Many experiments and studies on life extension have found the interesting and important result that lowering blood glucose (blood sugar) and/or restricting dietary carbohydrates means longer life. This has been found using several different lab animals and in humans as well. It’s possible to have longer life through lower blood sugar.
Acarbose is an anti-diabetic drug that works by inhibiting enzymes in the gut that break down carbohydrates to glucose, and therefore less glucose is absorbed.
Male mice that were fed acarbose lived 22% longer than controls, although the female mice lived only about 7% longer.
A lifespan increase of 22% is large, among the longer lifespan extensions seen with other interventions, comparable to rapamycin and a larger increase than fat-tissue insulin receptor knockout. Acarbose reduced fasting insulin in male mice but not in females, which may account for the difference in lifespan extension.
IGF-1 was decreased in both sexes, and fibroblast growth factor 21 (FGF21) was increased, and both of these hormonal changes could be involved in life extension.
In humans with type 2 diabetes, long-term acarbose treatment was associated with a huge 50% decrease in the risk of cardiovascular events such as heart attack and stroke. Importantly, the risk reduction was associated with a decrease in postprandial hyperglycemia, or a rise in blood sugar after eating.
A meta-analysis of acarbose found similar large reductions in CVD events.
Since dietary carbohydrates, especially grains, sugar, and starches, are the primary determinant of blood sugar, why not just cut carbohydrates instead?
Metformin is the most prescribed anti-diabetic drug, and it lowers blood sugar and insulin. Similar large reductions in death rates have been found with metformin use, so much so that diabetics using metformin may outlive non-diabetics who don’t use it.
Would cutting carbohydrates cause the same life extension and anti-aging as metformin?
An argument against that is that diabetics taking metformin may live longer than non-diabetics who don’t take it. Therefore, metformin may be causing a real anti-aging effect.
An argument for it is that most non-diabetics eat large amounts of carbohydrates, with the average American eating about 50% of his or her calories as carbohydrate. And among average people, Dr. Joseph Kraft showed that large numbers, perhaps up to 80%, have some degree of impaired glucose tolerance, i.e. they’re insulin resistant.
If metformin increased lifespan in animals or people who ate little or no carbohydrates, that would be convincing, but to my knowledge, it has not.
Glucosamine is an over-the-counter supplement commonly taken for arthritis and joint pain. Glucosamine extends lifespan in mice through
an induction of mitochondrial biogenesis, lowered blood glucose levels, enhanced expression of several murine amino-acid transporters, as well as increased amino-acid catabolism. Taken together, we provide evidence that GlcN [glucosamine] extends life span in evolutionary distinct species by mimicking a low-carbohydrate diet. [My emphasis.]
Glucosamine impairs glycolysis (glucose metabolism) and therefore lowers blood glucose levels.
Glucosamine also activates autophagy, the cellular self-cleansing process that retards aging, and inhibits mTOR, the cellular growth engine that accelerates aging.
In humans, use of glucosamine is associated with an 18% lower death rate.
Again, if glucosamine mimics a low-carbohydrate diet, why not just eliminate the middleman and refrain from eating carbohydrates?
Fasting, eating a very low amount of carbohydrates (usually less than 50 grams daily), or taking ketone supplements or MCT oil raises the amount of molecules known as ketones in the bloodstream. Increased ketones mimic the effects of food restriction by lowering blood glucose and insulin.
While ketone supplements are generally beneficial in my opinion, if you cut the carbohydrates, albeit radically, you’re in ketosis (producing ketones) and presumably extending your lifespan and fighting aging by doing so.
Feeding glucose to the worm C. elegans shortens its lifespan.
When carbohydrates are digested, they become glucose inside the body, since most carbohydrates are just long chains of glucose. (Sugars may incorporate other molecules, such as fructose and galactose.)
So why not just restrict carbohydrates?
As we’ve seen from the studies above, multiple lines of evidence lead to the conclusion that restricting carbohydrates and thus preventing high blood glucose, whether spikes in it or a higher average glucose, leads to longer life.
These same lines of evidence lead to the conclusion that carbohydrates can promote aging and shorten life.
Note that some carbohydrates, namely complex carbohydrates found in non-starchy vegetables, don’t raise blood sugar much if at all.
The foods that contain abundant carbohydrates and increase blood glucose are the ones to restrict or eliminate, and they include grains (wheat, rice, corn, etc.), sugar, and starchy tubers such as potatoes.
Someone who is very insulin sensitive may not be harmed much by carbohydrates. These people include athletes and other lean people who exercise or labor at physically demanding jobs.
Anyone else, and that includes most people, would likely see a big improvement in health by restricting carbohydrates.