While man’s connection with alcohol dates back several millennia, most would say this is far from a healthy relationship. Loved for its ability to help us let our hair down and relax, alcohol is also among the most highly addictive and abused substances we know of.
The health of millions of people across the world is affected today due to alcohol abuse, and research is showing that it does far more damage than cause liver and heart disease. It is a known carcinogen, reduces the strength of our immune system and wreaks havoc on the digestive system.
In this article we will discuss the effect of alcohol on our gastrointestinal tract, the first thing that anything we ingest contacts. The gut’s health plays an important role in the overall health of the body, and anything causing damage to it has consequences far beyond the intestines.
“Alcohol is absorbed in the small intestine and travels to the liver where it is metabolised. Enzymes present in the liver break down the alcohol into its by-products – acetaldehyde and acetate, which are toxic to the body,” says Dr Amit Yelsangikar, senior consultant and gastroenterologist, Aster CMI Hospital, Bengaluru.
Dr Yelsangikar walks us through the damage alcohol can cause to different organs of our gastrointestinal tract when consumed in excess and over long periods.
Alcohol causes damage to the stomach
Alcohol is known to cause a number of stomach problems, the most common being acid reflux and stomach ulcers.
“It [alcohol] causes relaxation of the junction or sphincter between [the] stomach and oesophagus. As the sphincter gets relaxed, the acid from [the] stomach moves towards the mouth thereby causing acid reflux,” explains Dr Yelsangikar.
Alcohol also damages the mucous layer that protects the stomach wall from digestive enzymes and gastric acid. With this layer being degraded, the enzymes and acid start damaging the wall of the stomach causing ulcers, he adds.
Alcohol leads to inflammation in the gut
“By-products of alcohol metabolism attract inflammatory cells in the intestine as well as liver. They produce various inflammatory chemicals known as cytokines, which cause gut inflammation,” says Dr Yelsangikar.
These cytokines make the wall of the gut permeable or ‘leaky’ by damaging its cells and tight junctions between them. It causes bacteria and toxins to get into the bloodstream, a phenomenon known as gut translocation. This can damage not only the intestine but other organs also.
In addition, they come in contact with immune cells of the intestine that generate a strong immune response. This immune response further enhances inflammation in the gut.
Alcohol causes damage to the intestines
Alcohol’s effect on the small intestine is both direct and indirect. “When [alcohol is] consumed in large amounts there is a direct toxicity to the intestine. This includes reduction of villi height, villi blunting and damage to enterocytes (cells lining the intestine),” says Dr Yelsangikar, adding that this can lead to ulceration in the small intestine.
The indirect damage occurs through inflammatory pathways in the intestine, which is very rich in blood supply and lymphatics. Inflammatory cells are recruited into the intestine by the by-products of alcohol metabolism via blood where they produce various inflammatory mediators that damage enterocytes (cells of the intestinal lining), he adds.
Alcohol also increases motility in the large intestine by affecting its muscle contraction, ultimately causing diarrhoea.
Alcohol reduces absorption of nutrients
“Long-term alcohol consumption causes malabsorption not only directly from the intestine but also indirectly because alcohol causes chronic enteritis. There is reduction in the absorption of nutrients such as amino acids, fats, vitamins, and minerals such as iron, calcium, zinc and magnesium,” says Dr Yelsangikar.
Chronic enteritis also leads to reduction in the absorption of protein, fat as well as fat soluble vitamins (A, D, E and K), he says. This causes malnutrition in people consuming alcohol including protein calorie malnutrition as well as vitamin and mineral deficiency.
Alcohol causes dysbiosis in the gut
Our intestine is home to billions of bacteria, collectively called the gut microbiome, which plays an important role in digestion and overall health.
“It [gut microbiome] is adversely affected by alcohol causing dysbiosis. There is a growth of harmful bacteria and fall in good bacteria population,” says Dr Yelsangikar. This can affect intestinal functions such as absorption of nutrients, and cause bloating and flatulence, he adds.
Gut dysbiosis, in turn, can negatively affect the physical health of individuals causing chronic fatigue, digestive problems, food intolerances and skin issues. Moreover, it can affect their mental and neurological health making them more prone to anxiety, depression, Alzheimer’s disease and Parkinson’s disease.
Alcohol’s association with cancer development
“Long-term alcohol consumption has been found to be directly or indirectly carcinogenic in multiple gastrointestinal tract organs and associated glands such as [the] stomach, large intestine, liver and pancreas,” says Dr Yelsangikar.
He adds that the risk of developing cancer due to alcohol consumption increases if a person is also a smoker or consumes tobacco and is genetically predisposed to developing the condition.
Alcohol-induced gut inflammation and DNA damage are thought to be the reasons behind alcohol’s carcinogenic properties. People who consume alcohol are more likely to get cancer in the pancreas and liver compared to those who do not drink.
Stomach cancer and colon cancer too are more common in people with long-term alcohol use, Dr Yelsangikar concludes.