In Nature Reviews Immunology, Teuwen et al. proposed that endothelial cells play a central role in the escalation of Covid-19, the disease caused by SARS-CoV-2. Endothelial cells line our blood vessels.

This made me think of quercetin. Quercetin is what’s known as a bioflavonoid. It’s pretty common in the human diet, especially if you eat healthy things like apples and onions, or enjoy red wine.

In in vitro (“test-tube”) studies, quercetin displays properties that may help keep our endothelial cells healthy. But as far as I know, no clinical studies have been performed on humans to look into this.

As Egert et al. reported in the Journal of Nutrition, a quercetin supplement can increase blood levels of quercetin in humans. Can it increase them enough to protect your endothelial cells, possibly even from Covid-19? Again, we need studies to determine this.

In the mean time, my wife and I have been taking a quercetin supplement, just in case it helps. We each take 1 capsule daily providing 500 mg of quercetin in the anhydrous form. (The Egert et al. study used quercetin dihydrate. I found out after making my purchase that it was quercetin anhydrous.) We take it with a meal, in case the fat and/or other food components enhance its absorption.

I figure it won’t hurt. Of course, there’s no guarantee. I recognize that 500 mg of quercetin is a “pharmacological” dose in the sense that it’s much higher than you’ll likely get from the typical diet.

Why did I choose a 500-mg supplement? I know that the bioavailability of quercetin is fairly poor. If it can provide any benefits to my endothelial cells, I figure it will require a pharmacological dose to do so. Besides that, the 500-mg product seemed like a relatively good deal on Amazon.

I am not recommending that you take a quercetin supplement. I’m just sharing this information for your interest. Of course, it goes without saying that the best way to get more quercetin is by eating more of the healthy foods it is found in. Stay safe and #MaskThatAss!