Sugar Changes Your Gut Biome

July 24, 2023

Sugar Changes Your Gut Biome - And Makes You Fat

I bet you have never heard of microbiota-induced or commensal Th17 cells. Well, you should know about them because they are what you are fighting over in your struggle to not be fat. It's not simple, but the evidence is there. Here is the story.

Your microbiome is a complicated system with at least 100 to possibly 1,000 times the DNA of your own genome. That's if we have a healthy biome in our colon. There is constant cross-talk between your gut, immune system, and brain. All are interdependent on each other. Scientists have now found a separate class of white blood cells called commensal Th17 cells that do some very interesting work. Commensal gut bacteria are those that live alongside the gut lining and do not initiate disease under normal conditions. There they "show" antigens that can be detected by the organism’s immune system and give rise to commensal-specific lymphocytes. When that goes awry, you get the rise of autoimmune diseases. The T cells that are made start in the thymus gland, but their generation of commensal T cells is dependent on the type of commensal microorganism present in the gut. Scientists have now found that segmented filamentous bacteria are particularly good at stimulating them. The study of those segmented filamentous bacteria is all the cutting edge of biome research right now. 

What happens when you eat sugar? Aha, there's the rub. A high-fat, high-sugar diet (think donuts, ice cream...) promotes metabolic disease by depleting those commensal Th17-inducing microbes. When they come back the commensal Th17 cells restored protection. Microbiome-induced Th17 cells provide protection by controlling lipid absorption across intestinal gut lining in an IL-17-dependent manner. The number of commensal Th-17 cells defines the absorption of fat, inversely. You want lots of Th-17 cells. Much less fat absorption. Sugar depletes them. And fat goes into the circulation to be added to your hips. That simple.

Table sugar, notably fructose, is not that great a friend. It is easy to show that fructose starts metabolic syndrome by overwhelming the liver, driving uric acid up, NAD down, and fatty liver to develop. Now we know that fructose adds to its Darth Vader reputation by knocking off those beneficial commensal Th17 cells.

www.What will Work for me. You get a modest amount of fructose in fruit. It becomes concentrated when to throw out the fiber and make it into fruit juice. The average American is eating 10-12% of their calories in the form of sugar. Any food in a package likely has some sugar added to it. Ultra-processed foods (more than 5 ingredients some of which you can't recognize, can't buy in the grocery store) almost always have sugar in some fake name form or another. Carob syrup or maltodextrin caught my eye this week. Yup,both on the sugar list.

References: Cell, J Inflam Research, Frontiers Microbiology, 56 Names for Sugar, Nutrients

Pop Quiz

1. What's the name for the white blood cells that appear to block the absorption of fat, if they are living in a health gut?                    Answer: Commensal Th17 cells

2. They have a conversation back and forth between themselves and what type of bacteria in the gut?           Answer: Segmented filamentous bacteria

3. What does sugar do to his equation?                          Answer: A dramatic loss of the Commensal Th17 cells.

4. What happens when you stop eating sugar?                        Answer: The Th17 cells reappear.

5. Taking probiotics will make up for my eating a donut? T or F.                    Answer: Ha Ha.