Paternal DHA supplementation before conception shapes offspring lipid metabolism in a sex- and postnatal diet-dependent manner.

Paternal obesity results in altered metabolic health and cognitive dysfunction in the offspring. Docosahexaenoic acid (DHA) supplementation has been reported to improve metabolic inflammation, insulin sensitivity, and sperm quality. This study investigated whether paternal DHA supplementation in healthy male rats could prevent metabolic dysfunction induced by a high-calorie diet in their offspring, with a special focus on liver lipid metabolism and sex-specific outcomes. Male Wistar rats received daily saline or DHA-rich fish oil by oral gavage from weaning to adulthood before mating with untreated females. Offspring were then fed either a standard diet or exposed to a free-choice high-fat, high-sugar (FcHFHS) diet. Supplementation with DHA did not alter body weight, circulating lipid profiles, or glucose concentration in the founder males. In offspring, FcHFHS diet feeding induced increased body weight and adiposity in both sexes regardless of paternal DHA supplementation. However, female offspring exhibited greater susceptibility than males to FcHFHS diet-induced dyslipidemia and liver triglyceride accumulation, together with altered hepatic expression of genes involved in lipogenesis and lipid export. Three-way ANOVA analyses revealed that sex and postnatal diet were the primary determinants of these gene expression changes, as well as strong interaction effects between sex and paternal DHA supplementation for key lipogenic genes, including GPAM, SCD1, and FAS. These results show that paternal DHA supplementation did not protect offspring from obesity or metabolic dysfunction. Instead, it induced sex- and diet-dependent programming effects of lipid metabolism driven by strong interactive influences of paternal diet, offspring sex, and postnatal nutritional environment.