Hi everyone,

My obsession with gut health, resistant starch, and prebiotics continues (surprise surprise?!)..

Just a few days ago I had one of my articles on the gut microbiome diet printed in the Fitness First magazine which I think you may all find enlightening!

It is definitely more in-depth than my usual posts, but hopefully this leaves you feeling more confident in your understanding of why I keep preaching these messages about gut health (I promise, I’m only slightly crazy!).

Happy reading 🙂

Gut Health – Microbiome Diet

Did you know that there are about 10 times more bacterial cells in our bodies than our own human cells (1)? Have no fear, many of these are very good for us, and although our bodies act as a home for them, they play an important role in protecting us from diseases and infections. Of particular interest these days are the bacterium located in the gastrointestinal (GI) tract, with their collective genome termed the gut microbiome. We have approximately 100 trillian bacterial cells living in our GI tracts (2), of which most are from the bacterial phyla know as Bacteroidetes and Firmicutes. New research is confirming that the gut flora profile, and in particular, the make up between these two phylas, can play a significant role in weight mananagement and disease prevention. Simultaneously, studies are also showing us that the foods we select to consume can play a huge role in determining our gut flora profile and therefore our health outcomes (3). The gut microbiome varies significantly between individuals, as well as changes over time within ourselves (4).

Gut Health – Microbiome Diet vs Weight Loss or Weight Gain:

One of the major studies within this field, looking at obesity and the gut bacteria, was performed in 2004 by Backhed and colleagues (5). When germ-free mice were colonized with bacteria from the intestines of normal mice, within 14 days, the previously germ-free mice, despite consuming less total food, saw an increase by 60% in their total body fat. Additionally, the formerly germ-free mice had greater carbohydrate absorption and increased triglyceride storage in their fat cells. More recently a follow-up study took germ-free mice and colonized them with gut bacteria from obese or lean mice (6). The germ-free mice that were colonized with bacteria from obese mice had a 47% increase in body fat compared with a 27% increase in body fat in the mice colonized with bacteria from lean mice, suggesting that gut bacteria may have a causal relationship with body fat. Interestingly, when they looked at the gut flora profile in more depth, it was found that the obese mice had more Firmicutes, whilst the lean mice had more Bacteroidetes. The obese mice also had fewer calories in their feces, implying that the Firmicutes may have a greater potential to extract energy (calories) from the food we consume, leading to an increase in fat accumulation.

How Your Calorie Intake Effects Your Microbiome:

It has been shown that the higher your energy intake is above that required to maintain your weight, the greater the increase in Firmicutes and the decrease in Bacteroidetes in your gut flora. This results in more calories being extracted from the food you consume rather than lost in your stools, making it harder to lose or maintain your weight (7). On the other hand, when you do lose weight, it appears that this ratio can switch, resulting in fewer Firmicutes, and additional Bacteroidetes presenting, which may assist your ability to maintain your new lower weight or leaner body composition.

Diet and Microbiome Profile:

Even more profound is the news that we are capable of influencing our gut flora for both the positive or the negative as a result of the dietary choices we select to make. A study performed in mice that had been colonized with human flora showed that in as little as one day, when diets were changed from being low-fat and high in plant carbohydrates to that of a more typical Western diet, higher in fat and sugar, changes in the gut flora and increases in fat stores could result instantaneously (8). Diets high in foods that contain prebiotic dietary fibers, resistants starches, and probiotics are the key to a strong gut. As you can see, maintaining a healthy gut, and consuming foods that support the growth of the good bacteria and reduce the likliehood of the proliferation of the bad bacteria is essential for overall wellbeing. So what exactly should we be eating?

Microbiome Diet: Practical Dietary Recommendation 1– Gut Health – Probiotic Rich Foods:

Probiotics are the live microrganisms we can consume which populate our gut; there are many different strains obtainable through fermented foods, as well as some dairy and non-dairy alternative products. Yoghurt, kefir, kimchi, tempeh, sauerkraut, and miso, are all foods that are rich in probiotics. It is important when you are purchasing products such as yoghurt that you look for those that mention they contain live probiotics, as heat treatment can destroy many strains. New products that are inflused with probiotic strains such as coconut yoghurts, kombucha beverages, and health bars are beginning to make their way onto the market. Make sure when you purchase these that they are coming from a credible company that has put into place the mechanisms required to ensure the viability of the probiotics stated to be within their products.

