Bananas -- sweet, satisfying to eat and pre-wrapped in their own convenient yellow package -- are a popular snack; Health Diaries notes that Americans consume roughly 28 pounds per person a year. Bananas are not only tasty but also rich in assorted vitamins and minerals. Although they are renowned for their healthy levels of beneficial potassium, bananas are also a good source of the amino acid tryptophan.
Tryptophan Features
Tryptophan is one of the 10 essential amino acids used by the body to synthesize protein. It is also used to produce serotonin -- a neurotransmitter needed for stable mood and restful sleep -- as well as niacin, or vitamin B-3. In addition, it is responsible for normal growth in infants and nitrogen balance in adults. After obtaining tryptophan through dietary sources, the body converts it to 5-hydroxytryptophan -- or 5-HTP -- which is in turn converted to serotonin, or 5-hydroxytryptomine. Tryptophan is not produced naturally in the body, and must be obtained from diet. Other good sources of tryptophan are poultry, meat, dairy products, peanut butter and soy.
The Specifics
One medium banana contains 0.011 g of tryptophan -- roughly one-third more than the amount found in a half grapefruit and almost five times the amount contained in a medium apple. It also provides 1.29 g of protein, 26.95 g of carbohydrates, 3.1 g of dietary fiber and 14.43 g of sugars. Bananas are low in salt and fat and are cholesterol-free; a medium banana contains a diet-friendly 105 calories.
Tryptophan Benefits
In addition to producing serotonin, tryptophan can induce the pineal gland to make more melatonin, a sleep-inducing hormone. There is some evidence that tryptophan can help conventional antidepressants work more effectively, and it is used as a prescription medicine in Canada for that purpose. According to My Fit Health and Fitness, tryptophan acts as a natural painkiller. Tryptophan may also help with mental tasks. In an article published in 2001 in "Nutrition and Food Science," the authors maintain that dietary tryptophan -- along with choline, another amino acid -- can positively influence motivational state by promoting increased brain activity, elevated mood and increased ability to concentrate. Some herbalists and natural healers believe that symptoms such as depression, anxiety, impulsiveness, poor dream recall and overeating can be eased by increasing dietary tryptophan, but this hasn't been clinically proven. Because tryptophan has a role in producing niacin, it can help prevent a deficiency of this B vitamin.
Considerations
Buy bananas when they are slightly green, making sure they are firm and free of bruises. It should take about three days for them to ripen to a bright yellow. According to Banana.com, bananas with a grayish tinge have been refrigerated, and won't ripen properly; avoid them. Although unripe bananas should never be refrigerated, fully ripened fruit may be stored in the refrigerator for up to two weeks. To get the most benefit from the tryptophan in a banana, eat some protein along with it; this can increase the availability of the tryptophan in the brain.
References
- USDA National Nutrient Database
- University of Maryland Medical Center; 5-Hydroxytryptophan; UMMC Staff; March 2009
- My Fit Health and Fitness: Foods High in Tryptophan
- "Nutrition and Food Science"; Influence of Dietary Choline and Tryptophan on Motivational State; Anna Robins and Don Davies; Vol. 31, 2001
- Banana.com: How to Buy Bananas
- Health Diaries: 25 Facts About Bananas
Member Comments