Eating for Fertility

by Victoria Shanta Retelny, RD, LD on May 01, 2008

Nutrition

What to eat if you want to improve your chances of getting pregnant.

In a perfect world, a couple’s desire to conceive a baby would be enough to guarantee a positive pregnancy test. Unfortunately, many would-be parents find themselves challenged by infertility. Now a new movement says that diet can play a helpful role in increasing fertility. But can the foods we eat really make a difference to our ability to reproduce, or is this just another flash-in-the-pan theory?

Facing Infertility

Although conceiving a child comes easily to the majority of people, fertility is elusive for some couples. One in six couples is affected by infertility during their reproductive lifetime (Chavarro et al. 2007). In fact, infertility is one of the most prevalent chronic health disorders involving young adults (Smith, Pfeifer & Collins 2003). Both the American Society for Repro­ductive Medicine and the American Col­lege of Obstetricians and Gyneco­logists recognize infertility as a disease (The National Infertility Association 2008).

According to The National Infertility Association, the term infertility is defined as having spent at least 1 year (6 months for women over age 35) attempting conception without success. Many factors can affect fertility, including the intricate interplay of hormones; the quality of sperm and egg; the timing and presence of ovulation; and body weight and fitness level. Although the causes of infertility vary, ovulation disorders are present in more than 25% of infertile female partners (Smith, Pfeifer & Collins 2003).

Fertility & Diet

Recently, there has been a focus on whether there is a relationship between diet and reproductive health. Researchers are now examining whether certain foods can stave off female infertility and increase the chances of conception.

Some of this research was the foundation for a new book—The Fertility Diet by Jorge Chavarro, MD, ScD, Walter Willett, MD, DrPH, and Patrick Skerrett (McGraw-Hill 2007)—that says diet is essential to anyone facing infertility. Essentially, the book’s authors recommend that women trying to conceive a child make the following dietary changes to increase their chances of conception:

  • Choose monounsaturated fats instead of dangerous trans fats.
  • Get protein and iron from plant sources, not animal sources.
  • Focus on complex carbohydrates and a moderate amount of full-fat dairy products.
  • Take multivitamins and supplements (Chavarro, Willett & Skerrett 2007).

Ovulatory Disorder Infertility

The focus of the fertility diet is on lowering the risk of a condition known as ovulatory disorder infertility. “Unlike other underlying conditions, such as blocked fallopian tubes, ovulation is a physiological process likely modifiable by environmental signals, including diet,” says Chavarro, one of the authors of The Fertility Diet and a research fellow in the department of nutrition at the Harvard School of Public Health.

Chavarro points to research that examined data from more than 17,500 women participating in the Nurses’ Health Study II who followed a proposed “fertility diet” (Chavarro et al. 2007). These women did not have a history of infertility and were trying to conceive or did conceive over an 8-year study period. At the end of the study, the researchers determined that the fertility diet—along with lifestyle modifications (i.e., physical activity)—might prevent ovulatory disorders in otherwise healthy women (Chavarro et al. 2007). “The most important point [of our findings] is that relatively simple changes to diet and lifestyle can have a profound effect on fertility,” says Chavarro.

Get Healthy, Get Pregnant

Other experts agree that a healthy lifestyle prepares the way for getting pregnant. “The best thing you can do to improve your chances of conception is to try to get healthy,” advises Laurence A. Jacobs, MD, a reproductive endocrinologist and a partner at The Fertility Centers of Illinois. “Moderation is the key word in this whole issue. Any extreme is not good. Being underweight or overweight makes it difficult to ovulate,” he says.

Jacobs’ entire clinical practice focuses on infertility issues, and the majority of his patients are 35 years and older. With fertility and diet making headlines these days, Jacobs cautions his patients not to take what they read out of context. For example, if women hear that full-fat dairy products can improve fertility, there is a real danger that they will miss the moderation message and eat beyond the point of any health benefit. And while Jacobs acknowledges that there may be strong associations between certain dietary patterns and improved ovulatory fertility, he also notes that no large randomized trials have examined the cause and effect of diet on infertility in women. “There are too many complicating variables [for us to] know which are the best diets out there for everyone,” warns Jacobs.

Body Weight & Fertility

Body weight, body mass index (BMI) and nutrition status have all been shown to be closely related to reproductive function (Lim, Noakes & Norman 2007). Obesity (i.e., having a BMI greater than 30) adversely affects pregnancy rates, even with fertility drugs or in vitro fertilization treatments (Jacobs 2007). A weight loss of 5%–10% of body weight can be enough to restore ovulation in obese patients (Jacobs 2007).

