Tryptophan is an essential amino acid that cannot be produced by the human body and must be obtained through your diet, primarily from animal or plant based protein sources. Tryptophan was discovered in the early 1900s after it was isolated from casein, a protein found in milk. Its molecular structure was determined a few years later.
Tryptophan plays a role in the production of serotonin, a mood stabilizer, melatonin, which helps regulate sleep patterns, niacin or vitamin B-3, and nicotinamide also known as vitamin B-6.
Over-the-counter use of synthetic tryptophan supplements were banned in the United States starting in 1989. However, tryptophan supplements were re-introduced in 2001 and are now available.
Why You Need Tryptophan
Tryptophan has the lowest concentration in the body of any amino acid, yet, it is vital for a wide variety of metabolic functions that affect your mood, cognition, and behavior.
Tryptophan elimination experiments have shown that tryptophan has a beneficial impact on:
- memory skills
- visual cognition
- Aggression control.
Research trials have shown it to have possible benefits when treating sleep disorders, seasonal affective disorder, premenstrual discomfort, and for reducing anxiety when quitting smoking. However, there is some disagreement on these results, indicating that more research is needed.
There is a common belief that tryptophan causes drowsiness. This has been associated with the U.S. holiday, Thanksgiving, where people who celebrate it report feeling tired after eating. Studies suggest that there may be some connection. Consuming large meals stimulates the production of insulin, and insulin clears the bloodstream of all amino acids except for tryptophan. In effect, insulin clears a path that can flood the brain with tryptophan.
However, there is uncertainty as to whether tryptophan causes this drowsiness. Insulin and large amounts of carbohydrates can also cause it. Additionally, there are other foods that contain more tryptophan than turkey, however, they aren't associated with drowsiness.
Foods with Tryptophan
L-Tryptophan is an essential amino acid that cannot be synthesized by humans. It is typically found in both plant and animal based proteins. Most people consume more than double the amount that is actually needed, typically getting 900-1000 milligrams per day, while the US Recommended Daily Allowance (RDA) is 250-425 milligrams per day.
Tryptophan can be found in the following foods:
Whole Milk is one of the largest sources of tryptophan, including 732 milligrams per quart. 2% reduced fat milk is also a good source, coming in at 551 milligrams per quart.
2. Canned Tuna
Canned tuna is another good source of tryptophan, including 472 milligrams per ounce.
3. Turkey and Chicken
Contrary to popular beliefs, turkey is a large source of tryptophan, but it is not the largest. Light meat contains 410 milligrams per pound (raw) and dark meat contains 303 milligrams per pound. Chicken also contains high amounts of tryptophan, with light meat containing 238 milligrams per pound, and dark meat containing 256 milligrams per pound.
Prepared oatmeal can also be a good source of tryptophan, with 147 milligrams per cup.
Though not as high in tryptophan as meat and other dairy sources, cheddar cheese contains 91 milligrams of tryptophan per ounce.
6. Nuts and Seeds
Peanuts, an example in this category, contain 65 milligrams per ounce.
Whole wheat bread can contain up to 19 milligrams per slice, and refined white bread can contain 22 milligrams per slice.
Chocolate can contain up to 18 milligrams of tryptophan per ounce.
Some fruits can also be a good source of tryptophan. For example, a medium-sized banana contains approximately 11 milligrams of it. Additionally, a medium-sized apple contains approximately 2 milligrams of tryptophan, while a single prune contains 2 milligrams of this amino acid.