Short-chain dietary fatty acids, such as propionate, drive the production of regulatory immune T-cells in patients with multiple sclerosis (MS), while long-chain acids promote T-cells that are involved in inflammatory processes.
Since the beneficial fatty acids are safe and can be obtained as over-the-counter dietary supplements, researchers suggest they could be used as an add-on treatment with established MS therapies.
The research suggests that diet changes that alter the types of fat people eat impact gut bacteria, which, in turn, change the gut’s immune cell mix.
Dr. Ralf Linker of the Friedrich-Alexander University Erlangen-Nuremberg, who presented the study, had previously discovered that the chain length of fatty acids — the main components of dietary fats — influence the promotion of T-cell subsets in mice.
Long-chain fatty acids drive the production of pro-inflammatory Th1 and Th17 cells. Short-chain fatty acids promote regulatory T-cell (Treg) production, expanding the population of these cells in the gut. Tregs are important because they modulate the immune system and prevent autoimmune disease.
Using these earlier insights, Linker’s research team tested how fatty acids would impact a mouse model of MS know as the experimental autoimmune encephalomyelitis model. They discovered that long-chained fats decreased the presence of short-chained ones in the gut, making disease symptoms worse. In contrast, short-chained fatty acids increased the production of Tregs in the mice, leading to milder symptoms.
To see if their findings would apply to humans with MS, the researchers gave both patients and healthy controls 1g daily of the short-chain fatty acid propionate for 14-60 days. Propionate is safe and has been approved as a food additive.
Measuring types of T-cells before and at several points after participants began taking propionate, the researchers demonstrated for the first time that the fatty acid had beneficial effects in humans. Treg numbers increased between 25 and 30 percent, and Th17 cells decreased in all participants.
When people stopped taking the supplement, it took two to three weeks before the Treg numbers started to drop. After two months, they were back to the same numbers as before the propionate treatment.
The study suggests that the type of fatty acids a person consumes impacts bacteria in the gut, which in turn promote the production of various types of T-cells — with effects far beyond the intestines.