Trimethylglycine, or TMG is a part of the methyl donor group. Found in abundant supply in the sugar beet, TMG is also known as anhydrous betaine. TMG works to maintain homocysteine levels by converting homocysteine into methionine through the donation of a methyl group. Normal homocysteine function and levels are important to cardiovascular health. TMG can also be found fish and other vegetable sources.