Update: This is a fairly technical blog post. Here are some less technical posts related to this topic:

• Eating During the Coronavirus Lockdown

• Interactions between COVID-19 and Chronic Diseases

• Getting More Vitamin D May Help You Fight Off the New Coronavirus

• Sugar Puts You in Greater Danger from Covid-19

• Appropriately Dosed Rapamycin and Metformin Can Improve Immune Function and Seem to Be Partial Preventatives for COVID-19

Since I wrote “Fasting Helps Avoid Collateral Damage in Fighting Bacterial Infections; Glucose Helps Avoid Collateral Damage in Fighting Viral Infections” about the potential dangers of being in a fasted state at the acute stage of COVID-19 when the immune system is hyperactive and immune system processes could do damage to own cells, I have been interested in possible other effects of fasting at other stages of infection. On this, note that the acute phase when one’s immune system is hyperactive is likely to be under a doctor’s care, so decisions then can probably be outsourced to that doctor; effects at other stages are more likely to be effects one needs to consider oneself.

In this post, I am going to talk about benefits of ketosis and benefits of fasting interchangeably. Fasting is the easiest and fastest way to get into ketosis. An extreme keto diet can also sometimes get to ketosis.

One important potential effect that I remember reading, but have lost the reference to, was a claim that ketosis could help reduce damage from being on a mechanical ventilator. I’d be glad for help finding that reference. But one thing that makes this a possible effect is that ketosis reduces production of carbon dioxide, which may reduce the amount of struggling to breathe. As long as medical technicians keep the actual level of oxygen adequate, less struggling to breathe may lead to less damage from the ventilator. (See the abstract shown below. Also see “Adaptation to chronic hypoxia during diet-induced ketosis” which sounds like another way in which ketosis could mute the effects of oxygen deprivation.)

Beyond that speculative effect on breathing struggles on a ventilator, measures such as fasting and going off sugar can reverse some chronic diseases such as diabetes, which appear to increase danger of dying if one gets infected by the novel coronavirus. (See “Interactions between COVID-19 and Chronic Diseases.”)

Two other potential benefits of fasting or a ketogenic diet are mentioned in the article shown at the top of this post that has an overstated title. Here is the first:

Flu-related inflammation can severely damage the lungs. It’s worth mentioning that shortness of breath is a marker symptom of the coronavirus, as well as influenza A. Coronavirus patients in critical care are also struggling with lung damage and the inability to breathe without a respirator.

To test the keto diet’s effects on flu-related inflammation, the Yale team fed mice infected with influenza A – the most serious type flu– either a keto or standard diet for a week before infection. After four days, all seven of the mice fed a standard diet succumbed to the infection, compared to only five out of the 10 mice on the keto diet. Additionally, these keto diet mice also didn’t lose as much weight, which is usually a sign of flu infection in animals.

It may be that this inflammation mechanism is not really distinct from the chronic disease interactions; it could be a major mechanism for those chronic-disease interactions. Anyway, beware of double-counting benefits.

Second, there is a possibility that fasting or a ketogenic diet channels the immune system toward a more helpful response: T-cells and mucus. From the same article at the top of this post:

The team at Yale was able to narrow down the exact effects keto had on the mice’s bodies. The keto diet boosted the numbers of a specific T cell that’s found in the lungs. T cells are part of the body’s immune response, and the amped number of those cells reduced the vulnerability of the cells lining the lunges, making them more resistant to infection and increasing mucus production.

Akiko Iwasaki says that the extra mucus is protecting the mice, and trapping the flu virus to stop it from spreading. While the bodies of mice to differ from humans, scientists do have a starting point from which to boost immunity and help cure coronavirus, influenza and more. 

Conclusion: I have to emphasize how speculative all of this is. However, also remember that chronic diseases kill more people each year than COVID-19 is likely to kill even in its peak year. So doing things that help with chronic diseases and might help in dealing with COVID-19 seems like a good idea.

For annotated links to other posts on diet and health, see:

• Miles Kimball on Diet and Health: A Reader's Guide