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Ergo-Log

18.12.2014


Less fat, more muscle - thanks to tryptophan supplementation?

You probably know L-tryptophan as an essential amino acid which helps you sleep better and lightens your mood. It seems that the same L-tryptophan might also improve body composition. An animal study published in Amino Acids by nutritionists from Nanchang University suggests this. We warn in advance that the Chinese publication raises significantly more questions than it answers.


Tryptophan supplementation improves body composition


Trytophan
Trytophan is a precursor of serotonin and melatonin, but also plays an as yet not completely understood role in the synthesis of proteins in the body. The Chinese attempted to gain more understanding of this role by performing an experiment in which they gave adult rats a daily oral dose of 200 mg L-tryptophan per kg bodyweight for a week. The human equivalent of this dose would be about 2-3 g per day.

During this period these rats gained a little weight than rats in a control group, which had been given no supplements.


Tryptophan supplementation improves body composition


Tryptophan supplementation improves body composition


Protein metabolism
The researchers found indications of increased protein synthesis in the rats' blood, such as a decrease in the concentration of isoleucine and valine. These amino acids are important building blocks for muscle tissue.

One possible mechanism is that tryptophan induces the small intestine to absorb more amino acids, the Chinese believe. The rats' small intestine became longer as a result of supplementation [figure below]. But how extra tryptophan may speed up muscle protein synthesis is still not clear.


Tryptophan supplementation improves body composition


Fat metabolism
The Chinese do not report whether the rats' muscles became larger or stronger. What they do say is that L-tryptophan reduced the animals' fat mass, although they do not say by how much. Instead they do provide information on the way in which the amino acid probably boosted the burning of fatty acids.

"We found that tryptophan supplementation affected lipid metabolism, leading to reduced fat deposition in the body of tryptophan supplemented group, compared with the control group", the researchers write. "Both acetoacetate and beta-hydroxybutyrate are products of fatty acid oxidation in liver, and the ratio of acetoacetate to hydroxybutyrate is an indicator of cytosolic and mitochondrial redox states."

"In this study, tryptophan supplementation increased the level of acetoacetate and decreased the level of beta-hydroxybutyrate in serum, thus elevated the ratio of acetoacetate to beta-hydroxybutyrate. The result suggested that tryptophan supplementation promoted the oxidation of fatty acid."

"So it would lead to a reduced availability of fatty acids for the synthesis of lipids, LDL and VLDL in the body. In support of this view, tryptophan supplementation decreased the serum concentrations of lipids, unsaturated lipids, LDL and VLDL in tryptophan supplemented group rats compared to the control group rats."

Source:
Amino Acids. 2014 Dec;46(12):2681-91.

More:
Supplement with tryptophan makes you more dominant 05.11.2018
Tryptophan supplementation increases emotional intelligence 29.10.2018
It's easier to say 'no' when you take an L-tryptophan supplement 28.12.2017

Archives:
Unusual Pathways of Anabolism
Amino Acids
Tryptophan


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