We have an important relationship with the microbes (mostly bacteria) that live in and on us. They help us extract nutrients from food, fight infection and can even affect our mood!
What is Your Microbiota?
The microbiota refers to all of the microorganisms that colonise the body’s surfaces, both inside and out (mucosal and extra-mucosal tissue sites) including the gastrointestinal tract (gut), mouth, nose and vagina. There has been lots of attention on the gut microbiota in recent years as we have come to realise the crucial role these resident microbes (mainly bacteria) play in health and disease.
There are good and bad (pathogenic- disease causing) bacteria that reside in our gut and generally the good bacteria will keep the pathogenic bacteria at bay. When there is an increase in pathogenic gut microbes, or a reduction in beneficial microbe populations this can lead to a state of dysbiosis. This imbalance in beneficial and pathogenic microbes has been linked to a number of disease states including inflammatory bowel disease, irritable bowel syndrome, allergies, asthma, metabolic disease such as diabetes, and obesity . Diversity in your resident microbes is typically associated with health while less diversity in your gut microbes has been associated with disease.
The gut and its resident microbiota make up our largest immune organ. They play an important role in keeping out invading pathogens and developing tolerance to dietary components and friendly bacteria, ensuring we mount a ‘normal’ immune response which regulates inflammation and oxidative stress. The bacteria in our gut are amazing as they:
Our gut microbiota are also important in the extraction of energy from food and certain bacteria species have been linked to causing obesity . Individuals with a stable weight have greater diversity in their gut microbes and eat more fibre . Indeed, interventions with different types of dietary fibers including prebiotics have been shown to modulate the gut microbiome and improve insulin sensitivity, low-grade chronic inflammation and lipid metabolism [6, 7].
Why is Fibre Important for our Microbiota?
Fibre is a food source for the gut microbiota and essential for the resident populations to make short chain fatty acids that can influence almost every process in the body. Some fibres are also ‘prebiotics’ as they stimulate the growth of good bacteria (essentially our resident probiotics).
Not all fibres are created equal though. While some fibres are good prebiotics others will be important in regulating the transit of food through the gut and providing fuel for the existing gut bacteria. Eating a variety of foods in your diet will help you get enough of the different fibre types (~25-30g fibre per day as a goal).
Which Foods Contain Prebiotics?
Prebiotics can be found under the names of inulin, oligofructose, lactulose, resistant starch, galactooligosaccharides, transgalactooligosaccharides and polydextrose. Rather than looking for foods that list these ingredients incorporate whole prebiotic foods into your diet- they are much easier to spot!
What is the Connection Between Your Gut Microbiota and Fertility?
There is now evidence that reproductive health is influenced by the resident microbes of your gut. This is not too surprising given how important our microbes are to other aspects of our health. Metabolites and enzymes produced by your gut bacteria are transported into your blood stream and can be sent to any tissue of the body, influencing the bacterial populations in other areas of your body such as the uterus. The function of reproductive organs is highly regulated by the estrogen metabolising functions of bacterial species contained within the gut. Your gut is in essence the window to your overall health and wellbeing.
In animal models, endometriosis is associated with lower concentrations of Lactobacilli bacteria and higher levels of gut inflammation . In endometriosis, the growth of endometrial lesions outside of the uterus is driven by estrogen and the gut microbiota plays a role in regulating estrogen levels. With gut dysbiosis (an imbalance of good bacteria or a reduction in diversity), estrogen metabolism may be disrupted. High levels of estrogen have been associated with endometrial hyperplasia while an imbalance between estrogen and progesterone is found in polycystic ovary syndrome (PCOS), where the gut microbiota is known to be altered .
The success of implantation following IVF has been related to certain species of the microbiota of the endometrium (uterus) . Women with a successful pregnancy following IVF had different vaginal microbiota than women who were unsuccessful . The microbiota of the fluid surrounding your eggs (follicular fluid) can also influence IVF outcome and beneficial populations of microbes found in sperm are associated with improved sperm quality.
How do I Increase my Microbiota Diversity?
Our diet, activity levels, stress and medication can all have an impact on the diversity of our microbiota. Eating a high fibre diet is a great way to feed the beneficial bacteria in your gut and people who exercise have greater microbial diversity. Antibiotics and stomach acid blockers are some medications that will negatively affect your microbiome so reducing antibiotic use, where medically safe and possible, should be a goal during fertility treatment.
You have your exercise plan so now look to incorporate more prebiotic foods listed above into your everyday eating!
1. Carding S, Verbeke K, Vipond DT, Corfe BM and Owen LJ. Dysbiosis of the gut microbiota in disease. Microb Ecol Health Dis. 2015;26: 26191.
2. Donohoe DR, Garge N, Zhang X, Sun W, O'Connell TM, Bunger MK, et al. The microbiome and butyrate regulate energy metabolism and autophagy in the mammalian colon. Cell Metab. 2011;13: 517-526.
3. Scharlau D, Borowicki A, Habermann N, Hofmann T, Klenow S, Miene C, et al. Mechanisms of primary cancer prevention by butyrate and other products formed during gut flora-mediated fermentation of dietary fibre. Mutat Res. 2009;682: 39-53.
4. Turnbaugh PJ, Hamady M, Yatsunenko T, Cantarel BL, Duncan A, Ley RE, et al. A core gut microbiome in obese and lean twins. Nature. 2009;457: 480-484.
5. Menni C, Jackson MA, Pallister T, Steves CJ, Spector TD and Valdes AM. Gut microbiome diversity and high-fibre intake are related to lower long-term weight gain. Int J Obes (Lond). 2017;41: 1099-1105.
6. Vulevic J, Juric A, Tzortzis G and Gibson GR. A mixture of trans-galactooligosaccharides reduces markers of metabolic syndrome and modulates the fecal microbiota and immune function of overweight adults. J Nutr. 2013;143: 324-331.
7. Lecerf JM, Depeint F, Clerc E, Dugenet Y, Niamba CN, Rhazi L, et al. Xylo-oligosaccharide (XOS) in combination with inulin modulates both the intestinal environment and immune status in healthy subjects, while XOS alone only shows prebiotic properties. Br J Nutr. 2012;108: 1847-1858.
8. Bailey MT and Coe CL. Endometriosis is associated with an altered profile of intestinal microflora in female rhesus monkeys. Human reproduction (Oxford, England). 2002;17: 1704-1708.
9. Liu R, Zhang C, Shi Y, Zhang F, Li L, Wang X, et al. Dysbiosis of Gut Microbiota Associated with Clinical Parameters in Polycystic Ovary Syndrome. Front Microbiol. 2017;8: 324.
10. Moreno I, Codoñer FM, Vilella F, Valbuena D, Martinez-Blanch JF, Jimenez-Almazán J, et al. (2015) Evidence that the endometrial microbiota has an effect on implantation success or failure. 62nd Annual Scientific Meeting of the Society for Reproductive Investigation. San Francisco, CA.
11. Hyman RW, Herndon CN, Jiang H, Palm C, Fukushima M, Bernstein D, et al. The dynamics of the vaginal microbiome during infertility therapy with in vitro fertilization-embryo transfer. Journal of assisted reproduction and genetics. 2012;29: 105-115.