Several studies have examined the relationship between isoflavone consumption and reduced symptoms associated with menopause in women. Isoflavones belong to the class effect of phytoestrogens.
They are powerful antioxidants, rich in the yellow soybean and its derivatives (soy beverage, tofu ...). It was formally shown that these compounds have biological activity similar to estrogen.
This course explains in part why the soy isoflavones reduced hot flashes. To take effect in the conditional, because the data on the subject are now highly contradictory, as the influence on the reduction of cardiovascular disease.
Fertility in question
High intakes of isoflavones have been correlated with a decline of fertility in animals, but data on humans are still scarce. A group of Harvard researchers has therefore interested in the association between consumption of soy products and isoflavones, and several parameters of sperm quality.
They therefore collected food intake of the last 3 months to 15 foods containing soy, in 99 men with chronic problems from infertility to semen analysis at the hospital.
The authors observed an inverse association between eating soy and sperm concentration. In other words, the more soy consumption rises, the quality of sperm decreases.
This association remained significant after taking into account the age of the subjects, time of abstinence, their Body Mass Index (BMI), their intake of caffeine and alcohol and tobacco use.
More specifically, researchers have found that the biggest consumers of soy products had 41 million sperm less per milliliter of semen, compared to subjects consuming the least.
Being overweight also
Further confirmation, if the relationship between the consumption of soy and sperm concentration was more pronounced in the extreme groups of consumption, it was also among subjects with overweight or obesity.
This demonstrates once more the influence of fat on reproductive capacity.
A diluting effect
As to the exact action of soy isoflavones, it is essentially quantitative. There is no association between intake of soy or isoflavones and mobility of sperm, their shape or volume of ejaculation. The authors conclude that this phenomenon is related mainly to a decline in sperm concentration. Studies should be conducted to explain the causes.
