LowSpermCount In Amer.Men Linked To Their Mothers Eating A Lot Of Beef When Preg

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Low Sperm Count In American Men Linked To Their Mothers Eating A Lot Of Beef

When Pregnant

28 Mar 2007

 

A new study suggests that low sperm count in American men born between 1949

and 1983 is strongly linked to their mothers eating a lot of beef while

pregnant.

 

The study is published in the journal Human Reproduction and was led by

researchers at the University of Rochester in New York.

 

The intention of the study was to look at the relationship between semen

quality and risks due to growth hormones and other chemicals in beef.

 

However, while the scientists found a strong correlation between mothers who

ate beef at least seven times a week and sons with the lowest sperm counts,

they could not pin this to specific hormones, pesticides or other chemicals

that might have been used in the rearing of the beef cattle.

 

Professor of Obstetrics and Director of the Center for Reproductive

Epidemiology at the University of Rochester Medical Center and lead author of

the

study, Dr Shanna H Swan said that the study's main contribution is that it

raises an issue rather than identifies a cause.

 

Prof Swan said the team found that, " The average sperm concentration of the

men in our study went down as their mothers' beef intake went up " .

 

" But this needs to be followed carefully before we can draw any

conclusions, " she cautioned.

 

Although some of the 387 men in the study had low sperm counts, they had all

conceived children without medical help.

 

But 18 per cent of the 51 men whose mothers had eaten the most beef while

pregnant had sperm counts of 20 million per millilitre or less, which is

classed by the World Health Organization (WHO) as " sub-fertile " .

 

Men whose mothers ate less beef while pregnant had on average 24 per cent

higher sperm counts, and only 5 per cent of them fell into the WHO's

" sub-fertile " category.

 

Swan said the message to be taken out of this research is that pregnant

women eating a lot of beef could affect the development of sperm in male

fetuses.

 

Although semen develops in three stages: before birth, during puberty and in

adulthood, the period around the end of the third month of pregnancy is a

critical time for quality semen to develop effectively in the male fetus said

the study authors.

 

The researchers enrolled participants from the Study for Future Families

(SFF), a multi-centre project supported by federal funds, including the

National

Institutes of Health, that gives scientists investigating links between

environment and reproductive health access to a cohort of mothers, fathers and

their children. Prof Swan has been the principal investigator of SFF since

1998.

 

The men were asked questions about their diet and gave sperm samples, and

their mothers were asked questions about their diet, including frequency and

type of meat consumption, when they were pregnant.

 

Sperm quality was assessed in a number of ways, for instance movement and

concentration were two key indices.

 

The study found no correlation between the men's own beef intake and sperm

quality.

 

The scientists found no significant links between maternal consumption of

other types of food (pork, lamb, veal, chicken, soya and vegetables) and sperm

quality.

 

The average number of beef meals per week consumed by the mothers was 4.3,

and those who ate more than one meal of beef per day on average were classed a

" high beef consumers " .

 

The reason that the researchers used data from men born between 1949 and

1983 was because this was a period in the US when it would have been very

difficult for most beef eating women to avoid eating meat from cattle reared

using

hormones and other chemical additives.

 

There are many explanations for the results of this study, and the authors

are keen to stress that it was not designed to pinpoint causes.

 

However, it is possible that chemical contaminants, pesticides and hormones

in the beef could be the reason for these results. But so could a range of

lifestyle factors. And asking mothers to remember how often they ate meat 20 to

50 years ago is not exactly watertight science, despite the fact that

pregnancy is a time when women probably have better awareness of their diet,

acknowledged the researchers.

 

Prof Swan concluded that the study should be replicated to confirm the

findings, and suggests that one way to " determine if prenatal exposure to

anabolic

steroids is responsible for a change in sperm count would be to repeat this

study in men born in Europe after 1988, when hormones were no longer

permitted in beef sold or produced there " .

 

The researchers said this study does not qualify them to advise women on how

much beef they should eat, but perhaps very high consumption should be

avoided.

 

" Semen quality of fertile US males in relation to their mothers' beef

consumption during pregnancy. "

S H Swan, F Liu, J W Overstreet, C Brazil, and N E Skakkebaek.

Hum. Reprod. Advance Access published on March 28, 2007.

doi:10.1093/humrep/dem068

 

_Click here for Abstract._

(http://humrep.oxfordjournals.org/cgi/content/abstract/dem068v1)

 

_Click here for What to Eat When Pregnant (Food Standards Agency, UK)._

(http://www.eatwell.gov.uk/agesandstages/pregnancy/whenyrpregnant/)

 

Written by: Catharine Paddock

Writer: Medical News Today

Article URL: http://www.medicalnewstoday.com/healthnews.php?newsid=66427

 

 

 

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