By Joel Brind
In one of my earlier posts on this blog, I discussed the largely reciprocal nature of the amino acids glycine and methionine. Specifically, too much dietary methionine depletes glycine, because your body uses up glycine in order to get rid of the excess methionine. This is a common condition these days, because the typical diet is high in methionine-rich muscle meats, but low in glycine-rich bone and connective tissue. Many are waking up to the benefits of getting more glycine by eating more wholesome meats by supplementing with bone broths, or gelatin (collagen) products. (I take the easy way out, by simply supplementing with the glycine product “sweetamine” which I formulated and sell myself.)
The key to understanding the complex relationship between glycine and methionine is to be aware that, in addition to the role of both of them in serving as protein building blocks, they also both have many critical metabolic and other roles as free amino acids. As free amino acids—which are small, water soluble molecules—both glycine and methionine cycle very quickly through the body in a matter of hours, compared to the weeks-to-months turnover time of protein molecules.
The key difference between glycine and methionine which has been the traditional focus of nutritional and metabolic research, is the fact that methionine is essential, i.e., you’ll eventually die if you don’t get adequate dietary intake, because your body cannot make it from simpler materials; but glycine is non-essential, i.e., your body can make it from simpler compounds. Hence, the importance of glycine in the diet has been largely ignored.
Methionine—when activated to form S-adenosylmethionine, or SAMe—is the universal methyl donor. As such, it performs the critical function of adding one-carbon methyl groups, an operation necessary to form and modify DNA bases, detoxify drugs, and make certain key molecules like the hormone adrenalin, to name a few examples. Since methionine is so important, the body—mainly the liver—has a number of pathways to reuse, regenerate and recycle methionine. Best known is the methionine cycle, whereby the methyl group—once donated by SAMe—gets added back to the “spent” SAMe (the amino acid homocysteine) to reform methionine. The result of all these pathways is to render the minimal methionine daily dietary requirement very small, i.e., a few hundred milligrams; more like a vitamin than a protein amino acid.
But the dark side of methionine—long ignored—is that too much is toxic, so that after eating that methionine-rich steak, your liver is not operating the methionine cycle to conserve methionine, but rather, getting rid of it as fast as it can. To do that, the liver needs to use up glycine. Therefore, the more methionine in the diet, the more glycine is needed to help get rid of it.
Although glycine is non-essential, your liver can’t make an unlimited amount, and the typical diet usually comes up short 8-10 grams of glycine per day. Meanwhile, glycine has critical functions in the body only recently discovered. Most relevant to human diet and health is the fact that glycine is the most important endogenous regulator of inflammation. In fact, I’m convinced that glycine deficiency lies at the core of most conditions that make people sick and die these days, from diabetes and arthritis to heart disease and cancer. That’s because they’re all traceable to chronic excess inflammation. If you are glycine-deficient, it will show up as chronic inflammation sooner or later, one way or another.
So that’s why I have been quick to say that most people eat too much methionine, and really should avoid supplements such as SAMe, TMG, etc, which boost methylating power. But in one of the comments after one of my posts on this site a few months ago, the suggestion that some people are “under-methylators” prompted me to have another look at what is going on. After all, it is well known that mutations of the gene for the enzyme MTHFR—which is critical for the regeneration of methionine from homocysteine—are quite common in all human populations (between 10 and 20%). People with defective forms of MTHFR do not regenerate methionine efficiently. Consequently, during periods of fasting (or even shorter periods of say, 4-6 hours between meals), they may actually be somewhat methionine-deficient, precisely because excess methionine is so efficiently removed after absorbing a meal’s worth of high protein.
Therefore, such people may endure chronic health problems by being both glycine AND methionine-deficient! So as a simple, harmless experiment, I suggested that one could eat a rich natural source of methionine for a snack between meals. Brazil nuts are the perfect such snack, comprised of 1% methionine by weight. That means a snack of 3 Brazil nuts provides about 100mg of methionine.
Then I looked further into the topic of “under-methylation” and realized that one of my own daughters fit the profile perfectly: prone to hypoglycemia between meals and always needing a high-protein snack to tide her over, and more seriously, suffering from recurrent bronchitis—a borderline asthmatic since childhood. Of course, being my kid, she’s been taking her sweetamine glycine supplement for a couple of years now, and although feeling somewhat better, the respiratory problems persisted.
So I suggested she try a few Brazil nuts as a snack between meals. The first sign that this suggestion was on the right track was the fact that she has always loved Brazil nuts (Talk about intuitive eating!), but had avoided them because they are relatively expensive compared to other high protein snacks (peanuts, string cheese, etc.).
But the most encouraging sign of spring (literally), is that for the first time I can remember, my daughter has gotten through a northeast winter (and this year was the worst in a long time) without a single major respiratory infection!
So at this point, my working hypothesis seems to be gathering some evidence for the advantage —at least for undermethylators—of supplementing with both glycine and methionine, starting the day with the former and taking Brazil nut snacks for methionine in between meals. (And btw, Brazil nuts are also a rich source of usable selenium, in the form of the rare but also essential amino acid, selenocysteine. Selenocysteine is essential for the formation of glutathione reductase, the enzyme which regenerates the key anti-oxidant glutathione.)
Finally, since I first made this suggestion on this blog, I’m very curious to know if anyone else has taken it up, and whether it has helped. Do tell.
About the Author
Joel Brind, Ph.D. has been a Professor of Biology and Endocrinology at Baruch College of the City University of New York for 28 years and a medical research biochemist since 1981. Long specializing in steroid biosynthesis and metabolism and endocrine-related cancers, he has specialized in amino acid metabolism in recent years, particularly in relation to glycine and one-carbon metabolism. In 2010 he founded Natural Food Science, LLC to make and market glycine supplement products via http://sweetamine.com , which includes his own blog HERE.