Buying organic food is expensive and it is hard to know if it is necessary when trying to conceive.
While there are studies that show that occupational exposure to pesticides can compromise fertility in both men and women,[1] there hasn’t been much data that shows that pesticide exposure in small quantities (in the foods we eat) can harm fertility.
Until now.
Study Details
Recently, there was a study published in JAMA that looked at just this[2]. It looked at 325 women undergoing fertility treatments and assessed the association between the amount of high-pesticide residue fruit and vegetable consumption and their rates of clinical pregnancy and live birth. All women enrolled in the study filled out a food-frequency questionnaire detailing how many fruits and vegetables they consumed per day, and specifically, which ones. Each fruit and vegetable was classified according degree of pesticide residue according to annual reports from the US Department of Agriculture Pesticide Data Program (PDP). Based on this data, every fruit and vegetable was categorized as a “high” or “low” pesticide residue food.
Results
Women who consumed the most high-residue fruits and vegetables (>2.3 servings per day) compared to those who consumed the least amount of high-residue fruits and vegetables (less than 1 serving per day) had an 18% lower probability of clinical pregnancy and a 26% lower probability of live birth. High pesticide residue fruits and vegetables were also associated with the probability of pregnancy loss.
Those that consumed the lowest amount (lowest quartile) of high pesticide foods had 7% chance of pregnancy loss, and those that consume the most (highest quartile) had a 34% chance of pregnancy loss. These results were statistically significant.
Study Limitations
This is a small study, that relies on dietary self-reporting and food frequency questionnaires, which can be unreliable. It is also an observational study and did not randomly assign women to consume high and low pesticide residue fruits and vegetables. This means, we cannot rely on the data to prove causation (consuming high pesticide residue foods CAUSES a decrease in pregnancy rates and lower probability of live birth rates) but rather just shows an association that could also be caused by a confounding variable.
Which Fruits and vegetables have highest pesticide residues?
When I reviewed full-text article I cite here, I found that the fruits and vegetables considered to have “high residues” of pesticides corresponded well to the Environmental Working Group’s list foods (clean fifteen and dirty dozen). This is likely because it relies on the same data. You can use this as a reference to guide your purchases.
Take-Home Points
First, I would caution the tendency to fear fruits and vegetables because they are potentially toxic. I strongly believe it is better to consume any fruits and vegetables vs. none at all. EVEN those high on the list of “high pesticide” residue foods. In other words, don’t reduce overall fruit and vegetable consumption for fear of toxicity. However, if you are undergoing an upcoming fertility treatment, and you would like to be extra prudent, I would suggest making the following changes:
- If you can afford it, consider buying organic fruits and vegetables, especially for those fruits and vegetables that are known to have high pesticide residues. You can reference the “dirty dozen” here.
- Wash all of your fruits and vegetables really, really well. We use a warm salt-water solution and let everything soak for 10-15 minutes at my house. We soak organic and non-organic fruits and vegetables separately.
- Don’t reduce the amount of fruits and vegetables you are eating out of fear, instead, switch out those that are high on the list of pesticide residues for those lower on the list.
There is definitely an overall lack of research on dietary patterns and fertility. I hope that this body of research continues to grow, so that we can continue to make decisions based on evidence.
References
[1] Snijder CA, Velde ET, Roeleveld N, Burdorf A. Occupational exposure to chemical substances and time to pregnancy: a systematic review. Human Reproduction Update. 2012;18(3):284–300.
[2] Chiu Y-H, Williams PL, Gillman MW, Gaskins AJ, Mínguez-Alarcón L, Souter I, et al. Association Between Pesticide Residue Intake From Consumption of Fruits and Vegetables and Pregnancy Outcomes Among Women Undergoing Infertility Treatment With Assisted Reproductive Technology. JAMA Internal Medicine. 2017;