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Nutrition for PCOS: A Dietitian’s Guide

Nutrition for PCOS

Polycystic Ovarian Syndrome (PCOS) is a common hormonal condition that affects 1 in 10 women. For women of reproductive age, it affects 12-18% of individuals, although reportedly up to 70% of women with the condition remain undiagnosed.

Polycystic literally means “many cysts.” Ovarian means it is in the ovaries. Therefore, PCOS stands for many cysts within the ovaries.

Polycystic ovarian syndrome diagram

Even though that is the translation, the diagnosis doesn’t rely on there being cysts. Some women may not even have cysts in their ovaries since the diagnosis involves having any two of these three factors:

  1. Lack of ovulation causing irregular menstrual cycles (either <21 days apart, >35 days apart or no cycle at all).
  2. Excess male hormone production (e.g. testosterone) detected through a blood test.
  3. Cysts on the ovaries as detected via ultrasound.

Other symptoms can include: hair growth/loss, skin changes (e.g. acne or darkening of the skin), weight gain, anxiety, depression, sleep apnoea and difficulty conceiving.

It also increases the risk of certain conditions including type 2 diabetes, cardiovascular disease and endometrial cancer.

There is no cure for PCOS, but there are lifestyle steps that you can take that can help manage the symptoms.

Insulin Resistance

Link between insulin resistance and PCOS

Around 85% of women with PCOS also experience insulin resistance with the numbers being slightly skewed based on other factors e.g. those who are lean are slightly less likely exhibit as much insulin resistance.

On average, women with PCOS are 35-40% less sensitive to insulin. And although insulin resistance is typically lower in leaner individuals, those with lean PCOS typically have insulin sensitivity that is ~50% lower on average in comparison to lean females without PCOS.

This insulin resistance is part of why the risk of type 2 diabetes is increased. The body is less able to remove glucose from the blood, which leads to higher insulin levels and potentially higher blood glucose levels as well.

A lot of the steps in managing PCOS involve attempting to reduce insulin resistance or the effects of it.

Overall Healthy Diet

Fresh vegetables, fruits, and nuts on gray background

The first step before going into specifics is to aim for an overall healthy diet. Consume a wide variety of nutritious foods with an emphasis on fruits, vegetables and lean protein sources. A lot of other general rules for a healthy diet also will apply to nutrition for PCOS as well.

Weight Management

Healthy high fibre plant-based food

Weight-loss can be beneficial for PCOS under a lot of circumstances. While lean PCOS does exist (and a lot of the other nutritional strategies will be beneficial for that), if somebody is carrying more body fat than ideal, weight-loss could help manage the symptoms of PCOS.

Using insulin resistance specifically as an example, decreases in body fat have consistently been strongly linked with decreases in insulin resistance for those with PCOS.

In addition to this, it could potentially be harder to lose weight with PCOS.

One aspect of this is that basal metabolic rate can actually be reduced by PCOS. This looks to be relevant for BOTH those with and without insulin resistance, but more impactful for those with insulin resistance.

It appears as though BMR can be 14-40% lower than what would be expected without PCOS and insulin resistance. And since BMR typically makes up 60-70% of total energy expenditure, this can have meaningful implications for weight management.

The same rules still apply. To lose weight, a calorie deficit is required. This just changes the number of calories required. But having this knowledge definitely creates a level of empathy for those who are in this situation and struggling with their weight.

Decreasing Carbohydrate Intake

Lower carb healthy meal

While a low carbohydrate diet can work very well, there are also still nutritional advantages from keeping carbs in the diet. Good quality carbohydrate sources can add fibre, micronutrients and beyond that, they can also help from a quality of life perspective; let’s be realistic, most people like carbs.

That being said, I would still recommend avoiding consuming an excessive amount of carbohydrates. All carbohydrates break down into glucose in the blood, which requires insulin to be utilised to take the excess glucose out of the blood. This is a more difficult job with insulin resistance.

Beyond that, carbohydrates contain calories, just like protein and fats do. Decreasing carbohydrate intake is also decreasing calorie intake unless it is replaced with more fats and proteins. Creating a calorie deficit is the key to getting leaner.

Taking this a step further, a ketogenic diet has small-scale evidence that it can help reduce symptoms through helping to reduce body weight (due to the calorie deficit that is typically created), improvements in hormone levels and a significant reduction in insulin levels.

One reason why I’m hesitant to recommend even a well-structured ketogenic diet that addresses most of the nutrients that are often lacking is that sticking with it is quite difficult. In the research that has been done so far, compliance is quite low over the long term and carbohydrate intake typically increases over time until the average intake is well above the range required to stay in ketosis. For some individuals, this isn’t an issue, but for the majority it is.

Aim for Lower GI Carbohydrates

Glycaemic Index

Aiming for lower GI carbohydrates as your main carbohydrate sources can help as well. Beyond directly helping to manage insulin resistance, this has been shown to reduce the risk of complications down the line such as endometrial cancer.


