Research confirms the importance of intestinal flora to our health

More and more studies are confirming the importance of intestinal flora to our health. A well-balanced intestinal flora strengthens our immune system and reduces the risk of infection. Some intestinal bacteria can even save our lives.

Awareness of the importance of intestinal flora has increased in the last decade. Our intestinal system, especially the large intestine, consists of healthy and disease-causing bacteria. The human intestinal tract contains around 100 billion microorganisms. This compilation of microorganisms is called the intestinal microbiota and consists mainly of the bacteria Firmicutes and Bacteroidetes, but also of fungi, yeast and viruses. A good microbiota is considered a crucial factor for our health. That’s why a lot of today’s medical studies focus on the microbiota’s role in the development of various diseases such as inflammatory bowel syndrome, cancer, type 2 diabetes and autoimmune rheumatological diseases. The intestinal microbiota is important from the moment we are born. It can be a matter of life and death for babies born very prematurely.

This year, a Swedish study was presented showing that provision of the lactic acid bacterium, Lactobacillus, can save the lives of a lot of premature babies. The study was led by scientists from Linköping University and was published in the Cell Reports Medicine journal.

Suffering from inflammation

Very premature babies can suffer from very severe intestinal inflammation. The condition is called necrotising enterocolitis, or NEC, because parts of the intestine die. As many as one in three children with NEC die, and those that survive often have long-term complications such as shortened intestines or delayed development.

In very premature babies, the bacterial composition in the gut is different from newborns born after normal pregnancies. For this reason, several studies have investigated whether the provision of certain bacteria, known as probiotics, can give positive effects.

The Swedish study is part of a clinical study conducted in Linköping and Stockholm, which included 132 children born between weeks 23 and 28 of pregnancy and who weighed less than a kilo at birth. The children were randomly divided into two groups, with one group receiving oil drops with probiotics and the other receiving drops of a placebo. The treatment took place daily until the week when the child should normally have been born. The scientists investigated how the bacterial flora were affected when Lactobacillus was added. Then they analysed the bacteria in the babies’ excrement at different times. The scientists saw a difference in the bacterial flora in the intestine during the first month among the babies who were given a probiotic treatment, compared with the placebo group. In the untreated group, the potentially pathogenic bacterial groups, Staphylococcus and Klebsiella, also appeared to a greater extent during their first week of life.

Probiotics are now being used in more and more neonatal wards because it is generally considered that there is scientific support for probiotics being useful and safe to give to premature babies.

Reduction of blood poisoning and NEC

Just as in the Swedish study, a British study published in the medical journal, Archives of Disease in Childhood, also shows that supplementation of probiotics saves the lives of premature babies. Researchers at the Norfolk and Norwich University Hospital (NNUH) in England have been keeping track of nearly 1,000 premature babies over a ten-year period. The results show a reduction in blood poisoning and necrotising enterocolitis, or NEC, in children who were given  probiotics. Norfolk and Norwich University Hospital (NNUH) was one of the first hospitals in the UK to introduce a daily dose of probiotics for premature babies in the neonatal ward.

Difficult to get nutrition

Babies born prematurely also have difficulty ingesting food because a lot of their organs are not properly developed. This means they are not getting enough nutrition either.

In another study on very premature babies, Chinese researchers investigated the effect of probiotics with food intake. They looked at whether the children gained weight and whether the time they needed to stay in hospital could be reduced if they were given probiotics. The study is what’s known as a meta-analysis, in which the researchers reviewed nine previously conducted studies using probiotics. Six of those studies showed that probiotics were beneficial. Children who weighed 1.5-18 kilos at birth and were given probiotics increased to about 1.9-2.6 kilos, while those who received placebos increased their weight more slowly, from 1.4-1.9 kilos at birth to 1.7-2.2 kilos. In four of the studies, they also showed that time spent in hospital was reduced.

Elderly people’s intestinal flora changed

But it’s not just premature babies who get a lot of benefit from probiotics. With age, biological as well as physiological changes occur which create an imbalance in the intestinal flora, known as dysbiosis, and there is a wealth of research literature describing age-related changes to the composition of the intestinal microbiota, which has a huge effect on our general health. A lot of older people also suffer from chronic, low-level inflammation.

