TMG (Trimethylglycine or betaine):

Functions:

• Reduce free radicals to reduce recovery time
• utilize fatty acids for energy production
• enhance the transfer of oxygen to muscle tissues.

Dietary sources: fish, beets, and legumes

Trimethylglycine, also known as "Betaine" is an extremely powerful antioxidant. TMG is a "methyl donor". The donation of methyl groups by betaine is very important to proper liver function, cellular replication, and detoxification reactions. Betaine also plays a role in the manufacture of carnitine and serves to protect the kidneys from damage. TMG helps to transport oxygen to muscle tissues as well as perform liptropic activity (fatty-acid utilization for energy production). Betaine has been reported to play a role in reducing blood levels of homocysteine, a toxic breakdown product of amino-acid metabolism that is believed to hinder recovery. TMG was first isolated from the sugar beet.

References

Selhub J. Homocysteine metabolism. Annu Rev Nutr 1999;19:217–46 [review].
Mindell E, Vitamin Bible, Warner Books, New York, NY;1991:pp.69-71, 146.
Barak AJ, Tuma DJ. Betaine, metabolic by-product or vital methylating agent? Life Sci 1983;32:771–4 [review]