The research investigated the influence of various concentrations of docosahexaenoic acid (DHA) — an omega-3 fatty oil — on lung and kidney lesions caused by the autoimmune condition lupus. Findings indicated that up to 96% of these lung lesions were halted with DHA.
The findings have significant physiologic relevance to how and what kind of fish oils should be included in a typical western diet.
“Because it’s produced in a controlled environment, the DHA-rich microalgal oil will not contain environmental contaminants,” said Dr James Pestka, university distinguished professor at Michigan State University and lead author of the study.
“Nevertheless, if obtained from a reputable manufacturer/supplier, omega 3s derived from fish can be similarly free of contaminants.”
In addition, the emphasis on omega-6 polyunsaturated fatty acids (PUFA) in the Western diet means increasing numbers are following diets deficient in omega-3 PUFA.
“We rely heavily on plant oils which contain primarily omega-6s,” explained Pestka. “We are unable to synthesise omega-3s. Therefore we need eat more omega-3-containing fish or take omega-3 supplements.”
The preclinical study looked at the effect of DHA on lupus lesions in the lungs and kidneys of female mice that were already genetically predisposed to the disease.
The mice were then fed diets containing 0.0, 0.4, 1.2 or 2.4% DHA. Two weeks after initiating feeding, mice were then exposed to 1 mg of crystalline silica (cSiO2) once per week for four weeks and maintained on the experimental diet for an additional 12 weeks.
cSiO2, also known as quartz, is a known trigger of the autoimmune response in the lungs and kidneys.
Mice were then assessed for markers of inflammation and autoimmunity in the lungs, blood and kidney.
Findings revealed that certain antibodies (CD45R+) in the lung were reduced in number by DHA consumption (0.4, 1.2, 2.4%) by 80, 98, and 96%, respectively,
DHA supplementation in the same concentrations reduced other immune cell (CD3+) numbers in the lung by 41, 79, and 83%, respectively.
Study author Jack Harkema believes the DHA may be modifying the method in which healthy cells, also known as macrophages, respond to the silica in the lungs and could even be changing the immune system's response.
Commenting on the results, Harkema said: "96% of the lung lesions were stopped with DHA after being triggered by the silica. I've never seen such a dramatic protective response in the lung before."
A body of studies have suggested that dietary omega-3 PUFA supplementation may suppress and even reverse immune cell-driven inflammation.
These dietary lipids have proved viable candidates for the prevention/treatment of chronic inflammatory diseases.
“While it should be emphasised that our study was performed in the mouse, a “preclinical” model, we believe our research provides new insight into how omega 3s could block environmental triggering of other autoimmune or inflammatory diseases,” said Pestka.
“For example, occupational exposure to silica has been linked to rheumatoid arthritis (RA). Consumption of omega 3s have been shown to benefit persons with RA.”
Current recommendations set by the European Food Safety Authority (EFSA) identify a 250mg intake of EPA+DHA per day for the general adult population with a maximum tolerated dose of 5g per day.
Upon extrapolation, a human eating 2000 kcal/d (8.368 MJ/d) would require 2, 6, and 12 g/d to correlate with the amounts consumed in this study.
“Future perspectives of this model should therefore focus on effects of consuming 5 g/d DHA or lower human equivalents (i.e. less than 2.4% of total energy intake) and consider effects of DHA consumption by lupus-prone mice during early life-stages on long-term susceptibility to environmental AD triggers,” the study concluded.