“An apple a day keeps the doctor away!” This old English proverb is probably familiar to many, as a mantra from early childhood that encourages you to eat all of the fruit and vegetables on your plate! While of course the proverb is an oversimplification, current dietary guidelines emphasize the importance of consuming a wide range of fruit and vegetables which can provide many positive health benefits including reducing the risk of chronic disease. However, agricultural practices often allow for pesticide usage, meaning lingering pesticide residue that may be present on fruit and vegetables can be consumed, the overall impact of which is relatively unknown. It has been determined, however, that pesticide exposure can alter hormonal signaling pathways in the body, an effect that may have an impact on gynecological disorders. Dr. Colette Davis, a postdoctoral research fellow in Dr. Holly Harris’s Group in Fred Hutch’s Public Health Sciences Division, and colleagues sought to understand whether residual pesticide consumption can impact the development of fibroids. Fibroids are non-cancerous growths that develop in the uterus and can cause serious symptoms for those who develop them, for example difficulty getting pregnant and pelvic pain. Explaining their study recently published in F&S Science in greater detail, Dr. Davis said “it is estimated that over 90% of the U.S. population has detectable concentrations of pesticides or related metabolites in their blood or urine, and the majority of the exposure among non-agricultural workers is through the ingestion of conventionally grown (non-organic) fruits and vegetables. According to our study, conventionally grown fruits and vegetables do not contribute to risk of fibroids but may very well protect against the risk of fibroids.”
As part of their study design, the authors utilized the Nurses’ Health Study II, a prospective questionnaire-based study that follows participants over time and can inform on risk factors for chronic disease. By engaging this cohort, the authors were able to assess fruit and vegetable consumption through self-reported questionnaires, as well as investigate the impact of pesticide residue. For pesticide residue the authors applied the pesticide residue burden score (PRBS) according to surveillance data from the USDA Pesticide Data Program. This allowed them to split fruit and vegetables into pesticide residue high and low subgroups, in addition to assessing the impact of total fruit and vegetable consumption on fibroid risk. Discussing the study design and use of the PRBS score in more detail, Dr. Davis noted that “to our knowledge this is the first study to examine the association between high- and low-pesticide-residue fruit and vegetable intake and risk of fibroids, and only the second prospective study to examine the association between fruit and vegetable intake and fibroid risk. It’s important to note the PRBS score has been validated in a longitudinal cohort through comparison with urinary pesticide biomarkers and urinary concentrations. A past study examined the association between high- and low-pesticide-residue fruit and vegetable intake and risk of endometriosis; however, more studies should examine PRBS (as the exposure variable) and various health outcomes, which includes other gynecological conditions.”
The authors determined no association between total fruit and vegetable consumption and risk of fibroids when comparing more than 6 daily servings to fewer than 2 daily servings, however, those participants who consumed 4 or more daily servings of fruit had a 10% lower risk of developing fibroids compared to those who only consumed 1 portion or less of fruit per day. The authors analyzed 30 fruit and vegetables with assigned PRBS scores, 18 with low PRBS scores and 12 with high PRBS scores. Interestingly, intake of fruit and vegetables with a high PRBS score was correlated with a lower risk of fibroids, while intake of fruit and vegetables with low PRBS scores did not impact fibroid risk. “Our findings of a lower risk of fibroids with higher intake of fruit and vegetables with high pesticide residue and a lower risk with a higher intake of total fruits indicate that the benefits of fruit and vegetable consumption may outweigh the potential impact of pesticide residue exposure,” summarized Dr. Davis.
The topic of residual pesticide consumption is of interest to many, and The Environmental Working Group releases a list annually of the “Clean 15” and “Dirty Dozen” with respect to pesticide exposure and fruits and vegetables. Discussing these lists and how they relate to their present fibroids study, Dr. Davis said “it would be interesting to witness the similarities and differences between the concentration of pesticide exposure of the Environmental Working Group lists and the annual reports from the USDA Pesticide Data Program (PDP) which classifies fruits and vegetables according to their average pesticide residue status in the U.S. To limit pesticide exposure, you can buy organically grown fruits and veggies or purchase fruits and veggies from Farmers Markets or local vendors. But it’s important to recognize that the cost of organic fruits and vegetables if often higher than conventional so that this not an option for all people. Importantly our study noted that, at least for fibroids, the advantages of consuming fruits and vegetables may outweigh the potential harm caused by pesticide residue exposure.”
As Dr. Davis highlighted, it is not possible for many people to eat only organic fruit and vegetables, thus additional research is necessary to understand the risk of fibroids and associated links to pesticide and fruit and vegetable consumption in a broader subset of the general population. “Future studies are needed to confirm if the nutrient properties associated with fruits specifically (regardless of pesticide residue) are particularly protective against fibroids. Further, given the age range of our study population, additional studies examining an exposure window more proximal to fibroid initiation among younger participants and assessing class specific pesticides are needed,” Dr. Davis explained. She concluded by noting that “the longitudinal cohort utilized in this study consist of predominantly White women. In the future, it’s important for these associations to be examined among populations that include Black women who are most impacted by fibroids.”
This work was supported by grants from the Eunice Kennedy Shriver National Institute of Child Health and Human Development, the National Institutes of Health, and the American Heart Association.
Fred Hutch/University of Washington/Seattle Children's Cancer Consortium member Holly Harris contributed to this work.
Davis CP, Garzia NA, Cushing-Haugen K, Terry KL, Chiu YH, Sandoval-Insausti H, Chavarro JE, Missmer SA, Harris HR. Fruit and vegetable consumption, pesticide residue intake from consumption of fruits and vegetables, and risk of uterine fibroids. F S Sci. 2023 Feb;4(1):90-99. doi: 10.1016/j.xfss.2022.12.001. Epub 2022 Dec 20. PMID: 36549440; PMCID: PMC9983709.