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By Geoffrey Cowley and Anne Underwood
Until recently, few Americans had heard of the stuff. An Italian firm developed it as a pharmaceutical in the early 1970s but lacked the will or the resources to make a run at a drug approval in the United States. Then, this spring, two U.S. vitamin companies, GNC and Pharmavite® LLC, started importing large quantities of SAMe to sell as a supplement. The product took off quickly—Pharmavite® LLC's Nature Made brand now ranks 25th among the 13,000 supplements sold in grocery and drugstores—and the impact is still growing. When you consider that some 50 million Americans suffer from arthritis or depression, the implications are staggering.
SAMe (known formally as S-adenosylmethionine) is not an herb or a hormone. It's a molecule that all living cells, including our own, produce constantly. To appreciate its importance, you need to understand a process called methylation (chart). It's a simple transaction in which one molecule donates a four-atom appendage—a so-called methyl group—to a neighboring molecule. Both the donor and the recipient change shape in the process, and the transformations can have far-reaching effects. Methylation occurs a billion times a second throughout the body, affecting everything from fetal development to brain function. It regulates the expression of genes. It preserves the fatty membranes that insulate our cells. And it helps regulate the action of various hormones and neurotransmitters, including serotonin, melatonin, dopamine and adrenaline. As biochemist Craig Cooney observes in his new book, "Methyl Magic," "Without methylation there could be no life as we know it."
And without SAMe, there could be no methylation as we know it. Though various molecules can pass methyl groups to their neighbors, SAMe is the most active of all methyl donors. Our bodies make SAMe from methionine, an amino acid found in protein-rich foods, then continually recycle it. Once a SAMe molecule loses its methyl group, it breaks down to form homocysteine. Homocysteine is extremely toxic if it builds up within cells. But with the help of several B vitamins (B6, B12 and folic acid), our bodies convert homocysteine into glutathione, a valuable antioxidant, or "remethylate" it back into methionine.
SAMe and homocysteine are essentially two versions of the same molecule—one benign and one dangerous. When our cells are well stocked with B vitamins, the brisk pace of methylation keeps homocysteine levels low. But when we're low on those vitamins, homocysteine can build up quickly, stalling the production of SAMe and causing countless health problems. High homocysteine is a major risk factor for heart attack and stroke. During pregnancy, it raises the risk of spina bifida and other birth defects. And many studies have implicated it in depression.
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