Can a Fasting-Induced Changing-of-the-Guard for Immune Cells Help Treat Auto-Immune Diseases?

Evolution could assume many things during the millions of years of human evolution. One was that with the challenges of getting food and avoiding predators and dealing with rivals of their own and related species, hominins would not be sedentary. The other was that hominins would go through substantial periods of time with little or no food. (These assumptions are also good ones for most other animals as well.) As a result of these assumptions, human bodies malfunction when they don’t have some minimum of physical activity. Human bodies also malfunction when they don’t get substantial periods of time with no food.

In particular, there is growing evidence that periods of time with little or no food are the times when our bodies take apart defective and otherwise low-quality proteins—and to some extent defective and otherwise low-quality cells—and use them for spare parts. That quality control protocol may not happen if you always eat three meals a day.

A new study gets quite specific about one dimension of this process, with a detailed study of mice and a confirmatory, though less detailed study of humans. From Fiona MacDonald’s Science Alert article “Fasting Diet Has Been Shown to Ease Multiple Sclerosis Symptoms in Early Trial” comes this quotation:

"During the fasting-mimicking diet, cortisone is produced and that initiates a killing of autoimmune cells," said lead researcher Valter Longo from the University of South California. "This process also leads to the production of new healthy cells."

That part of the description of results gives hope that fasting might help with other autoimmune diseases as well. But there was also one effect more specific to treating multiple sclerosis. Let me add emphasis in bold italics:

"On the one hand, this fasting-mimicking diet kills bad immune cells," said Longo. "Then, after the mice return to the normal diet, the good immune cells but also the myelin-producing cells are generated, allowing a percentage of mice to reach a disease-free state."

Myelin is the protective sheathing around the long axons in nerves, that also helps make particular nerves transmit signals more readily. Problems with myelin producing cells are a big part of multiple sclerosis.

Serious clinical trials should be conducted on the effects of fasting on all the major autoimmune diseases. In addition, for those who have an autoimmune disease and don’t want to wait for the results of those clinical trials, it could be reasonable to decide that fasting is safe enough that it is worth doing an experiments of one’s own.

Autoimmune diseases have been listed among “diseases of civilization.” Our modern dietary practices—including when and how often we eat as well as what we eat—along with our sedentary lives are key suspects for all of the diseases of civilization. Hence, it is worth experimenting with a combination of exercise and periodic fasting as a home remedy for autoimmune diseases. It might or might not work, but the benefit if it does work is likely to be substantial, while the cost if it doesn’t work shouldn’t be that bad.

Let me end on an even more speculative note. Though we don’t yet understand long Covid very well, it is possible that for some people it has an important autoimmune component. After all, many of the people who die of Covid in its acute phase die because of an overreaction of the immune system. It seems possible that long Covid sometimes involves a less extreme overreaction of the immune system. If so, rebooting the immune system through a serious fast might help. Again, this might or might not work, but the mechanism is plausible, the cost is modest and the benefit if it does work is substantial. So it might be worth a try.