According to a recent study conducted by the University of Eastern Finland and the International Agency for Research on Cancer (IARC), adults who eat wholegrain rye, have lower levels of serotonin in the plasma than people who eat white bread, low-fiber foods. It has also been found in the study that fiber intake of rye or wheat reduces serotonin in the large intestine of mice. In light of the health benefits of whole grains may be due, at least in part, to changes in serotonin in the gut, which produces most of the serotonin in the body. The results were published in the American Journal of Clinical Nutrition.
Consumption of whole grains has been associated with a lower risk of developing type 2 diabetes, cardiovascular diseaseand some cancers, but the underlying mechanisms are still poorly understood. Possible effects on the biologically active compounds contained in the whole grain, phytochemical and fibrous materials, from which the intestinal bacteria produce a variety of metabolites.
New study investigated as rye wholegrain consumption modulates the concentration of various metabolites in the bloodstream. The study used metabolite profiling diversion, also known as metabolomics, which can simultaneously detect multiple metabolites, including previously unknown.
During the first four weeks of the study participants ate from 6 to 10 pieces per day of wheat bread and low-fiber, and then another four weeks the same amount of whole grain rye bread or white bread with the addition of rye fiber. Otherwise, they did not change their diet. At the end of both periods they gave blood samples that were analyzed by a combination of liquid chromatography and mass spectrometry. Their plasma metabolite profiles between diet periods were then compared.
The consumption of whole grain rye led, among other things, to significantly lower concentrations of serotonin as compared with the consumption of white bread with a low fiber content. The researchers also tested on mice, whether supplementation with dietary fiber effect on cereal production of serotonin in the gut. A diet of mice for nine weeks complemented rye bran, wheat bran or cellulose flour. In mice treated with rye or wheat bran, serotonin was significantly lower in the colon.
Serotonin is best known as a neurotransmitter in the brain. However, serotonin produced in the gut, is separate from the brain, serving a variety of peripheral functions, including modulation of intestinal motility. Elevated levels of serotonin in the blood is also associated with high blood glucose levels.
"On the other hand, it is known that whole grains reduce the risk of diabetes, and based on these new results the effect can be at least partly due to lower levels of serotonin," - says the researcher of the Academy of Katie Hanhineva of the University of Eastern Finland.
Researchers are also interested in serotonin association with colorectal cancer.
"Some recent studies have shown that cancer patients plasma serotonin level higher than that of healthy people", - adds the scientist Pekka Keski-Rahkonen from IARC.
Consumption of whole grain rye bread was also associated with lower concentrations of taurine in plasma glitserofosfoholina and two endogenous glycerophospholipids. In addition, the researchers identified 15 rye phytochemicals, whose level in the blood increased with the consumption of rye fiber.