Itty Bitty Beans

Of late, you can see headlines of numerous publications screaming that eating soy products lowers a man's sperm count. But this fails to give an accurate account of the effects of soy on male sperm. These dire predictions are based on a very small preliminary study by Dr. Jorge Chavarro which was published in the online edition of Human Reproduction. Chavarro's study was based on recollections relating to the participants' remembered intake of foods produced from soybeans rather than from a prescribed diet.

True Measure

Dr. Tammy Hedlund is determined to clarify this issue. Hedlund is a researcher in the field of prostate cancer prevention with the University of Colorado's Health Sciences Center's Department of Pathology. Dr. Hedlund says that Chavarro's study determined that dietary intake of soy products bears no correlation to, "total sperm count, ejaculate volume, sperm motility, or sperm morphology," and these are the true measure of both sperm quality and a man's fertility

Chavarro's study did not factor in items like intake of other foods, supplements, medications, sexual activity, medication, or a participant's environment, all of which may have generated a decline in sperm count. In addition to these facts, Chavarro classified less than 3 ounces of a soy beverage drunk daily or an 8 ounce glass of the same beverage every few days as a high intake of soy food. Most experts would not agree that these amounts constitute a high intake of soy or any other type of food.

A past president of the American Urology Association, Dr. Larry Ross, explained that Chavarro's study differs from the majority of epidemiological studies because it is retrospective. That makes the study subject to many biases which would affect its outcome.

Wide Variations

For one thing, the study looked at only 100 subjects and not much is known about outside factors that might have affected the sperm counts of these participants. Ross explains that all experts are aware that a man's sperm count can have wide variations from day to day or even from season to season. This is illustrated by the idea that the normal range for sperm counts spans from 20 to 200,000 million sperm per cc of seminal fluid.

Chavarro's study found that the men who had the highest intakes of soy foods had the largest amount of ejaculate volume but with equal amounts of sperm to the ejaculate of those men who ate smaller amounts of soy products. The larger volume of fluid led to an erroneous line of thinking that speaks to a lower concentration of sperm in the ejaculate of those who ate more soy products, rather than fewer overall sperm. 

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