Previously, it was thought the western diet alone was behind the imbalance in the intestinal flora and the accompanying age-related inflammation. We know that an unhealthy diet and lifestyle can reduce the amount of beneficial bacteria and instead increase the growth of unwanted bacteria, which brings with it a risk of various diseases. But recently, Emeline Ragonnaud, a visiting researcher at the University of Copenhagen and Arya Biragyn, a researcher and director at the National Institute of Aging, NIA in Baltimore, USA, showed that change can be built into the ageing process. What happens is that the good bacteria seem to decrease with age and instead they are replaced by bacteria that promote chronic inflammation.

But, even if we cannot prevent ageing, there is nothing to say that we can not improve our intestinal flora and thereby feel good even as we get older. Studies have shown that taking probiotics can significantly help inhibit pro-inflammatory markers in older people. Probiotics together with prebiotics, so-called resistant starches or insoluble fibres as well as proteins play a role in reducing inflammation in the elderly.

Beneficial chilli

Regardless of whether we’re young or old, our intestines and our health will benefit from having a varied, well-balanced intestinal flora. We can find probiotics in our diets from, for example, raw, unheated, acidic foods such as yogurt, buttermilk, herring and sauerkraut and, for the body to absorb and retain probiotics, there are prebiotics in foods such as cold potatoes, legumes, asparagus, bananas, oatmeal, almonds and honey. To take care of our intestinal health, we should also use spices. One spice plant that is regarded as having particularly good properties is chili pepper or rather capsaicin, the molecule found in chili.

Previous studies on capsaicin have shown a beneficial effect because it has anti-inflammatory properties and can also protect against obesity. The reason is that capsaicin is good for the intestinal microbiota.

To find out how regular consumption of capsaicin affects the intestinal microbiota, researchers from the USA and Japan used an in vitro model in a recently published study on human intestinal flora. An in vitro model involves studying microbiota from humans in a test tube. Using a combination of the latest type of gene sequencing and metabolomics, which can be very simply described as studying small molecules in a biological sample in a single chemical analysis, the researchers found that a regular intake of capsaicin changed the structure of the microbiota, among other things. an increased diversity of bacteria and certain short-chain fatty acids was observed, especially butyrate or butyric acid, which help the intestinal mucosa to stay impervious and strong, and to form a barrier against toxic substances that could pass through the intestine.

Most researchers now agree that intestinal flora is important for both our physical and mental well-being. However, we do not yet know which are good or bad intestinal flora. But the field of research has literally exploded and the connection between intestinal flora and health is now being studied around the world. And, who knows – maybe one day it will be possible to individually tailor diets to each person’s specific intestinal flora?



Effects of Lactobacillus reuteri DSM 17938 supplementation on the gut microbiota in extremely preterm infants in a randomised placebo-controlled trial.

Magalí Martí, Johanne E. Spreckels, Purnika Damindi Ranasinghe, Erik Wejryd, Giovanna Marchini, Eva Sverremark-Ekström, Maria C. Jenmalm och Thomas Abrahamsson, (2021), Cell Reports Medicine, published online 22 februari 2021.

Robertson C, Savva GM, Clapuci R, Jones J, Maimouni H, Brown E, Minocha A, Hall LJ, Clarke P. Incidence of necrotising enterocolitis before and after introducing routine prophylactic Lactobacillus and Bifidobacterium probiotics. Arch Dis Child Fetal Neonatal Ed. 2020 Jul.

Zhang W, Wang S, Xing Y, Wang H, Fu B, Long M, Cao J. Clinical efficacy of probiotics on feeding intolerance in preterm infants: a systematic review and meta-analysis. Transl Pediatr. 2022 Feb.

Warman DJ, Jia H, Kato H. The Potential Roles of Probiotics, Resistant Starch, and Resistant Proteins in Ameliorating Inflammation during Aging (Inflammaging). Nutrients. 2022 Feb 10.

Ragonnaud E, Biragyn A. Gut microbiota as the key controllers of “healthy” aging of elderly people. Immun Ageing. 2021 Jan 5.

Mahalak KK, Bobokalonov J, Firrman J, Williams R, Evans B, Fanelli B, Soares JW, Kobori M, Liu L. Analysis of the Ability of Capsaicin to Modulate the Human Gut Microbiota In Vitro. Nutrients. 2022 Mar 18.

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