Two handfuls of walnuts a day (around 75 grams/day), and your sperm quality will improve "in terms of concentration, vitality, movement, shape and chromosome abnormalities," according to a study recounted in the latest issue of the journal Biology of Reproduction.
source : http://www.biolreprod.org/content/early/2012/08/07/biolreprod.112.101634.abstract; http://www.bbc.co.uk/news/health-19254383; http://io9.com/5935284/todays-sexy-body-hack-eat-walnuts-to-boost-sperm-health
