The gut – an underestimated organ that affects the whole body
In the phrase: “a healthy gut is a healthy body” there is no exaggeration. If you take good care of it, it will return the favour by supporting the health of the whole body. The gut is best taken care of with a healthy diet that supports the diversity of the bacterial flora. By taking care of it, you can eliminate skin problems, boost immunity and even start to cope better with excessive stress. A gut-healthy menu has a direct impact on the quality of your life.
The primary role of the gut is, of course, to participate in the digestion and absorption of food, but this is only a superficial role. In fact, the gut performs even more important functions. First and foremost, it is the habitat in which millions (actually hundreds of trillions) of gut bacteria that make up the microbiome reside.
The gut microbiome has an incredible impact on the human body, and scientists are still discovering new functions and links between microbes and all areas of the human body, such as:
- Immune system – microbes secrete, among others, signalling molecules capable of communicating with immune cells. The microbes inhabiting the gut, for example, determine how the body responds to infection.
- Metabolism and digestion – gut bacteria help digest food with the support of enzymes that the human body does not produce. This produces, for example, healthy short-chain fatty acids (SCFAs) that nourish intestinal cells.
- Effect on the brain – there is a direct connection between the gut and the brain called the brain-gut axis. It is no coincidence that a common reaction to stress is intestinal problems, and the English idiom gut feeling meaning a “hunch” refers precisely to feeling something in the gut. The gut bacteria set also has a direct impact on our mood and ability to concentrate.
- Impact on body weight – poor and little diversified gut microflora predisposes to obesity and metabolic syndrome. Some implausible-sounding studies even suggest that microbes in obese people are able to “manipulate” their host and induce them to reach for the food preferred by the dominant bacteria, causing food cravings. Increasing bacterial diversity partially eliminates this problem.
- Predisposition to type 2 diabetes and other glycaemic disorders – gut bacteria may indirectly manage glucose metabolism through their influence on the liver, involvement in carbohydrate digestion and participation in the body’s inflammatory response. Scientists are very serious about understanding the connection between gut microbes and the mechanisms of diabetes.
- Vitamin production – the human body does not have the capacity to produce vitamins, but gut bacteria can synthesise them. With the participation of microbes in the gut, vitamin K and B vitamins (B12, B1, B2, B3, B5, folate, B6), for example, are formed. A healthy bacterial flora is therefore, colloquially speaking: a residue-driven vitamin factory that is always with you.
The microbes populating the gut are such a unique composition that no two people have the same microflora composition. Based on the composition of the gut microflora, scientists are able to tell if a person is obese, if their BMI is normal, how varied their diet is, and even determine if they may be more prone to depression.
It is no small challenge for researchers to define what exactly a “healthy gut microflora” should look like, as it is very individual. It depends, for example, on age, physical activity, place of upbringing and many other factors. However, it is known that healthy microbes are primarily species-diverse and abundant in the gut. When composing a diet for intestinal health, it is therefore worth focusing on nutrition and diversity.
Diet for a healthy gut – how do you eat to improve your body?
Following a diet for gut health, or in fact a diet for the health of the microbes that inhabit it, is a way to improve the overall health of the body. Strong, diverse and well-functioning gut bacteria improve the whole body. The so-called “gut diet” may therefore prove to be the missing puzzle in your journey to health. It can improve stress management, boost immunity, reduce digestive problems, and generally make you feel much better.
A diet for the gut is best used preventively. You should focus on nutrition that supports microbial diversity before serious health problems occur.
Here are some universal tips to follow:
- Ensure adequate intake of fibre
The direct food for intestinal bacteria is fibre, i.e. “indigestible” dietary fibres, which (strictly speaking) are not digested by the human body’s cells and secreted molecules, but only in part precisely by the bacteria inhabiting the intestines. Fibre produces energy raw materials for microbes and is direct food for them. It has been shown that people who follow a low-fibre (so-called typical Western) diet, which is processed, based on refined carbohydrate sources, poor in vegetables and fruit and rich in meat, are characterised by a less diverse microflora of poor quality.
