It seems like almost every day we are learning more and more about the importance of the GOOD bacteria that live inside our digestive system. Even though these bacteria live within our intestines, they have a positive impact throughout our bodies, on almost every area of our health, including our reproductive health.
Recent research indicates that a healthy population of gut bacteria is critically important in controlling our blood sugar response to a meal, and this is one crucial way that a healthy gut microbiome can promote fertility.
Why is blood sugar balance so important to reproductive health?
When we eat a meal that contains carbohydrates, such as bread, pasta and rice, these they are broken down into glucose and released into the bloodstream (we call this blood sugar).
How our blood sugar responds after a meal depends on the quality and quantity of carbohydrate in that meal – a meal that contains a lot of refined carbohydrates (e.g. white bread) will cause a rapid spike in blood sugar, while a meal that contains a balance of slow-release whole grain carbohydrates (e.g. oats) will result in a much smaller increase in blood sugar levels.
When our diet contains too many refined carbohydrates, we will have high blood sugar levels and also produce large amounts of the hormone insulin to help balance this blood sugar. We know that this combination of high blood glucose and high insulin can impact our reproductive health negatively in a number of ways:
- Insulin is a hormone and it can disrupt production of other hormones in the body. In fact, if insulin levels are too high, this can promote testosterone production in women and negatively impact ovulation. This negative impact of insulin is even more pronounced for women with PCOS.
- Women who were found to have higher blood sugar levels over a six-month period were only half as likely to get pregnant as those who had low levels of blood sugar over those six months. (1)
- High blood glucose and insulin levels over a number of months have been shown to negatively impact egg quality during assisted conception. (2)
How to achieve blood sugar balance
Achieving blood sugar balance is a key aim of any nutritional programme to support fertility, and this can be achieved through a number of straightforward dietary changes:
- Avoid refined carbohydrates, such as white rice, bread and pasta, and replace with slow release whole grain carbohydrates, including whole grain brown bread, brown rice, oats and whole grain pasta.
- Avoid sugary treats such as chocolate, sweets, biscuits, cakes and soft drinks, and treat them as treats, eating them a maximum of 2-3 times a week.
- Eat good quality protein, such as eggs, dairy products, nuts and seeds, chicken, fish or lean red meat, with every meal and snack. Protein helps to stabilise our blood sugar after a meal.
- Learn to love your legumes – beans and lentils are a key food to help us achieve blood glucose balance as they release energy in a slow and sustained manner, helping us to avoid blood sugar spikes.
BUT – these dietary changes are really only half of the story when we are trying to achieve good blood sugar balance. Recent research tells us that the good bacteria within our digestive system are just as important as good dietary choices in helping to control our blood sugar and insulin levels after a meal. (3)
Why are gut bacteria so important for blood sugar balance?
A recent study has found that different individuals (even identical twins) can have a very different blood sugar response after identical meals; some individuals will experience blood sugar spikes while others will have a healthy blood sugar response.
The researchers discovered that one of the factors that helped to control this response in individuals was their gut bacteria population. Individuals with a more varied and healthier blood glucose population had healthier blood glucose responses after a meal and, therefore, found it easier to achieve blood sugar balance.
We are still learning about the exact way in which good bacteria support blood glucose balance. However, we know that these good bacteria can slow down our digestive process, ensuring that blood sugar is released more gradually and helping to avoid blood sugar spikes. The good bacteria are also known to produce substances that help our body cope better with blood sugar spikes. (4)
A number of clinical studies have shown that improving levels of gut bacteria by using a probiotic supplement (a capsule that provides a super dose of good bacteria) can reduce blood sugar and insulin levels. (5) So, together with dietary changes, supplementing with a good probiotic supplement is key in helping us achieve blood sugar balance, and this will have a positive knock-on effect on our reproductive health.
(1) Hjollund NHI et al Is glycosylated haemoglobin a marker of fertility? A follow-up study of first pregnancy planners Hum Reprod 1999 14 1472-82
(2) Jinno M et al Advanced glycation end-products accumulation compromises embryonic development and achievement of pregnancy by assisted reproductive technology Hum Reprod 2011 26 (3) 604-10
(3) Berry SE et al Human postprandial responses to food and potential for precision nutrition Nature Medicine 2020 26 963-73
(4) Valdes AM et al Role of Gut Microbiota in Nutrition and Health BMJ 2018 361 2179
(5) Gomes AC et al Gut Microbiota, probiotics and diabetes Nutrition Journal 2014 13 60