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Bacteria – important for gut feeling

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In the major population survey, Malmö Offspring Study, researchers are trying to discover how our intestinal flora is affected by diet and the consequences this has on health.
“We have about one and a half kilos of bacteria in our intestines”, says Louise Brunkwall – doctoral student in the research group Diabetes and Cardiovascular Disease – Genetic Epidemiology.

The Malmö Offspring Study is based on a previous population study conducted in the early 1990s – Malmö Kost Cancer – which involved about 30 000 people. The new study invites the children and grandchildren of around 6 000 of the previous participants to take part in the survey. This makes it possible to follow major widespread diseases over several generations. The study involves research on various diseases including different types of cancer, type 2 diabetes, cardiovascular diseases and dementia. Louise Brunkwall’s research focuses on the links between diet, health and intestinal flora.

The role of the intestinal flora

The intestines contain the largest bacterial ecosystem in the human body. We live in a symbiotic relationship with the bacteria we carry around with us. Different types of bacteria fulfil different roles and affect us in various ways.

“The intestinal flora consists of an incredible number of different types – some good and some bad”, says Louise Brunkwall.

The health-promoting bacteria help us to break down difficult-to-digest substances that we cannot otherwise assimilate. For example, they break down fibre into short-chain fatty acids that are important for intestinal health and are believed to counteract cancer by retaining the intestine’s mucous membrane. In addition, the bacteria help us to assimilate important vitamins and ensure that harmful bacteria types cannot grow unhindered.

The intestinal flora is important for our health

“You can clearly see how important the intestinal flora is for how we feel when it’s knocked out, by antibiotic treatment for example”, states Louise Brunkwall, who explains that this can lead to considerable problems, as harmful bacteria grow faster than the good type.

Stress and parasites are among the other factors that can upset the system. It is believed that an imbalance in the intestinal flora could be linked to certain inflammatory and autoimmune diseases and it is also thought that there is a connection between intestinal bacteria and obesity.

Our study gives us a much broader picture

“As the gastrointestinal tract constitutes such a large part of the body and contains so many bacteria, there are probably not many diseases unconnected to intestinal health in one way or another”, says Louise Brunkwall.What is a “normal” intestinal flora?

If the intestinal flora is damaged, it can take a long time for the system to recover and become “normal” again. However, the fact is that at present we do not know what a “normal” intestinal flora is – for example, it can vary greatly from one country to another. Louise Brunkwall hopes that the new study in Malmö will help us close in on the answer to that question.

“Earlier studies of the intestinal flora have often been quite narrow and focused on the differences between small, extreme groups such as people who are seriously overweight and those of average weight”, she says and continues:

“Our study gives us a much broader picture of the situation at population level.”

Can you trace the bacterial flora in old blood samples?

In the 1990s, when the first population study was conducted, no samples were taken of the bacterial flora in the intestines, however the blood samples from the test subjects are still available. Louise Brunkwall is therefore looking for a connection between the intestinal flora and molecules that can be found in the blood. As the Malmö Offspring Study crosses generational boundaries, it is possible to see the role of genetics in the system.

Diet affects the intestinal flora

On the question of how diet affects the bacterial flora and what you should eat to optimise it, Louise Brunkwall answers that most previous studies have also been limited and extreme along the lines of “only eat cheese for three days and see what happens”.

“Selective measures can be taken that lead to changes in the intestinal flora, but it’s long-term habits that produce lasting effects”, points out Louise Brunkwall, who continues:

“Fibre is good! Fruit and vegetables, not much meat and reduce sugar and alcohol. In general, it seems that what is good for us is also good for the bacteria.”