Should We Avoid Animal Protein to Optimize Methylation?

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A reader asked me to respond to a newsletter recently distributed through email by a representative of a company called Biotics Research Canada that cited two older articles by Dr. Lawrence Wilson and Dr. Mark Hyman arguing that animal protein should be restricted to optimize a biochemical process that is incredibly important to our health known as methylation, and that many fermented foods, especially kombucha, should be avoided because of their content of dangerous compounds known as aldehydes. Since these two questions are very different from one another, I will address them in two separate blog posts. In this one, I address the question of whether we should restrict animal protein to optimize the methylation process.

I have written about methylation before. The most relevant article for background to this particular question is “Beyond Good and Evil: Synergy and Context with Dietary Nutrients.” The theme of this article was that once the modern science of nutrition divorced individual nutrients from the context of real food and the approaches to dietary balance that governed human dietary choices across time and space right up until the modern era, we lost the perspective needed to understand that nutrients are neither good nor evil but are all capable of goodness when used in the right way and in the proper context. One of the examples given was the need to balance muscle meats with vegetables, organ meats, skin, and bones. All traditional diets, whether they were primarily animal foods, primarily plant foods, or somewhere in between, emphasized the economical use of the whole animal to the extent an animal would be eaten, naturally leading to a balance between these different animal parts. That article explains why the methylation process can indeed go awry when muscle meats are consumed in excess of these other foods. That principle applies to this question. I will reiterate the basic points here, but also add some additional points about why it could be beneficial to balance these foods by consuming more of the ones that are missing instead of restricting those that seem in excess.

Methylation can most easily be thought of as adding a single carbon to a molecule. Technically, a methyl group is a carbon with three hydrogen atoms bound to it, but these hydrogen atoms are essentially space-fillers. Since we, like all living beings, are made of carbon-containing compounds (known as “organic” compounds), the addition or subtraction of single carbons plays a role in synthesizing or regulating hundreds of different things within our cells, and is thus important to hundreds of different health effects. The articles I am criticizing herein list many of these health effects in great detail. Here, I will only note as illustrative examples that methylation is important for growth, healing, preventing cancer, lengthening life span, and optimizing mental, emotional, and physical health.

The nutrients most important to the methylation process are folate, vitamin B12, and methionine. Folate is a B vitamin that is most abundant in liver, legumes, and leafy green vegetables. Vitamin B12 is another B vitamin that is found almost exclusively in animal products, especially in shellfish and the dark flesh of fin fish, but also in three known examples of edible algae: chlorella, green laver, and purple laver (also known as green and purple nori). Methionine is an amino acid that is found in virtually any animal or plant protein but is about twice as abundant in most animal proteins than in most plant proteins. Most animal foods, moreover, are much richer in total protein than most plant foods, making most animal foods contain far more than twice as much methionine as most plant foods.

As shown in this figure, which is simplified compared to what would be found in a biochemistry textbook for the sake of emphasizing the most nutritionally relevant aspects of the process, each time methionine donates a methyl group for one of the many methylation reactions, it becomes homocysteine. Homocysteine itself is dangerous, and homocysteine is, moreover, not capable of donating methyl groups; therefore, it is necessary to recycle homocysteine and, from it, regenerate methionine. this is the role of folate and vitamin B12: folate passes a methyl group to vitamin B12, and vitamin B12 passes that same methyl group to homocysteine, thereby converting homocysteine back to methionine. This eliminates the potential dangers of homocysteine accumulation, while allowing the newly regenerated methionine to contribute to another methylation reaction.

As shown in this figure, glycine absorbs extra methyl groups from methionine when methionine reaches high concentrations. It thus acts as a buffer to prevent excessive methylation. Glycine is far more abundant in the protein of skin and bones than in the protein of muscle meats or plant food. This emphasizes the need to balance muscle meats with the skin and bones that are naturally attached to them.

The two articles I was asked to respond to do not claim that animal protein is bad because it will promote excessive methylation. Indeed, that could only be argued if one were to also argue that we should restrict folate and vitamin B12, and restricting folate would mean that we should avoid eating leafy green vegetables, an argument that few people make. The article by Dr. Wilson, in fact, argues that “most people today have inadequate methylation.”

What, then, is their concern?  The article by Dr. Wilson only vaguely states that “too much methionine may negatively affect methylation.”  It is difficult to make any sense out of such a vague statement, but the article by Dr. Hyman makes a more specific claim: excess animal protein can elevate homocysteine.

This claim is certainly true when one consider the effects of methionine in a vacuum. As can be seen in this figure however, excess methionine would only cause homocysteine to accumulate when vitamin B12, folate, vitamin B6, and glycine are inadequate to balance it.

One should then ask this question: is it better to achieve this balance by restricting methionine, or is it better to achieve this balance by adding vitamin B12, folate, vitamin B6 and glycine?  The figure linked to above suggests a benefit to consuming these nutrients together: when the entire network of nutrients is present, extra methionine does not cause homocysteine to accumulate; rather, it allows the synthesis of taurine, sulfate, and glutathione. Taurine is very important to the function of the brain and retina.  Sulfate is added to many compounds to regulate or detoxify them. Glutathione is the master antioxidant of the cell, one of the key compounds involved in detoxification, and a key regulator of protein function. Poor glutathione status appears to contribute to a wide array of degenerative diseases, including diabetes, asthma, and most of the negative effects that we associate with aging. Restricting methionine is one way of preventing homocysteine from accumulating; but restricting methionine compromises the supply of taurine, sulfate, and glutathione. By contrast, supplying the nutrients that synergize with methionine both prevents homocysteine from accumulating and allows the synthesis of these three incredibly important compounds.

Of course, we should presume that there is a point after which we have had enough of all these nutrients. The problem is that no one really knows what that point is. Preliminary evidence in humans suggests that we can maximize glutathione synthesis by consuming one gram of protein per kilogram body weight per day, with virtually any type of protein providing adequate methionine. That evidence, however, was obtained using isolated nutrients rather than whole foods, and was obtained without examining the effect of the many other contextual factors involved. Glycine and vitamin B6 are both needed to allow methionine to contribute to the synthesis of glutathione. A diet rich in fruits and vegetables will increase the synthesis of glutathione, thereby increasing the amount of the amino acids needed to synthesize glutathione. The body will, moreover, synthesize more glutathione when exposed to conditions that require more glutathione. Thus, during conditions of illness, stress, recovery from injury, or recovery from toxicity, more glutathione will be synthesized and more of the amino acids that are used in that synthesis will be required in the diet. Given that so many contextual factors are involved that have not been exhaustively studied, I personally do not feel comfortable attaching a very specific number to the amount of meat one should eat.

Instead, my practical advice is as follows:

• To the extent you eat meat, balance it with skin and bones in similar proportions as they would occur in the animal. To get a sense of these proportions, try buying whole or almost-whole animals such as roast chickens for a while.
• To the extent you eat these animal products, accompany them with rich supplies of a diverse array of plant foods, especially green leafy vegetables.
• Follow your intuition and appetite, within the restrictions of your social life and cultural ties, to the extent you operate comfortably within them.
• Beyond this, in the absence of a specific problem that needs addressing, relax, and start eating food instead of analyzing it.

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