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The gut is home to a wide array of microbiota that influences various interactions within our bodies. These microbes also regulate gut functioning, digestive processes, absorption of essential vitamins and minerals, and so on. When the gut is not functioning correctly, our bodies suffer. Long-term effects of an unhealthy gut include increased risks of metabolic problems, depression, obesity, cancer, autoimmunity, liver disease, ulcers, heart disease, and other illnesses and health problems.

Of particular interest is the Paleo diet, which restricts the consumption of all grains (bread, rice, pasta, cereals, quinoa, etc) including whole grains, as well as legumes. The most notable limitation of this diet is the loss of soluble and insoluble fibres found within these foods. Let’s explore this important nutrient first.

Part of what keeps the gut functioning correctly is ensuring it gets plenty of fibre. Fibre is good for the gut microbiota. They feed off it and thrive as they should. So naturally, one should always consider the impacts on long-term impacts on gut health when making dietary changes. Besides benefiting gut functioning, fibre also helps lower cholesterol, regulate blood sugar levels, and assists with better weight management. Healthy gut functioning also helps keep TMAO (Trimethylamine N-oxide) levels low, which is a molecule generated via microbial metabolism linked to increased levels of cardiovascular disease, as well as hypothesized neurological disorders. As a whole, what occurs when someone follows the Paleo diet long-term is the levels of good gut microbiota decrease and the amount of TMAO in the body increases. This is primarily contributed to the increase in protein consumption through meat and fish and the removal of whole grains and legumes. While some fibre is consumed through various fruits and vegetables, two essential microbiomes in the gut are not getting fed. Bifidobacterial thrives from starches found in bread and grains, while Roseburia thrives from beta-glucans found in oats and barley. A recent research study followed different control groups that stayed on the Paleo for a year. There were three different groups – a control group, a strict Paleo group, and a pseudo-Paleo group. At the end of the study, those in the strict Paleo group and the pseudo-Paleo group had a noticeable decrease in good gut microbiota. The participants did get plenty of fibre from fruits and vegetables. Yet, they were not getting the right balance of fibre to feed every type of healthy gut microbiome. There was also a noticeable increase in TMAO levels in study participants.1 Another study conducted by the same researchers, looked at the short-term microbiome shifts in the gut while on the Paleo diet. That study concluded that short-term use of the diet did not have long-term shifts in the microbiome.2 In conclusion, the studies show that following the Paleo diet long-term can reduce the healthy gut microbiota and increase TMAO levels. It doesn't mean that a Paleo diet can’t be followed long-term, but ensuring to modify and account for missing fibre sources is important. If you want more about dietary impacts on your gut, as well as effective approaches that are not carb-free or starch-free, please feel free to contact Toronto naturopathic doctor, Dr. Courtney Homberg at 647-351-7282 to schedule your appointment today. Sources:

  1. Genoni, A., Christophersen, C.T., Lo, J. et al. Long-term Paleolithic diet is associated with lower resistant starch intake, different gut microbiota composition and increased serum TMAO concentrations. Eur J Nutr 59, 1845–1858 (2020).

  2. Janeiro MH, Ramírez MJ, Milagro FI, Martínez JA, Solas M. Implication of Trimethylamine N-Oxide (TMAO) in Disease: Potential Biomarker or New Therapeutic Target. Nutrients. 2018;10(10):1398. Published 2018 Oct 1.

  3. Genoni A, Lo J, Lyons-Wall P, et al. A Paleolithic diet lowers resistant starch intake but does not affect serum trimethylamine-N-oxide concentrations in healthy women. Br J Nutr. 2019;121(3):322-329.

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