By: Rachel Neifeld, RD, CDN
It is known that diet plays a role in fertility, but new research shows just how much a woman’s diet can affect her ability to become pregnant. Results from the Harvard’s Nurses’ Health Study suggest that the majority of infertility cases due to ovulation disorders are preventable through modifications of diet and lifestyle. This large study followed 17,544 women without a history of infertility for 8 years while they tried to become or became pregnant. Researches think that a woman’s diet affects ovulation, and hypothesize that women with healthy insulin levels- the hormone that controls blood sugar- are more likely to ovulate normally. Those who have insulin resistance or diabetes are more prone to irregular ovulation. The following are five diet and lifestyle factors that the Nurses’ Health Study found to be influence a woman’s fertility:
- Take a Multivitamin: Women who took a multivitamin containing folic acid were more likely to become pregnant. Folic acid helps prevent birth defects of the brain and spinal cord. All women who can get pregnant should take a daily multivitamin containing 400 micrograms of folic acid every day.
- Get Your Iron From Plants: Women with higher iron-intakes were also more likely to become pregnant, but the iron had to come from plant sources or supplements, not red meat. Vegetables, beans, nuts, and soy products are all good sources of iron. Consuming plant-sources of iron with vitamin C, found in many fruits- especially citrus, helps aid in absorption.
- Avoid Trans Fats: The study suggests that trans fats may disrupt hormone balance and increase insulin resistance. The researches, along with health experts, recommend eating as little as possible. Try replacing processed foods such as margarine, doughnuts, cookies, and chips, with less processed and more nutritious foods such as whole grains, fruits, and vegetables. This appears to have a beneficial effect on insulin levels, helping to promote healthy ovulation.
- Get to a Healthy Body Weight: The coauthors of The Fertility Diet, the book based on the Nurses Health Study, states “…the most important thing would be to get to a healthy body weight.” Women who had a body mass index between 20 and 24 had the best chance of getting pregnant. Numerous studies have shown that overweight woman can jump-start ovulation by losing just 5 to 10 percent of their body weight. The fertility diet recommends aiming for a 7½ percent weight loss, which is 15 pounds for a woman who currently weighs 200 pounds.
- Have One Daily Serving of Full Fat Dairy: This may not be a recommendation you’re used to hearing, and one that the authors of the study are somewhat skeptical of. Nevertheless, the results of the Nurses’ Health Study found that a daily serving of a full-fat dairy food, such as whole milk, ice cream, or cheddar cheese, increased a woman’s pregnancy odds. The beneficial effect of ice cream was seen at two servings per week of ½ cup - so a pint of ice cream should last two weeks. Instead of risking going overboard on ice cream, a better idea would be having one serving of whole milk instead of skim, or replacing once serving of low fat yogurt with full fat. This part of the diet is considered optional by the researchers since high-fat dairy foods have been connected to poor insulin levels in other research. If you’ve been told by your doctor to gain less or maintain your weight during pregnancy, you should leave the full fat dairy products out.
Following the “fertility” diet pattern and controlling body weight by exercising for 30 minutes every day may help prevent the majority of infertility cases due to problems with ovulation in otherwise healthy women. Most of the advice that stems from this study is consistent with an overall healthy lifestyle- plus it won’t only increase the odds of becoming pregnant but can decrease future disease risks too. This study gives women another great reason to eat less processed foods, more fruits, veggies, whole grains, and lean protein and to stay active.
Obstetrics & Gynecology: November 2007- volume 110- Issue 5- pp 1050-1058