Consumption of foods rich in docosahexaenoic acid (DHA), an omega-3 fatty acid, can prevent the onset of systemic lupus erythematosus (SLE) and possibly other autoimmune diseases, according to a study published in the journal PLoS One.
The study, by Melissa Bates from Michigan State University and colleagues, is titled “Silica-Triggered Autoimmunity in Lupus-Prone Mice Blocked by Docosahexaenoic Acid Consumption.”
Lupus is a genetic disorder characterized by an abnormal immune system response (autoimmune disease). Certain factors have been identified as SLE triggers, such as inhaling crystalline silica or sun exposure. Quartz is the most common and dangerous form of crystalline silica, and people are often exposed to it when they breathe in mineral dust from agricultural, construction, and mining activities.
Diet is another factor that influences susceptibility to autoimmune disorders, and omega-3 fatty acids such as docosahexaenoic acid (DHA) have a recognized anti-inflammatory action. DHA can be found in fatty, cold-water fish, like salmon, sardines and anchovies, as well as in fish like halibut and tuna, and in algae or fish oil supplements.
The objective of the study was to investigate whether DHA could have a beneficial role in controlling the excessive response of the immune system in female mice with SLE induced by silica inhalation. To do so, mice were fed with DHA-enrich diets in different percentages of DHA (estimated to be similar to human consumption of this molecule) for one month, after which, SLE lesions in their lungs and kidneys were analyzed.
According to the researchers, 97 percent of the lung lesions were improved by DHA consumption, an effect that increased with DHA dose.
“Cells in the lung can gobble up the silica, but it’s so toxic, it kills these cells,” Jack Harkema, one of the study’s authors, said in a news release. “When they die, signals are sent out to the immune system that something is wrong. The body then produces such a strong response that it also starts to target healthy cells.”
But the mechanism by which DHA is able to prevent SLE remains unknown. The team believes that DHA may change how cells in the immune system react to silica in the lungs, and work to control their response so that it is not exaggerated. DHA may also help immune cells to remove silica from the lungs without dying, and without causing an over-reactive inflammatory response.
“What we do know is this study is a clear indication that eating DHA can prevent this one type of environmental triggering of lupus,” said James Pestka, the study’s senior author. “It can suppress many of the disease’s signaling pathways, which current drugs on the market now try to target and treat.”
More studies are necessary to understand whether DHA-enriched foods can indeed be a practical and low-cost strategy to prevent or delay autoimmune diseases in people, as well as identifying the mechanism of action of this molecule.