Nutrition, An Under-Recognized Factor In Bacterial Vaginosis

Suboptimal nutrition can alter immune function and increase susceptibility to infections. Previous research has focused on the association of nutrition, particularly micronutrient vitamins and minerals and, in more recent decades, dietary fats and fatty acids, with a spectrum of infections ranging from measles, diarrheal disease, acute and chronic respiratory tract infections, and more recently, with human papilloma virus (HPV) and HIV (1). Little is known, however, about the association of nutrition with infections of the lower reproductive tract (LRTI), even though immune mechanisms in the lower reproductive tract are critically important for the prevention of LRTI and HIV infection (2). In this issue of The Journal of Nutrition, Neggers et al. (3) report on nutritional factors that may contribute to increased bacterial vaginosis in a study of 15to 45-y-old nonpregnant women. Genital tract infections are common in women. Organisms frequently considered responsible for symptomatic infections include group B Streptococi, Neisseria gonorrhea, Chlamydia trachomatis, Candida albicans, Gardnerella vaginalis, and Triochomonas vaginalis (4). Bacterial vaginosis (BV) is the single most common LRTI in women of childbearing age. It involves a shift from the predominant hydrogen–peroxide producing bacteria to a polymicrobial flora that results in high vaginal pH. BV is associated not only with great discomfort, but in case of pregnant women, it is also associated with an increased risk of premature rupture of membranes and consequently premature birth [(5) and reviewed in (4)]. In addition, BV strongly increases the risk of acquiring other sexually-transmitted infections such as N. gonorrhea, Chlamydia, and HIV in both pregnant and nonpregnant women [(6) and reviewed in (7)]. The risk factors for BV comprise several sociodemographic factors, including race and lifestyle/behavioral factors such as smoking, IUD contraceptive use, douching, sexual behavior– related factors, and stress. In recent years, researchers have begun to hypothesize that nutrition is another putative risk factor for BV. This hypothesis, although biologically grounded, has been examined only in few cross-sectional studies across the world (4,7–9). The study by Neggers et al. (3) is the first, to our knowledge, to report the association of BV with dietary intakes (energy, as well as macro and micro-nutrients) in 15to 45-y-old nonpregnant women. This study is also unique because of its prospective design and follow-up with subjects over a number of visits to examine the evolution of the infection. Another interesting feature of this study is that, for statistical analyses purposes, BV was considered in 2 ways: BV (defined by Nugent score $7) and severe BV (Nugent score $9 and vaginal pH $5). For each nutrient, intakes were considered as quartiles and OR were obtained using the lowest quartile as the reference group. Noteworthy findings from this study show that after adjusting for demographic and behavioral covariates, at baseline, the risk of BV was 40% higher in women who had a high energy intake (P 1⁄4 0.05). Over follow-up, ;19% women who started the study without BV (n 1⁄4 893), developed BV by the follow-up visit (visit 3). Interestingly, total energy intake was the only nutrient that remained marginally associated with incident BV (adjusted OR: 1.7; 95% CI: 1.0–2.9). Although this association was only marginally significant both for the entire study sample and for incident cases of BV, its consistency in the 2 situations suggests its importance and warrants further consideration in future investigations. Secondly, among all the macroand micronutrients examined, only total fat was significantly associated with BV in the entire study sample; compared with Quartile 1 of fat intake, presence in Quartile 4 was associated with a 50% higher frequency of BV (95% CI: 1.1–2.4). When the relationship of nutrient intake with severe BV (Nugent score $9 and vaginal pH $5) was examined in adjusted models, the higher fat intake remained associated with higher frequency of BV. In addition, inverse associations were noted between severe BV and intake of protein, vitamin E, folic acid, and calcium: adjusted OR for each of these nutrients fell between 0.4 and 0.5 (P , 0.05). The findings of the study generally fit well with the roles of these nutrients in modulating immune function, which have been previously described (1). The strengths of the study include its large sample size covering a broad age range (15–45 y) and simultaneous adjustment for demographic and lifestyle factors, as well as energy intake, when appropriate, in the logistic regression models. In summary, the findings by Neggers et al. (3) demonstrate the importance of optimal nutrition in BV infection. These results were obtained using the Block’s validated FFQ, which 1 Author disclosures: N. Ahluwalia and H. Grandjean, no conflicts of interest. 2 Abbreviations used: BV, bacterial vaginosis; HPV, human papilloma virus; LRTI, infections of the lower reproductive tract. * To whom correspondence should be addressed. E-mail: naman123@cict.fr or ahluwalia.n@chu-toulouse.fr.