Eating 75 grams of walnuts/day improves vitality, motility, and morphology of sperm in healthy men aged 21 – 35. Walnuts are high in α-linolenic acid (ALA), a natural plant source of omega-3. Also fewer chromosomal abnormalities present after the 12-week dietary intervention. The control group experienced no changes.
Robbins WA, Xun L, FitzGerald LZ, Esguerra S, Henning SM, Carpenter CL. Walnuts improve semen quality in men consuming a Western-style diet: randomized control dietary intervention trial. Biology of Reproduction, 2012