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Plant-Based Diets for Treating Poly Cystic Ovarian Syndrome (PCOS)

Hello Ladies, many of you may be new to my blog, so I just wanted to introduce myself. I'm Lucy, a registered dietitian with a Master's in Public Health. Because of my health degrees, I love to share my knowledge about optimal nutrition and lifestyle because I really believe nutrition information should be available to everyone. So I hope you help this blog very informative and helpful! If you are someone who wants to connect about how I can support and encourage you as you transition to a more plant-based diet, then I'd love to touch base.

PCOS: What is it?

According to Deswal et al, PCOS prevalence may be anywhere between 4% and 20% worldwide. It is believed to be the most prevalent endocrine disorder in women. Despite this, it is confusing and not well understood.

It is currently understood to be a condition affecting a heterogenous group with different phenotypes. However, the presence of some or all of these conditions may be seen in these phenotypes: clinical/biochemical hyperandrogenism (high "male" hormones), oligoanovulation (disruption in ovulation), oligomenorrhea/amenorhhea (disruption in periods), and polycystic ovaries. In adolescence, it may be diagnosed with abnormal uterine bleeding for age that persists for 1-2 years, hyperandrogenism, hirsutism (male pattern hair growth), or acne vulgaris.

Last but not least, if having these issues were not enough, many women with PCOS struggle to maintain lower body weight and are often diagnosed with insulin resistance, which can turn into type 2 diabetes later in life. They struggle with metabolic disturbances, excess production of insulin, glucose intolerance, dyslipidemia which can lead to heart disease complications, acne, male pattern hair growth, hair thinning, hyperkeratosis of skin, skin tags, long-term risks of endometrial cancer, psychological distress, and what breaks most hearts- infertility (Deswal et al).

Treatment protocols for women with PCOS include many pharmaceuticals aimed at

  • regulating menstruation (birth control, progestins, and progesterones) which may lead to insulin resistance, weight gain, mood changes, bloating, hair loss, and of course, low chances of getting pregnant.

  • Insulin resistance and diabetes drugs which may lead to abdominal complaints and weight gain.

  • Fertility drugs (ovulation induction, gonadotropins, and IVF) which may lead to higher rates of multiple pregnancies and cost lots of money.

  • Drugs for hyperandrogenism, hirsutism, acne, depression and anxiety, and obesity/weight loss.

  • Supplements such as Myo-inositol and D-chiro-inositol, berberine, apple cider vinegar, cinnamon, folate, B12, and the list goes on.

Most professionals would agree that diet and lifestyle are important in the management of PCOS from as early an age as possible.

While there are many possible methods of controlling PCOS symptoms with diet and lifestyle including following a low GI diet, low carbohydrate diet, or balanced diet, I hope to present a different lifestyle that I believe can address many of the complications and symptoms of PCOS directly, and therefore is the ideal lifestyle for those with this condition.

Let's go through some of the major complications of this disease, and what a whole foods plant-based diet has to offer for each.

PS. What's the difference between vegan and WFPB? See my other article here (coming soon).

Insulin Resistance

A lot of the conditions that present in PCOS are interconnected and it's hard to iron out which came first. However, many women with PCOS end up developing insulin resistance at some point and are prescribed medications like Metformin or other pharmaceuticals.

Insulin resistance is defined as the inability of some types of tissues to respond to normal levels of insulin, leading to more insulin being produced in order for it to do its job. What's causing those tissues to not respond to insulin?

Research points to insulin resistance being a complication of excess fat in our liver and skeletal muscle cells, which leads to the downregulation (the power off switch) of insulin receptors. Essentially, our cells that normally thrive off and absorb lots of glucose (liver and muscle) have fat being delivered and stored there instead which is blocking the mechanism for insulin to open the cell to receive glucose. As a result, glucose remains in our blood (high blood sugar) and causes damage and inflammation (Shin-Hae Lee et al.)

What causes fat to be stored in muscle and liver cells? It is associated with obesity (and therefore a diet that promotes excess weight such as the standard American diet). In other words, a diet high in fat and sugar (processed, not whole carbohydrates) may be the cause ( Therkelsen et al).

Plant-based diets are naturally low-fat and unrefined, as they are based on whole foods such as beans, potatoes and tubers, vegetables, fruits, nuts, and seeds. Population studies have found that people groups who consume more plant-based diets have lower incidences of insulin resistance among other health conditions (Orlich and Fraser).

