LOS ANGELES (Reuters) - Good nutrition has long been the key to a healthy
pregnancy, but it may also be a crucial element of male fertility, a new study
has found. Folic acid, a well-established birth-defect preventative for pregnant
women, together with zinc, which is also involved in DNA synthesis, improves
sperm quality in men with fertility problems, according to the study by the
University Medical Center Nijmegen in the Netherlands.
Researchers theorized that the two
nutrients might affect semen quality since they play key roles in gene function.
In addition, since enzymes involved in testosterone synthesis also need zinc,
supplements of the mineral may stimulate testosterone production, and
consequently the volume of sperm, said Regine Steegers-Theunissen, associate
professor in obstetrics and gynecology at the Dutch university and author of the
study.
Folic acid, a B vitamin found in leafy green vegetables and legumes, is known
to protect against congenital neural tube defects such as spina bifida. Zinc,
found in foods like red meat and poultry, is needed for uptake of some folate
enzymes.
The researchers studied 108 fertile men, whose wives had conceived within a
year of unprotected intercourse, and 103 men with fertility problems of unknown
cause, whose wives had failed to become pregnant and whose semen had a sperm
concentration of 5 million to 20 million per milliliter.
Men considered fertile have sperm counts of more than 20 million per
milliliter. The study did not involve men who were infertile, defined as a sperm
count of less than 5 million per milliliter.
Before the study, both groups of men had similar concentrations of folate and
zinc in their blood and seminal fluid.
Over 26 weeks, men in both groups followed one of four regimens: daily doses
of folic acid and zinc sulfate, folic acid alone, zinc sulfate alone, or
placebos.
After treatment, the subfertile men given both supplements showed a 74
percent increase in the number of normal sperm in their semen and a 4 percent
increase in abnormal sperm. Men in the fertile group had small increases in
sperm count when given folic acid plus zinc, or zinc alone, according to the
study.
The 74 percent was not always enough to boost sperm levels into the normal
range, but the cut-off point of 20 million per milliliter is somewhat arbitrary
and even fertile men can experience subpar sperm levels due to factors like
illness or stress, Steegers-Theunissen said.
Unlike genetic factors, nutrition can be changed, but more studies need to
done to establish whether nutritional supplements will boost conception odds,
the researchers said.
"Both genetics and environmental influences play a part in the complex
process of sperm production," said Dr. William Keye Jr., president of the
American Society for Reproductive Medicine. "... The next step is to see whether
the effects of nutritional supplements can result in any increase in pregnancy
rates."
