We don’t yet fully understand the cause of many inflammatory and autoimmune disorders, like multiple sclerosis (MS), but researchers have long suspected diet as a potential factor. And a new study pinpoints a specific amino acid found in food that could be a key culprit.
Here’s the rub: Reducing levels of the amino acid methionine in a person’s diet could help slow the development and progression of inflammatory and autoimmune disorders, says a new study published in Cell Metabolism.
Methionine is found in most foods, but it’s found in higher quantities in animal products like meat and eggs. But that’s not to say everyone should cut these foods out of their diets altogether.
Ironically, methionine is a necessity if you have a healthy immune system (it protects and nourishes cells), said study author Russell Jones, Ph.D., program leader of Van Andel Institute's Metabolic and Nutritional Programming group, in a news release. But, for people predisposed to inflammatory and autoimmune disorders like multiple sclerosis, reducing methionine intake can dampen the immune cells that cause disease, leading to better outcomes. These findings provide further basis for dietary interventions as future treatments for these disorders."
The researchers found that dietary methionine encourages the body to send T cells to parts of the body to fight off pathogens, which is what occurs during an immune response. So, in a person with an autoimmune disorder, where the immune system is reacting unnecessarily and attacking healthy tissue with T cells, that methionine only compounds the problem.
"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," said Dr. Jones.
That said, the study authors say more research is needed before experts can develop dietary guidelines about methionine. If you have an autoimmune disease, talk with your doctor before making any major changes.
Understanding Autoimmune Disorders
Autoimmune disorders—like MS, psoriasis, rheumatoid arthritis, and type 1 diabetes—develop when a person’s immune system turns on itself, mistakenly attacking and destroying normal tissues in the body. For many autoimmune disorders, like MS, there aren’t many effective treatments that can help slow the disease’s progression.
"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," said study author Catherine Larochelle, M.D., a clinician-scientist in neuroimmunology and neurologist at the Multiple Sclerosis Clinic at the Centre Hospitalier de l'Université de Montréal, in a news release. "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."
Other theoretical causes and risk factors of autoimmune disorders include the following, according to Hopkins Medicine:
- Environmental triggers. Microorganisms like bacteria and viruses or even certain medications could trigger changes that cause the immune system to malfunction.
- Genetics. Genes may play a key role in making some people more likely to develop an autoimmune disease.
- Weight. Some research shows that being overweight raises your risk of developing certain autoimmune diseases.