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Vitamin B12 for Fertility

author image Kelli Cooper
Kelli Cooper has been a writer since 2009, specializing in health and fitness. She holds a Bachelor of Arts in political science from Rutgers University and is a certified personal trainer with the American Council on Exercise.
Vitamin B12 for Fertility
B-12 levels might affect both men and women's fertility. Photo Credit Thinkstock/Comstock/Getty Images

While your body only requires minuscule amounts of B-12, it performs several important functions in the body. Limited research, much of it older, suggests low levels of this vitamin might impact infertility in both sexes. If you are having trouble conceiving, see your doctor, who can run the appropriate tests, including one to determine if you have low levels of this vitamin. He can suggest the most appropriate treatment plan to improve your chances of having a baby. If actually trying to get pregnant is farther down the road and you are just trying to get your body into an optimal state for conception, make sure you are getting enough B-12 through diet or supplementation.

Infertility in Women

A review of case reports published in the March 2001 issue of the "Journal of Reproductive Medicine'' observed that women who were deficient in B-12 experienced repeated miscarriages and prolonged periods of infertility. Low B-12 levels might produce changes in the blood that lead to miscarriage as well as changes that contribute to abnormal ovulation, impaired development of the egg and difficulty implanting a fertilized egg.

A case report published in the January 1991 issue of the "International Journal of Fertility" notes that a patient taking various treatments to undergo conception finally achieved pregnancy after adding 1,000 mcg of B-12 to the regimen. Like the above study, researchers suggest a link between B-12 deficiency and absent ovulation.

Infertility in Men

Low B-12 levels might also affect sperm count. The University of Michigan Health System reports several studies have found B-12 shots improved sperm counts. It also points to a study performed in the mid-1980s that found taking 1,500 mcg of B-12 daily for between two and 13 months resulted in raised sperm counts in 60 percent of the men participating.

B-12 in the Diet

B-12 naturally occurs in all animal foods. Many foods have also been fortified with this vitamin, along with the other B-vitamins. The claim that you can get B-12 from plant sources does not appear to be accurate. Registered dietitian Reed Mangels of the Vegetarian Resource Group explains B-12 exists in an active form and an inactive form and that purported vegetarian sources, such as sea vegetables, primarily contain the inactive form your body cannot use.


You can also supplement with B-12 if you feel you cannot adequately meet your body's needs through diet. The more you take at once, the less you absorb. Mangels recommends either supplementing with 10 mcg daily or 2,000 mcg once a week. If you have already been trying to get pregnant and have a known B-12 deficiency, your doctor can suggest the appropriate dose to correct this problem.

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