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SPERM COUNTS OPEN TO SAUCY SUGGESTION

Dominion 3/09/01

A Christchurch scientist thinks soy products and vegetarianism may have lowered the world’s sperm count.

To understand where the professor is coming from we must go back a bit.

The story started in 1992 when Danish epidemiologists reported that, based on 61 studies, sperm counts had fallen worldwide in the previous 50 years.

A flood of critics dismissed the study because the sperm were up in some places but down in others and had been counted in different ways in different places.

So new surveys were undertaken, with mixed results.

Young Scotsmen were discovered to have only a quarter of the sperm produced by older Scots. Parisian men were up, but those in Toulouse were down.

New Yorkers had the highest counts in the United States but Nigerians were the lowest in the world.

A Californian study showed that nothing had changed in the US during the past 50 years.

To settle matters, University of Missouri-Columbia scientists undertook a global study, analysing 101 previous surveys with great mathematical sophistication.

Last year, the team confirmed the worldwide fall in sperm counts, reckoning that Americans were producing 2 per cent fewer sperm annually and Europeans and Australians 3 per cent fewer. The fall has been blamed variously on stress, smoking, diesel fumes, eating iodised salt, taxi-driving, smoking dope and everything else.

Wearing Y-fronts was another possibility but a study on New Yorkers (reported in the Journal of Urology) showed that “tighty whites do not elevate testicular temperatures as previous supposed”.

None of these things could satisfactorily explain lowered sperm counts.

Suspicion falls most consistently on increasing exposure the chemicals in the environment especially the female hormone oestrogen, or a similar chemical used to make the plastic PVC.

Enter biochemist Professor Ian Shaw of the Institute of Environmental Science Research, Christchurch.

In the latest New Zealand Science Review, he reports that we take hardly any plastic-making oestrogen into our blood, but tons of oestrogen from soy products – 1430 times more!

He suggests that falling sperm counts have coincided with the increasing popularity of soy products and vegetarianism in Western diets.

The professor gets some support from Tokyo where only 4 per cent of young men are up to WHO sperm standards.

Sperm counts have also fallen here in Wellington since 1993. Stress? Smoking dope? Taxi-driving? Tight pants?

Not likely. More likely our lads have fallen slave to tofu-eating chic.