A research in mice has shown that dietary change can delay diseases that require immune system activation, such as multiple sclerosis (MS). Could the findings lead to better human treatments?
According to reports, almost 1 million people over the age of 18 in the United States live with an MS diagnosis.
MS is the most common of the autoimmune component inflammatory disorders which refers to the immune system that attacks and damages healthy tissue.
In MS, the immune system attacks the myelin sheaths that shield the brain and spinal cord nerve cells, disrupting the signals from the nerves to and from the brain.
The result can include muscle weakness, numbness, balance and coordination problems, and cognitive decline, all of which can get worse over time.
MS is most often diagnosed by physicians in young adults, although the diagnosis can be made any time.
Currently no medical treatment will prevent or delay MS without increasing the risk of infection or cancer considerably. But what if dietary changes can delay the onset and progression of the disease in persons at high risk?
Researchers recently explored the role of methionine, an amino acid, in the overactive inflammatory response of conditions like MS.
Results from the team now appear in the Cell Metabolism journal.
The effects of reducing methionine intake
Although methionine is essential for a healthy immune system, it affects people at risk of autoimmune disease.
Russell Jones, Ph.D., of Van Andel University, is the senior author of the study in Grand Rapids, Michigan. Commenting on the findings, he explains:
“Our results suggest[ that] for people predisposed to inflammatory and autoimmune disorders such as multiple sclerosis, decreasing methionine intake will potentially dampen the disease-causing immune cells, leading to better outcomes.”
Several cell types all over the body generate methionine, a protein building block and a source of fuel.
Defense immune cells that respond to threats— called T cells — do not produce their own methionine but rely on food sources instead.
Many animal products, such as meat and eggs, contain particularly large quantities of methionine.
One way the body protects itself from threats like viruses, or germs, is by flooding the affected area with T cells.
The researchers found that ingested methionine added fuel to this cycle by allowing the T cells to multiply and branch out more rapidly into different subtypes.
However, some of those “reprogrammed” T cells, once boosted by methionine, caused inflammation or swelling.
This is normally a healthy immune response, but if the swelling continues it can cause damage such as that which characterizes MS.
Scientists found that dramatically reducing the amount of methionine in mice’s diet with induced MS modified the reprogramming of their T cells and reduced the capacity of the cells to cause swelling in the brain and spinal cord.
This, in turn, has slowed the progression of the illness.
Why dietary interventions are key
“These findings provide additional basis as future treatments for these disorders for dietary interventions,” Jones notes.
“By restricting methionine in the diet, the fuel for this overactive inflammatory response is essentially removed without compromising the rest of the immune system.”– Russell Jones, Ph.D.
Nonetheless, researchers must prove that these findings are also felt by people before dietary guidelines can be drawn up.
There is currently no comprehensive understanding of the cause of MS, though genes linked to the immune system, as do environmental and metabolic factors such as obesity, play a role.
“The fact that metabolic factors such as obesity increase the risk of developing multiple sclerosis makes the idea of dietary intervention to relax the immune system particularly appealing,” says co-author Catherine Larochelle, Ph.D., of the University of Montreal, Canada.
The researchers will also discuss the possibility of developing new drugs to control methionine metabolism.
The present study is only the latest in exploring the role of limiting dietary methionine in treating disease.
A Locasale Lab study at Duke University, Durham, NC, showed in 2019 that the cancer-fighting effects of chemotherapy and radiation could be improved by reducing the intake of methionine.