How whole-grain rye consumption can improve gut health
17 May, 2019
Researchers know that whole grains are good for health, but the mechanisms at play remain unclear. However, a recent study in humans and mouse models now shows just how certain whole grains help regulate gut health.
Studies from the past few years have shown, variously, that eating whole grains and foods containing them can help maintain a healthy gut.
It can even help prevent type 2 diabetes and reduce the risk of colorectal cancer.
Although we know that consuming whole grains brings us benefits, it remains unclear what biological mechanisms are at play.
Recent research has pointed to the impact on metabolites, molecules formed and used during metabolic processes, when it comes to the positive effects of whole grains on gut health.
A new study has looked further into how eating whole-grain rye and wheat impacts gut metabolism. Its findings may hold an answer to why whole grains can help prevent gut problems and conditions such as colorectal cancer.
The research — by scientists from the University of Eastern Finland in Kuopio and the International Agency for Research on Cancer in Lyon, France — suggests that consuming whole-grain rye or wheat has an impact on plasma (blood) serotonin levels, with implications for health.
The team reports these findings in The American Journal of Clinical Nutrition.
Lower blood serotonin levels
In their new study, the scientists analyzed how whole grains affected the concentration of different metabolites in the blood — first in humans, and then in mouse models.
For the first part of the research, they recruited 15 adult participants. For 4 weeks, the participants ate between six and 10 slices of low-fiber wheat bread per day.
Then, for another 4 weeks, they each ate six to 10 slices per day of either whole-grain rye bread or wheat bread supplemented with rye fiber. Aside from this, none of the participants made any changes to their normal diets.
The researchers collected blood samples from each participant once at the end of the first 4-week period and again after the next 4 weeks. This was so they could compare the samples for any changes driven by the consumption of whole grains.
Analysis of these blood samples indicated that people who had added whole-grain rye into their diets had significantly lower plasma serotonin levels, compared with when they had eaten low-fiber white bread.
In the second part of their research, the investigators worked with mice in an attempt to find out whether introducing cereal fiber to one's diet can affect the levels of serotonin the intestines produce.
People may be familiar with the concept of the hormone and neurotransmitter serotonin, which is linked to the regulation of emotions, being present in the brain. However, the gut also produces this hormone independently.
Gut serotonin serves other functions, such as the regulation of gut motility and the gastrointestinal tract's muscles' ability to relax and contract, which allows food to pass through.
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