Two case-control studies have examined the associations between fruit and vegetable intake and endometriosis risk with contrasting results.
Diets rich in fruits and vegetables include higher levels of pro-vitamin A nutrients ( alpha-carotene, beta-carotene, beta-cryptoxanthin ) and women with endometriosis have been reported to have lower intake of vitamin A than women without endometriosis.
A prospective cohort study used data collected from 70 835 premenopausal women from 1991 to 2013 as part of the Nurses' Health Study II cohort.
Diet was assessed with a validated food frequency questionnaire ( FFQ ) every 4 years.
Cases were restricted to laparoscopically confirmed endometriosis.
During 840 012 person-years of follow-up, 2609 incident cases of laparoscopically confirmed endometriosis were reported ( incidence rate = 311 per 100 000 person-years ).
Researchers observed a non-linear inverse association between higher fruit consumption and risk of laparoscopically confirmed endometriosis ( P significance of the curve = 0.005 ).
This inverse association was particularly evident for citrus fruits.
Women consuming 1 or more servings of citrus fruits/day had a 22% lower endometriosis risk ( 95% CI = 0.69-0.89; P trend = 0.004 ) compared to those consuming less than 1 serving/week.
No association was observed between total vegetable intake and endometriosis risk. However, women consuming 1or more servings/day cruciferous vegetables had a 13% higher risk of endometriosis ( 95% CI = 0.95-1.34; P trend = 0.03 ) compared to those consuming less than 1 serving/week.
Of the nutrients examined, only beta-cryptoxanthin intake was significantly associated with lower endometriosis risk ( RR fifth quintile = 0.88; 95% CI = 0.78-1.00; P trend = 0.02 ).
These findings suggest that a higher intake of fruits, particularly citrus fruits, is associated with a lower risk of endometriosis, and beta-cryptoxanthin in these foods may partially explain this association.
In contrast to what researchers hypothesized, consumption of some vegetables increased endometriosis risk which may indicate a role of gastrointestinal symptoms in both the presentation and exacerbation of endometriosis-related pain; however, it is not clear what components of these foods might underlie the observed associations.
Future studies examining dietary patterns that consider different combinations of food intake may help clarify these associations. ( Xagena )
Harris HR et al, Hum Reprod 2018; Epub ahead of print