SAMe

Here's some research links to a suppliment called SAMe. This stands for S-adenosylmethionine.

From one site:
S-Adenosylmethionine (SAMe) is a naturally occurring compound that is involved in many biochemical processes in the body. SAMe plays a role in the immune system, maintains cell membranes, and helps produce and break down brain chemicals such as serotonin, melatonin, and dopamine as well as vitamin B12. SAMe also participates in the making of genetic material, known as DNA, and cartilage. Low amounts of folate (vitamin B9) in the body may lead to reduced levels of SAMe.

Numerous scientific studies indicate that SAMe may be useful in the treatment of depression, osteoarthritis, fibromyalgia, and liver disorders. Although it has been available in Europe by prescription for a number of years, SAMe was only recently introduced as a dietary supplement in the United States.

Another Site:

SAMe is the "linch pin" of three major biochemical pathways- transmethylation, transsulfuration, and aminopropylation- which regulate or impact virtually every biochemical reaction in humans and animals.