L-tryptophan is an essential amino acid that must be obtained from food or supplements because the body cannot create it. This amino acid is necessary for normal growth in babies, and for nitrogen balance in all people. Additionally, the body can convert tryptophan to vitamin B3 (niacin), and uses tryptophan to produce the neurotransmitters melatonin and serotonin. Many foods contain L-tryptophan, primarily meat and seafood, but certain vegetables and other foods do as well.
Meat
Certain types of meat have the highest amounts of L-tryoptophan. Elk has the greatest concentration, with about 750 mg of this amino acid per 200 calories, as listed by nutritiondata.com. Other types of meat with high levels of tryptophan include caribou, buffalo and pork, all generally containing between 400 and 550 mg per 200-calorie serving. Turkey and chicken, both light and dark meat, also contain 400 to 500 mg tryptophan per 200 calories, while beef generally has somewhat lower amounts, between 270 to 430 mg, depending on the cut.
Seafood
Seafood contains high levels of tryptophan. Halibut, lobster, king and queen crab and crayfish all provide about 550 to 600 mg per 200 calories. Many other types of fish have 400 to 500 mg. Some examples include canned or fresh tuna, cod, grouper, haddock, ling, mackerel, perch, snapper, sunfish, tilapia, northern pike and walleye pike.
Cheese
People can also obtain L-tryptophan by eating cheese. Mozzarella, low-fat cheddar or Colby and low-fat cottage cheese all contain about 330 to 400 mg tryptophan per 200-calorie serving. Shredded Parmesan cheese has 270 mg.
Vegetables
Certain vegetables also are excellent sources of L-tryptophan. Raw spirulina seaweed has nearly as much tryptophan as elk meat, with 739 mg per 200 calories. Dried spirulina contains about 640 mg. Cooked frozen spinach has nearly 600 mg, and cooked frozen cooked turnip greens 400 mg. Raw watercress also has high amounts at 545 mg per 200 calories. Raw white mushrooms, grilled portabella mushrooms, beet greens and red leaf lettuce have 275 to 310 mg.
Legumes and Other Sources
AskDrSears.com, the website of physician William Sears and registered nurse Martha Sears, recommends eating certain tryptophan-containing foods before bedtime to help promote sleep. Not all these foods have the high levels of tryptophan found in meat and seafood, but they are still good sources of this amino acid. They include whole grain foods, rice, hazelnuts, peanuts, sunflower seeds, eggs, beans, lentils and hummus. Soy is one type of legume with high amounts of L-tryptophan, with over 400 mg per 200 calories of soy protein isolate or tofu.
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