In addition to nourishing the digestive bacteria, fibre has other functions to ensure intestinal health. It facilitates intestinal passage and stool formation. That’s not all. Bacteria ferment the fibre and at the same time secrete short-chain fatty acids (SCFAs) – acetate, butyrate and propionate. These are compounds with very broad health effects on the gut, which are often taken in the form of supplements to support gut health. They improve the intestinal barrier function, regulate intestinal metabolism, and can even support the nervous system function as well as indirectly increase stress resistance!
How much fibre to eat daily for gut health? According to WHO guidelines, there should be at least 25 g of naturally occurring fibre in the diet of adults and children over 10 years of age. The average Pole consumes too little of it (women about 17.5 g/day, men about 20.9 g/day).
Fibre-rich foods include, for instance, whole-grain cereals, vegetables and fruit, legumes, nuts and seeds.
It is a good idea to increase the amount of fibre in the diet gradually to reduce the risk of side effects such as gas, bloating or a feeling of overeating. Even if, after trying to increase the proportion of fibre in your diet, these symptoms appear, don’t get discouraged. The body needs time to adapt to larger portions of fibre, and the gut bacteria need to adjust to the larger portion of food they can consume.
Increasing the intake of dietary fibre is the best, and still under-appreciated, step you can take to take care of your gut health and the nutrition of your gut microbes. This is probably more important and effective than the trendy probiotic therapy or eating pickles.
Hint: High-fibre foods are generally healthier than lower-fibre ones, but very physically active people and athletes often deliberately (and rightly so!) turn to refined carbohydrate sources: white rice, pasta or white bread, for example. Particularly in pre-workout meals, before high exertion, lower fibre intake provides greater intestinal comfort.
- Opt for a variety of plant-based foods
The gut and intestinal bacteria love a variety of food. The more diverse the diet, the greater the variability in the fraction of fibre, flavonoids and other molecules provided in the food. It also supports species diversity of gut bacteria, and this (as you already know) is one of the most important aspects in assessing microflora health. Each type and species of bacteria has different preferences for growth and development conditions. By providing varied food, you facilitate populating the gut with bacteria that have a variety of preferences for the food (or rather the leftovers) on which they grow.
In a study published in 2022, scientists in China bluntly confirmed that a more diverse diet means greater diversity of gut microbes. Furthermore, people with a more varied diet showed an increased prevalence of bacterial strains that are positive for human health, and bacteria that are potentially pathogenic for humans were detected less frequently.
Focus especially on choosing a variety of plant-based foods. Eat salads rich in several types of fruit and vegetables, and add fresh herbs to your meals to increase the range of products used. Create your own mixes of seeds and nuts – use them in the kitchen to supply different elements. Creating homemade muesli from several types of whole-grain flakes, nuts, seeds, grains and dried fruit, for example, is also good advice. In terms of macronutrients alone, a diet can be balanced from just a few dozen base foods, but diversifying them is an advantage for gut health.
How do you know if your diet is sufficiently varied? Calculate how many different plant-based products you eat in a week. A diet can be considered varied with a weekly menu in which you use at least 30 separate plant-based products. This is a figure suggested by scientists working on a huge project studying the human microbiome: American Gut Project.
- Follow a plant-based diet
A plant-based diet supports a healthy microflora, which is an indisputable fact. It does not necessarily mean a vegan or vegetarian diet, but a way of eating that is plant-based. It is, of course, mainly about the fibre found in these products. It cannot be derived from food of animal origin.
A plant-based diet increases bacterial diversity and promotes microbial species that have a benign effect on body function. Plant fibres increase the presence of desirable lactic bacteria (e.g. Ruminococcus, E. rectale and Roseburia), and reduce the growth of potentially pathogenic bacteria of the Clostridium and Enterococcus species.
