Fertility Diet: Can nutrition affect fertility?

July 8, 2010Carole 4 Comments »

Yes! Nutrition can affect fertility but there is no magic fertility diet. Assuming that you don’t suffer from celiac disease or polycystic ovarian syndrome which have underlying metabolic disorders to begin with, most of us will optimize our fertility by eating (in moderation) a healthy diet which keeps us somewhere near our ideal weight. Extreme diets that emphasize one leg of the nutritional triad, carbs, fats or proteins to the exclusion of the others are probably a bad idea.

The largest data base on nutrition habits and health outcomes is the Nurses’ Health Study, which is currently in its third roll-out. The original study was started in 1976, with a second nurses study started in 1989 with a younger cohort (age 25-42).  Nurses agreed to answer an on-going questionnaire every two years on various lifestyle habits and on their current health. In the original survey, 122,000 nurses out of the 170,000 responded to the survey. In the second survey, 116,686 women out of 517,000 responded. Starting in 1991, food frequency surveys were conducted every two years.  About 90% of enrollees continued to participate over time. Recruiting for a third study group is occurring now. This huge database has been mined for all types of associations between diet and cardiovascular health, overall health and recently, fertility. The downside of this study is that all the observations are associations between diet habits and outcomes. Associations do not prove cause and effect, but since randomized controlled trial data on the effect of preconception lifestyle on pregnancy outcome is scarce or non-existent, animal data and large population studies are what we have to work with.

Jorge Chavarro, an investigator on the Nurses’ Health Study and research fellow at the Harvard School of Public with coauthors Walter Willet and Patrick Skerrett wrote a book called the Fertility Diet which summarized their analysis of data from the nurses study. The abstract of their original paper can be found here. Although all their recommendations are based on positive associations with certain dietary habits and ovulatory function, which are associations and not proof, their advice dovetails nicely with other healthy diet recommendations.

Their advice based on the Nurses’s study boils down to a few basic reccomendations to optimize your nutritional state for fertility. US News (Health) interviewed Dr. Chavarro and he gives a more complete explanation in that interview.

Slow carbs, instead of no carbs. Eating lots of white bread, potatoes and sugared sodas is associated with a higher incidence of ovulatory infertility (irregular cycles, problems with ovulation).  These easily digested sugars resulted in sky rocketing glucose levels and insulin levels. Poorly regulated insulin levels and obesity play a role in infertility associated with polycystic ovarian disease, so it makes sense that eating in a way that controls these levels and prevents obesity may be protective of fertility.  The amount of carbohydrates consumed by nurses didn’t seem to be as important as the type of carbohydrates consumed. Eating whole grains, beans, vegetables, brown rice, pasta, dark breads and whole fruits are examples of slow carbohydrates.  A diet favoring slow carbs instead of fast carbs was associated with a lower probability of having ovulatory infertility.

Balancing Fats. Fat in the diet is necessary for normal steroid production which obviously affects fertility. However, the type of fats in the diet were found to be significant. Trans fats were found to be strongly associated with an increased risk of ovulatory infertility. In the Nurses’ study, ingesting even 4 grams of trans fat a day had a negative effect according to Chavarro’s analysis of the survey data. He goes on to say that 4 grams a day of trans fat is LESS trans fat than the average American eats in one day. Four grams of trans fat can be found in two tablespoons of a stick of margarine, one medium order of fast-food french fries or one doughnut. Polyunsaturated fat or mono-unsaturated fats are better choices for fat intake. Mono-unsaturated fats have long been advocated for reducing total cholesterol and LDL cholesterol. Examples of foods rich in mono-unsataurated fats are peanuts, walnuts, almonds, pistachios, avocado, canola and olive oil. Examples of foods rich in poly-unsaturated fats are salmon, fish oil, corn, soy, safflower and sunflower oils.  Frankly, if you do your own cooking, and avoid processed prepared foods, you can do a lot to eliminate trans-fats from your diet.

