Tryptophan is an amino acid needed for normal growth in infants and for nitrogen balance in adults. It is an essential amino acid, which means your body cannot produce it -- you must get it from your diet.

The body uses tryptophan to help make niacin and serotonin. Serotonin is thought to produce healthy sleep and a stable mood.

In order for tryptophan in the diet to be changed into niacin, the body needs to have enough:

• Iron
• Riboflavin
• Vitamin B6

Tryptophan can be found in:

• Cheese
• Chicken
• Eggs
• Fish
• Milk
• Nuts
• Peanut butter
• Peanuts
• Pumpkin seeds
• Sesame seeds
• Soy
• Tofu
• Turkey

Dietary Guidelines for Americans - 2005. Washington, DC. US Dept of Health and Human Services and US Dept of Agriculture: 2005.