In addition to fibre, plant-based food contains valuable polyphenols. They have a beneficial effect on the intestines, as they have anti-inflammatory properties and provide a good growth environment for the desirable bacteria from the Bifidobacterium and Lactobacillus groups, which synthesise the short-chain fatty acids (SCFAs) already mentioned as invaluable for intestinal health.
You can’t build a healthy diet without a sufficient supply of plant-based foods! For gut health, it is best to follow the least processed menu rich in vegetables, fruit, seeds, grains, nuts and legumes. Meat substitutes can also supplement the diet, but let them not be the basis of it. They contain, for example, emulsifiers whose effects on intestinal health are controversial.
- Opt for natural probiotics
Fermented foods support gut health, even children know this. However, it is very important to introduce fermented products together with an adequate supply of fibre. Fermentation has been known to mankind for hundreds of thousands of years, and some form of fermented products can be found in the culinary traditions of almost every region of the world. The Japanese eat fermented natto soybeans, Koreans have kimchi, and we are very familiar with pickles and fermented dairy products.
Lactic acid bacteria consumed with fermented foods definitely contribute to biodiversity, but are unlikely to populate the gut directly. Because of the stomach acid, even healthy bacteria from food are unlikely to reach the gut alive. Nevertheless, it is definitely worth eating fermented foods. Scientific evidence clearly shows that people who consume it on a daily basis reap short- and long-term benefits.
Include the following in your diet:
- pickles (cucumbers, cabbage, kimchi, but also the less well-known pickled cauliflower or radishes),
- fermented dairy products (kephir, yoghurt, buttermilk),
- refreshing kombucha (fermented tea),
- miso and fish sauce,
- tempeh (a meat substitute made from fermented soybeans),
- sourdough products (kvass, sourdough bread).
For gut support, you could also consider a probiotic therapy, but don’t let this be your first step. Make dietary improvements first, and well-chosen probiotics can support this. It is necessary to adapt the strain of probiotic bacteria to individual needs.
You can read more about this in the article: “5 Supplements for Athletes That Don’t Deliver What They Promise. Don’t Waste Your Money on Them!”
A light gut-relief diet – what to eat when intestinal problems arise?
There is also another definition of the term “gut diet”, which is of interest to people who are looking for a diet that relieves the burden on their digestive system. The diet for the gut when it starts to fail is quite different from the diet for the prevention of intestinal diseases, which I have discussed in detail above and which will work for most Poles. Once intestinal problems or chronic intestinal diseases have developed, a different strategy needs to be embraced.
An easily digestible diet is then often introduced to provide nutrients, relieving the intestines as much as possible. Obviously, you have to give up on hard-to-digest foods, such as fried food, but that’s not all. You reduce fibre and bloating products, in some cases follow a semi-liquid diet, and temporarily rely on light, refined grain products.
A similar strategy is also used to increase the intestinal comfort of long-distance athletes before competitions. The menu for normalising the intestines before a long-distance run or cycling race consists of meals that are easily digestible, rich in simple carbohydrates and low in fibre: the opposite of what a typical Smith is recommended to eat on a daily basis.
In the diet for intestinal diseases, it is also often necessary to modify healthy eating habits and (temporarily) exclude healthy products, such as whole-grain cereals or nuts and high-fibre vegetables in larger doses.
The intestinal diet for diseases and disorders has to be adapted to the specific requirements of the disease or problem. It is worth consulting a dietician or doctor to tailor nutrition to your individual situation.
Here are some of the dietary strategies undertaken for gut problems:
- When diagnosed with IBS (irritable bowel syndrome), it is worth introducing the low FODMAP diet with limited fermentable carbohydrates.
- With inflammatory bowel diseases (e.g. ulcerative colitis or Crohn’s disease), the amount of fibre and the entire diet must be adapted to the requirements during periods of exacerbation and remission.
