Balance in your gut microbiome is key to your general wellbeing and what you eat is one of the more influential factors on your microbiome's health.
Although the research exploring the link between microbiome and health is still within the early stages, it is now possible to measure the potential of your microbiome to contribute to certain proinflammatory conditions and metabolic diseases, such as insulin resistance, cardiovascular disease, mental health conditions, IBS (Irritable Bowel Syndrome) and IBD (Inflammatory Bowel Disease)1,2. Microbiome diversity, a measure of the number and quantities of different species in your microbiome is a good measure of overall microbiome health. High diversity is generally reflective of good health while the opposite is true with low diversity suggesting poor microbiome health.
The following are five simple dietary changes you can implement into your everyday life to improve gut health and the diversity and overall health of your microbiome as supported by scientific literature.
1. Getting enough fibre.
The best way to increase the diversity of the microbiome is to eat sufficient dietary fibre. The Nutrient Reference Values for Australia and New Zealand recommend women and men should aim to consume at least 28g and 38g of fibre per day, respectively. Foods with high levels of fibre include fruits, vegetables, nuts, seeds, wholegrain cereals, legumes and pulses. Switching up your fruits and vegetables to match what is in season and aim to have different sources of wholegrains throughout the day (such a high fibre breakfast cereal, rolled oats, dense grainy bread, rice, quinoa or polenta) is a great way to vary up your intake of high fibre containing foods.
2. Get the balance right!
Our microbiome contains both fibre and protein digesting microbes. Ideally, we want to promote fibre digesting microbes which produce short chain fatty acids, which play many health promoting roles including feeding gut cells to maintain gut barrier function. Mainstream fad diets which support low carbohydrate, high fat and/or high protein-based diets can shift the proportion of the microbiome to be in favour of protein digesting species. In some cases, these species can release pro-inflammatory compounds. Aiming for a high fibre intake combined with moderate intakes of low-fat protein foods, such as recommended by the Australian Dietary Guidelines or the Mediterranean diet, is the best way to ensure a balance of fibre and protein digesting microbes.
3. Limiting saturated fats.
Bilophila wadsworthia is a normal part of the gut microbiome, however it can become problematic at high levels. Elevated amounts of this bacterial species have been observed in individuals with intestinal inflammation, colon cancer and diets high in animal (saturated) fat3. Reducing intake of foods high in saturated fat may help decrease levels of this bacteria. The Nutrient Reference Values for Australia and New Zealand recommend saturated fat should provide less than 10% of your total energy intake, which on average is less than 24g/day for the average Australian adult. Foods which are high in saturated fats include full fat dairy products, processed meats, certain oils like palm oil or coconut oil, and treat foods like pastries, biscuits and chocolates.
4. Limiting artificial sweeteners.
Artificial sweeteners are commonly found in low sugar or ‘diet foods’, such as diet soft drink, low energy desserts and weight loss products. Originally developed as a sugar substitute to help manage diabetes and obesity, research in humans is now suggesting the effects of artificial sweeteners may be contributing to metabolic syndrome and the obesity epidemic. It appears that artificial sweeteners could alter the human gut microbiome, resulting in a negative impact on glucose metabolism in the body. This is associated with increased calorie intake and consequently results in increased weight gain4.
5. Including fermented foods into the diet.
Fermented foods such as kimchi, kefir and kombucha have been part of the human diet for a long time. However, there is limited scientific research regarding the impact of these foods on the microbiome or in support of the many health claims associated with their consumption. In addition to the probiotic bacteria found in these foods some fermented foods e.g. Kimchi or sauerkraut contain prebiotic fibres which fuel the microbiome. It may be worth mentioning that fermented foods may not be ideal for all people. Some fermented foods are high in salt which can increase blood pressure. It is also good to note that the fermentation process can also create alcohol. Although all commercially sold kombucha must contain less than 1% alcohol content people fermenting their own kombucha may wish to exercise caution with reports in the scientific literature of kombucha having triggered liver dysfunction in susceptible individuals.
- Feng, Q., Liang, S., Jia, H., Stadlmayr, A., Tang, L., Lan, Z., … & Su, L. (2015). Gut microbiome development along the colorectal adenoma–carcinoma sequence. Nature communications, 6, 6528. http://dx.doi.org/10.1038/ncomms7528
- Cani, P. D., Amar, J., Iglesias, M. A., Poggi, M., Knauf, C., Bastelica, D., … & Waget, A. (2007). Metabolic endotoxemia initiates obesity and insulin resistance. Diabetes, 56(7), 1761-1772. https://doi.org/10.2337/db06-1491
- Devkota, S., Wang, Y., Musch, M. W., Leone, V., Fehlner-Peach, H., Nadimpalli, A., … & Chang, E. B. (2012). Dietary-fat-induced taurocholic acid promotes pathobiont expansion and colitis in Il10−/− mice. Nature, 487(7405), 104. https://doi.org/10.1038/nature11225
- Bian, X., Chi, L., Gao, B., Tu, P., Ru, H., & Lu, K. (2017). The artificial sweetener acesulfame potassium affects the gut microbiome and body weight gain in CD-1 mice. PLOS one, 12(6), e0178426. https://doi.org/10.1371/journal.pone.0178426