 1 gram per serving. Albacore tuna lands at 1.3 grams. Even leaner fish like cod or tilapia contain some omega-3s, though far less than their oilier counterparts.
Farmed salmon often gets a bad reputation, but farmed fillets contain comparable grams of omega-3s to wild salmon because farmed fish carry more total fat. Wild salmon tends to be leaner with a more favorable omega-3 to omega-6 ratio, but both are solid choices nutritionally.
Heart Disease Protection
The cardiovascular benefits of seafood are among the most studied in nutrition science. A large meta-analysis published in Circulation pooled data from multiple long-term studies and found a clear dose-response pattern: the more fish people ate, the lower their risk of dying from coronary heart disease. Eating fish once a week was associated with a 15% reduction in heart disease mortality. Bumping that up to two to four times per week dropped the risk by 23%. People who ate fish five or more times per week saw a 38% reduction.
Each additional 20 grams of daily fish intake (less than one ounce) corresponded to a 7% further decrease in risk. The protective effect comes primarily from omega-3s, which help lower triglycerides, reduce blood pressure slightly, and stabilize heart rhythm to prevent dangerous arrhythmias.
Brain Health and Dementia Risk
Seafood’s benefits extend well beyond the heart. A systematic review of prospective studies found that people with the highest fish consumption had a 44% lower risk of dying from Alzheimer’s disease compared to those who ate the least. Even broader cognitive decline was reduced: high seafood consumers had a 30% lower risk of subjective cognitive decline, the kind of memory and thinking changes that often precede dementia.
The brain is roughly 60% fat by dry weight, and DHA is one of the primary structural fats in brain tissue. Consistently supplying your brain with DHA through diet appears to support the maintenance of neural connections over time, which helps explain the link between fish intake and preserved cognitive function in older adults.
Benefits During Pregnancy
Seafood is especially valuable for pregnant and breastfeeding women. An FDA assessment estimated that maternal fish consumption improves infant neurodevelopment by an average of nearly 0.7 IQ points at the population level, with a potential maximum benefit of about 3 IQ points depending on the types and amounts consumed. For verbal development specifically, the benefit was even larger, equivalent to about 1.4 IQ points on average. In tests of visual recognition memory given to infants between 5 and 8 months old, each additional weekly serving of fish the mother consumed was associated with a 4-point gain.
The guidelines recommend pregnant women eat 8 to 12 ounces of seafood per week, choosing lower-mercury options like salmon, sardines, shrimp, cod, tilapia, pollock, catfish, and light tuna. Shark, swordfish, and king mackerel should be avoided during pregnancy due to high mercury levels.
Minerals You Won’t Find Easily Elsewhere
Seafood is one of the best natural sources of iodine and selenium, two minerals essential for thyroid function and immune health. Baked cod contains about 186 micrograms of iodine per 100-gram serving, which exceeds the daily recommended intake of 150 micrograms in a single portion. Oysters provide roughly 109 micrograms per serving. Shrimp is lower at about 15 micrograms per 100 grams but still contributes meaningfully, especially as part of a varied diet. Many people in landlocked regions or those who don’t use iodized salt are mildly deficient in iodine, making seafood a practical fix.
Oily Fish and Diabetes Prevention
A genetic study published in Frontiers in Nutrition found that higher oily fish intake was associated with a nearly 39% lower risk of developing type 2 diabetes. The researchers used a method called Mendelian randomization, which leverages genetic data to approximate a randomized trial, strengthening the case that the relationship is causal rather than coincidental. Interestingly, non-oily fish (like cod or haddock) showed no significant link to diabetes risk. This suggests the protective effect comes specifically from omega-3-rich fatty fish like salmon, mackerel, sardines, and herring rather than from seafood in general.
Mercury: What to Watch For
Mercury is the main safety concern with seafood, and it matters most for young children, pregnant women, and those who eat fish frequently. The FDA and EPA categorize fish into three tiers based on mercury concentration. Fish averaging 0.15 micrograms of mercury per gram or less are “Best Choices” that you can safely eat two to three times a week. This category includes salmon, shrimp, sardines, tilapia, pollock, and catfish. Fish between 0.15 and 0.46 micrograms per gram are “Good Choices” limited to once a week, and this includes albacore tuna, halibut, and snapper. Anything above 0.46 micrograms per gram is a “Choice to Avoid,” which covers shark, swordfish, king mackerel, and tilefish from the Gulf of Mexico.
For most adults eating a few servings per week, mercury exposure from fish classified as Best Choices is well below any threshold of concern. The key is variety. Rotating between different species spreads out your exposure to any single contaminant while diversifying the nutrients you take in.
Microplastics in Seafood
Microplastics are a newer concern. A 2025 survey of commercial seafood products sold in Germany found plastic particles in most samples, with counts ranging from 0 to 183 particles per gram. The median was 0.9 particles per gram across all products, though canned fish had the highest counts at a median of 2.4 particles per gram. No significant differences were found between species or whether the fish was wild-caught or farmed.
The health implications of ingesting microplastics at these levels are still not well understood. Current evidence does not suggest that the amounts found in seafood pose an acute health risk, and most nutrition researchers consider the proven benefits of eating fish to outweigh this uncertain concern. That said, it’s worth noting that microplastics are also present in bottled water, table salt, and many other foods, so seafood isn’t uniquely problematic.
How to Get the Most Benefit
If you’re eating little to no seafood right now, even adding one serving per week makes a measurable difference for heart health. Two to three servings of fatty fish weekly is the sweet spot for maximizing omega-3 intake without overthinking mercury. A serving is about 4 ounces cooked, roughly the size of a deck of cards.
Preparation matters too. Baking, grilling, or poaching preserves the omega-3 content, while deep frying adds unhealthy fats and may reduce the cardiovascular benefit. Canned sardines and salmon are inexpensive, shelf-stable, and nutritionally comparable to fresh options, with the added bonus of soft, edible bones that supply calcium. If you dislike the taste of fish, shrimp, scallops, and mild white fish like cod or tilapia are easy entry points with very little “fishy” flavor.