Scientists talked about the effect of blueberries on the microbiome of the elderly
Daily consumption of blueberries may be accompanied by changes in individual genes of intestinal microorganisms in elderly people with mild symptoms of depression. This was shown by a small study by American scientists. However, the authors have not yet received convincing evidence that berries improve the emotional state. How the experiment went and what was established is in the Izvestia material.
Why did scientists choose blueberries?
The researchers were interested in a possible connection between blueberry components, intestinal microorganisms and mood. Berries contain fiber and anthocyanins, substances that, according to the authors, can affect the microbiome and its metabolic products.
The gut microbiome is a community of microorganisms living in it and a collection of their genes. When studying it, it is important to take into account not only which bacteria are present, but also what biochemical processes they are capable of providing.
The study's lead author, Courtney Millar, a researcher at the Hindu and Arthur Marcus Institute for Aging Research, explained that the task was to pre-evaluate the effect of blueberries on the microbiome, its metabolites, and the severity of depressive symptoms.
Three months with berry powder
The experiment included people aged 65 and over who led a sedentary lifestyle and experienced mild depressive symptoms. The study was completed by 18 participants: ten in the blueberry group and eight in the placebo group. Their average ages were 71 and 75, respectively. Most of the participants were women.
For three months, the first group received 48 grams of blueberry powder daily. According to the authors, this corresponds to about two cups of fresh berries. The second group consumed a comparable placebo powder. The participants were randomly assigned to groups. The study was double-blind: neither the participants nor the researchers who interacted with them were supposed to know who got the berry powder and who got the placebo. This approach helps to reduce the impact of expectations on results.
Before and after the experiment, the researchers assessed depressive symptoms using validated questionnaires. At the same time, they analyzed fecal samples: they determined the representation of bacterial species and their genes, and also measured the content of short—chain fatty acids, the metabolic products of intestinal microorganisms.
What has changed in the intestine
The scientists did not find any noticeable changes in the representation of intestinal microorganisms. The studied parameters of metabolic pathways, as well as the content of short-chain fatty acids, have not changed.
At the same time, statistically significant changes in the representation of genes associated with several enzymes of the microbiome were detected within the blueberry-treated group. In other words, the differences were found at the level of individual genetic indicators, although the overall picture of the composition of bacteria remained the same.
One of these indicators related to an enzyme involved in the transport of polyamines. The authors associate it with the formation of gamma-aminobutyric acid, or GABA, a substance involved in the transmission of signals between nerve cells.
However, a change in the representation of microbial genes does not in itself prove that there is more GABA in the body or that brain function has changed. According to these data, it is also impossible to determine whether the detected differences affected the mood of the participants.
Has it become easier for the participants
In the blueberry group, the decrease in the severity of depressive symptoms looked more pronounced, and the results of the participants were more uniform. However, when compared with the placebo group, the differences did not reach statistical significance.
This is a key caveat of the study. The observed positive dynamics were not enough to confidently associate it with the consumption of berries. The authors obtained a preliminary result that requires verification in a larger experiment.
It is also important that changes in individual genetic parameters were found when comparing the condition of the blueberry group participants before and after the intervention. This result does not mean that the entire alleged chain has been proven: eating berries changes the work of intestinal microorganisms, and these changes reduce depressive symptoms.
Why are the conclusions still preliminary?
The study was a pilot — a small experiment to initially test the hypothesis. It involved people of a certain age, with low physical activity and mild depressive symptoms. Therefore, the results cannot be automatically transferred to young people, physically active adults, or patients with more severe conditions.
In addition, the researchers studied the daily intake of a certain amount of berry powder for three months. The work does not allow us to determine whether a small portion of fresh berries or their irregular consumption will give a similar result.
The authors believe that the data obtained provide grounds to continue studying the relationship between blueberries, the microbiome and mood in old age. To draw more definite conclusions, it is necessary to check whether the detected changes are reproduced in a larger number of people and whether they are accompanied by a steady improvement in the emotional state. So far, there is no reason to consider blueberries a proven remedy for depression.
Переведено сервисом «Яндекс Переводчик»
