Haddock is a low-fat, low-calorie saltwater fish related to cod. Haddock is good for you -- it's an excellent source of lean animal protein, as well as some vitamins and minerals, when eaten as part of a larger well-balanced diet. However, if you choose a diet that stresses haddock, while excluding other foods, you run the risk of vitamin and mineral deficiencies, increased cholesterol levels, hypertension and other health problems.
A 150-g haddock fillet cooked with dry heat contains 135 calories, 30 g of protein, 0.8 g of fat, 0.2 g of saturated fat, 392 mg of sodium and 99 mg of cholesterol, according to USDA calculations. Haddock's calorie composition is roughly 89 percent protein and 11 percent fat.
The same haddock fillet offers 132 percent of the vitamin B-12, 39 percent of the niacin, 29 percent of the vitamin B-6, and 15 percent of the pantothenic acid that the Food and Nutrition Board of the Institute of Medicine recommends adults consume daily. All four of these vitamins are water-soluble B-complex vitamins, and they play vital roles in metabolism, DNA and red blood cell formation, nervous system function and hormone production. Haddock contains only trace amounts of thiamine, riboflavin, folate, and vitamins A, E and K, and no vitamin C. A diet that emphasized haddock to the exclusion of other foods could quickly lead to vitamin deficiencies. Vitamin C deficiencies cause scurvy; low maternal levels of folate are associated with increased risk of fetal birth defect; thiamine deficiencies can cause mental confusion; vitamin A deficiency can cause night blindness; and a lack of vitamin K can inhibit blood clotting.
A 150-g serving of haddock provides 86 percent of the selenium and 60 percent of the phosphorus adults require daily. Selenium aids in thyroid and immune function, and phosphorus is essential to energy production and blood oxygenation. Haddock contains smaller amounts of potassium, magnesium and zinc, but contains only trace amounts of iron and calcium. A diet focusing exclusively on haddock could lead to iron and calcium deficiencies, which are associated with iron-deficiency anemia and loss of bone density.
A 150-g serving of haddock contains 33 percent of the cholesterol and 17 percent of the sodium that MayoClinic.com advises adults to limit themselves to daily. Consuming too much haddock could quickly cause you to exceed daily cholesterol and sodium recommendations. Increased cholesterol levels are associated with heart disease, and increased sodium intake can exacerbate hypertension. Haddock also contains zero fiber, and a diet without enough fiber will quickly cause you digestive problems and could contribute to constipation.
No diet that emphasizes one food or one type of food to the exclusion of all others can be considered healthy. Haddock is an appropriate and healthy part of a well-balanced diet that includes fruits, vegetables, whole grains and lean protein sources. Consult your physician before beginning any diet plan.