Protein from plant sources is better. Protein is an essential part of a healthy diet. The source of the protein is significant. Beans and protein-rich nuts were a better protein source for optimizing fertility than beef, chicken or pork. Replacing one serving of animal meat with a serving of beans, peas, tofu or soybeans, peanuts or other nuts was protective against ovulatory infertility.  Women in the highest-protein intake group had more fertility problems than women from the lowest-protein intake group. So, based on these results, an Atkins type diet which emphasizes protein intake at the expense of most everything else- except fats, is probably also a poor choice for optimal fertility.

Dairy. Another finding of their study was that a “daily serving or two of whole milk and foods made from whole milk—full-fat yogurt, cottage cheese, and, yes, even ice cream—seem to offer some protection against ovulatory infertility, while skim and low-fat milk do the opposite.” That doesn’t mean you get to eat a pint of whole ice cream a day– in fact a pint should last two weeks!! –based on their estimate of the  ideal amount of whole fat dairy to add to your diet.

Avoid Obesity. Many studies have shown that obesity can wreak havoc with fertility because it can deregulate insulin and hormonal regulation, causing ovulatory infertility. The American Society for Reproductive Medicine has published an educational bulletin on the effects of obesity on fertility.  Granted, obese people get pregnant, but avoiding obesity may make the difference in borderline fertility. We all have a net fertility level, based on various genetic and environmental factors in ourselves and combined with the fertility status of our partner. For those of us that are struggling with some sub-optimal factors, obesity may be the one extra thing that pushes us into infertility. Another thing to consider is that achieving pregnancy is not the end game. Having a healthy pregnancy and bringing home a healthy baby is really the point of infertility treatment. Lots of research data has been collected showing that obese women have more difficult pregnancies and a higher risk of pregnancy complications and miscarriage.

Nutrition likely impacts our fertility status if we have ovulatory problems. But what about other fertility problems? If our ovaries are fine but our tubes are blocked, diet will not help with our fertility. So is good nutrition still important? Yes! because taking good care of ourselves before we get pregnant results in healthier pregnancies. The March of Dimes organization has identified fourteen area of preconception care which can prevent adverse pregnancy outcomes. Having folic acid in your diet before you become pregnant is essential to reducing the risk of your child having neural tube defects like spina bifida.

There may be some special forms of infertility which may benefit from specific diets. Women who have polycystic ovarian syndrome may benefit from diets that are skewed toward low calorie high protein diets coupled with exercise to reduce weight based on this small pilot study. High fat diets may be especially problematic for causing insulin resistance in the ovary which is known to be involved with etiology of  PCOS.  Here’s my disclaimer. Please talk to your doctor about any planned dietary changes, especially if they are unbalanced dietary changes because I am not a nutritionist or a physician.

It turns out that your mother was right. Eating healthy and in moderation is the best way to live– and apparently– procreate.

© 2010, Carole. All rights reserved.

4 Responses to this entry

  • E Says:

    thank you so much for this information! This is so helpful! I was about to embark on a protein diet and I won’t now.

    also: can you comment on the difference/effectiveness of 3 day vs 5 day transfers?

  • Anonymous Says:

    Is checking for PCOS a part of evaluating infertility? How is it diagnosed?

  • Carole Says:

    PCOS can be a part of the work up for infertility, particularly if the patient complains of irregular cycles and symptoms of abnormally high androgen levels causing male-like coarse hair growth on the face (hirsutism) or severe acne. Ultrasound examination of the ovaries to look for evidence of multiple ovarian cysts is also used to make a diagnosis. In some cases, insulin resistance is part of the underlying metabolic issues that cause PCOS.
    Here is a link to an article that explains in detail the diagnosis and management of PCOS

  • You (and your sperm) are what you eat | Fertility Lab Insider Says:

    […] infertility book, The Fertility Diet. I blogged about his research in a previous post, “Fertility Diet: Can nutrition affect fertility?“. Chavarro’s study  of just under 100 men revealed that men who eat diets that contain […]

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