Some studies tried to explore the impact of diet on male or female fertility, but very few focused on both. The aim of our study is to assess the role of nutrition in both fertile and infertile couples, taking into account most of factors relating to lifestyle. Clinical, anthropometric (BMI, fat mass), biological markers (non specific - glycaemia, lipids, inflammation, electrolytes - and specific - vitamins E, A, C, D, B, including folates and MTHFR polymorphism) and semen analysis, will be combined with validated questionnaires (nutrition, drugs, alcohol, tobacco, physical activity, sleep and stress).