As you move away from animal products and focus more on plant-based foods, your intake of saturated fat significantly decreases, and your intake of magnesium and anti-inflammatory phytonutrients (plant-based nutrients) increases, which has been shown to reduce insulin resistance. Switching out animal-based proteins (meat, dairy, etc) for plant-based alternatives in a plant-based diet has been associated with weight loss and improved insulin resistance (Banaszak et al).

Dr.Neal Barnard and colleagues have repeatedly shown the benefits of a low-fat vegan diet for the improvements in weight, HOMA-IR index, predicted insulin sensitivity, and intracellular and hepatic lipid levels, compared to a group instructed to make no change in diet.

Excess Weight

Not only are those who follow a plant-based diet for a long time more likely to be leaner (Orlich and Fraser), but following a plant-based diet is an effective tool for losing weight after it has been put on as well (Tran et al). One research study comparing omnivorous diets to variations of plant-based diets found that those consuming a vegan (most plant-based) diet saw 4.8% weight loss at 2 months compared to 2.2% loss following an omnivorous diet without an emphasis on calorie restriction.

Another study saw a 6.5 kg (14 lbs) reduction in body weight following a plant-based diet for 16 weeks (4 months) (Kahleova et al) without changing exercise habits.

Why do plant-based diets seem to be so effective at reducing weight without calorie restriction or changes in exercise? They are diets predominantly focused on carbohydrates (carbohydrates have 4 calories/gram, protein has 4 calories/gram, and fat has 9 calories/gram). Carbohydrates from whole food sources such as grains, legumes, starchy vegetables, and fruit are also laden with fiber and water, which fills and stretches our stomachs without contributing many calories.

Think about it, you could eat 3 small cubes of cheese or 3 whole apples for fewer calories, which one would make you feel more full?

Fiber from food also plays a role in weight management as it delays the speed at which we digest food, keeps our blood sugar level, and plays a MAJOR role in our gastrointestinal tract. Short-chain fatty acids produced by bacteria when they ferment fiber may have a regulatory role with our hunger and satiety hormones leading to reduced appetite overall (Hernandez et al).

Reducing weight can play a significant role in reducing androgen hormones as fat tissue is a site of androgen hormone production. Therefore following a plant-based diet may also be a consideration for a reduction in these hormones. Androgen hormones can also be synthesized from cholesterol, and therefore following a low-cholesterol plant-based diet may provide another mechanism for reducing this hormone (Schiffer et al).


According to a study done by Kazemi et al, improving diet quality (they used Mediterranean and Dash diet recommendations which are plant-forward) may "improve ovarian function and reproductive outcomes across the lifespan".

Also, research by Lim et al revealed that adherence to a healthy plant-based diet was associated with higher fecundability (the probability of getting pregnant in 1 menstrual cycle).

According to research conducted by Daniel Cramer, countries that had the highest dairy consumption had the greatest reduction in fertility by age. In Thailand, where dairy consumption is close to 22 grams/day, women only saw a 26% drop in fertility between 30-40 years of age. In the United States where daily dairy consumption is close to 462 grams/day (2 servings of milk), there was an 83% drop in fertility from 30-40 years. This researcher believes this is related to galactose, the type of sugar found in milk, and its toxicity to ovaries.

Since plant-based diets eliminate dairy consumption, there is a good chance that following this dietary pattern should improve fertility.

There has been an identified role in oxidative stress in both male and female infertility (Agarwal et al). Plant-based diets (such as the Mediterranean diet or DASH diets) have been shown to have lower levels of oxidative stress and damage than western diets which are high in red and processed meat, energy-dense foods, refined carbohydrates, and excess sugar (Aleksandrova et al).

Whole foods plant-based diets are rich in antioxidants which fight oxidative stress and therefore may be a key factor in creating an environment conducive to conception and healthy pregnancy.

Maintaining an optimal weight also plays a role in both male and female fertility. Therefore for the reasons mentioned above, choosing plant-based diets to manage weight may also provide another mechanism for improving fertility. On top of that, diets high in glycemic index, animal protein, trans fatty acids, and saturated fat may negatively impact fertility (Skoracka et al).

Worried about the health of the baby if you consume a plant-based diet while pregnant? Research indicates that among well-planned and calorically adequate plant-based diets, pregnant mothers may have a reduced risk for gestational diabetes, preeclampsia, preterm birth, positive associations with healthy fetal development, and reduced exposure of babies to harmful compounds in red and processed meat and fish. Vegetarians' breastmilk composition may have healthier fatty acid profiles and DHA (if supplemented) than non-vegetarians (Sebastiani et al).

