Table 1.

Summary of the main results reported in this review, showing the associated references.

Lipids involved	Main results and associated references
	Animal models	Refs.	Humans	Refs.
Cholesterol	Rabbits fed a cholesterol-enriched diet (0.5%) present multiple sperm dysfunctions of epididymal origin due to membrane lipid microdomain alterations. High plasma cholesterol levels, but no changes in seminal plasma or sperm cholesterol levels.	[14, 15]	Studies on hypocholesterolemic compounds (statins, cholestyramine) gave heterogeneous results concerning sperm parameters.	[34–38]
	Rabbits fed with 0.05% cholesterol diet showed the same dysfunctions but with increased sperm cholesterol contents. A dietary supplementation with 7% olive oil restored normal characteristics.	[16, 17]
	Sperm parameters were affected in rabbits with a dietary-triggered metabolic syndrome, deficiency in capacitation associated with an increase in sperm cholesterol levels.	[23]
	Dietary cholesterol-induced dyslipidemia provokes posttesticular infertility in LXR-deficient mice.	[26, 27]
	Cholesterol-enriched-diet altered sperm functions in rats.	[29]
Fatty acids	Dietary supplementation with n-3 polyunsaturated fatty acids modifies the n-6/n-3 ratio and ameliorates sperm quality, fertility ratio, and reproductive performance of ageing roosters (artificial insemination). Increased amounts of DHA are associated with these improvements.	[44–47]	Nut consumption for several weeks improves sperm count, vitality, total motility, progressive motility, morphology, and sperm DNA fragmentation compared to the control group.	[32, 61]
	Dietary supplementation with DHA-enriched oils improves fresh and cryopreserved bovine sperm quality, in association with higher n-3 PUFA contents (for cryopreserved samples).	[49–52]	Dietary supplementation with 500 mg/day DHA for 10 weeks has no effect on sperm parameters or sperm membrane lipid composition.	[64]
	The n-3/n-6 ratio of dietary oils ameliorates reproductive outcomes of male rats.	[54]	A review based on literature search tools showed positive influence of dietary supplementation with n-3 fatty acids on total sperm motility and seminal plasma DHA concentration without modification of sperm content.	[65]
	Dietary supplementation with 0.2% DHA restores the infertility due to spermatogenesis arrest in D6-desaturase invalidated mice.	[57]
Links with oxidative stress	The most important benefits observed on rooster sperm parameters and fertility were obtained when dietary supplementation included vitamin E to protect sperm from lipoperoxidation.	[46, 47]	Obesity causes a systemic inflammatory response that has negative consequences on sperm parameters and quality, associated with an increased exposure of sperm to ROS.	[85]
	Vitamin E supplementation is also efficient in rats and in vitro on bull spermatozoa.	[73, 74]	Diet (n-3 fatty acids from fish oil and nuts) and antioxidant supplementation have been shown to be effective in limiting oxidative damage to sperm.	[90, 91]