TUESDAY, Oct. 26 (HealthDay News) -- Men who eat foods
containing a lot of saturated fats -- think burgers and fries --
and monounsaturated fats may be harming their sperm, a new study by
Harvard researchers suggests.
Men consuming a lot of these types of fats may be producing
fewer and less active sperm.
Conversely, men who consume foods containing healthier,
polyunsaturated fats such as omega-3 and omega-6 fatty acids (fish,
whole grains) may be producing healthier sperm, the study
"We observed significant relationships between dietary fat and semen quality," said lead researcher Dr. Jill Attaman, an instructor in obstetrics, gynecology and reproductive biology. "This shows an association between modifiable lifestyle factors, specifically nutrition, and male fertility potential."
The reasons for the apparent connection aren't clear, Attaman
said. But, she added, different types of fats are treated
differently in the body.
"Polyunsaturated fats are important components of sperm cell membranes and may influence the ability of sperm to fertilize an egg," she explained, adding that they "may [also] stimulate hormone production."
The results of the study were presented Monday at the American
Society for Reproductive Medicine annual meeting, in Denver.
For the study, Attaman's team analyzed the sperm of 91 men who
were attending the Massachusetts General Hospital Fertility Center
in Boston. The men also answered questions about their diet and the
types of fats they ate. A number of the men also had levels of
fatty acids in their sperm and semen measured, the researchers
The researchers found that men with the highest intake of
saturated fat had 41 percent fewer sperm than men who ate the
lowest amount of saturated fat. And men with the highest intake of
monounsaturated fat had 46 percent fewer sperm compared with men
with the lowest intake of monounsaturated fat.
On the other hand, men who had a higher intake of omega-6
polyunsaturated fats had greater sperm motility, and a higher
intake of omega-3 polyunsaturated fats was related to better sperm
"morphology" -- the size and shape of sperm.
"Whether these finding are important may depend on an individual male," Attaman said.
For example, a 40 percent difference is large, but may be
important to some men and not to others. If a man has a marginal
sperm concentration, such as 25 million sperm per milliliter, a 40
percent reduction could bring his sperm count down to 15 million
per milliliter, which is abnormal, Attaman said.
But, if a man's sperm count is closer to 100 million per
milliliter, a 40 percent decrease would still maintain a normal
sperm count of 60 million per milliliter, she said.
"That would be unlikely to make a difference in fertility potential," Attaman said.
Saturated fat is the main dietary source of high blood
cholesterol and can be found mostly in foods from animals and some
plants, such as beef, veal, lamb, milk and cheese. Monounsaturated
fats are found in vegetable oils such as olive oil, canola oil,
peanut oil, sunflower oil and sesame oil. Other sources include
avocados, peanut butter, and many nuts and seeds, according to the
American Heart Association.
Polyunsaturated fats are found in fish, whole grains and some
seeds and nuts.
Dr. David Katz, director of the Prevention Research Center at
Yale Unioversity School of Medicine, said that "this is a small
study of association between variations in dietary intake, and
variations in sperm quantity and function. It does not directly
Some of the findings, such as an inverse association between
monounsaturated fat intake, which is a staple of the Mediterranean
diet, and sperm count are counter-intuitive, he noted. The
association between polyunsaturated fat intake, and in particular
balanced intake of omega-6 and omega-3 fat, with sperm vitality is
in accord with general health knowledge, he said.
"Overall, the study makes this provocative suggestion: Not only is it true that we are what we eat, but we start to be so before we are ever conceived," Katz said. "The dietary pattern of a father-to-be is affecting the composition of the sperm that will be delivering half of the genes to a future son or daughter. So, it's one more reason to choose our foods wisely."
For more on infertility, visit the
U.S. National Library of Medicine.
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