Can Fibre Improve PCOS Parameters?

I've written many posts about PCOS, and today I want to explore the relationship between PCOS and dietary fibre.

To recap, polycystic ovary syndrome (PCOS) is the most common hormonal disorder in reproductive-aged women. Whenever I mention PCOS to my clients, many of them say that they don't have cysts on their ovaries. Here's the thing, you can be diagnosed with PCOS without having cysts.

To be diagnosed, you need at least 2 of the 3 following criteria:

1. Delayed ovulation or irregular menstrual cycles (oligomenorrhea)
2. High androgenic hormones like testosterone
3. Polycystic ovaries on ultrasound

Whenever I'm suspecting PCOS, I like to run blood work to determine androgen levels. In addition, because insulin resistance is common with PCOS, it's important to also assess those parameters.

Some of the tests I like to run:

• Free testosterone
• Total testosterone
• DHEA-S
• Sex Hormone Binding Globulin (SHBG)
• Fasting insulin
• Fasting glucose

A 2019 study looked at the relationship between fibre, insulin resistance and PCOS. It demonstrated that a low fibre intake in people with PCOS is a significant factor in insulin resistance, and people with PCOS consumed less fibre than those without PCOS.

Fibre is a complex carbohydrate that isn't digestible. There are 2 types - soluble and insoluble. Soluble helps to lower things like blood glucose and cholesterol. While insoluble helps to bulk up stool, improve motility, and it can also increase insulin sensitivity.

However, many of us don't eat nearly as much fibre as we should. A low-fibre diet is associated with many health problems including type 2 diabetes and metabolic syndrome (which is essentially a cluster of syndromes including increased blood pressure, high blood sugar, excess body fat around the waist, and abnormal cholesterol or triglyceride levels).

Fibre can help regulate blood glucose by slowing it's absorption in the blood, which then improves glucose tolerance. The 2019 study also showed that in people with PCOS who did not eat much fibre, they tended to have increased testosterone and DHEAS levels. Moreover, insulin resistance may actually worsen high androgens.

This means that including more fibre-rich foods in your diet may lower insulin resistance and manage high androgen levels and improve those PCOS parameters.

Foods that are rich in fibre include fruits, vegetables, beans and legumes, as well as grains. Some fibre-rich foods include:

• Raspberries - 4g of fibre for 1/2 cup
• Pear - 5.2g of fibre for 1 medium pear
• Apple - 3.3g of fibre for 1 medium apple
• Brussel sprouts (cooked) - 3.2g of fibre for 1/2 cup
• Carrots - 3g of fibre for 1 large carrot
• Lentils (cooked) - 10.4g for 2/3 cup
• Black beans (cooked) - 7.5g for 1/2 cup
• Peanut butter (chunky) - 2.6g for 2 tbsp
• Brown rice (cooked) - 1.8g for 1/2 cup
• Rolled oats (cooked) - 4.2g for 3/4 cup

Ideally people with PCOS should be aiming for 30-35g of fibre per day. As you increase your fibre intake, be sure to make sure you're also increasing the amount of water you're drinking per day (this is because fibre can bind water).

Reference

Cutler, D., Pride, S., & Cheung, A. (2019). Low intakes of dietary fiber and magnesium are associated with insulin resistance and hyperandrogenism in polycystic ovary syndrome: A cohort study. Food Science & Nutrition, 7(4), 1426-1437. doi: 10.1002/fsn3.977