Sadly, most physicians fail to mention body weight when counseling or treating their fertility patients. Jacobs is not shy about emphasizing weight loss to his obese patients and for good reason: excess body fat (or adipose tissue) has been shown to cause hormonal imbalances by throwing off the delicate functioning of the hypothalamus and pituitary glands and triggering the body to secrete abnormal amounts of insulin (Jacobs 2007). This, in turn, can eventually lead to anovulation, or the loss of ovulation (Jacobs 2007).

Ovulation can be thwarted by a condition called polycystic ovary syndrome (PCOS). More than half of the women who are diagnosed with PCOS are overweight or obese (Liepa, Sengupta & Karsies 2008). Some experts have suggested that weight loss is more important than diet composition for improving reproductive function in overweight women, according to two small randomized trials involving women with PCOS (Moran et al. 2003; Stamets et al. 2004). But it’s not just the numbers on the scale that count: it’s also the woman’s body composition—her lean tissue (muscle, bone and organs) versus fat tissue. To improve their chances of conceiving, some of Jacobs’ overweight infertility patients wear adjustable weight vests to help them increase muscle mass, burn more calories and lose weight (Jacobs 2007; Morrison & Jacobs 2007).

The Impact of Insulin

When obese women suffer from PCOS, they become insulin resistant, meaning the cells of the body are no longer as sensitive to insulin. This becomes a vicious cycle because decreased insulin sensitivity causes the body to overcompensate by producing even higher levels of insulin in order to keep blood glucose levels normal. High levels of circulating insulin then cause increased fat storage and ultimately disrupt normal ovarian hormone production, which increases certain hormones and prevents proper ovulation (Jacobs 2007).

Insulin sensitivity is a main premise of the fertility diet. “Even though there is more work to be done in specific patient populations (in regard to infertility), our findings are in agreement with the overall hypothesis that insulin sensitivity is an important determinant of ovulatory function and fertility,” contends Chavarro. Other fertility doctors and researchers agree that diet quality counts. “It’s not so much low carb, but slow carbs,” advises Jacobs.

Because insulin resistance is one of the hallmarks of PCOS, many experts say that women with PCOS should adopt a diet similar to the one recommended for people with type 2 diabetes (Liepa Sengupta & Karsies 2008). To avoid surges in blood sugar and insulin levels, type 2 diabetics need to eat high-fiber whole grains (i.e., “slow carbs”), which take longer to digest, instead of high-sugar, more refined carbohydrates (i.e., “fast carbs”), such as soda, white bread and potatoes. “There is strong evidence showing that diet and lifestyle changes have a greater impact on insulin sensitivity than even some commonly used diabetes medications,” says Chavarro.

Sure-Fire Fertility Actions

“We know that it is the synergy of healthy behaviors that positively impacts fertility,” says Dawn Jackson Blatner, RD, LD, a national spokesperson for the American Dietetic Association. In addition to physical activity, certain foods play an important role in balancing hormone levels and keeping the reproductive system humming along. Blatner recommends getting a sufficient daily amount of “healthy” fats, such as those contained in fish, walnuts, almonds and olive oil, and avoiding “unhealthy” fats, such as trans fats. “Don’t be nervous to get some fat from dairy,” condones Blatner. However, Blatner is quick to add that women need to be careful about the quantity of healthy fats they get, since fat calories add up quickly. This applies to both saturated fat from full-fat dairy and unsaturated fat from nuts and olive oil.

Blatner also agrees with the authors of The Fertility Diet that consuming vegetable protein (e.g., beans, soy and nut butters) instead of animal protein is healthful for fertility. However, she cautions women to rein in their intake of full-fat dairy products to only one serving each day. It should be noted that in research studies, the beneficial effect of fats on fertility rates were seen with as little as two half-cup servings of full-fat products per week.

Blatner does agree that it is vital that women who wish to conceive take a daily multivitamin to get adequate amounts of iron and folic acid. Because so many women forget to take their daily multivitamin, Blatner suggests they put their vitamins in a place they go to every day; for example, next to their computer or toothbrush or in the drink holder in their car.

How Society Affects Fertility 

The way we now live in society is also taking its toll on fertility rates. Many women are delaying parenthood until later in life; are stressed with full-time jobs; and have little time to plan healthy meals and prepare family dinners each night. As a result, people turn to fast foods. “Eating at McDonald’s and Dunkin’ Donuts is good contraception,” Jacobs says half-jokingly.

With people consuming large amounts of saturated and trans fats, sugary beverages and low-fiber carbohydrates on a regular basis, increased body fat can also cause infertility. “Simply telling a patient to lose weight does not work,” says Jacobs. As an alternative, he says, motivation, counseling and behavior modification need to be the cornerstones for diet and lifestyle changes (Jacobs 2007).

