The Dietary Inflammatory Index Is Directly Associated With Polycystic Ovary Syndrome

A Case-Control Study

Elnaz Zirak Sharkesh; Seyed A. Keshavarz; Leila Nazari; Behnood Abbasi


Clin Endocrinol. 2022;96(5):698-706. 

In This Article

Abstract and Introduction


Introduction: The association between diet and polycystic ovary syndrome (PCOS) might be mediated by the inflammatory properties of the diet. The study aimed to investigate the relationships between the dietary inflammatory index (DII) with odds of PCOS among the adult population.

Methods: In the hospital-based case-control study, 203 patients with PCOS and 291 non-PCOS controls were enroled. DII was calculated via a validated 147-item quantitative food frequency questionnaire (FFQ). Thirty-six macro- and micronutrients were extracted from FFQ and used to calculate DII. Employing a case-control design, odds ratios (ORs) and 95% confidence intervals (CIs) were obtained, with a dose-response effect confirmed by the test for trend (p for trend).

Results: The mean ± SD age and body mass index (BMI) of the study participants were 29.67 ± 5.92 years and 24.51 ± 4.71 kg/m2, respectively. Compared with controls subjects, PCOS patients had significantly higher weight, BMI, and waist circumferences, but had lower physical activity. PCOS subjects had higher intakes of carbohydrate, cholesterol, and refined grains, but lower intakes of polyunsaturated fatty acids, fibre, vitamin B12, vitamin D, and dairy as compared to controls. Compared with participants in the lowest quartile of DII, those in the highest quartile had a significantly higher OR for PCOS after further adjustment for potential confounders (OR = 1.75, 95% CI: 0.95–3.22).

Conclusion: Our data suggest that high DII was associated with an increased odds of PCOS diagnosis. Prospective dietary intervention studies and observational prospective cohorts are required to confirm these findings.


Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women of childbearing age worldwide with a prevalence of 8%–13% according to Rotterdam diagnostic criteria.[1] PCOS is characterised by menstrual irregularities, hyperandrogenism, polycystic ovaries, hyperinsulinemia, obesity, and mild to chronic inflammation, and may increase the risk of metabolic syndrome, type 2 diabetes, and cardiovascular disease.[2–4]

Although the exact cause of PCOS is not yet known, studies have shown the role of genetic and environmental factors, such as unhealthy lifestyles that lead to obesity and insulin resistance, as well as their interactions in the development of this syndrome.[3,5] However, new evidence suggests a key role for proinflammatory and inflammatory mediators in the pathophysiology of PCOS, which appears to be independent of obesity and other factors.[6] So that, reports of women in both obese and normal weight groups indicate high levels of circulating serum tumour necrosis factor (TNF)-α, C-reactive protein (CRP), monocytes, lymphocytes, and the penetration of inflammation into ovarian tissue.[7]

In addition, many studies show the important role of diet in increasing levels of inflammatory factors as well as mild to chronic inflammation in various patients. Some dietary components such as fruits, vegetables, fibre, omega-3 fatty acids, vitamin C, and vitamin E have been shown to reduce inflammation in the body.[8–11] On the other hand, some dietary components such as saturated fatty acids (SFAs), foods with high blood sugar index, and high nsaturated fatty acid (PUFA) ratio n-6/n-3, increase the level of inflammation.[8] Insofar as most of the nutrients in the diet are usually consumed together and may have synergistic effects on each other, the examination of dietary patterns that reflect all the characteristics of the diet compared to specific nutrients or foods are more appropriate to be extrapolated into the real-world scenario.[8]

One of the dietary indices that has recently come to the attention of scientists is the dietary inflammation index (DII), which has been developed to assess the inflammatory potential of an individual's diet and to compare different populations.[12,13] The DII has been validated in association with variety of inflammatory biomarkers such as CRP, TNF-α, and interleukin-6 (IL-6).[13]

Several lines of evidence have shown the potential relation between DII and reduce the risk of chronic diseases such as type 2 diabetes,[14] metabolic syndrome and oxidative stress markers,[15] cancer,[16] and cardiovascular disease,[17] which share common metabolic parameters with PCOS. However, to the best of our knowledge, the association between DII and risk of PCOS have not yet been investigated.

Due to the role of inflammation and oxidative stress in the pathogenesis of this syndrome and the role that diet can play in causing inflammation and oxidative stress, this study aimed to investigate the relationship between DII and the risk of PCOS in a case-control sample of Iranian adults.