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Keen To Go Green For Your Gut?

Choosing a vegan diet for January could positively influence the bacteria in your gut

Over half a million people signed up for Veganuary last year. [9]  Moving to the ‘green side’ has been linked to health and environmental benefits [4 & 6]. But did you know that a plant-based diet could influence the bacteria in your gut?

The importance of the microbiome

Image designed by Elle Campbell

Our bodies house up to 39 trillion different bacteria; collectively, they make up our microbiome [8]. These constant companions can influence how our bodies fight infections, our risk of developing certain diseases and even our moods.

Your diet can affect your microbiome

Recent evidence suggests our diet affects what lives inside our guts. A diverse microbiome is a happy microbiome [2]. Scientists have shown that becoming vegan can increase microbiome diversity in just 24 hours [10].

The range of fruit and veg you eat is also important. Dr Megan Rossi, a lead science nutritionist, recommends eating 30 different plant-based foods each week for the optimum microbiome [1].

Similarly, eating a vegan diet can reduce the number of disease-causing bacteria within your gut. A study, involving more than 500 volunteers, found that people who ate a plant-based diet lowered their amount of five different gut bacterial groups linked to disease and intestinal infections [12].

Health benefits of a vegan microbiome

Even though evidence is from small cohorts, current science suggests a vegan diet may be the ideal choice for our microbiomes [6]. Fibre is especially abundant in plant-based foods, which favour the growth of the protective bacterial group called Prevotella [11].

These little gut soldiers compete with other bacteria that cause disease, reducing the number of pathological strains in your body – a phenomenon often seen in mainly vegetarian African communities [3]. The Prevotella species are particularly good at converting plant fibres into the short-chain fatty acids that help regulate our immune systems [11].

Converting to a vegan diet can also reduce your chance of cardiovascular disease and obesity, by promoting lower levels of Bacteroides species [5] A recent study found that microbiomes of meat-eaters produce higher levels of trimethylamine-N-oxide, which is linked to increased levels of cholesterol [7].

So perhaps you too might follow the science and help both the planet and your own microscopic world by being keen to go green this Veganuary.


  1. BBC. (2017). Anxiety? It might be in your gut. BBC: Health and Wellbeing. [Online]. Available at: [Accessed on the 30th January 2021.]
  2. Dong, T.S. & Gupta, A. (2019). Influence of Early Life, Diet, and the Environment on the Microbiome. Clinical Gastroenterology and Hepatology. 17 (2) pp.231–242.
  3. de Filippo, C., Cavalieri, D., di Paola, M., Ramazzotti, M., et al. (2010). Impact of diet in shaping gut microbiota revealed by a comparative study in children from Europe and rural Africa. Proceedings of the National Academy of Sciences of the United States of America. 107 (33), pp. 14691–14696.
  4. Glick-Bauer, M. & Yeh, M.C. (2014). The health advantage of a vegan diet: Exploring the gut microbiota connection. Nutrients. 6 (11) pp.4822–4838.
  5. Hjorth, M.F., Roager, H.M., Larsen, T.M., Poulsen, S.K., et al. (2018). Pre-treatment microbial Prevotella-to-Bacteroides ratio, determines body fat loss success during a 6-month randomized controlled diet intervention. International Journal of Obesity. 42 (3), pp. 580–583.
  6. Medawar, E., Huhn, S., Villringer, A. & Veronica Witte, A. (2019). The effects of plant-based diets on the body and the brain: a systematic review. Translational Psychiatry. 9 (1) pp.1–17.
  7. Park, J.E., Miller, M., Rhyne, J., Wang, Z., et al. (2019). Differential effect of short-term popular diets on TMAO and other cardio-metabolic risk markers. Nutrition, Metabolism and Cardiovascular Diseases. 29 (5), pp. 513–517.
  8. Sender, R., Fuchs, S. & Milo, R. (2016). Revised estimates for the number of human and bacteria cells in the body. bioRxiv. [Online] 036103. Available from: doi:10.1101/036103 [Accessed: 24 January 2021].
  9. Veganuary, (2021.) Veganuary. [Online]. Available from: [Accessed: 4th November 2021].
  10. Wu, G.D., Chen, J., Hoffmann, C., Bittinger, K., et al. (2011). Linking long-term dietary patterns with gut microbial enterotypes. Science. 334 (6052), pp. 105–108.
  11. Wu, G.D., Compher, C., Chen, E.Z., Smith, S.A., et al. (2016). Comparative metabolomics in vegans and omnivores reveal constraints on diet-dependent gut microbiota metabolite production. Gut. 65 (1), pp. 63–72.
  12. Zimmer, J., Lange, B., Frick, J.S., Sauer, H., et al. (2012). A vegan or vegetarian diet substantially alters the human colonic faecal microbiota. European Journal of Clinical Nutrition. 66 (1), pp. 53–60.

Elle Campbell

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