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Good bugs in the gut

“Gut microorganisms” make up two kilos of our total body weight
Many of our actions have an uncontrollable, instant reaction in the gut

Dr. Gita Mathai   |     |   Published 17.09.19, 01:46 PM

We all think we are composed of human cells, but actually a part of us has always been alien, as we are colonised with microorganisms. Bacteria start living in our intestines soon after birth. These “gut microorganisms” make up two kilos (65 per cent of the total number of body cells) of our total body weight.

Many of our actions have an uncontrollable, instant reaction in the gut. It can be anxiety-causing nausea and diarrhoea, tension and stress contributing to the symptoms of IBS (inflammatory bowel disease), or heartburn, ulcers and even Crohn’s disease. Our stomach can “tie itself up in knots”.

Even when antispasmodics, antimotility agents and antacids are used, the response to specific medication may not be optimal. When antianxiety or anti-depression agents are added, the response improves rapidly. If the gut bacteria are also tackled, the response is better. The vagus nerve connects the smooth muscles of the intestines to the brain. It might be responsible for carrying the unconnected symptoms.

The symptoms may in part be due to the two kilos of microbes in our intestines. They use nutrients from the food we eat and produce waste products. These excretory products also have a local action on the intestines and a distant action on parts of the body, particularly the brain. Gut bacteria release chemicals such as cytokines that produce inflammation. This contributes to pain, muscle spasms and motility problems.

The microbes colonising the gut are very individual. They vary by race and country. Scientists found that gut bacteria in persons with autism, Alzheimer’s, Parkinson’s, dementia, neurological and muscular degenerative diseases were different from that in normal people. They have a role in controlling appetite and the chemicals they release may reset the appetite centre in the brain, contributing to obesity. They also help with glucose utilisation and can alter the ratio between white and brown fat-storing cells.

Gut bacteria synthesizse essential vitamins, especially those belonging to the B complex group and several antioxidants. These help the body develop immunity and fight disease. They help improve the breakdown of lactic acid, which they use as a nutrient. This reduces fatigue, increases endurance and improves performance in athletes. Elite athletes have specific gut bacteria, different from those found in sedentary people.

Antibiotics indiscriminately kill bacteria, both disease-causing organisms and beneficial ones. They can cause an unbalanced overgrowth of harmful bacteria resulting in diarrhoea, vitamin and mineral deficiencies and even dangerous conditions such as necrotising enterocolitis.

The pharmaceutical industry promotes theconcept of good and bad bacteria by advocating the administration of pre and probiotics along with antibiotics. Prebiotics are dietary fibre which theoretically act as a base for the growth of good bacteria. Probiotics are good bacteria, which are meant to populate the gut. To work, probiotics have to be live cultures. These can be killed by heat, stomach acids or with prolonged storage. Neither has been proven to be efficient.

It is possible to try to populate your gut with healthy microbes. Whatever you eat provides nutrition for yourself and your inner bacteria.

  • Eat at least 4-6 helpings of fresh fruits and uncooked vegetables a day
  • Eat a variety of food and vegetables
  • Do not take unnecessary antibiotics, especially OTC (over the counter) and for viral infections
  • Drink three litres of water a day
  • Increase the fibre content of food by using nuts and whole grains
  • Limit the quantity of red meat eaten
  • Highly processed food with colours and preservative chemicals are harmful to gut bacteria
  • Eat natural probiotics such as homemade curd. Expensive supplements may not be worth the 

The writer is a paediatrician with a family practice at Vellore and author of Staying Healthy in Modern India. If you have any questions on health issues, please write to


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