tryptophan

What can high-tryptophan foods do for you?

• Help regulate your appetite
• Help you sleep better
• Elevate your mood

What events can indicate a need for more high-tryptophan foods?

• Depression
• Anxiety
• Irritability
• Impatience
• Impulsiveness
• Inability to concentrate
• Weight gain or unexplained weight loss
• Slow growth in children
• Overeating and/or carbohydrate cravings
• Poor dream recall
• Insomnia

Food sources of tryptophan include red meat, dairy products, nuts, seeds, legumes, soybeans and soy products, tuna, shellfish, and turkey.

Description

What is tryptophan?

Tryptophan is one of the 10 essential amino acids that the body uses to synthesize the proteins it needs. It's well-known for its role in the production of nervous system messengers, especially those related to relaxation, restfulness, and sleep.

How it Functions

What is the function of tryptophan?

Preventing Niacin Deficiency

Tryptophan has two important functions. First, a small amount of the tryptophan we get in our diet (about 3%) is converted into niacin (vitamin B3) by the liver. This conversion can help prevent the symptoms associated with niacin deficiency when dietary intake of this vitamin is low.

Raising Serotonin Levels

Second, tryptophan serves as a precursor for serotonin, a neurotransmitter that helps the body regulate appetite, sleep patterns, and mood. Because of its ability to raise serotonin levels, tryptophan has been used therapeutically in the treatment of a variety of conditions, most notably insomnia, depression, and anxiety.

Deficiency Symptoms

What are deficiency symptoms for tryptophan?

As an essential amino acid, dietary deficiency of tryptophan may cause the symptoms characteristic of protein deficiency, which include weight loss and impaired growth in infants and children.

When accompanied by dietary niacin deficiency, lack of tryptophan in the diet may also cause pellagra, the classic niacin deficiency disease that is characterized by the "4 Ds" —dermatitis, diarrhea, dementia, and death. This condition is very rare in the United States, however, and cannot occur simply because of a tryptophan deficiency.

Dietary deficiency of tryptophan may lead to low levels of serotonin. Low serotonin levels are associated with depression, anxiety, irritability, impatience, impulsiveness, inability to concentrate, weight gain, overeating, carbohydrate cravings, poor dream recall, and insomnia.

Toxicity Symptoms

What are toxicity symptoms for tryptophan?

High dietary intake of tryptophan from food sources is not known to cause any symptoms of toxicity. In addition, tryptophan has been given therapeutically, as a prescription medicine or dietary supplement, in doses exceeding five grams per day with no report of adverse effects.

However, in 1989, the use of dietary supplements containing tryptophan was blamed for the development of a serious condition called eosinophilia-myalgia syndrome (EMS), which caused severe muscle and joint pain, high fever, weakness, swelling of the arms and legs, and shortness of breath in more than a thousand people. In addition, more than 30 deaths were attributed to EMS caused by tryptophan supplements.

Many experts believe that the EMS was caused by a contaminant that was found in one batch of tryptophan sold by one manufacturer and occurred in only a small number of susceptible individuals. However, the United States Food and Drug Administration, the agency responsible for overseeing the dietary supplement industry, remained convinced that high doses of tryptophan were categorically unsafe. Since 1989, tryptophan has not been available as a dietary supplement in the United States.

To date, a Tolerable Upper Intake Level (TUL) for tryptophan has not yet been established by the Institute of Medicine at the National Academy of Sciences.

Impact of Cooking, Storage and Processing

How do cooking, storage or processing affect tryptophan?

There is no research showing problematic effects of cooking, storage, or processing on tryptophan levels in food.

Factors that Affect Function

What factors might contribute to a deficiency of tryptophan?

Vitamin B6 is necessary for the conversion of tryptophan to both niacin and serotonin. Consequently, a dietary deficiency of vitamin B6 may result in low serotonin levels and/or impaired conversion of tryptophan to niacin.

In addition, several dietary, lifestyle, and health factors reduce the conversion of tryptophan to serotonin, including cigarette smoking, high sugar intake, alcohol abuse, excessive consumption of protein, hypoglycemia and diabetes.

Drug-Nutrient Interactions

What medications affect tryptophan?

People taking the anti-depressant medications known as selective serotonin reuptake inhibitors (SSRIs) (including Prozac, Paxil, and Zoloft) should consult a physician before taking any other supplement or medication that also increases the amount of, or the effect of, serotonin, in the body.

Nutrient Interactions

How do other nutrients interact with tryptophan?

Because of this, some healthcare practitioners believe that food sources of tryptophan do not cause a significant enough increase in blood levels of tryptophan to produce therapeutic results, and that tryptophan must, therefore, be taken as a supplement to increase its blood levels.

Health Conditions

What health conditions require special emphasis on tryptophan?

Tryptophan may play a role in the prevention and/or treatment of the following health conditions::

• Anxiety
• Depression
• Headaches
• Insomnia
• Nightmares
• Obesity
• Obsessive/compulsive disorder
• Pain
• Premenstrual syndrome
• Senile dementia
• Tourette's syndrome

Form in Dietary Supplements

What forms of tryptophan are found in dietary supplements?

Until 1989, tryptophan supplementation was standard practice in many countries around the world - including the United States - to treat insomnia, depression, and anxiety.

In the summer and fall of 1989, hundreds of people taking tryptophan supplements in the U.S. began to report the development of serious side effects including muscle and joint pain, high fever, weakness, swelling of the arms and legs, and shortness of breath, a constellation of symptoms that later became known as eosiniphilia-myalgia syndrome (EMS).

Upon investigation, it was discovered that nearly all of the cases of EMS could be traced back to a contaminant found in one batch of tryptophan produced by a Japanese manufacturer called Showa Denko K.K.

While all manufacturers of supplemental tryptophan synthesized this amino acid through a fementation process using bacteria, several months before the outbreak of EMS, Showa Denko K.K. had altered its process to make it more efficient and was apparently unaware that a toxic contaminant was being produced.

A few years ago, a new tryptophan-like supplement emerged in the U.S. marketplace. This supplement is called 5-hydroxytryptophan or 5-HTP. 5-HTP has been used in much the same way as tryptophan for the treatment of depression and insomnia, and for weight loss.

The reason is simple: the body ordinarily takes tryptophan and converts it into 5-HTP, and then takes the 5-HTP and converts it into serotonin. By taking 5-HTP, a person is taking a compound that is actually one step closer to serotonin than tryptophan.

Food Sources

Introduction to Nutrient Rating System Chart

Public Health Recommendations

What are current public health recommendations for tryptophan?

In its most recent 2005 public health recommendations for amino acids (published as the Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients), National Academies Press, 2005), the National Academy of Sciences (NAS) established a general principle for tryptophan intake. The NAS recommended that all individuals 1 year of age or greater consume 7 milligrams of tryptophan for every 1 gram of food protein. Here is how that recommendation would look for each age and gender group, assuming RDA-level protein intake for each group:

• Children 1-3 years: 91 mg of tryptophan
• Children 4-8 years: 133 mg of tryptophan
• Males 9-13 years: 238 mg of tryptophan
• Males 14-18 years: 364 mg of tryptophan
• Males 19 years and older: 392 mg of tryptophan
• Females 9-13 years: 238 mg of tryptophan
• Females 14 years and older: 322 mg of tryptophan
• Pregnant or lactating females: 497 mg of tryptophan

References

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