Can Your Diet Affect Fertility?
May 4, 2012
By Brianna Gray, M.S.
About one in six couples in the United States experience infertility. Assisted reproductive technologies (ART) are methods couples use to help couples have children.
Both the success rates and the number of people who use ART, such as in vitro fertilization, have grown over the past few decades. However, these methods do not guarantee pregnancy. Although lifestyle changes, such as following a healthy diet, may not replace fertility treatments, they can significantly improve both your health and your fertility.
Even if you are not experiencing fertility problems, boosting your health before pregnancy will make it easier for you to conceive, reduce pregnancy complications and improve your baby's health. The following recommendations can help increase your chances of conceiving.
Research has found that women with body mass indexes (BMI) between 20 and 24 (21 is optimal) have the best chance of getting pregnant. Women with BMIs outside that range have more difficulty conceiving. (Calculate your BMI here.
Being underweight or overweight can alter the body's hormonal cycles and interfere with ovulation. Excess weight is also associated with insulin resistance and can lower the success rate of ART. Men should also be mindful of their weight. Being overweight lowers testosterone and sperm production.
The good news? If you are underweight, gaining just 5 to 10 pounds could help restart ovulation and improve fertility. If you are overweight, losing just 5% to 10% of your body weight significantly improves fertility, even if you are well above the ideal body weight range.
Diets like Atkins, South Beach and Dukan have given carbohydrates a bad rap. But for overall health and to improve fertility, it's important to include high-quality carbohydrates in your diet every day.
Low glycemic index (GI) carbohydrates (whole grains, beans and legumes, and fruits and vegetables) stabilize blood sugar and insulin. They are better for fertility than high GI carbohydrates (white bread, pasta or rice, soda, fruit juice and candy). It's unknown exactly how elevated blood sugar and insulin resistance contribute to infertility. But studies have found a link between diets high in low GI carbohydrates and ovulatory fertility.
Women with polycystic ovary syndrome (PCOS), a disorder characterized by poor insulin sensitivity and infertility, have improved fertility rates following treatment with insulin-sensitizing drugs. In addition to keeping blood sugar steady, low GI carbohydrates also have more fiber, vitamins, minerals and protein than their refined counterparts.
Research has found that replacing animal proteins with plant proteins reduces the risk of infertility by 50%. For a fertility boost, aim for at least half of your protein to come from nuts and nut butters, beans and legumes, edemame, tofu and eggs.
Including healthy fats in your diet, and avoiding the unhealthy ones, is an important step to improved fertility. Unhealthy trans fats (hydrogenated oils found in many baked goods, crackers and cookies) promote inflammation and insulin resistance.
Inflammation can reduce the body's sensitivity to insulin by blocking key proteins, such as adiponectin and PPAR-gamma, involved in insulin-sensitivity. Also, insulin resistance has been associated with infertility. Mono- and polyunsaturated fats have the opposite effect they reduce inflammation and are good for fertility. Replacing trans fats with mono- and polyunsaturated fats is a great way to improve your fertility and overall health.
This is one case when whole milk gets the thumbs up. Research has found that women who drank one serving of whole milk a day had an easier time getting pregnant that those who did not drink milk or who ate low-fat dairy foods.
Whole milk contains fat-soluble hormones that appear to be important for fertility. These hormones are lost during the skimming process. Thus, whole milk's better hormonal mix may explain the improvement in fertility among women who drank it compared with those who drank 1% or skim.
Full-fat dairy products may improve fertility, but don't overdo it. Remember, maintaining a healthy weight is an important piece of the fertility puzzle. Once you are pregnant, it's a good idea to drink heart-healthy skim or 1% milk again.
Conception requires extra folic acid and iron. Folic acid is essential during the early prenatal period to prevent neural tube defects birth defects of the brain and spinal cord. Taking a prenatal vitamin is associated with improved fertility in women. And daily multivitamin/mineral supplements improve sperm counts in men.
Women who are planning a pregnancy should take a prenatal vitamin that contains nonheme iron (from plant sources) as this appears to help fertility more than heme iron. Men who are looking to boost their fertility do best sticking with a standard multivitamin/mineral supplement.
Simple, inexpensive changes to your diet and lifestyle could greatly improve your chances of getting pregnant and having a healthy pregnancy. So:
CDC. Fertility, Family Planning, and Reproductive Health of U.S.Women: Data From the 2002 National Survey of Family Growth Series 23, No. 25, Table 69. Dec 2005. Retrieved from: http://www.cdc.gov/nchs/data/series/sr_23/sr23_025.pdf.
Brianna Gray, M.S., is a dietetic intern at Brigham and Women's Hospital.