Serotonin levels may be increased by supplement of 5-hydroxitryptophan (5-HTP) and tryptophan. However, increasing foods rich
in tryptophan (eg, meats, proteins) does not increase serotonin levels, due to competition with other amino acids. What is
required to increase serotonin production is an increase in the ratio of tryptophan to phenylalanine and leucine. Fruits with
a good ratio include dates, papaya and banana. Foods with a lower ratio inhibit the production of serotonin. These include
whole wheat and rye bread. Much research has indicated that vigorous aerobic exercise improves mood, believed to be
facilitated by an increase in serotonin levels. Research also suggests that eating a diet rich in whole grain carbohydrates
and low in protein will increase serotonin by secreting insulin, which helps in amino acid competition. However, increasing
insulin for a long period of time can sometimes onset insulin resistance, which is related to obesity, type 2 diabetes, and
lower serotonin levels. It is also believed that muscles use many of the amino acids except tryptophan, allowing men to have
more serotonin than women. Bright light therapy is another popular method which prevents the conversion of serotonin to melatonin.
A similar effect is obtained by spending more time in natural sunlight. Recently, acupuncture has been shown to stimulate
the release of serotonin levels in lab animals.