This is a continuation from the previous post in which one of my readers asked about methionine restriction as it relates to longevity and methionine content in eggs. I never claim to be “the knower of the answer” but I like to provide enough information for people to form their own, and perhaps new, ideas.
As I mentioned last time an increase in metabolism will always result in an elevation of all ROS in cells. This, by default, speeds cell turnover and aging. Inversely, reduced metabolism reduces turnover and aging of cells. This is the same mechanism through which caloric restriction is theorized to promote longevity.
Restriction of any substance that is severe enough to slow down metabolism causes the mind and body to go into a torpor-like state. If it doesn’t, damage is incurred. I see this regularly in my practice as a condition that I have termed “Boulder Syndrome” which I’ve talked about in previous posts.
It seems that in order to live longer though means of dietary restriction, you have stop fully living or suffer health consequences. Take SAMe as an example. SAMe is made from methionine in the liver and acts as the rate limiting step in the production of several neurotransmitters. These include dopamine, serotonin, norepinephrine and its conversion in the brain to epinephrine. Low levels of these neurotransmitters tend to reduce mental clarity, motivation, drive and overall energy. This is likely part of the whole conservation mechanism that would naturally slow down the body in times of protein scarcity.
Eggs are so interesting because they contain all the essential nutrients to carry out Phase 1 detoxification and methylation in the liver (choline, methionine, magnesium, B12, B6 and folate). It happens that a deficiency of any one or more of these essential nutrients has a documented effect on reducing fertility. (Sorry, I just didn’t have time to find that many references for one statement but I can assure you it is a fact). As I mentioned in the previous post, this could be from some type of signaling from Phase 1 that would indicate the presence of sufficient nutients available for reproduction. I suspect that if the above nutrients are scarce, Phase 1 probably slows for the purpose of conserving them to maintain other bodily functions more consistent with survival and not reproduction.
Consider how we evolved eating eggs. In non-tropical zones, eggs are in abundance mainly in the spring and early summer. As the weather warms the insects hatch providing a sustainable protein source for birds. The increase in dietary protein, and thus methionine, in birds’ diets would signal the appropriate anabolic processes for them to become fertile and produce eggs. A few weeks later, early humans would have access to these eggs which would provide the appropriate nutrients for signaling anabolic processes to start preparing them for reproduction. Methionine moves like a wave through the food chain, from sulfur in soil to plants to insects to birds to humans, signaling the anabolic processes that enable reproduction.
In tropical zones, eggs would have been available most of the time as would an abundance of nutrients that would support reproduction. This scenario applies more to the people of the developed world.
I don’t think simple reduction of dietary methionine intake is sufficient enough to slow aging. I think it has to be fairly extreme. Alternatively, I do think that excess amounts of methionine, which would imply excess amounts of protein could be damaging especially if intake of magnesium, folic acid, B12 and B6 is insufficient. We also have to consider that if we reduce methionine enough to slow down metabolism, caloric consumption must be reduced as well or the slower metabolism will lead to weight gain.
That said, if you would still like to try to reduce your dietary methionine here are some things to consider. With regards to dietary intake, you have to look at absorption rates. This is influenced by the ratio of methionine to the other amino acids in the protein source. As a general rule, amino acids will compete with one another for absorption. For example, if you have low levels of threonine, high valine levels inhibit the absorption of methionine (Anyone want to research which protein sources have these ratios? Good data at http://www.nutritiondata.com/ ) The higher the ratios of other amino acids the lower the absorption will be of methionine. Animal proteins contain high levels of methionine but much higher ratios of the various other amino acids so ultimately methionine absorption is diminished. I checked some methionine levels in various protein sources and unfortunately got varying results. It turns out that methionine content of food is related to sulfur content in the soil so there will be significant variability depending on the geography of the food source. However as a general rule, cottage cheese, eggs and fish were all similar in methionine content. Pork and poultry were a bit higher. Beef was high but had really high levels of competing amino acids. Legumes and seeds were much lower. NOW FOR THE INTERESTING PART. It has been suggested that a vegan diet offers less methionine and would contribute to longevity through methionine restriction. However, I found a study done on amino acid absorption in rats. It turns out that pinto beans, one of the least rich protein sources of methionine, had the highest absorption rate the amino acid. I’m sure absorption of methionine from soy is low as well because some of the chemicals in soy interfere with overall amino acid absorption.
However, soy introduces an extremely important consideration that might make it impossible for humans to benefit from methionine restriction. Soy contains estrogen-mimicking phytochemicals which will have some effect on producing anabolic processes. (the exact thing we’re trying to prevent to extend longevity) These chemicals must be detoxified by Phase 1 enzymes in the liver. If this pathway is not working because of a deficiency of methionine, folic acid etc then there will be accumulation of these chemicals in the fat tissues possibly increasing incidence of hormone-sensitive cancers. There are hundreds of anabolic hormone-mimicking chemicals that are now ubiquitous in our environment including BPA, several pesticides and hormones from pharmaceutical use. Any steps taken to reduce methionine will slow detoxification of these chemicals to a trickle.
If you want to continue to think creatively, be active, fully participate in life and be able to detoxify various environmental chemicals, you have no choice but to consume foods that allow your body to do this. If you want to attempt to extend your life through the means of caloric and methionine restriction then you will spend your life existing, not fully living and you might still get cancer. Perhaps one way of using the current knowledge of caloric and methionine restriction to extend life is to follow what would naturally happen with the seasons. For example, reduce your activity in the winter and practice caloric and methionine restriction. Personally, I love skiing too much and need lots of protein to be able to do it. That said, I’m going to continue to eat 8-10 eggs per week along with lots of kale.by