Study
links folate with healthier sperm
20/03/2008- A new study has identified a possible link
between men's intake of folate and reduced chromosomal abnormalities in sperm
- a finding that, if substantiated by more research, may indicate that men
should up their intake before conception as well as women.
Although the link between a woman's
intake of folate and healthy foetal development has long been known (folate
greatly reduces the risk of neural tube defects like spina bifida), the
study, published today in the journal Human
Reproduction, is claimed to be the first indication that paternal
diet may play a role after conception.
Aneuploidy is the general term given
to changes in the number of chromosomes. It is estimated that between 1 and 4
per cent of a healthy man's sperm have some form of aneuploidy.
Aneuploidy has been implicated in
failure to conceive and miscarriages, as well as children born with
conditions such as Down's syndrome, Turner's syndrome and Klinefelter's
syndrome.
The study involved 89 healthy,
non-smoking men who gave sperm samples and were questioned about their total
intake of the nutrients zinc, folate, vitamin C, vitamin E and beta-carotene
- both from food sources (such as green leafy vegetables, fruit and pulses)
and from dietary supplements (folic acid, the synthetic form of the vitamin).
The researchers found that there was a
statistically significant association between high folate intake and lower
sperm aneuploidy.
Men in the upper 25th
percentile, who had the highest folate intake of between 772 and 1150
micrograms per day, were seen to 20 to 30 per cent less sperm aneuploidy than
those with the lowest folate intake.
Despite this association, Professor
Brenda Eskenazi, one of the researchers from the University of California,
was somewhat cautious about how the study be interpreted.
"This
study cannot prove that high folate intake caused the lower sperm aneuploidy
levels, only that there is an association," she said. "This
is the first study of its kind and the results indicate the need for further
research, especially a randomised controlled trial, on this topic."
The researchers admitted that one of
the difficulties of the study was being able to disentangle the effects of
folate from other micronutrients. However, they said they were able to do
this through statistical analyses of several different nutrients.
The results of these different
analyses were different, which they said gave them confidence that they could
look at the effect of the micronutrients separately.
Again, however, any doubt over this
could be cleared up with a randomised controlled trial using supplements.
The mandatory addition to folic acid
to certain foodstuffs, such as bread, has been a hot topic for debate for a
number of years.
The US and Canada made the addition of
the vitamin to bread mandatory in 1998 in order to reduce the number of
pregnancies affected by neural tube defects. The UK,
Ireland, and Australia
have all meet considering the same action for some time, but it has proved
controversial for a number of reasons.
For example, consumer groups say it
would severely restrict consumer choice, and believe it should be down to the
consumer what they chose to consume. In elderly people with a certain form of
anaemia, taking folic acid may mask other deficiencies, thus standing in the
way of appropriate intervention.
In addition, emerging science has
suggested that folate intake may be linked to an increased risk of colorectal
and bowel cancer.
The UK is deferring a decision on
mandatory fortification until 2009, pending review of the latest research.
Source
Human Reproduction (advance access)
Doi:10.1093/humrep/den036
"The association of folate, zinc and antioxidant
intake with sperm aneuploidy in healthy non-smoking men"
Authors: S S Young, B
Eskenazi, FM Marchetti, G Block, and AJ Wyrobek
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