Tryptophan: 5 Fast Facts You Need to Know

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Tryptophan is widely thought to be the reason why we feel drowsy after Thanksgiving. We just ate plates full of carbohydrates, but it must be the tryptophan in the turkey that makes us sleepy, right? Wrong! While turkey meat does have the amino acid tryptophan, it is not true that it alone is the reason why turkey makes us sleepy.

Why does tryptophan get the blame and what does it really do? Here’s a look at what it is.

1. Tryptophan Is an Ingredient Your Body Needs to Make Protein

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L-Tryptophan is a naturally occurring amino acid, but it’s not one that the body creates itself, The Scientific American notes. Amino acids are the building blocks of protein, which everyone needs. Therefore, you need to eat foods that contain the nutrient tryptophan.

Our bodies use tryptophan to create the neurotransmitter serotonin, and also niacin and auxins. Serotonin is known to make fruit flies sleepy. Amita Sehgal of the University of Pennsylvania School of Medicine in Philadelphia told the Scientific American that studies have shown that serotonin also can make nonhuman mammals sleepy and it could have the same affect on humans.

Therefore, tryptophan could play a role in making us feel sleepy, but eating turkey alone isn’t going to do it.

2. Turkey Meat Doesn’t Contain an Abnormal Amount of Tryptophan

While it is true that turkey meat is a good source of tryptophan, it is not that much more than other foods. Turkey has 0.24 grams of tryptophan per 100 grams of meat. Meanwhile, an egg white has 1 gram of tryptophan per 100 grams.

The USDA shows that one turkey breast has 3.141 grams of tryptophan. That chart also shows that 1 pound of raw ground turkey has 1.012 grams.

Neuropharmacologist Richard Wurtman of the Massachusetts Institute of Technology’s Department of Brain and Cognitive Sciences told the Scientific American that turkey doesn’t have enough tryptophan to create an abnormal amount of serotonin that you would actually feel sleepy.

Wurtman also notes that tryptophan isn’t the only amino acid contained in the protein-rich foods like turkey. It’s actually a small amount of the amino acids trying to reach the brain. If tryptophan was the only amino acid contained in turkey, then it might have an affect.

Other foods that contain a good amount of tryptophan include peanuts, chocolate, oats, dates, milk, yogurt, cottage cheese, eggs, fish and red meat.

3. Tryptophan Is Available as an Over the Counter Supplement as a Sleep Aid

Sleep aid supplements that include tryptophan as an ingredient are available over the counter.

According to the University of Michigan Health System, there is reliable data that shows that L-tryptophan can be used to combat insomnia when a person takes one to four grams at bedtime.

“Some research indicates that people with more severe forms of insomnia may need to take L-tryptophan for several nights before improvement in sleep is noticed,” the university notes, although it added that there were other studies that found it was not effect or “effective only for people who awaken more frequently at night compared with those who awaken less frequently.”

The University of Michigan Health System also states that l-tryptophan has been found to help “increase tolerance to acute pain” and “Some research suggests that L-tryptophan may help balance mood symptoms associated with PMS.”

However, Supplements-And-Health notes that there have been other studies that showed disappointing results for using tryptophan as a sleep aide. “A safe, effective, more versatile alternative to tryptophan (and 5-hydroxy tryptophan) for sleeplessness, insomnia, and mood disorders is gamma amino butyric acid (GABA),” the site notes.

4. There Have Been Studies to See if Tryptophan Can Help Fight Depression

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There have been studies to see if tryptophan, once it is converted to 5-hydroxytryptophan before becoming serotonin, can help those suffering from depression. The author of one study first published in 2002 found that their evidence “does suggest these substances are better than placebo at alleviating depression,” but called for more studies before use of tryptophan for this purpose could be recommended.

The University of Michigan Health System notes that there are trials showing tryptophan being “as effective as antidepressant medications,” but says that people should consult their doctor before use.

WebMD also notes that there is “insufficient evidence” that tryptophan will help fight depression.

5. Having a Full Stomach on Thanksgiving Could be to Blame For Your Drowsiness

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Blaming turkey for making you sleepy isn’t fair to the turkey. Eating everything on your plate also makes you really sleepy, especially when you are piling on the carbs.

“Studies have indicated that stretching of the small intestine induces sleepiness and a protein–fat loading of the stomach induces sleepiness and, more blood going to the gastrointestinal tract means less going elsewhere,” biologist H. Craig Heller at Stanford University explained to the Scientific American. “Also, there is the general phenomenon of parasympathetic tone—rest and digest—that is conducive to sleep.”

So, the parasympathetic nervous system tries to conserve energy by reducing your heart rate and blood pressure to includes salivation and gastric action, the Scientific American notes.

What you drink with your meal could also have an impact. Wine, beer and other drinks can make you feel tired.