How whole-grain rye consumption can improve gut health

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.
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.
Some long-sought-after explanations?
During their research in mice, the scientists fed them additional rye bran, wheat bran, or cellulose flour for a period of 9 weeks.
The rodents whose diets the scientists enriched with rye or wheat bran had much lower serotonin levels in the colon, compared with rodents who had been on the cellulose flour diet.
These findings could explain why consuming whole grains could help prevent diabetes, since high plasma serotonin levels are also associated with high blood sugar.
Possible clinical implications
Other study findings indicate that incorporating whole-grain rye bread into one’s diet is also linked to lower blood levels of taurine, a compound present in many tissues and some biological fluids, such as bile.
A diet high in these whole grains was further linked to lower plasma levels of other metabolites, such as glycerophosphocholine, and two types of glycerophospholipid.
Up to 15 phytochemicals (plant-derived chemicals) from rye were present in higher concentrations in the blood of people who had eaten these whole grains regularly.

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