 Why is high dietary intake of saturated fat associated with reduced semen quality? What's the connection? Well, a significant percentage of the saturated fat intake in the study was derived from dairy products, and residues of industrial chemicals may bioaccumulate up the food chain into cow fat, and then some of these lipophilic fat-loving chemicals may have hormone-disrupting abilities. The EPA performed a national survey of persistent bioaccumulative and toxic pollutants in the US milk supply. Since milk fat is likely to be among the highest dietary sources of exposure to this pollution, it's important to understand their levels. They tested milk from all over the country and found a witch's brew of chemicals. They estimate that dairy products alone contribute about 30 to 50% dioxin exposure, and like dioxin, other toxic pollutants tend to be widely dispersed in the environment, bioaccumulated through the food chain, and ultimately result in low-level contamination in most animal fats. This may explain higher pollutant concentrations in fish eaters. Xenoestrogens like PCBs are associated with the fats of fish or animal flesh and cannot be fully removed by washing or cooking, so can accumulate in our fat, too. Xenoestrogens are chemicals with demasculinizing or theminizing effects, but even in a non-polluted world, animal fats have actual estrogen, not xenoestrogen, but estrogen estrogens, which are unavoidable constituents in non-vegetarian nutrition. All foodstuff of animal origin contains estradiol, which is at least 10,000 fold more potent than most xenoestrogens. And dietary exposure, meat, dairy products, and eggs to these natural sex steroids is therefore highly relevant since the hormones in these animals are identical to our own. Cow estrogen works just like human estrogen. Estrogens are also contained in meat and eggs, but the major sources are milk and dairy products, by drinking a glass of milk. A child's intake of estrodial is 4,000 times the intake of xenoestrogens in terms of hormone activity. See, modern genetically improved dairy cows can lactate throughout their pregnancy. The problem is that's when the estrogen levels can jump as much as 30-fold. Though cheese intake has been associated with lower sperm concentration, dairy food intake has also been associated with abnormal sperm shape and movement. So this suggests a dairy intake may be implicated in direct testicular damage and not just potential suppression of sperm production due to the estrogen. While milk products supply most of our ingested female sex steroids, eggs are a considerable source as well, contributing as much as meat or fish, approximately. I guess it could be expected as eggs are produced directly in the hen's ovaries. Meat may also come hormone enriched in the U.S. anabolic sex steroids, maybe administered to animals for growth promotion, practiced banned in Europe 25 years ago. This study in New York found a progressively lower sperm count associated with processed meat consumption, but similar studies in Europe after the ban found the same thing. So it may not be the implanted hormones, but rather a consequence of other things in meat, such as the saturated fat, perhaps through cholesterol. We've known for decades that men with high cholesterol levels show abnormalities in their spermograms. Decreased sperm concentration? About a third of the normal sperm movement and half the normal sperm shape. 25 years later, we're finding the same thing. Cholesterol is bad for sperm. In the largest studies to date, higher levels of cholesterol in our blood is associated with significantly lower percentage of normal sperm. Cholesterol was also associated with reductions in semen volume and live sperm count. These results highlight the role of fats in the blood in male fertility and should be of concern, given the rising prevalence of obesity and cholesterol problems. Though a healthier diet may be associated with healthier sperm counts, cholesterol-lowering statin drugs did not seem to help.