Will This Affect My Fertility?

If you've affected the cycle enough (with natural estrogens or medications) that ovulation is interrupted, then your periods are going to get messed up as well. So, if you're cycling normally with your periods, you're likely to be ovulating normally, too, despite the soy in your diet. If you're on birth control pills, the point is moot, since the birth control pills are suppressing your normal cycle with hormones anyway. Even if you have messed up your cycles with dietary estrogens, simply removing the source of the interference should see a complete return to normal, just as getting off birth control pills should see a return of natural cycling.

A regular monthly period can usually be the signal that you're not affecting anything. If your periods are irregular, your gynecologist can help get you straight again.

On the other hand, soy foods have been associated with lower sperm concentrations, according to a June 2008 Science Daily report. In one Harvard School of Public Health study, men who ate a half serving of soy each day had on average 41 million fewer sperm per milliliter than men who did not. (Normal sperm count is between 80 and 120 million per millileter.) The result was more pronounced in overweight or obese men. Still, the researchers say that the clinical significance of their research is not certain, and further trials are needed.

Trans-fats are bad for weight and for heart health, but what about fertility and conception?

Harvard researchers Jorge Chavarro, MD, and Walter Willett, MD, who wrote The Fertility Diet, say, "Across the board, the more trans fats in the diet, the greater the likelihood of developing ovulatory infertility."

A study they analyzed for their book showed that for every two percent increase in calories coming from trans fats instead of carbohydrates, women have a 73 percent increased risk for infertility, and the risk rises to 79 percent when trans fats are replacing omega-6 polyunsaturated fats. Women consuming just four grams a day are at risk. (See Which Foods Are High in Trans Fats to learn how little that is.)

The effects of trans fats on women with polycystic ovarian syndrome (PCOS) may be even more dramatic, because trans fats seem to amplify the symptoms of PCOS.

Drs. Chavarro and Willett stress that their advice is not to give up fats altogether. Just trans fats. They say, "Think of trans fats as the evil cousins of the healthy omega-3 fats in fish, flaxseeds, and walnuts." (For an excerpt from their book, see 10 Steps to Increasing Your Fertility.)