The phospholipids of mammalian spermatozoa possess a distinctive fatty acid composition with high proportion of long chain polyunsaturated fatty acids.

The lipid composition is a major determinant of the membrane flexibility and sperm motility required for proper fertilization. It also influences the sperm plasma membrane's fluidity, chilling sensitivity and thermotropic lipid phase transition (LPT) and these parameters determine our ability to cryopreserve these cells. Our hypotheses is that by providing dietary supplementation of omega-3 polyunsaturated fatty acids an improvement of sperm parameters (number, motility, viability) can be achieved. We also expect alteration spermatozoal plasma membrane fatty acid composition, making it more chilling resistant. Experimental methodology: 1) Characterize fatty acid composition of the spermatozoa of normal and abnormal spermatozoa by gas chromatography. 2) Characterize sperm plasma membrane LPT by FTIR spectrometer. 3) Run a randomized double-blind, placebo controlled, crossed-over dietary fatty acid supplementation pilot trial in human sub-fertile patients. Large scale trial will follow, if justified. In both trials sperm characterization of each participant will be conducted before, during and following the trial. Subfertile males will benefit greatly if their sperm parameters can be improved and cryopreserved while ensuring enhanced post-thawing survival. We believe that changing the fatty acid composition of sperm plasma membrane by simple dietary means will open the way to improve the fertility of those that needs it the most.