A decade ago, Australian Professor Felice Jacka became the first to show a direct relationship between diet quality and hippocampal volume in humans.
People with depression tend to have smaller hippocampal volume. Jacka, a leading researcher of nutritional psychiatry, wanted to understand what impact our diet might have on that part of the brain associated with mood, memory and appetite regulation.
Spoon-feeding your way to better mental health?Credit: Getty Images
She found that eating a healthier diet was associated with a larger hippocampus, while a higher intake of processed or junk foods was linked with a smaller hippocampus.
Yet, the relationship remained a correlation.
So for a new study, Jacka and her team at Deakin University’s Food and Mood Centre collaborated with neuroimaging experts at Monash University to test the idea that certain foods affect the brain in a way that has the potential to benefit mood, memory, and learning.
Specifically, they wanted to look at fermented foods.
In 2017, Jacka and her colleagues, published the SMILES trial, finding that those who made positive changes to their diet (by embracing a Mediterranean-style approach) experienced significant reductions in depression compared with a social support group.
Researchers believe that the gut microbiome influences brain structure and function via immune, metabolic, and neural pathways. For instance, a healthy gut microbiome is key for producing neurotransmitters like serotonin that regulate mood.
This relationship between the gut and the brain led researchers to explore the effects of prebiotics which act as food for the beneficial bacteria and microorganisms in our gut, called probiotics.
Fermented foods may be brain food.Credit: Getty Images
Promising as prebiotics and probiotics seemed to be in preclinical trials, fermented foods, such as yoghurt and fermented vegetables, contain a combination of these probiotic and prebiotic components.
This, along with other compounds that are produced during the fermentation process, including neurotransmitters, meant experts theorised that fermented foods may be even better for psychological and cognitive functioning.
In the new study, published in the journal, Gut, they randomly assigned 40 healthy women aged 18–55 years into one of two groups. For eight weeks, one group consumed 130 grams per day of a fermented probiotic yoghurt (containing bifidobacterium lactis (BB-12), of streptococcus thermophilus and lactobacillus bulgaricus), while the other had a dairy-based placebo.
Using magnetic resonance spectroscopy, they measured the participants hippocampal metabolites at the beginning and end of the eight weeks.
They found differences in the gut’s microbiome profile and glutathione levels in the hippocampus, an antioxidant which helps to protect the brain.
“And it seemed to have an impact on the size of the hippocampus and the degree of connectivity with the frontal lobe, which suggests that it might have benefits for mood, for memory, for learning, for appetite regulation,” explains Jacka.
Although the results did not remain statistically significant after multiple adjustments, the overall pattern they observed in the study were positive, says the study’s lead author Dr Wolfgang Marx.
“Together with the changes in hippocampal connectivity, it suggests that fermented probiotic foods may influence brain-related biology,” he says. “We see this as a preliminary signal that needs to be tested in larger studies.”
Heidi Staudacher, an associate professor in nutrition and dietetics at Monash University, remains cautious about overstating the findings, but agrees that it lays the groundwork for the next steps of the research: to test the effects of fermented foods in people with depression.
Many of the risk factors for mental disorders are not things that we can change, such as genetics and early life trauma. Diet, however, is a factor we can modify.
“The evidence suggests that it’s very important for mental health,” says Jacka.
She points out that in Australia, adolescents have on average seven serves of junk food a day, and less than 4 per cent eat enough vegetables, while only about 5 per cent of adults eat according to the dietary guidelines.
“We’re all eating really badly,” she says
“And so we’re looking at different strategies for mitigating that terrible impact of the industrialised food system on our eating habits and hopefully mental health.”
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Disclaimer : This story is auto aggregated by a computer programme and has not been created or edited by DOWNTHENEWS. Publisher: www.smh.com.au
