L-Tryptophan Is Safe Once Again

After hearing that his obituary had been published in the New York Journal, Mark Twain responded with the now-famous line, “The reports of my death are greatly exaggerated.” The same might be said of L-tryptophan (LT), which is good news for the millions of people who have used this amino acid in the past for a variety of purposes. You may have noticed that this supplement was off the market for a while. What happened to spur premature reports of LT’s demise? 

A Bad Batch

Almost 20 years ago, a single raw-material supplier of L-tryptophan released a bad batch containing chemical impurities. That contaminated batch found its way into many dietary supplements. As a result, more than 1,500 people developed a condition called eosinophilia-myalgia syndrome (EMS), and 37 of those people died. The U.S. Food and Drug Administration (FDA) then instituted a restriction on the sale of LT products and issued an import alert.

LT’s Status in the Market

While the EMS outbreak was terrible and preventable, it’s important to put it in the proper perspective. LT was sold as a dietary supplement for at least a decade before EMS occurred, and no incidences of LT-associated EMS were reported in the literature prior to 1989. This raises the question of why all L-tryptophan was removed from the market when it appears that the illness stemmed from the contaminated product of a single manufacturer. Remember the recent spinach and E. coli incident? Spinach was temporarily removed from the market but reappeared a few weeks later when its safety was re-established. FDA didn’t permanently ban spinach due to a bad batch—yet that’s what happened to L-tryptophan.   

Following the passage of the Dietary Supplement Health and Education Act (DSHEA) of 1994, FDA continued to express concern about LT supplements. It did not, however, exercise its power to prohibit the sale and marketing of such supplements. Under DSHEA, manufacturers are responsible for ensuring LT’s safety. Liability insurance was an initial hurdle to its reintroduction. Just recently, that changed when a top carrier, convinced of one product’s safety and quality, endorsed the supplier. LT is back on the market!

What Is L-Tryptophan?

An essential amino acid, LT cannot be made in the body so it must be consumed in food. Eventually, L-tryptophan is converted to the neurotransmitter serotonin, which affects mood levels. Serotonin may be primarily responsible for all the wonderful things attributed to LT. For example, serotonin is the precursor to the sleep hormone, melatonin.

Good for Sleep

At least 40 controlled studies have demonstrated that LT can help promote sleepiness in humans. Most of the evidence shows that 1 g or more is effective, although one study found that LT may be effective in lower doses (250 to 500 mg). Another study showed that LT is effective in inducing sleep the first night of administration in younger insomniacs, while those with more chronic and established insomnia may require repeated administration of low doses of L-tryptophan over time for sleep improvement.

Helpful for PMS

Although the precise cause of premenstrual syndrome (PMS) is still unknown, it may involve altered serotonin activity. Since LT boosts serotonin levels, it’s not surprising that research shows supplementation with this amino acid is effective in treating premenstrual dysphoric disorder, a severe form of PMS. In a double-blind, randomized, controlled clinical trial, women given 6 g LT daily for 17 days from the time of ovulation to the third day of menstruation experienced a significant therapeutic effect for a cluster of mood symptoms (including mood swings, tension, and irritability). An earlier study showed similar results, and other research has found that as little as 2 g daily (1 g, twice daily) every other day for 10 days premenstrually for two consecutive menstrual cycles was also effective at relieving PMS symptoms.

A Natural Antidepressant

Research shows that LT helps improve the effects of some antidepressant drugs. In one study, 30 patients with major depressive disorder were treated for more than eight weeks with 20 mg of fluoxetine (Prozac) per day and either tryptophan (2 to 4 g per day) or a placebo. The results showed a significantly greater decrease in depression scores in the tryptophan/fluoxetine group than in the placebo/fluoxetine group. Note: Due to the risk of serotonin syndrome (a rare but potentially life-threatening drug reaction from excess serotonergic activity at central nervous system and peripheral serotonin receptors), do not take LT with an SSRI medication (such as fluoxetine) without prior approval from your physician.

In addition, decades’ worth of research demonstrates that tryptophan improves the effectiveness of an older category of antidepressants called monoamine oxidase inhibitors. Research also shows that LT was useful when compared to the tricyclic antidepressant amitriptyline, as well as in combination with amitriptyline. In addition, LT has been shown to be effective in treating seasonal affective disorder, another type of depression.

Stop Smoking with LT

Cigarettes are as addictive as heroin or cocaine. Quitting isn’t easy, but LT may be able to help. In one research project, LT (50 mg per kg of weight per day) and high-carbohydrate diets, together with more traditional smoking cessation treatment techniques, were used to help reduce the effects of smoking withdrawal and improve abstinence rates.

Appetite and Weight Loss

Since serotonin is involved in appetite regulation, LT may have value for reducing appetite. One mechanism by which this may take place is inhibiting stomach emptying. Research shows that, when taken as a liquid, LT inhibits gastric emptying in humans, significantly reducing hunger. In addition, a placebo-controlled, double-blind study compared the ability of LT (750 mg, twice daily, orally, for three months) or a placebo to influence weight loss among 62 obese outpatients who were on a strict diet. The results showed that the LT significantly enhanced weight loss among moderately obese subjects. This group experienced significant weight loss during both the first treatment month and throughout the total three-month test period.