The question "What does choline do" is a complex one. Once it enters the body, it can be directed toward several very different jobs. It can help build cell membranes, become the neurotransmitter acetylcholine, or e converted into betaine and contribute methyl groups to the methylation cycle.

Your body actually has two major pathways for recycling homocysteine back into methionine. One depends primarily on folate and vitamin B12. The other uses choline-derived betaine.

You get your bloodwork back and your homocysteine is elevated. If you've ever looked at Instagram ever your first thought is probably "It must be MTHFR!" You might be right, especially if you have an MTHFR C677T variant, which is most closely associated with high homocysteine. But there are many other reasons for homocysteine to be elevated, so don't stop looking once you see MTHFR.