Changing a person’s diet to reduce the amount of methionine (amino acid found in food) could delay the development and progression of inflammatory and autoimmune disorders, including multiple sclerosis (MS).

That finding was described in the study “Methionine Metabolism Shapes T Helper Cell Responses through Regulation of Epigenetic Reprogramming,” published recently in the journal Cell Metabolism.

Methionine is an amino acid that serves as a building block of proteins, but also can be processed within cells to create a molecule called S-adenosyl-L-methionine (SAM); SAM helps regulate certain hormones and gene activity.

In people with MS, immune cells called T-cells, which normally would defend the body against foreign substances, mistakenly attack myelin (the protective coat surrounding nerve cells of the brain and spinal cord).

Although several cell types produce methionine, T-cells do not. Instead, T-cells need to absorb methionine that comes from a person’s diet. Meat and eggs are particularly rich in methionine. 

A team led by researchers at McGill University in Canada, looked into the relationship between the presence of methionine, and the ability of T-cells to replicate and divide into subpopulations that produce an inflammatory response.

Researchers found that during an immune response, activated T-cells quickly absorbed methionine and transformed it into SAM. Having a steady level of SAM was seen as necessary to increase the expression of genes involved in the proliferation of a T-cell subtype called Th17 cells, which is linked to inflammation (a normal process of an immune response, but which can cause damage if prolonged). 

The team then used a mouse model of MS to see what the effect would be of significantly reducing the amount of methionine in their diets. Results showed that mice eating reduced amounts of methionine had decreased proliferation of Th17 cells, leading to a delay in disease onset and progression and a reduction in T-cell-mediated neuroinflammation.

Based on the results, the team believes that by restricting methionine in the diet, the fuel for an overactive T-cell inflammatory response is removed.

“Methionine is critical for a healthy immune system. Our results suggest, for people predisposed to inflammatory and autoimmune disorders like multiple sclerosis, reducing methionine intake can actually dampen the immune cells that cause disease, leading to better outcomes” Russell Jones, PhD, said in a press release. Jones is the study’s senior author and program leader of the Van Andel Institute’s Metabolic and Nutritional Programming group.

Overall, “these findings provide further basis for dietary interventions as future treatments for these disorders [inflammatory and autoimmune disorders],” Jones said.

Catherine Larochelle, MD, PhD, study co-author, added: “The fact that metabolic factors like obesity increase the risk of developing multiple sclerosis makes the idea of dietary intervention to calm down the immune system particularly appealing.”