Isoflavone-rich Diet Boosts Gut Health, Lessening MS Severity
Isoflavone-rich diets boost gut health and lessen multiple sclerosis (MS) severity, a new study in mice suggests.
In the study, mice with MS that were fed a diet rich in isoflavone — a plant-based compound — developed diverse and abundant gut bacteria, particularly isoflavone-digesting bacteria, which produced compounds that reduced inflammation in the brain and spinal cord.
“Our new study provides evidence that the combination of dietary isoflavones and these isoflavone metabolizing gut bacteria may serve as a potential treatment for MS,” Ashutosh Mangalam, PhD, associate professor at the University of Iowa and the study’s lead author, said in a press release.
The study, “Isoflavone diet ameliorates experimental autoimmune encephalomyelitis through modulation of gut bacteria depleted in patients with multiple sclerosis,” was published in the journal Science Advances.
The gut microbiota — the total number of bacteria, viruses, parasites, and fungi in the gut — is associated with health and illness. Research suggests that diverse and abundant gut bacteria are protective against infections and diseases, and that specific foods and dietary patterns influence their range and abundance.
Isoflavones are plant-based compounds that resemble estrogen. They are abundant in legumes such as soy and chickpeas and have anti-inflammatory and antioxidant properties.
The prevalence of MS is significantly lower in countries such as China and Japan, where citizens eat high amounts of isoflavones, compared to Western countries where isoflavone consumption is lower. Moreover, prior studies have shown that people with MS have different gut bacteria profiles compared to healthy people. Specifically, people with MS have higher quantities of some bacteria, while others, such as isoflavone-digesting bacteria, are diminished.
Now, a team led by researchers at the University of Iowa sought to determine whether consuming a diet rich in isoflavones could prevent brain and spinal cord inflammation and potentially reduce MS severity.
Mice with MS were fed an isoflavone-rich or isoflavone-free diet for six weeks, then injected with myelin oligodendrocyte glycoprotein (MOG) to induce brain and spinal cord inflammation — a condition called experimental autoimmune encephalomyelitis (EAE) that mimics MS in humans. Researchers then
assessed inflammation by measuring immune cell numbers and inflammatory proteins in the brain and spinal cord. They also evaluated the diversity and numbers of gut bacteria.
Mice fed an isoflavone-free diet had more severe disease, with greater numbers of inflammatory cells than mice fed isoflavone-rich diets.
These results were confirmed in other animal models of MS. “In several models of autoimmune inflammation in the CNS [central nervous system, the brain and spinal cord], our results demonstrate that the presence of isoflavones in the diet significantly reduces the severity of EAE disease,” the researchers wrote.
Mice fed the isoflavone-free diet also had fewer types and quantities of bacteria than those fed the isoflavone-rich diet. Specifically, isoflavone-digesting bacteria — Adlercreutzia and Parabacteroides distasonis — were abundant in mice fed isoflavone-rich diets, but deficient in those fed isoflavone-free diets.
These results are in line with what is seen in MS patients.
“Notably, both genera [Adlercreutzia and Parabacteroides distasonis] were enriched in healthy individuals but depleted in patients with MS,” the researchers wrote.
Conversely, Akkermansia muciniphila — a bacteria species commonly found in people with MS compared to healthy people — was more abundant in mice fed isoflavone-free diets compared to those fed isoflavone-rich diets.
Furthermore, isoflavone-digesting bacteria produced S-equol, a compound that protected mice against EAE, but the pathway involved was unclear.
“We report that an isoflavone diet provides protection against disease, which is dependent on the presence of isoflavone-metabolizing bacteria and their metabolite equol,” the researchers wrote. “This lays the groundwork for future studies investigating the cellular and molecular pathways responsible for equol-induced EAE suppression.”
Since diet influences gut bacteria, it is crucial to take this relationship into consideration when developing diet strategies or therapies that involve the gut bacteria for people with MS and other disorders.
“Ultimately, these studies will inform our use of diet and gut microbiome-based therapies as a complement to conventional disease-modifying therapies … for the treatment of MS and other diseases,” the team concluded.