Consuming too much or too little of this trace mineral can harm sperm levels. Men should get 55 mcg daily. Where to get it: Selenium is found in Brazil nuts (544 mcg in 1 ounce), Tuna (63 mcg in 3 ounces), beef (35 mcg in 3 1/2 ounces), turkey (32 mcg in 3 1/2 ounces) and enriched breads and cereals (4-15 mcg per serving).
Preliminary research at Harvard University has shown that eating less than one serving of soy foods (such as tofu, tempeh, soy milk or soy-based meat analogs) a day or more can reduce male fertility, especially in obese men. The researchers aren't sure why the two are linked, but soy can increase estrogen activity and interfere with male hormones. While researchers said that the findings were not substantial enough to cut out soy foods completely, they did suggest that men who were trying to conceive could limit their intake of soy foods. Where to cut back: Soy is found in lots of processed foods these days, including protein bars, protein powders, and even "diet" snack foods. Tofu, edamame, and soy beverages are also high in soy.
Some research has found that a lack of zinc can reduce sperm count and affect testosterone levels. Vegetarian men need to be sure to get enough of this key nutrient, but meat eaters usually don't need to worry about it, since meat is high in zinc. which is found in beans, yogurt and nuts. Where to get it: Beans, yogurt and nuts are high in zinc. Learn more about adequate zinc intake.
Future dads need to follow the same advice as their female counterparts: Eat right, exercise regularly, and take care of themselves!
Becky Hand, a licensed and registered dietitian, reviewed, approved and contributed to this article.