A Misunderstood Effect of Tryptophan and Turkey

November 30th, 2009

Turkey and TryptophanIt’s common for people to experience drowsiness after the large turkey dinners that are often a part of the Thanksgiving and Christmas holidays. Although most people attribute the drowsiness to the tryptophan in turkey, this is unlikely to be the cause. Despite this somewhat negative perception of tryptophan, it’s actually an important nutrient that has considerable benefits.

Tryptophan is an amino acid that’s needed by the body to assemble proteins that are involved in numerous biological functions. Tryptophan is also an essential amino acid which means that it cannot be synthesized by the body and must be obtained through diet. When tryptophan is not consumed in adequate amounts, it can lead to a number of issues including mood disorders.

How Tryptophan Influences Your Health and Wellbeing

In addition to being an amino acid that’s needed to build the proteins that support the basic biology of life, tryptophan has an especially important effect on mental wellness. This is because it’s a precursor to the neurotransmitter serotonin which has a significant impact on mood. An inadequate intake of tryptophan can cause serotonin deficiency, and in turn, also cause depression, anxiety, low self esteem, obsessiveness, and irritability.

Because serotonin is derived from tryptophan, and because tryptophan must be obtained through diet, the food you eat has a significant influence on your mood. Someone who doesn’t eat enough food that contains tryptophan is more likely to have a deficiency of serotonin, and in turn, experience unpleasant moods.

Tryptophan is also a precursor to niacin which is a B vitamin and is involved in a number of physiological functions including metabolism, hormone production, circulation, and nervous system function. Niacin is also believed to help reduce the risk of heart disease by reducing the amount of very low density lipoproteins which are an undesirable carrier of cholesterol.

Factors that Influence the Utilization of Tryptophan

The effects of tryptophan aren’t only based on the amount of it consumed. The blood vessels that transport nutrients to the brain are lined with cells that act as filters and only allow certain substances to pass through. These cells represent what is known as the blood brain barrier and amino acids can only pass through it with the assistance of special transport proteins.

The hormone insulin is primarily known for its involvement in the absorption of glucose. It also increases the absorption of amino acids, but not tryptophan. As a result, whenever the body’s sensitivity to insulin increases, or whenever insulin production increases, more amino acids are absorbed and the ratio of tryptophan remaining in the blood increases. Because of this increased ratio, more tryptophan can bind with transport proteins and enter the brain where it can be used to synthesize serotonin. As such, anything that promotes an increase in insulin production or sensitivity can also promote an increase in serotonin production.1

Because exercise increases sensitivity to insulin, it also facilitates the transport of more tryptophan to the brain and the production of more serotonin. This is one of the primary reasons why exercise can improve mood and relieve depression and anxiety. Similarly, consumption of sugar and refined carbohydrates increases the production of insulin which also results in more tryptophan entering the brain and more serotonin production. However, sugar and refined carbohydrates are unhealthy, and for people who are suffering from serotonin deficiency, this temporary boost in mood is one of the reasons why such foods are addictive.

The Real Cause of Post Turkey Drowsiness

Because serotonin is a precursor to the sleep promoting hormone melatonin, anything that causes an excessive production of serotonin can also cause drowsiness. Since excessive carbohydrate consumption can cause too much tryptophan to enter the brain, and in turn, cause too much serotonin to be produced, this is more likely to be the cause of the drowsiness that is so common after large turkey dinners. Alcohol and blood sugar fluctuation can contribute to the drowsiness as well.

Sources of Tryptophan

Some of the best sources of tryptophan include turkey, pork, chicken, beef, salmon, cheese, and eggs. As such, most people who follow a healthy diet that’s based on natural whole foods such as these shouldn’t have to worry much about their tryptophan intake. For your diet to have the most impact, it’s best to choose pasture raised meat, minimally contaminated fish, and organic cheese made from raw milk.

For people who are genetically susceptible to serotonin deficiency or are fighting sugar addiction, supplements can be helpful. Although tryptophan is available in supplement form, 5 HTP is usually preferred because it’s a derivative of tryptophan and is a more immediate precursor to serotonin. However, some people have more success with tryptophan than 5 HTP.

If you search for additional information on tryptophan, you might come across some controversy. In response to a number of cases of a rare neurological disorder, tryptophan was banned as a supplement in the United States in 1990. The cause of this outbreak was determined to be a tainted supply of tryptophan from Japan that was improperly manufactured. Because tryptophan supplementation has been proven to help mood disorders, many people believe that the FDA was influenced to impose the ban so that doctors could be encouraged to recommend Prozac instead. Fortunately, the ban was lifted in 1995 and tryptophan is once again available as a supplement.

Learn How to Improve Your Moods Naturally

Obtaining a sufficient amount of tryptophan through a healthy diet is only one of the many factors that can greatly improve your moods. For more information on how to improve your mental wellness through diet and other natural lifestyle habits, I highly recommend that your read The Mood Cure by Julia Ross.

[1. Wurtman RJ, Wurtman JJ. "Do carbohydrates affect food intake via neurotransmitter activity?." Appetite. 1988. 11(1):42-47.]

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