I also can personally testify that my pregnancy and breastfeeding journey as a predominantly plant-based mother was very healthy and I never struggled to eat enough or produce breast milk following this dietary pattern. Although I had an early miscarriage during my first pregnancy (achieved after 1 cycle of trying), I was able to conceive again within the next month.

Glycemic Index

Many women diagnosed with PCOS or insulin resistance are encouraged to eat foods that are low in Glycemic Index. This index was created to help people with insulin resistance judge which foods are more likely to increase their blood sugar.

Most foods that are high GI are those that are processed and rich in refined carbohydrates. Women who consume higher GI diets have been shown to have less favorable metabolic and higher BMI and waist circumference (Graff et al). Low GI carbohydrates are those that contain a lot of fiber, such as whole grains, legumes, whole wheat pasta, etc. These are the types of carbohydrates recommended in a plant-based diet.

Cardio Health and Cancer Risk

Women with PCOS are told that they are at a higher risk for heart disease and female cancers. While this is true, many risk factors for cardiovascular disease and cancer can be mitigated by following a plant-based diet. This diet is rich in fiber, low in saturated and total fat, high in antioxidants which play a preventative role in inflammation and cancer, and avoids dairy and red and processed meats which have been shown to increase cardiovascular disease and cancer risk (Szabo et al).

Gut Microbiome Dysbiosis

The newest hot topic in PCOS research has been the role that the gut microbiome may play in the pathology of PCOS and vice versa, how overweight and obesity, insulin resistance, and other factors with PCOS may inhibit healthy gut flora.

We don't really know which came first, the chicken or the egg in this situation. One research group believes the driving factor behind dysbiosis is the excess weight/obesity that seems to accompany PCOS (Liang et al). It could be that weight-related gut bacteria changes lead to increases in certain metabolites that influence sex hormones and their effects in women with PCOS (Zhou et al). Other research indicates that the excess androgen hormones from PCOS could be the driving factor behind fewer bacterial species (when it comes to gut bacteria, generally more diversity of species is better) (Torres et al).

There is hope though! Just because you have PCOS does not mean that you will have gut dysbiosis forever. One research team found that women with PCOS who were lean had similar gut diversity to the control women, but that having extra weight meant more dysbiosis (Mammadova et al).

Not only can a plant-based diet improve weight as mentioned above it can also quickly and significantly change the human gut microbiome (David et al). This is because gut microbiota thrives on fiber which is only present in plant foods. Neal Barnard's team at the Physicians Committee for Responsible Medicine saw statistically significant changes in the gut microbiome following a plant-based diet for just 16 weeks (Khaleova et al).

Gut bacteria is not only positively influenced by high-fiber foods, but can be negatively influenced by interaction with high-fat foods (Xu et al) red meat, and processed meats (Abu-Ghazaleh et al). The evidence supports choosing a diet rich in plant-based foods and limited in animal-based foods for microbiome diversity and the prevention of other chronic diseases.

Environmentally and Budget Friendly

We can't neglect the fact that our world is getting sicker and sicker, not just our people. Choosing a vegan or vegetarian diet reduces our environmental footprint the most in comparison to other diet types (Turner-McGrievy et al). It also is cost savings, as many plant-based staples such as dried beans, dried grains, potatoes, and produce are relatively low-cost.


I have barely skimmed the surface of why following a plant-based diet can improve symptoms of PCOS. Other unmentioned benefits could be their richness in vitamins and minerals, including folate and B vitamins (recommended supplements for those with PCOS). Following a plant-based diet not only puts you in a place of optimal health for PCOS, insulin resistance, cardiovascular disease, and fertility, it can also help prevent or treat autoimmune conditions, GI conditions such as IBS or Chron's disease, predispose children in the womb to have a life of health rather than chronic diseases, and so much more.

I also don't have the time to cover every other treatment option for PCOS and compare their cost, side effects, or other considerations to a plant-based diet. But I believe that a plant-based diet could be an effective treatment on its own, or in combination with common PCOS medications such as metformin or spironolactone and supplements.

Ditch-the-disease Program

Lucy again.

Thanks for making it to the end of that incredibly long article. I hope you found it insightful and of course convincing.

I help women with PCOS, insulin resistance, or both feel empowered to see improvements in their symptoms using diet and lifestyle.

If you are feeling fed up with traditional approaches to managing this disease and are ready to try something new, please go ahead and sign up for a 15-minute discovery call. I'd love to get to know you and see if I can offer you help to deal with this incredibly difficult and frustrating disease.

This article was written by:

Wondering what "evidence-based restorative nutrition" is? I'm committed to giving you evidence-based nutrition advice that helps your body return to its natural most healthful way of functioning. Let's restore your health together!

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