Microbiome Diet: Practical Dietary Recommendation 2 – Gut Health – Prebiotic Rich Foods:

Prebiotics dietary fibers are non digestible, or selectively digestible carbohydrates that fuel the good bacteria in our gut. They can be found in plant based foods, and are most commonly found in health food products in the form of oligosaccharides or inulin. These soluble fibres have been extracted from chicory root or Jerusalem artichokes, and provide a slightly sweet flavour to the end product. Other foods that provide prebiotic dietary fibres include konjac root (which low calorie “shirataki” noodles are made out of), beta-glucan found in oats, or psylium husk which can be added into a smoothie or over a bowl of high fibre cereal. All of these options are great ways of boosting your prebiotic fibre intake and will support strong gut health.

Microbiome Diet: Practical Dietary Recommendation 3 – Gut Health – Resistant Starch Rich Foods:

Finally, there is resistant starch, a non digestible carbohydrate that selectively fuels the growth of the good bacteria in your gut. Resistant starch can be found in unripe bananas and plantains, cooked and then cooled grains such as sushi rice and cold pasta salads, as well as cooled potatoes, and legumes. Currently intakes are down as low as 5g per day in the Western world, while we are advised to aim for around 20g per day (9).


By increasing your intake of many plant based foods, such as vegetables, legumes, fruit, whole grains, nuts and seeds, you will be strongly supporting your digestive health and assisting the growth of the good bacteria that will make up your gut flora profile. Reducing your intake of high refined and processed foods that are rich in sugars and saturated fats would also be advised. The science in this area is continually evolving and strengthening; by implementing the suggestions made here, you will leave yourself in a strengthened position when it comes to seamlessly achieving your health and body composition goals.


As you can see, there is certainly a lot to keep learning and taking in on this ever evolving topic of nutrition and gut health. I hope this post proves useful for you and that you feel excited to take on board some of the practical gut microbiome diet recommendations!

If you feel others would value from this information please do share it with them.

Until next time,

TD x


References: 1. Cani, PD and Delzenne NM (2009). “The role of the gut microbiota in energy metabolism and metabolic disease.” Curr Pharm Des 15(13): 1546-1558 2. Chow J, Lee SM, Shen Y, Khosravi A, Mazmanian SK. Host-bacterial symbiosis in health and disease. Adv Immunol. 2010;107:243-274. 3. Backhed F, Ley RE, Sonnenburg JL, Peterson DA, Gordon JI. Host-bacterial mutualism in the human intestine. Science. 2005;307(5717);1915-1920. 4. Eckburg PB, Bik EM, Bernstein CN, et al. Diversity of the human intestinal microbial flora. Science. 2005;308(5728):1635-1638. 5.Backhed F, Ding H, Wang T, et al. The gut microbiota as an environmental factor that regulates fat storage. Proc Natl Acad Sci U S A. 2004;101(44):15718-15723. 6. Turnbaugh PJ, Ley RE, Mahowald MA, Magrini V, Mardis ER, Gordon JI. An obesity-associated gut microbiome with increased capacity for energy harvest. Nature. 2006;444(7122):1027-1031. 7. Ley RE, Turnbaugh PJ, Klein S, Gordon JI. Microbial ecology: human gut microbes associated with obesity. Nature. 2006;444(7122):1022-1023. 8. Turnbaugh PJ, Ridaura VK, Faith JJ, Rey FE, Knight R, Gordon JI. The effect of diet on the human gut microbiome: a metagenomic analysis in humanized gnotobiotic mice. Sci Transl Med. 2009;1(6):6ra14. 9. CSIRO. (2012). “Resistant starch may offer potential to help protect against bowel cancer.” 2012, Retrieved from http://www.csiro.au/Portals/Media/resistant-starch-may-offer-potential-to-help-protect- against-bowel-cancer.aspx.