Lipopolysaccharides — LPS for short — are components of the outer membrane of certain bacteria that live in the gut. For the body, they represent an unambiguous alarm signal: wherever LPS appear, the immune system knows something is wrong.
As long as the gut wall is intact, LPS stay where they belong — inside the gut. The problem begins when the gut barrier is compromised through Leaky Gut and LPS enter the bloodstream.
What LPS trigger in the body #
LPS that enter the bloodstream travel directly via the portal vein to the liver. There, they activate Kupffer cells — the liver’s immune sentinels — through a receptor called TLR4. The response is an inflammatory cascade involving the release of cytokines including TNF-alpha and IL-1beta. These inflammatory messengers damage liver cells and simultaneously increase the permeability of the gut wall further — a cycle that drives itself.
In chronic alcohol use, LPS levels in the blood are persistently elevated. Researchers call this state endotoxaemia. It is recognised as one of the central mechanisms behind alcoholic fatty liver, hepatitis and liver cirrhosis.
LPS and the brain #
LPS are not confined to the liver. Via the bloodstream they also reach the brain, where they can initiate inflammatory processes. Current research shows connections between elevated LPS levels and the inflammatory marker IL-8 — a messenger substance that in people with alcohol use disorder correlates directly with the intensity of craving. The gut therefore influences not just the liver, but possibly the urge to drink itself.
LPS are closely linked to dysbiosis and Leaky Gut — and through the gut-brain axis they are part of a larger picture that explains why alcohol affects not just the body, but the mind and addictive behaviour as well.
What are lipopolysaccharides?
Lipopolysaccharides (LPS) are components of the outer membrane of gram-negative gut bacteria. They act as a powerful alarm signal for the immune system. In a healthy gut they remain inside the intestine. When the gut wall becomes permeable through leaky gut, they enter the bloodstream and trigger systemic inflammatory responses.
What do LPS have to do with alcohol?
Alcohol damages the gut wall and promotes the growth of LPS-producing bacteria. Together, these effects cause elevated amounts of LPS to enter the bloodstream. This state — called endotoxaemia — is a central mechanism behind alcohol-related liver damage and systemic inflammation.
How do LPS damage the liver?
LPS travel via the portal vein directly to the liver, where they activate Kupffer cells — the organ’s immune guards. These release inflammatory messengers that attack liver cells. With sustained LPS exposure, this can lead to fatty liver, hepatitis and cirrhosis.
Bernd Guzek, MD, PhD #
Physician, author & co-founder of Bye-Bye-Booze
Specialized in biochemical mechanisms of addiction and brain metabolism.
