Vitamin E is the most important vitamin for fertility. Folic acid is the most important vitamin for the normal development of the baby. However, in the 5 per cent of women who benefit from vitamin supplementation, an unusually large number will have twins or triplets. The herb most likely to help women seeking to get pregnant is vitex. This herb lowers testosterone levels. This property makes vitex helpful for women who have PCOS (polycystic ovarian syndrome), especially if their symptoms include acne and unusual hair growth. It usually takes 3 to 4 months for vitex to work. Although vitex is very helpful for some women, no man seeking to become a father should ever take it. Lowering testosterone may enhance women's fertility, but will decrease men's fertility.
Women seeking to become pregnant should not take supplemental quercetin, nor should they "load up" on fruits and vegetables that are high in quercetin, such as grapefruit, apples, and onions. This plant compound counteracts the enzyme hyaluronidase, which helps the egg break free of the follicle that holds it. Certain nutritional supplements increase male fertility. When there is zinc deficiency, taking up to 30 mg of zinc a day can help. A simple way to tell whether a man needs zinc is his reaction to putting a zinc tablet on his tongue. If it leaves a metallic aftertaste, the man is not zinc deficient and zinc supplements will not increase fertility. If there is no metallic aftertaste, then the man is probably not zinc deficient.
Men, like women, need folic acid for fertility. The recommended daily intake, however, is enough. When the problem with the man's fertility is asthenospermia, or lack of "swimming ability" rather than a low sperm count, L-carnitine may be helpful. This supplement helps sperm generate the energy they need to migrate from the cervix to reach the egg for fertilization. In one study, taking 3,000 mg of L-carnitine every day for 4 months increased viable sperm counts from 26 to 37 per cent. This was enough to enable men to impregnate their partners. Men who smoke should take 500 mg of vitamin C a day. In smokers, but not in non-smokers, vitamin C seems to increase sperm counts.