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Thursday, 2 March, 2000, 01:21 GMT
Sperm count fall blamed on salt
Iodine in salt blamed for smaller testicles
The addition of iodine to salt is to blame for low sperm counts, claim scientists.

They tested the theory on rats and found that starving them of iodine led to increased sperm production and larger testicle sizes.

There's a danger people could get exactly the wrong message and decide that sperm counts are more important than brain development

James Crissman
They therefore deduced that iodine was responsible for smaller testicle size and lower sperm counts.

Iodine is needed by the body to make the thryoid hormone thyroxine, which is vital for developing brains.

A deficiency can cause impaired mental development and it is therefore added to salt to aid brain development.

James Crissman and colleagues at the health and environmental research laboratory of the Dow Chemical Company, Michigan, carried out the study after identifying a link between a fall in sperm rates in the US in the 1960s and the introduction of iodine to salt there in 1924.

Brain development

But Crissman warned against cutting down on iodine. "There's a danger people could get exactly the wrong message and decide that sperm counts are more important than brain development," he told New Scientist magazine.

Richard Sharpe of the Medical Research Council's reproductive biology unit in Edinburgh said there were cases of men with underactive thyroids having enlarged testicles.

But he was sceptical of the study's conclusions, saying that sperm count data are "so variable".

Dr Gulam Bahadur, at University College London's medical school, also disputed the findings of the study.

"We know that something is happening, but we don't know what is responsible for the sperm count decline," he said.

"I don't think the results in rats would reflect in humans. Animal models and human models are totally different.

"Also you have them in a confined area in a laboratory where you feed them with rich diets or specific concentrations. I don't think that reflects what happens in the environment."

The results of Crissman's studies were published in the journal Toxicological Sciences.

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13 Sep 99 |  Health
Ignorance over male infertility
02 Jan 00 |  Health
Hope for infertile men
27 Jul 99 |  Medical notes
Salt factfile
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