Tissue fatty acid composition, prostaglandin synthesis, and antibody production in rats fed corn, soybean, or low erucic acid rapeseed oil (canola oil)

Abstract

Because low erucic acid rapeseed (canola) oil is a new edible oil in the U.S., its effects on lipid metabolism and immunity are of interest. To investigate whether canola oil affected tissue fatty acid composition, prostaglandin (PG) synthesis or immune responses differently than other dietary oils, rats were fed a semipurified diet containing either 10% corn ( ω6/ ω3=50.8), soybean ( ω6/ ω3=7.2) or canola ( ω6/ ω3=2.3) oil for 38 days. Ten days prior to sacrifice, rats were injected intraperitoneally with the antigen fluorescein 17BSA. At the end of the feeding period, fatty acid composition of serum, spleen, liver, and thymus was determined. Prostaglandin E 2 (PGE 2) and Prostaglandin F 2 α (PGF 2 α) production were measured in spleen and liver homogenates and the relative concentration of anti-fluorescein antibodies was determined. Linoleic acid levels were reduced markedly in all tissues examined (except serum) in the rats fed canola oil. Canola oil-feeding also reduced arachidonic acid levels in spleen, serum, and liver. PGE 2 and PGF 2 α synthesis was lower with rats fed canola oil, although this reduction was statistically significant only with production of PGE 2 from liver homogenates. Serum antibody titers were higher in rats fed either soybean or canola oil than those in rats fed corn oil.