Multiple sclerosis (MS) is a chronic autoimmune inflammatory disease that affects the central nervous system. It affects around 110,000 people in France. A new study, carried out by American researchers from the Icahn School of Medicine in New York, diets rich in palm oil worsen neuroinflammation and the progression of the disease.
Background of the study
In the central nervous system, bringing together the brain and spinal cord, the extensions of neurons (axons) are covered of a lipid membrane which helps isolate them, protect them and quickly transmit nerve impulses. It is the myelin sheath made up of sphingomyelin.
To know! Sphingomyelins, phosphosphingolipids, are the main constituents of the myelin sheath. They are formed by the assembly of sphingosine linked to a fatty acid by an amide bond (sphingolipid), and choline, linked to sphingosine by a phosphodiester bond.
High levels specific sphingolipids such as C16 ceramides have been observed in various neurodegenerative diseases such as Parkinson’s disease, Alzheimer’s disease and multiple sclerosis.
MS is characterized by autoimmune mechanisms (immune system directed against the self) attacking the myelin sheath. The resulting lesions, found in the form of plaques, are the site of inflammation, demyelination and, often, degeneration of the axon.
Lpalmitic acid which is abundant in palm oil is the substrate which allows the synthesis of ceramides, and in particular the ceramide C16using specific enzymes.
To know! Palmitic acid is a long-chain saturated fatty acid (LCFA). This acid is found in most fats and oils, such as soybean oil. It is found in foods such as palm oil, butter, meat, milk and cheese.
Based on this observation, American researchers wanted to understand what are the consequences of stopping the synthesis of ceramides 16 on the progressive course of multiple sclerosis.
“This toxic molecule – C16 ceramide – found in several neurodegenerative diseases is responsible for damage to mitochondria, which deprives neurons of the energy they need to counter inflammation in the brain. We therefore wondered whether inactivation of these enzymes would confer neuroprotection”explains Patrizia Casaccia, senior author of the American publication.
Prevent the synthesis of C16 ceramides
In this study, researchers worked on mouse models of multiple sclerosis capable or unable to express the CerS5 and CerS6 enzymes which are involved in the synthesis of C14 and C16 ceramides.
The results showed that mice not expressing these two enzymes presented a slowed progression of the disease et less pronounced neuroinflammation compared to those expressing these enzymes. Identical conclusions were found even if the mice were fed a diet enriched with palm oil.
Next step for researchers? Studying how inhibition of enzymes responsible for C16 ceramide synthesis may constitute a therapeutic target to reduce the severity of MS.
The benefits of the Mediterranean diet
This study therefore indirectly confirms the deleterious effect of diets rich in fats containing palmitic acid, the molecule at the basis of the synthesis of the neurotoxic C16 ceramide.
It therefore supports the importance, for MS patients of a healthy diet as a modulator of the progression of the disease by avoiding palmitic acid.
A summary of the work relating to the links between diet and MS highlights the benefits of a Mediterranean type diet. Indeed, this anti-inflammatory diet with high fiber consumption and low intake of saturated fatty acids would have beneficial effects in patients affected by MS: improvement of the inflammatory state and reduction of symptoms linked to MS such as fatigue, quality of life, number of relapses and cognitive dysfunction.
To know! The Mediterranean-type diet is based on the consumption of fruits, vegetables, fish, whole grains and quality fats such as olive oil. It limits the intake of red meats, cold meats, sugars and industrial products.
Sources
– Multiple sclerosis: how saturated fatty acids are toxic to neurons. www.lequotidiendumedecin.fr. Accessed November 12.
– Neuroprotective effect of neuron-specific deletion of the C16 ceramide synthetic enzymes in an animal model of multiple sclerosis. onlinelibrary.wiley.com. Consulté le 12 novembre.