The MOST important Macronutrient for our Microbiome

The MOST important Macronutrient for our Microbiome


Nurturing a healthy gut ecosystem depends on one key macronutrient- Carbohydrate! That’s right – carbohydrate is essential to fuel your gut microbiota and boost gut diversity. A diverse gut microbiota nurtures your reproductive health by supporting better sex hormone balance, reducing inflammation, regulating our menstrual cycle and supporting conception.

While carbohydrate is necessary to feed your gut bacteria, the type of carbohydrate you choose to nourish your microbiota will make all the difference.

What Carbohydrate is Best?

Wholegrains, rather than refined grains, are the key carbohydrates you want to incorporate in your diet. Think of brown rice, multigrain bread, rye and quinoa- these are all wholegrains.

Wholegrains are essentially the complete package – nothing has been stripped away. They have an outer layer that is packed full of fibre, B vitamins and minerals, and contain the inner core (or germ) that delivers vitamin E, phytochemicals and healthy fats.

Wholegrains are 'Microbiota Accessible Carbohydrates'. This means they make it all the way to your large intestine where your gut microbes ferment them to prodcue reprodutive health nurturing metabolites like butyrate.

What if I have Insulin Resistance or PCOS?

Wholegrains actualy support better management of blood sugars and improve insulin resistance.

In adults with insulin resistance, eating all their carbohydrate as wholegrains for 12 weeks reduced markers of inflammation by 38%, and significantly reduced body fat compared to those avoiding wholegrains [1].

There is often a fear of carbohydrates, particularly if you have PCOS, but these are actually one of the most important dietary components to ultimately improve gut dysbiosis (imbalances in your gut microbes). One study has shown that women with PCOS have less wholegrain carbohydrates and legumes in their diet [2]. This starves our beneficial microbiota and it becomes more difficult for them to support our metabolic and reproductive health.

Want to know which dietary component is associated with pregnancy success? Wholegrains! A greater wholegrain intake in the 12 months prior to fertility treatment is a positive predictor of pregnancy success and live birth [3]. Even for overall health, greater wholegrain intakes are associated with reduced risk of cardiovascular disease and cancer [4].

What’s the Connection?

Wholegrains provide food for your gut microbes. They are prebiotic which means they selectively promote the growth of beneficial bacterial species living in your gut to reduce inflammation, regulate blood sugar, enhance insulin sensitivity, and improve our immune system [5].

3 Simple Steps to Add More Wholegrains to your Day

Incorporating more wholegrains into your day doesn’t have to be hard. Simple steps will help deliver more wholegrains and the prebiotics that nurture your gut microbiota.

1. For breakfast include some oats, bircher muesli or prebiotic pancakes. Ensure you add some protein (eg. nuts, eggs, cottage cheese, high protein yoghurt) to keep you feeling fuller for longer!

2. Swap white rice for a combination of brown rice and quinoa. Cook extra and then freeze this so you have a wholegrain base ready for a quick dinner on busy days.

3. Bake away with wholegrain flours so you have some tasty snacks on hand. How does a wholegrain packed Date loaf or Berry muffin sound for afternoon tea?


If you are on a gluten free diet and struggling to get enough fibre filled wholegrains in your day, check out our post on “Where to Find Fibre When Gluten is off the Menu”.



  1. Katcher, H.I., et al., The effects of a whole grain-enriched hypocaloric diet on cardiovascular disease risk factors in men and women with metabolic syndrome. Am J Clin Nutr, 2008. 87(1): p. 79-90.
  2. Shishehgar, F., et al., Comparison of Dietary Intake between Polycystic Ovary Syndrome Women and Controls. Glob J Health Sci, 2016. 8(9): p. 54801.
  3. Gaskins, A.J., et al., Maternal whole grain intake and outcomes of in vitro fertilization. Fertility and sterility, 2016. 105(6): p. 1503-1510.e4.
  4. Aune, D., et al., Whole grain consumption and risk of cardiovascular disease, cancer, and all cause and cause specific mortality: systematic review and dose-response meta-analysis of prospective studies. BMJ, 2016. 353: p. i2716.
  5. Martinez, I., et al., Gut microbiome composition is linked to whole grain-induced immunological improvements. ISME J, 2013. 7(2): p. 269-80.


About the Author

Hi, I'm Dr Cecilia Kitic founder of Fertile Gut. We can't wait to help support you on your journey to improving your gut health! Having spent over 20 years researching in the areas of immunonutrition, physiology, biochemistry and gut health we now get to translate science into practice, sooner. Our gut microbiome provides a foundation for our immune system, metabolism, brain and heart health, and hormone balance. With our scientifically crafted natural formulations you will be creating a Fertile Gut!

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