|dc.description.abstract||Polycystic ovary syndrome (PCOS) is a complex endocrinopathy associated with adverse cardio-metabolic, reproductive, and quality of life outcomes. Controversy surrounds the optimal diet composition to mediate favourable health-related outcomes for women with PCOS. The main hypothesis of the present work was that a nutritionally balanced, low-glycemic index, pulse-based diet containing lentils, beans, split peas, and chickpeas would increase insulin sensitivity; thereby, improving multiple health-related outcomes of PCOS. The objectives of the present work were 1) to examine the prevalence and characteristics of metabolic syndrome (MetS), glucoregulation, type 2 diabetes, and risk factors for cardiovascular disease in women with PCOS, and 2) to compare the effect of a pulse-based diet to the National Cholesterol Education Program’s Therapeutic Lifestyle Changes (TLC) diet on reproductive health measures, cardio-metabolic risk profile, health-related quality of life (HRQoL) indices, dietary intakes, and pulse consumption behaviours in women with PCOS.
To examine the study Objective 1, data were pooled from 2 prospective and cross-sectional studies on 237 women with PCOS and 42 (non-PCOS) controls (18-36y; Chapter 3). The prevalence of metabolic syndrome was 29.5% in the PCOS group, approximately 6-fold higher than age-matched controls (P<0.001), with worse glucose control, acanthosis nigricans, body mass index (BMI), systolic blood pressure (SBP), triglyceride (TG), high- (HDL-C) and low- (LDL-C) density lipoprotein cholesterol, total cholesterol to HDL-C (TC/HDL-C), and highly sensitive C-reactive protein levels (P<0.001 to P=0.03). Women with PCOS and MetS exhibited exacerbated levels of insulin and glucose responses to an oral glucose tolerance test (OGTT), TC, TC/HDL-C ratio, hirsutism, and acanthosis nigricans than BMI-matched counterparts without MetS (P<0.001 to P=0.05). Our observations support the opinion that MetS exacerbates hyperandrogenism, dyslipidemia, and glucose control in PCOS, possibly by aggravating inherent insulin resistance.
To address the main goal of the study, Objective 2, 95 women with PCOS (18-35y) were randomized to receive either the pulse-based diet or the TLC diet, without purposefully inducing calorie restriction, for 16 weeks. All women participated in an aerobic exercise program and received education and counselling about PCOS and lifestyle modification. Thirty women in the pulse-based diet and 31 in TLC diet group completed the study. Chapter 4 represents the reproductive outcome results of Objective 2. Bilateral antral follicle count, ovarian volume, total testosterone (TT) levels, average and longest intervals between menses decreased over time in both groups (P≤0.05). Sex-hormone binding globulin levels increased (P<0.01) in both groups with a tendency for a greater increase in the pulse-based diet group (P=0.07). In Chapter 5, cardio-metabolic outcomes of Objective 2 are addressed. The pulse-based diet group had a greater reduction in total area under the curve (AUC) for insulin response to an OGTT than the TLC diet group (P=0.05). Following the intervention, the pulse-based diet group exhibited lower diastolic BP, TG, LDL-C, and TC/HDL-C, as well as a greater increase in HDL-C when compared to the TLC diet group (P≤0.05). Body weight, waist circumference, percent body fat, SBP, homeostatic model assessment of insulin resistance, glucose AUC, and TC decreased in both groups (P≤0.03). Both groups maintained some of the improvements in cardio-metabolic and endocrine measures after 16 and 12 months post-intervention, including TT, HDL-C, and TC/HDL-C levels (P≥0.05); however, contrary to our hypothesis, groups had a tendency to revert to the baseline measures for certain cardio-metabolic and endocrine measures including fasting insulin and TC levels 6 and 12 months after the completion of the intervention (P≤0.05).
Following the 16-week intervention, the HRQoL scores of both groups increased in the domains of knowledge, concerns about PCOS, healthcare satisfaction, and lifestyle practices comprised of physical activity and healthy diets (P<0.05; Chapter 6). The dietary component of Objective 2 is addressed in Chapter 7. Both intervention groups voluntarily reduced their average daily energy intake from baseline (P<0.001). Dietary intakes increased for fiber, folate, magnesium, iron, and decreased for cholesterol in the pulse-based diet group compared to the TLC diet group (P<0.05). Women in the pulse-based diet group exhibited higher scores in the domain of knowledge about the nutritional composition of pulses, recommended servings of legumes based on Canada’s Food Guide, environmental, and economic benefits of pulse consumption when compared with the TLC diet group (P<0.05). Both groups exhibited increased scores in the domain of attitudes about the palatability, accessibility, preparation, and affordability of pulse foods over the 16 weeks (P<0.01).
Supported by the favourable health outcomes from the present intervention, an evidence-based pulse-based recipe resource guide has been developed for use by allied healthcare professionals and their clients (Appendix C).
In conclusion, both dietary interventions, without calorie restriction, in combination with aerobic exercise, education, and healthcare counselling yielded substantial improvements in multiple PCOS-specific health outcomes. The pulse-based diet was more effective than the TLC diet in decreasing insulin response to OGTT, improving many key risk factors for cardiometabolic disease, and the overall dietary intakes in women with PCOS. In general, women did not maintain the reproductive and metabolic improvements. Further research is required to promote the consumption of nutrient-rich pulse foods and sustainable adherence to healthy lifestyle behaviours in women with PCOS in the long term.||