By vegan naturopath Robyn Chuter
PCOS is believed to affect up to 1 in 10 women of reproductive age in both Australia and the US. It is the most common cause of female infertility, since women with PCOS either only ovulate occasionally, or not at all.
I have seen many clients with PCOS over my 20 years in practice, which is one of the reasons why I was looking forward to Brie Turner-McGrievy’s presentation on it at the 2015 International Plant-Based Nutrition Healthcare Conference. (The other was that she has published some amazing studies comparing the effectiveness of various diets for weight loss, but more on that a little later…)
Symptoms of PCOS include:
- Infrequent, absent, and/or irregular menstrual periods
- Multiple cysts on the ovaries which can be seen on ultrasound
- Acne (particularly cystic acne), oily skin, or dandruff
- Weight gain or obesity, particularly around the waist
- Pelvic pain
- Male-pattern baldness or thinning hair
- Increased facial hair
- Dark patches of skin
- Skin tags
- Anxiety or depression
- Sleep apnea
Woman with PCOS make too many androgens (‘male hormones’) in their ovaries, so they have elevated levels of these hormone in their blood. In addition they have low concentrations of sex hormone binding globulin (SHBG), a protein which keeps testosterone and estrogen in an inactive ‘storage’ state. Low SHBG translates to higher levels of active testosterone, which contributes to all the symptoms of PCOS, including infertility.
In addition, women with PCOS are insulin-resistant – that is, their cells don’t respond to the signals sent by the hormone insulin, resulting in high levels of glucose and triglycerides in their bloodstreams, and increased fat storage.
As a result of these metabolic abnormalities, women with PCOS have a higher risk of developing several chronic diseases, including:
- Some forms of cancer
- Cardiovascular disease
- Metabolic Syndrome
The first-line treatment for PCOS is pretty simple, if not necessarily easy: lose weight. The problem, as Turner-McGrievy pointed out, is that up until recently, there had been no studies done to establish the most effective weight loss diet for PCOS sufferers. So she did what any self-respecting nutrition researcher with a history of co-authoring studies with the amazing Dr Neal Barnard, founder of the Physician’s Committee for Responsible Medicine, would do – she decided to run such a study herself.
By way of background, Dr Barnard had found in an earlier study that women suffering from severe period pain had a significantly higher serum SHBG concentration when they were placed on a vegan diet than when they were eating their standard omnivorous diet (remember, women with PCOS have lower than average SHBG).
Then, in later Barnard-led studies that Brie Turner-McGrievy contributed to, an ad libitum (all you can eat) low-fat vegan diet was found to cause significantly more weight loss in overweight, postmenopausal women than the US government-developed National Cholesterol Education Program Step II diet, despite the lack of restrictions on portion size and energy intake in the vegan diet group. Not only were the participants randomised to the vegan diet considerably lighter after the 14-week study wrapped up; they were far more successful than the ‘standard’ dieters at keeping the weight off, at both 1-year and 2-year follow-up.
The same diet was found to cause significantly more weight loss in type 2 diabetics, along with greater decreases in HbA1c (a measure of long-term blood sugar control), fasting glucose, cholesterol and LDL, than the ‘official’ American Diabetes Association diet – highly relevant to PCOS sufferers due to their increased risk of diabetes.
So Turner-McGrievy conceived the Healthy Eating for Reproductive Health (HER Health) study, to compare a low-fat, low-glycaemic index vegan diet with no caloric restriction to a standard, low-calorie diet for weight loss in women with PCOS. With very minimal instruction and 1:1 contact, the women assigned to the vegan diet group still managed to lose significantly more weight than the low-cal dieters at the 3 month mark, as well as having greater improvements in dietary intake at the 6 month mark.
Turner-McGrievy then went on to conduct the New Dietary Interventions to Enhance the Treatments for weight loss (New DIETs) study – a 2-month weight loss intervention with a 4-month follow-up period, which randomised overweight participants to either a vegan, vegetarian, pesco-vegetarian, semi-vegetarian, or omnivorous diet. All the test diets were carefully designed so that they were low in fat and glycaemic index. And the winner was… the vegan diet, which resulted in the loss of 7.5% of initial body weight after 6 months. Interestingly, although participants in all test diet groups lost weight by 2 months, the pesco-vegetarian, semi-vegetarian and omnivorous dieters began regaining weight after that, while those in the vegetarian and vegan diet groups kept losing weight.