Faculty of Medicine

Salmon changes your stool

Individuals consuming salmon for five days a week for eight weeks had a change in the bacterial flora in the large intestine. This is the conclusion of a new study from the Centre for Nutrition.

Lakseskive på fjøl med salt, krydder og sitron

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It is well known that what we eat influences gastrointestinal function. Different types of carbohydrates, especially fiber, can influence the bacterial composition in our intestine and can have both positive and negative health effects. So far, it has not been shown before that the choice of protein source can also influence gastrointestinal function.

Researchers at the Centre for Nutrition asked 67 healthy adults with overweight to eat either cod, salmon, or no fish at all for five days a week for a total of eight weeks. The study was originally designed to investigate whether fish intake influences blood glucose regulation in these individuals.

"It was a bit surprising that only salmon had a positive effect on blood glucose, while cod had no effect", says Odrunn Anita Gudbrandsen from the Centre for Nutrition, Department of Clinical Medicine.

Salmon consumers had less of the unfavorable bacteria

There is a link between gut bacteria and blood glucose which is the reason why the researchers wanted to investigate whether the composition of the intestinal flora changed with high fish intake. They selected 15 participants in each dietary intervention group of which they collected stool samples.

It turned out that those who had eaten salmon five times a week had changed their intestinal flora, and it was particularly interesting that they had fewer Bacteroidetes in their stool. That was an exciting result according to Gudbrandsen because the amount of these bacteria is often increased in patients with type 2 diabetes.

"This supports our previous articles that showed that salmon improved blood glucose regulation in this group", emphasizes Gudbrandsen.

Not as big of a change in those eating meat

Fish consumers were compared to a group consuming meat for dinner every day. They did not have a similar change in the occurrence of this bacteria after eight weeks:

"It is difficult to say whether it is the high salmon intake or the absence of meat that causes the change in the salmon group. At the same time, we do not see this change in intestinal flora in those who only consumed cod, so we think we have reason to say that it is the intake of salmon causing our findings", says Gudbrandsen.

"Normal" food can influence our health

The consistency and type of stool did not change during the study period and all participants were healthy and had a healthy gut. This means that there are no grounds for saying that eating a lot of salmon causes a healthier gut:

"We know a good deal about what unhealthy intestinal flora is, but we know less about the healthy intestinal flora. This finding gives us new knowledge in a relatively young field. We need research on how the food we eat influences our health through our intestinal flora", says Gudbrandsen.

In this study, participants consumed fish five times a week, which is a lot more than recommended by the health authorities. In the next study, the researchers want to investigate whether a lower fish.

Read the full article here: https://pubmed.ncbi.nlm.nih.gov/28606215/