The study, published in the Journal of Leukocyte Biology, suggests that instead of supressing the immune system by reducing inflammation, consumption of DHA and EPA-rich fish oil may actually enhance the function of immune B cells.
Led by Dr Jenifer Fenton from Michigan State University, USA, the research team noted that while DHA and EPA are widely believed to help prevent disease by reducing inflammation, until now, many scientists were not completely certain of any immune enhancing effects.
But new findings now show that DHA-rich fish oil enhances the activity of white blood cells known as B cell – so challenging the idea that fish oil is only immunosuppressive.
“These results support the hypothesis and an emerging concept that fish oil enhances B cell function in vivo,” confirmed the researchers.
"This work confirms similar findings on fish oil and B cells from our lab, and moves us one step closer to understanding the immune enhancing properties of EPA and DHA," said Dr S. Raza Shaikh from East Carolina University – also involved in the work.
Fenton also suggest that the findings hint at possible immune enhancing properties of fish oil, “that could benefit immunocompromised individuals."
The team used two groups of mice, fed either a control diet, or a diet supplemented with DHA-rich fish oil for five weeks. B cells were then harvested from several tissues and stimulated in culture.
Fenton and her team then looked for markers of B cell activation on the cell surface, in addition to alterations in cell membranes and cytokine production.
“This study tested the hypothesis that DHA from fish oil is incorporated into the B cell membrane to alter lipid microdomain clustering and enhance B cell function,” the team said.
They found that DHA-enriched fish oil enhanced B cell activation and select antibody production – something Fenton and her colleagues suggested may aid immune responses associated with pathogen clearance, while possibly dampening the totality of the inflammatory response.
DHA supplementation was found to enhance LPS-induced B cell secretion of immune cytokines IL-6 and TNF-alpha and increase expression of CD40 compared with the control diet.
Supplementation also increased lymphoid tissue B cell populations and surface markers of activation, they said – adding that mice fed with DHA had significantly higher plasma IL-5, IL-13, and IL-9 (Th2-biasing cytokines) and cecal IgA compared with the control diet mice.