Scientists have long suspected that the keto diet could calm an overactive immune system and help some people with diseases like multiple sclerosis.
Now they have reason to believe it could be true.
Scientists at UC San Francisco have discovered that diet causes the gut and its microbes to produce two factors that alleviate MS symptoms in mice.
If the study applies to humans, it opens the door to a new way to treat MS and other autoimmune diseases with supplements.
The keto diet severely restricts high-carb foods like bread, pasta, fruit, and sugar, but allows unlimited fat consumption.
Without carbohydrates to use as fuel, the body breaks down fats, producing compounds called ketone bodies. Ketone bodies provide energy to cells and can also modify the immune system.
Working with a mouse model of MS, researchers found that mice that produced more of a particular ketone body, called β-hydroxybutyrate (βHB), had less severe disease.
The additional βHB also induced the gut bacteria to Lactobacillus murinus to produce a metabolite called indole lactic acid (ILA). This blocked the activation of T helper 17 immune cells, which are implicated in MS and other autoimmune diseases.
What was really exciting was discovering that we could protect these mice from inflammatory diseases simply by feeding them a diet supplemented with these compounds.
Peter Turnbaugh, PhD, of the Benioff Center for Microbiome Medicine
Earlier, Turnbaugh had shown that when secreted from the intestine, βHB counteracts immune activation. This prompted a postdoctoral researcher then working in his lab, Margaret Alexander, PhD, to see if the compound could alleviate MS symptoms in mice.
In the new study, published on November 4 in Cell ReportsThe team looked at how the ketone-rich diet affected mice unable to produce βHB in their intestines and found that their inflammation was more severe.
But when the researchers supplemented their diet with βHB, the mice improved.
To find out how βHB affects the gut microbiome, the team isolated bacteria from the guts of three groups of mice fed either the keto diet, a high-fat diet, or a high-fat diet supplemented with βHB. .
Next, they looked at the metabolic products of distinct microbes from each group in an immune assay and determined that the positive effects of the diet came from one member of the group. Lactobacilli genre: L. murinus.
Two other techniques, genome sequencing and mass spectrometry, confirmed that the L. murinus they found produced indole lactic acid, known to affect the immune system.
Finally, the researchers treated the MS mice with ILA or L. murinus, and their symptoms improved.
Turnbaugh cautioned that the complementary approach still needs to be tested in people with autoimmune diseases.
“The big question now is how well this will translate into actual patients,” he said. “But I think these results give hope for developing a more tolerable alternative to help these people than asking them to stick to a restrictive and demanding diet.” »
