Diet and sperm quality: Nutrients, foods and dietary patterns.

Human semen quality has declined worldwide in the last 40 years, by some accounts as much as 50-60%, causing serious concerns and implications for human fertility. Even though it has been shown to be a worldwide problem, this decrease is more pronounced in developed and industrialized countries, pointing to changes in modifiable lifestyle factors (e.g. unhealthy diets, lifestyles, and pollution) as the main causes. Studies investigating the relation between diet and semen quality can be classified into three groups; studies assessing the association between semen quality and 1) nutrients, dietary supplements and antioxidants, 2) food, and 3) dietary patterns. The present narrative review provides a wide-ranging vision of the positive associations and effects of diet on sperm quality. Although the picture of the relationship between diet and sperm quality and fertility is far from complete, a number of broad conclusions have emerged. First, increased intake of selenium and zinc, omega-3 (ω-3) fatty acids, CoenzymeQ10 (CoQ10) and carnitine supplements have been positively related to sperm quality. In terms of food groups, vegetables, fruits, nuts and whole cereals, all rich in fiber and antioxidants, and fish, seafood, shellfish, poultry, and low-fat dairy products have been positively associated with sperm quality. Finally, adherence to healthy dietary patterns is positively associated with sperm concentration and sperm motility.