Tryptophan is an essential amino acid, or one you must obtain from diet for proper body function. The body uses the essential amino acids, found in abundance in animal foods, to synthesize the proteins it needs. These proteins are used to manufacture hormones, enzymes and antibodies, for example. Tryptophan, in particular, plays a role in producing chemical messengers in the brain, or neurotransmitters, such as serotonin, according to the Franklin Institute. These neurotransmitters are responsible for appetite, mood, sleep and relaxation. Fish, poultry, beef and legumes are rich in protein and tryptophan.
Fish and Shellfish
Fish, like other animal foods, are rich in protein, providing about 7 g per ounce, according to the Harvard School of Public Health. Animal proteins contain all of the essential amino acids, including tryptophan. Types of fish and shellfish particularly rich in tryptophan, according to the World's Healthiest Foods, include shrimp, cod, yellowfin tuna, snapper, halibut, scallops, sardines and salmon. Yellowfin tuna is one of the richest protein sources of tryptophan. A 4-oz. serving of cooked yellowfin provides over 25 g protein and 0.38 g tryptophan, meeting over 110 percent of the Recommended Daily Value or DV based on a requirement of 0.32 g daily. Shrimp, snapper and Chinook salmon are also excellent sources of protein and tryptophan. A 4-oz. cooked portion of any of these choices provides almost 30 g protein and 0.33 g tryptophan, or just over 100 percent of the DV.
Poultry, Pork and Beef
Turkey is known for helping you to feel "relaxed." This is due to its high tryptophan content. Poultry, such as chicken and turkey, are high in both protein and tryptophan. According to the Top 200 Food Sources website, a 3.5-oz. cooked portion of roasted light meat turkey provides 0.34 g tryptophan, or roughly 108 percent of the DV, and over 20 g protein. A 3.5-oz. portion of roasted chicken breast provides the same amount of protein but slightly more tryptophan, 0.35 g, or nearly 110 percent of the DV. Pork is slightly richer in tryptophan than poultry. A 3.5-oz. cooked portion of lean pork tenderloin or center-cut pork chops provides over 20 g protein and 0.38 g tryptophan. A 3.5-oz. serving of top round steak offers 0.39 g tryptophan or about 122 percent of the DV.
While meats and animal proteins are the richest food sources of tryptophan, they are hardly the only ones. For example, according to the World's Healthiest Foods, a 4-oz. portion of raw tofu provides 0.14 g tryptophan, or 44 percent of the DV and 8 g protein. Cooked soybeans are particularly rich in both protein and tryptophan. One cup, cooked, provides 29 g protein and 0.37 g tryptophan. Split peas, black and red kidney beans each provide 0.18 g tryptophan, or 56 percent of the DV per cup, as well as 16 g protein.