Slowing Inflammatory Diseases with Diet

In a study published today in Cell Metabolism, researchers found that significantly reducing dietary levels of methionine could slow the onset and progression of inflammatory and autoimmune disorders like multiple sclerosis. Their results suggest that dietary interventions could be used in the future to treat such disorders.

“Methionine is critical for a healthy immune system,” says senior author Russell Jones. “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.”

Autoimmune disorders occur when the immune system mistakenly attacks and destroys healthy tissue. For example, in multiple sclerosis, the immune system targets myelin sheaths, resulting in progressively worsening symptoms like numbness, muscle weakness, coordination and balance problems, and cognitive decline. There currently are no treatments that significantly slow or stop multiple sclerosis without greatly increasing the risk of infection or cancer.

“What causes multiple sclerosis is still not completely understood. We know that genes related to the immune system are implicated, but environmental factors also have a role to play,” says coauthor Catherine Larochelle. “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.”

During an immune response, T cells flood the affected area to help the body fend off pathogens. The researchers found that dietary methionine fuels this process by helping “reprogram” T cells to respond to the threat by more quickly replicating and differentiating into specialized subtypes. Some of these reprogrammed T cells cause inflammation, which is a normal part of an immune response but can cause damage if it lingers.

The researchers also found that significantly reducing methionine in the diets of mouse models of multiple sclerosis altered the reprogramming of T cells, limiting their ability to cause inflammation in the brain and spinal cord. The result was a delay in the disease’s onset and slowed progression.

“By restricting methionine in the diet, you’re essentially removing the fuel for this over-active inflammatory response without compromising the rest of the immune system,” Jones says.

However, Jones cautions that the findings must be verified in humans before dietary guidelines can be developed. Additionally, the team plans to investigate whether new medications can be designed that target methionine metabolism.