It is too soon to say if the fertility diet will improve conception rates for women. But it is probably a good start and is mostly in keeping with many current nutrition standards. “Our recommendations are unlikely to cause harm to women who wish to try them and may, on the other hand, help them achieve the goal of becoming pregnant and serve as a guideline on how to continue a healthy diet afterwards,” Chavarro concludes.

SIDEBAR: Best Foods for Fertility

The following foods and supplements can increase your chances of getting pregnant, according to a new book called The Fertility Diet by Jorge Chavarro, MD, ScD, Walter Willett, MD, DrPH, and Patrick Skerrett (McGraw-Hill, 2008):

  • a daily multivitamin and mineral supplement, with at least 400 micrograms of folic acid (100% of the Daily Value [DV]) and 27 milligrams of iron (150% DV)
  • legumes and beans (black, kidney, pinto, white, navy, lentils, soy beans and lima)
  • nut butters (all-natural peanut butter or almond butter)
  • fish (salmon, tuna, halibut, mackerel or herring)
  • whole grains (whole-grain bread or tortillas, whole-wheat pasta, brown rice, whole-grain couscous, quinoa, oats, spelt and amaranth)
  • full-fat dairy products (whole milk, regular ice cream or cheese) Caution: Keep portions to no more than 1 cup milk, a half-cup ice cream or 1 ounce cheese, and limit your full-fat dairy choices to one serving per day.
  • dark, leafy greens/vegetables (spinach, kale and mustard greens, broccoli, asparagus and brussel sprouts)
  • healthy oils (extra-virgin olive oil and canola)

SIDEBAR: Fertility Resources

  • The American Society of Reproductive Medicine: a nonprofit, international multidisciplinary organization with a mission to provide information, education, advocacy and standards in the field of reproductive medicine; www.asrm.org
  • RESOLVE: The National Infertility Association, a national organization with more than 50 local chapters that is dedicated to providing education, advocacy and support; www.resolve.org 

Victoria Shanta Retelny, RD, LD, is a registered dietitian in private practice in Chicago. She operates a nutrition consulting business called LivingWell Communications (www.livingwellcommunications.com).

References

Chavarro, J.E., et al. 2007. Diet and lifestyle in the prevention of ovulatory disorder infertility. Obstetrics & Gynecology, 110 (5), 1050–8.

Chavarro, J.E., Willett, W., & Skerrett, P. 2007. The Fertility Diet. New York: McGraw-Hill.

Jacobs, L.A. 2007. Weight loss & conditioning improve fertility. Fertility Today (Spring).

Kovacs, G.T. 2004. Polycystic ovarian disease: An overview. Reviews in Gynaecological Practice, 4, 97–104.

Liepa, G.U., Sengupta, A., & Karsies, D. 2008. Polycystic ovary syndrome (PCOS) and other androgen excess-related conditions: Can changes in dietary intake make a difference? Nutrition in Clinical Practice, 23 (1), 63–71.

Lim, S. S., Noakes, M., & Norman, R.J. 2007. Dietary effects on fertility treatment and pregnancy outcomes. Current Opinion in Endocrinology, Diabetes and Obesity, 14 (6), 465–69.

Moran, L.J., et al. 2003. Dietary composition in restoring reproductive and metabolic physiology in overweight women with polycystic ovary syndrome. The Journal of Clinical Endocrinology & Metabolism, 88 (2), 812–19.

Morrison, G., & Jacobs, L.A. 2007. Fitness misconceptions, a fitness plan & a big important fact to improve fertility. Fertility Today (Winter).

National Infertility Association. www.resolve.org; retrieved Feb. 2008.

Smith, S., Pfeifer, S. & Collins, J.A. 2003. Diagnosis and management of female infertility. Journal of the American Medical Association, 290 (13), 1767–70.

Stamets, K., et al. 2004. A randomized trial of the effects of two types of short-term hypocaloric diets on weight loss in women with polycystic ovary syndrome. Fertility and Sterility, 81 (3), 630–37.

IDEA Fitness Journal, Volume 5, Issue 5

© 2008 by IDEA Health & Fitness Inc. All rights reserved. Reproduction without permission is strictly prohibited.

About the Author

Victoria Shanta Retelny, RD, LD IDEA Author/Presenter

Victoria Shanta Retelny, RD, LD, is a registered, licensed dietitian who runs Living Well Communications, a nutrition communications consulting practice, based in Chicago (www.livingwellcommunications...