- With constipation, it is worth getting to the root of the problem and then introducing adequate fluids and gradually increasing the amount of fibre in the diet.
- In celiac disease (which is also an intestinal disease!), you have to absolutely give up eating gluten.
- In athletes with periodic intestinal problems (e.g. during intense exercise), so-called “gut training” is used to overcome gastrointestinal problems caused by the ingestion of a large dose of simple carbohydrates.
These, of course, are not all the disorders, diseases and bowel dysfunctions where it is worthwhile to act and introduce a proper diet. It is very important to distinguish between the concepts of a gut diet (intended to maintain intestinal health) and a gut diet when intestinal problems have likely already developed.
If you want to support the whole body and improve overall gut health, eat at least 25 g of fibre every day, introduce fermented foods, have a varied diet and include plant-based foods in your menu. If you have certain bowel dysfunctions that prevent you from comfortably implementing these recommendations, it is better to take advice from an experienced dietician and consult your doctor to get to the root of your bowel problems and find the best solution for you.
…………
References:
1. Guinane CM, Cotter PD. Role of the gut microbiota in health and chronic gastrointestinal disease: understanding a hidden metabolic organ. Therap Adv Gastroenterol. 2013 Jul;6(4):295-308. doi: 10.1177/1756283X13482996. PMID: 23814609; PMCID: PMC3667473.
2. www.who.int.
3. Jarosz M., et al. „Normy żywienia dla populacji Polski i ich zastosowanie.” 2020, rozdział: „Błonnik pokarmowy” A. Wojtasik, E. Pietraś, H. Kunachowicz, s. 148-170.
4. Rowland I, Gibson G, Heinken A, Scott K, Swann J, Thiele I, Tuohy K. Gut microbiota functions: metabolism of nutrients and other food components. Eur J Nutr. 2018 Feb;57(1):1-24. doi: 10.1007/s00394-017-1445-8. Epub 2017 Apr 9. PMID: 28393285; PMCID: PMC5847071.
5. Li WZ, Stirling K, Yang JJ, Zhang L. Gut microbiota and diabetes: From correlation to causality and mechanism. World J Diabetes. 2020 Jul 15;11(7):293-308. doi: 10.4239/wjd.v11.i7.293. PMID: 32843932; PMCID: PMC7415231.
6. Huang X, Gao Y, Chen W, Hu Q, He Z, Wang X, Li D, Lin R. Dietary variety relates to gut microbiota diversity and abundance in humans. Eur J Nutr. 2022 Dec;61(8):3915-3928. doi: 10.1007/s00394-022-02929-5. Epub 2022 Jun 28. PMID: 35764724.
7. McDonald D., et al. ; American Gut Consortium; Knight R. American Gut: an Open Platform for Citizen Science Microbiome Research. mSystems. 2018 May 15;3(3):e00031-18. doi: 10.1128/mSystems.00031-18. PMID: 29795809; PMCID: PMC5954204.
8. Tomova A, Bukovsky I, Rembert E, Yonas W, Alwarith J, Barnard ND, Kahleova H. The Effects of Vegetarian and Vegan Diets on Gut Microbiota. Front Nutr. 2019 Apr 17;6:47. doi: 10.3389/fnut.2019.00047. PMID: 31058160; PMCID: PMC6478664.
9. Silva YP, Bernardi A, Frozza RL. The Role of Short-Chain Fatty Acids From Gut Microbiota in Gut-Brain Communication. Front Endocrinol (Lausanne). 2020 Jan 31;11:25. doi: 10.3389/fendo.2020.00025. PMID: 32082260; PMCID: PMC7005631.
10. Leeuwendaal NK, Stanton C, O'Toole PW, Beresford TP. Fermented Foods, Health and the Gut Microbiome. Nutrients. 2022 Apr 6;14(7):1527. doi: 10.3390/nu14071527. PMID: 35406140; PMCID: PMC9003261.