Fish is a low-fat, high-protein food that also contains a variety of water- and fat-soluble vitamins. The types and amounts of vitamins vary according to the variety of fish. The vitamins found in fish help support many of your body functions, including maintaining a healthy immune system and manufacturing new cells and proteins.
Tuna and trout are particularly rich sources of the water-soluble vitamin B-6. USDA reports that a 3-oz. serving of baked or broiled tuna contains 0.8 mg of vitamin B-6, more than 50 percent of the recommended daily allowance established by the Institute of Medicine. A similar serving of trout contains 0.6 mg of vitamin B-6. Cod and swordfish are also rich in vitamin B-6, with 0.4 mg and 0.3 mg per 3-oz. serving.
Vitamin B-6 supports the production of red and white blood cells, and aids in the healthy function of your immune and nervous systems. Vitamin B-6 also aids the metabolism of proteins and glucose in your liver and other body tissues.
Trout and salmon supply your body with high concentrations of the essential water-soluble vitamin B-12. The Institute of Medicine RDA for vitamin B-12 is 2.4 micrograms daily. A 3-oz. serving of baked or broiled trout includes 3.2 micrograms of vitamin B-12. A similar serving of salmon provides 2.3 micrograms, states the USDA. Other fish that contain 50 percent or more of the RDA for vitamin B-12 include swordfish, tilapia and halibut. Certain types of shellfish, including crab, lobster, scallops, clams and mussels, also contain high concentrations of vitamin B-12.
Your bone marrow requires vitamin B-12 to produce red blood cells. Your nervous system also requires vitamin B-12, which aids in the production and maintenance of the chemicals that protect and support your nerves. Formation of many essential body proteins, hormones and other chemicals relies on an adequate supply of vitamin B-12.
Fish is one of the few natural dietary sources of vitamin D. The USDA reports that a 3-oz. serving of baked or broiled trout contains nearly 15 micrograms of vitamin D, representing three times the RDA for adults age 19 to 50. Similar servings of swordfish and salmon contain 10 micrograms and 8 micrograms of vitamin D, respectively. Tilapia and halibut also contain significant amounts of vitamin D, with approximately 3 micrograms per 3-oz. serving.
Vitamin D is essential for the absorption of bone-enriching calcium from your small bowel. Your immune system and muscles also require vitamin D to function efficiently. Ongoing research is examining whether vitamin D may have a role in the prevention of certain types of cancer.