Eat, Drink and Be Fertile?
"The Holiday Season." That single phrase likely conjures a mix of memories, emotions, sentiments, and anticipation. For many of us, the holiday season is an opportunity to gather with friends and family and to share in traditions both old and new. There are parties to attend, religious observances to be remembered, and shopping to be done. And then there is the food (oh, the food!) foisted upon us from seemingly every conceivable direction. My mouth still waters in thinking back to the Christmas dinner my wife prepared last year - beef tenderloin with whipped horseradish, spiced potatoes, green bean casserole, and pumpkin cheesecake for dessert. I also recall, less fondly, my pants fitting a little bit tighter and the bathroom scale coldly confirming what I already knew to be true. The New Year's resolution then invariably turns out to be some vague commitment to A) weight loss, B) exercise, C) better diet, or D) all of the above.
For couples dealing with issues of fertility, matters of weight and diet often take on an additional gravity. When meeting with patients in my fertility clinic, one of the most common questions that I am asked is, "What kind of diet should we be on to improve our fertility?" The answer to the basic concept of lifestyle change to improve fertility is nuanced and there is no "one size fits all" response to the question.
There does exist a clear relationship between weight and fertility. Women who are either
overweight or underweight can have an extended time to conception. On average, it takes women with a body mass index (BMI) greater than 35 or less than 19 twice as long and four times as long, respectively, to conceive. (There are numerous online calculators to determine your own BMI - simply use the search term "BMI calculator" to find one.) Obesity is closely associated with difficulty ovulating, poorer response to fertility treatments, and increased rates of miscarriage. In men, obesity can be linked to a lower quantity and quality of sperm, lower testosterone levels, and an increased incidence of erectile dysfunction.
A recent study from Harvard showed an improved response (more eggs retrieved) in IVF treatment in overweight and obese women who had a modest, short-term weight loss prior to initiating a cycle (Chavarro, et al. Fert Steril 2012). Moreover, a normalization of body weight in women at the extremes of BMI has consistently been shown by multiple researchers to improve pregnancy rates and pregnancy outcomes.
While a healthy diet is generally recommended to patients for reasons both related and unrelated to fertility, many patients are unclear as to what constitutes a healthy diet. Little evidence exists that dietary variants such as vegetarian diets, low-fat diets, antioxidants, or herbal supplements have a positive impact on fertility. Studies have shown, however, that there may be a benefit to increasing slowly digested carbohydrates (fiber-rich carbs) over simple sugars. In addition, reducing animal protein in favor of plant protein, using unsaturated vegetable oils, drinking whole milk instead of skim (surprisingly),and staying hydrated with water instead of sugary soda can all help improve fertility based on observational data from the landmark Nurses' Health Study.
Alcohol consumption does not have a clear association with fertility. Studies looking at the effect of alcohol on fertility have shown conflicting results. Both an increased and a decreased fertility rate with moderate alcohol consumption (up to 2 drinks per day) have been reported. Still other studies have shown no effect. A practical recommendation would be to limit alcohol consumption to less than two drinks per day while trying to conceive and most importantly, stop alcohol consumption altogether with pregnancy.
Caffeine, like alcohol, is probably best taken in moderation. High caffeine intake (5 or more cups of coffee per day or 500 mg of caffeine) is associated with decreased fertility. During pregnancy, there is evidence to suggest that 200 - 300 mg of caffeine per day (the equivalent of more than two cups of coffee) is linked to a higher miscarriage rate. One to two cups of coffee per day or its equivalent while trying to conceive or during pregnancy does not appear to have an adverse effect.
Finally, stop smoking. Women who smoke enter menopause one to four years earlier on average than their non-smoking counterparts. In addition, women who smoke are 60% more likely to be infertile than women who do not. Lastly, smoking during pregnancy increases the chance of miscarriage. The evidence regarding male fertility and smoking is less established.
Taken in sum, the bottom line is to enjoy this holiday season with your friends and loved ones with moderation being the key. And if you have that extra slice of grandma's pumpkin pie or one more flute of champagne, fear not, New Year's is just around the corner and you can pledge anew that this will be the year that you will keep your resolution.