Polycystic Ovary Syndrome – the fundamentals

18 Nov 2019

By Dr Yvonne Jeanes, Principal Lecturer in Clinical Nutrition, University of Roehampton.

Polycystic Ovary Syndrome affects millions of women in the UK – around 1 in 10 women.4 (See refernces below) There is no cure, so treatment involves improving the presenting symptoms. Dr Yvonne Jeanes, specialises in the treatment of PCOS and provides an update on the latest evidence  

Polycystic ovary syndrome (PCOS) is a common endocrine disorder associated with infertility, hyperandrogenism, obesity, cardiovascular disease (CVD) and type 2 diabetes . Weight management, through lifestyle modification, is the first line of treatment within international guidelines for treating women with PCOS.1,2,3

A recent survey of 1,012 women with PCOS, by Verity (the UK charity for women with PCOS), indicated an astonishing 90% felt they did not get ‘sufficient support from the NHS to help them deal with PCOS’ (unpublished data).

Within the dietetic resource Practice-based Evidence in Nutrition which is free for all BDA members, I authored the updated PCOS content published in 2015.Here, I summarised some of the key information incorporating the latest evidence available. The content published in PEN is more comprehensive and covers greater breadth.

Risks of developing type 2 diabetes and cardiovascular disease

There is consistent evidence that the prevalence of impaired glucose tolerance, gestational diabetes and type 2 diabetes is higher among women with PCOS than among BMI-matched women from the general population.7,8 Women with PCOS have more cardiovascular disease risk factors, including dyslipidemia, metabolic syndrome and compromised endothelial function compared with healthy controls.9,10 International guidelines recommend screening women with PCOS for cardiovascular disease risk factors and using an oral glucose tolerance test to screen for impaired glucose tolerance and type 2 diabetes in either all women with PCOS or those with a family history of diabetes, over the age of 40 years and/or those who are overweight/obese.1,2,3

Effects of weight loss on PCOS symptoms

There is a greater prevalence of overweight and obesity amongst women with PCOS.11 Meta-analyses have shown a 5-15% body weight loss among overweight/obese women with PCOS improves many PCOS symptoms inclusive of serum testosterone, glucose tolerance, hirsutism and ovulation.12,13,14 Small studies in women with PCOS have shown bariatric surgery resulted in marked improvement of multiple biochemical abnormalities, hirsutism, menstrual cycle regularity and improved fertility.15,16

Improving PCOS symptoms with diet

Evidence from relatively small, energy-restricted dietary intervention studies have generally found similar improvements in weight loss, fertility and symptom management of PCOS irrespective of the protein and carbohydrate content.17 A healthy energy-restricted diet and lifestyle that overweight/obese women with PCOS can follow may be one of the most important considerations in recommending a weight loss plan.

Lower glycaemic index dietary interventions have demonstrated improved insulin sensitivity in women with PCOS compared to a conventional healthy eating diet plan, independent to weight loss.18, 19,20 For lean women with PCOS an isocaloric lower GI diet has been shown to improve insulin sensitivity.19

PCOS and eating disorders

Small studies have indicated higher prevalence of PCOS in patients with eating disorders21,22 and disordered eating and bulimia nervosa was more common among women with PCOS23,24 – Michelmore et al. (2001) found similar prevalence.25 This evidence does not indicate that there is a causal relationship and it is clear more research is needed. It is important to be aware of the possibly higher prevalence of eating disorders in women with PCOS when interacting with women with PCOS and tailoring advice accordingly.

Can supplements help with symptoms?

Mny supplements have been proposed to have beneficial effects for women with PCOS, though there is very little research to support recommending any specifically for PCOS symptoms.

Vitamin D supplementation has been suggested as a deficiency has been associated with insulin resistance in women with PCOS, though clinical supplementation studies have provided inconsistent findings.6 Several small trials with omega 3 fatty acid supplementation (2.4-4 g/day for eight weeks) indicate beneficial effects on menstrual cyclicity, blood lipids, glucose and insulin levels in women with PCOS. Though any effects on reproductive hormones or outcomes have not been reported.6 A chromium picolinate supplementation trial indicated improvements in insulin sensitivity after 200g/day for three months among women with PCOS26, further trials are warranted to study any benefits in more detail. Cinnamon supplements of 1.5g/day have improved menstrual cyclicity in women with PCOS compared with placebo, however the results are limited by a high drop-out rate. Cinnamon extract is theorised to improve insulin sensitivity, however, there were no effects on insulin nor androgen levels.27 There are no clinical studies to support the use of herbal supplements agnus castus nor saw palmetto for women with PCOS. There is insufficient evidence to support recommending D-chiro-inositol or myo-inositol for women with PCOS. A meta-analysis indicated that supplementation with D-chiro-inositol or myo-inositol may improve insulin sensitivity, glucose tolerance, menstrual regularity and ovulation rate among women with PCOS.28 However, D-chiro-inositol has been reported to worsen the quality of oocytes and the safety of inositol has not been adequately studied.29

First-line treatment

For overweight/obese women with PCOS, weight management through lifestyle modification is the first line treatment. There is evidence for the beneficial effects of weight loss, however how it is achieved is very much centred on the individual. There is evolving evidence for the beneficial effects of a lower glycaemic load for women with PCOS. To date there is insufficient evidence to support recommending supplements specific to PCOS.

Dr Yvonne wrote a chapter on polycystic ovary syndrome for the 5th edition of the Manual of Dietetic Practice.


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