Promotes satiety and supports healthy eating patterns.*
May promote weight loss as part of a weight loss plan.*
An exciting area of research recently regaining attention is the relationship between serotonin and appetite—and therefore its potential to aid in the maintenance of a healthy weight. While serotonin is reknown for its function in the brain, 95% of serotonin is actually found in the gastrointestinal tract. Accordingly, serotonin is deeply involved in gut physiology, including visceral perception and weight maintenance.8 In research where 5-HTP was administered at higher doses, it was discovered that these high doses of 5-HTP produced weight loss in subjects, mainly through its influence on satiety and an altered appetite for specific macronutrients.
A study that orally administered either 5-HTP or placebo to 19 women for 5 weeks (without any dietary restrictions) resulted in significantly decreased food intake and weight loss in the women taking 5-HTP, compared to placebo.9 In a double-blind, randomized study, 20 subjects received either 5-HTP capsules or placebo for 6 weeks with dietary restrictions, and then for 6 weeks without dietary restrictions. During both periods (with or without dietary restrictions), the 5-HTP subjects experienced early satiety, a reduction in carbohydrate intake, and significant weight loss compared to placebo.10 In a subsequent double-blind, randomized study, 11 subjects received placebo and 9 subjects received 5-HTP capsules for 2 weeks. The 5-HTP group experienced weight loss through a significant decrease in carbohydrate and fat intake.11
An animal study took experimental use of 5-HTP a step further by investigating food deprivation and also stress-induced eating. Although the 5-HTP was injected rather than orally administered in the rats, results clearly showed that administration of 5-HTP suppressed e
ting compared to placebo treatment in food-deprived rats and even more so in rats undergoing stress.12
May improve quality of sleep.*
Studies have shown that 5-HTP influences the quality of sleep by increasing REM (rapid eye movement) sleep. Administration of as little as 200 mg of 5-HTP in the evening prior to bedtime has been shown to increase the duration of REM sleep from 5 to 53% and decrease the amount of non-REM sleep.13
Potent scavenger of free radicals.*
Compounds such as vitamin E and flavonoids derive their free-radical quenching ability from their hydroxyl groups (–OH), which donate electrons to oxidants. 5-HTP is formed from tryptophan by the addition of an –OH group, which gives 5-HTP its antioxidant properties. This is in contrast to tryptophan, which is sensitive to oxidation. The effectiveness of 5-HTP in preventing lipid and protein oxidation is believed to contribute to liver cell integrity by countering membrane rigidity.14 A recent laboratory test demonstrated that 5-HTP is a more effective hydroxyl radical scavenger than even vitamin C.15
Oral administration of 5-HTP in clinical studies has resulted in gastrointestinal disturbances such as nausea, vomiting and diarrhea. According to a review of several studies, these effects are tolerated by most patients and tend to lessen over time. Side effects are more marked with higher doses.5 A recent review in a toxicology journal concludes that while undue speculation was raised years ago, 'there is no evidence to implement 5-HTP intake as a cause of any illness'.16
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