Anti-Inflammatory Style Diet

Anti-Inflammatory foods for PCOS

Dietary approaches that are high in monounsaturated fats, omega 3’s, fibre and antioxidants seem to help manage the symptoms of PCOS as well.

For example, a Mediterranean diet has been frequently studied for PCOS with positive outcomes. This style of diet is high in vegetables, fruits, legumes, wholegrains, fish, poultry and healthy fats such as extra virgin olive oil, avocado, nuts and salmon.

In addition to the main symptoms of PCOS, this dietary pattern has been strongly linked with reduced symptoms of anxiety and depression.

Antioxidants

High antioxidant anti-inflammatory foods

PCOS features a lot of symptoms linked with oxidative stress. There also appears to be reduced levels of antioxidants and overall nutrient levels in women with PCOS. Increased antioxidant intake, in general, appears to help manage symptoms of PCOS.

I’m typically cautious with antioxidant supplementation, since oxidative stress is still a vital process in a lot of the body’s functions. Whenever studies involve increasing antioxidant intake through food, there are typically no downsides. Sometimes downsides appear when high dosages of supplements are used for the same purposes though.

That being said, there is a study showing reductions in testosterone and insulin resistance in those who took resveratrol supplements.


Supplements

When it comes to PCOS, there are quite a few supplements that can help. Prioritising your overall nutrition will help far more than what any individual supplement can do, but supplements can certainly provide some value.

When it comes to supplements, often they are only beneficial whenever there is a deficiency or inadequate intake. Adding the supplement in addition to an already optimal intake likely won’t provide any additional benefit.

Personally, I would not recommend trying to supplement with all/most of these at once. But if you have an interest in one or a couple of them, it could be worth looking into.

Inositol

There is a lot of solid evidence for how Inositol can help for people with PCOS. It appears to improve insulin sensitivity, lower testosterone and aid fertility. The recommended dosage is 2-4g per day of myo-inositol.

Magnesium

Magnesium can help improve insulin sensitivity and if taken at night, reduce fasting blood glucose levels (BGL’s). The recommended dosage is 300mg taken 1hr before bedtime, however, I would strongly wager that if you meet your magnesium needs through foods, this won’t be necessary. The vast majority of people do not meet the RDI for magnesium through food though, which indicates that this potentially could be helpful for quite a few people.

Omega 3’s

Omega 3’s can help reduce inflammation and improve metabolic markers such as cholesterol and blood pressure. It may also help reduce testosterone and help with the regularity of the menstrual cycle. Ideally, you would obtain this through food by consuming fish 2-3 times per week (where at least one time is oily fish such as salmon), or consuming plant-based options such as seeds or walnuts. If you are supplementing, the recommended dosage is 1000-3000mg daily.

Zinc

Zinc can be effective for reducing hair growth or reducing hair loss associated with PCOS. It can also potentially help reduce insulin resistance. The dosage used in research is 50mg/per day, which is significantly higher than the RDI of 8mg/day, indicating that it would be difficult to meet this mark through food since most people also do not reach the RDI consistently.

Cinnamon

Cinnamon may help under certain circumstances. It can potentially help menstrual cycle irregularities while also aiding in blood glucose control by improving the use of glucose in cells and also slowing the rate at which glucose enters the blood. The recommended dosage is 1-2g per day.

N-acetylcystein (NAC)

There is a bit of research indicating that NAC may lead to improvements in pregnancy and ovulation rates. For me, this is a bit of a watch this space area though as the evidence isn’t very strong yet. NAC increases the cellular levels of antioxidant and reduces glutathione at higher doses, which theoretically can translate to improved insulin sensitivity, but the current research doesn’t support that in practice. The dosage commonly used in research is 1200-1800mg per day.

Berberine

Berberine is a Chinese medicinal herb. It may help with insulin resistance and also other metabolic markers, but more controlled research is needed. The dosage recommended for PCOS is 1.5g daily.

Chromium

A systematic review from 2017 on 7 randomised control trials featuring chromium demonstrated that chromium could potentially help reduce insulin resistance and testosterone. It does not appear to improve ovulation, however. The recommended dosage is 200µg of chromium picolinate per day.

Vitamin D

Vitamin D is another supplement that has a bit of evidence of improving insulin resistance. A lot of people with PCOS happen to be deficient in vitamin D, but that leads to a chicken or the egg scenario: Does PCOS contribute to deficiency, or does deficiency contribute to PCOS? Either way, supplementation will only likely be beneficial if you are deficient. The first step should be to get a blood test for deficiency and then address it from there. The recommended dosage is 1000IU per day, or higher if your doctor recommends it.

Summary

Although PCOS isn’t curable, taking some of these steps could significantly reduce the symptoms associated with PCOS. There are many different nutritional strategies that can be utilised, but these tips mentioned are likely to help significantly if implemented.

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