Microbiome Diet ~ 4.1 Harmful Foods - Alcohol

We know that our diet is one of the most powerful modulators on the composition and function of the microbiota. This influence is so strong that changes in our diet can affect how our microbes develop and adapt. So what is the connection between alcohol consumption and gut health?

This is part 4.1 of the articles about the Microbiome Diet. Read part 3 here: Microbiome Diet 3: Boost the Beneficial Bacteria and part 4.2 here: Microbiome Diet 4.2: Harmful Foods - Artificial Sweeteners .

The connection between our gut and immune system

Our gut and our immune system constantly exchange information : Which microbes are dangerous and which should be tolerated?

A strong core of beneficial microbes maintains intestinal balance and  regulates how our body responds to potential threats .  When beneficial bacteria ferment complex carbohydrates, they mainly produce short-chain fatty acids (SCFA) which are essential for modulating and mediating the immune system .

SCFA also supports the cells in the gut that make up the inner walls of our intestines. These cells and the mucus they produce make up the intestinal barrier, i.e. the first line of defense against invaders. SCFA strengthens this barrier and prevents unwanted openings. This is essential to prevent bacteria and toxins from "penetrating" through the intestinal wall and into our bloodstream. The consequences would be serious: Endotoxemia (the presence of bacterial toxins in the blood) , autoimmune diseases, mental disorders (depression), diabetes, inflammatory bowel disease and multiple sclerosis.

In addition, SCFA has important anti-inflammatory effects on intestinal immune cells.

And on top of this, SCFA also affect organs far away from the gut , such as the brain, liver, pancreas, and skin.

Alcohol and gut health

We know that excessive alcohol consumption is harmful to human health. It costs the European healthcare system over 22 billion euros every year. Around 25% of heavy drinkers develop some kind of liver disease, such as alcoholic steatohepatitis or cirrhosis . And these negative effects also affect our gut microbiome and immune system .

How does alcohol affect our gut?

Heavy alcohol consumption alters the relative abundance of some microbes, leading to major changes in diversity. In particular, it causes a reduction in bacteria with anti-inflammatory properties, such as the Bacteroidetes and Firmicutes phyla, while increasing the number of microbes that thrive in inflammatory environments.

Alcohol abuse also disrupts the intestinal barrier and damages the intestinal lining. This allows bacterial or harmful components of their membrane to leak into the bloodstream and reach other organs, where they can be damaged.

This combination can ultimately lead to dysbiosis and inflammation in the gut.

Gut-liver axis

Although the so-called "gut-liver axis" is a relatively new concept, it can be understood as a two-way interaction between the gut and the liver, which also involves the immune system.

The portal vein is a direct biological connection that conducts nutrients and intestinal-derived products towards the liver, which produces bile acids, proteins, lipids, and immune components.

Excessive alcohol consumption disrupts this gut-liver communication and sets off a chain of inflammatory interactions that damage the liver.

Some practical advice

When it comes to alcohol and gut health...

1. Minimize your consumption : It is a good idea to moderate your intake, limiting it to a maximum of 4 units of alcohol per day or 10 units per week.
2. Choose red wine : We recommend consuming red wine instead of other alcoholic beverages, due to its polyphenol content.
3. Avoid sugary drinks : Unfortunately, many drinks, cocktails, and sodas are loaded with sugar or artificial sweeteners. And some tonics have more sugar than cola. It's a good idea to check the ingredients before you drink them to avoid a sugar crash.
4. Drink the 'traditional' way : In some cultures, wine is only consumed with a main meal. Wine should be considered a "treat" to be enjoyed responsibly and in moderation.

Author: Cecilia Clausen (Clinical Dietitian)