Haddock is one of the most nutritious lean proteins you can eat. A 100-gram serving delivers nearly 19 grams of protein for just 87 calories and less than 1 gram of fat. It’s also packed with iodine, selenium, and vitamin B12, making it a standout choice for people watching their weight or looking to improve their overall diet.
Protein and Calorie Breakdown
Haddock is a complete protein, meaning it contains all nine essential amino acids your body can’t make on its own. Its amino acid score hits 100%, with especially high levels of lysine (152% of the recommended daily intake per serving) and leucine, an amino acid that plays a key role in muscle repair and growth. For context, a single cooked serving exceeds 100% of the recommended intake for every essential amino acid.
With less than 1 gram of fat per fillet, haddock is one of the leanest fish available. That low calorie density makes it particularly useful if you’re trying to lose weight or add protein without piling on extra calories. Research on the satiety index of common foods found that fish scored 225% compared to white bread’s baseline of 100%, making it more than twice as filling per calorie. High protein content is one of the main reasons: protein satisfies hunger more effectively than fat or carbohydrates and keeps you feeling full longer.
Key Vitamins and Minerals
Haddock is one of the richest dietary sources of iodine, a mineral most people don’t think about but that your thyroid gland depends on to regulate metabolism, energy levels, and body temperature. A single 150-gram serving of oven-baked or pan-fried haddock can deliver roughly 350% of the recommended daily iodine intake. Even steamed, it still provides about 120%. Few foods come close to that concentration, and iodine deficiency remains common in many parts of the world.
Selenium is another mineral haddock delivers in significant amounts, with about 38 micrograms per 100 grams. That’s close to 70% of most adults’ daily needs. Selenium supports your immune system and acts as an antioxidant, helping protect cells from damage. Haddock also provides around 2.1 micrograms of vitamin B12 per 100 grams, which covers most of your daily requirement. B12 is essential for nerve function and the production of red blood cells, and it’s a nutrient that many people, especially older adults, fall short on.
Omega-3 Content
Haddock does contain omega-3 fatty acids, but in modest amounts. A 100-gram serving provides about 0.2 grams combined of EPA and DHA, the two forms of omega-3 that benefit heart health and reduce inflammation. That’s meaningful but far less than what you’d get from fatty fish like salmon, which can deliver 1 to 2 grams per serving.
Still, haddock offers more omega-3s than its close relative, cod. If you eat haddock a few times per week alongside other omega-3 sources, it contributes to your overall intake. For people who prefer milder, leaner fish, it’s a reasonable way to get some heart-healthy fats without the stronger flavor or higher calorie count of oily fish.
Mercury and Safety
Haddock is a low-mercury fish. The FDA measured its mean mercury concentration at 0.055 parts per million, which is well below the levels found in fish that carry consumption warnings, like swordfish, shark, or king mackerel. For comparison, the FDA’s action level for mercury in fish is 1.0 ppm, so haddock sits at roughly one-twentieth of that threshold.
This low mercury level means haddock is safe to eat multiple times per week for most people, including pregnant women and young children, who are most vulnerable to mercury’s effects on the developing nervous system.
Haddock vs. Cod vs. Salmon
Haddock and cod are close nutritional relatives. Both are extremely lean, both provide 18 to 20 grams of protein per 100 grams, and both are low in mercury. The main differences are subtle: haddock has a slightly stronger flavor, firmer texture, and a bit more omega-3 fat than cod.
Salmon is a different category of fish entirely. It’s higher in total fat, higher in omega-3s, and slightly higher in protein (20 to 29 grams per 100 grams depending on the species). That extra fat makes salmon more calorie-dense but also more filling and a better source of anti-inflammatory omega-3s. If your main goal is maximizing omega-3 intake, salmon wins. If you want lean, low-calorie protein with exceptional iodine and selenium content, haddock is the better pick.
Best Ways to Prepare It
How you cook haddock affects its nutritional value. Oven-baking and pan-frying preserve the most iodine, while steaming retains less (though still a substantial amount). Baking haddock with a light coating of olive oil, lemon, and herbs keeps the calorie count low while adding some healthy monounsaturated fat. Deep-frying, as in traditional fish and chips, adds significant calories and negates much of the lean-protein advantage.
Haddock’s mild flavor and firm texture make it versatile enough for chowders, fish tacos, grain bowls, or simple roasted fillets. Because it’s so low in fat, it cooks quickly and can dry out if overdone. Pulling it from the heat when the flesh just turns opaque and flakes easily keeps it moist.