Nutrition: Why is it that intestinal health is so important?

27/03/2015 - 7 Comments - Nutrition |

This text and image are by Laura Leite.

A few months ago, I first started to know Laura, even without knowing her - through comments made by Jo about her researches and studies. Jo and I often discuss via email, thinking about what the best topics would be to address and elucidate here in the Nutrition column.
And through the concepts she presented to me, we arrived at the conclusion that, in order to understand the influence of nutrition over us, it is essential to know how the digestive system works, with a special attention to the intestines.
I got curious to learn about Laura's line of thought, and finally we were introduced when Jo proposed that she could write in this space about the importance of paying attention to intestinal health - both individually, so that we have understanding and autonomy over our own body and health, as well as in the health professionals scope who treat and educate the general public. I pass the floor to Jo now.

About two years ago, Laura has introduced me to the Paleolithic diet and all the science behind this ancestral nutritional template. At every conversation I discovered something new, I found a new way of thinking and acting regarding all things related to the conventional nutritional practice (that one based on the food pyramid, eating every three hours, and that generally prescribed macronutrients ratio, among other characteristics). From there, I began to admire her effort and ability to study the more complex topics of the nutritional science. Whenever I needed support, either with her opinion as in bibliography, there she was with all her coherence. All of my texts were written with Flora's help, who drives the topics through doubts and questions that serve as guide; and also with help from Laura, who would review the text, suggest additional reads and bibliographical reference. The "intestinal health" topic is very important for those curious to know how our bodies work and the influence of food on it. Yet, I feel my studies on this organ are still raw. And the person I know who has a great understanding on the topic is Laura. So today, with great joy, Flora and I open the space for this wonderful person who has so much to contribute with our column. Welcome, Laura!

Thank you Flora and Jo for introducing me :)
My name is Laura Mattos Leite and I am very glad to be invited to write here! I think Flora's site is a delicious read, full of inviting images, ideas and information. It reminds me of my beloved aunt Lola's home in Ribeirão Preto, where I only felt love and comfort all through my childhood, experimenting the delicacies she would prepare with such care.

I have graduated in Social Communication at PUC RJ and I also work as a consultant and mentor in Professional Communication. Since 1997 I started to have a greater interest in nutrition, due to a serious crisis of mysterious allergies I had while studying yoga living in India. I completely healed by eliminating gluten, and I never looked back.

Since then, I have been certified as Personal Trainer, Pilates Instructor, and have received trainings from very generous and wonderful teachers in several forms of movement.
In 2009, I had contact with the "anti-inflammatory" diet, which radically reduces the sources of Omega 6 from the meals. Since, I have been working and participating in symposiums on this topic, including what is now in vogue called - although not scientifically - the "Paleolithic Diet". I have always avoided labeling diets, since I feel it is associated with formulas. I don't believe in formulas, but in doing what is best for each person individually, within their life context. I am at the end of the Funcional Diagnostic Nutrition course, accomplishing the desire to better understand hormones and thus being able to better help people. I believe food is a powerful medicine, and I see cooking as an Art, Therapy and Fun. I love to cook, feel free to drop by my instagram, I will love your visit!
I confess Jo is responsible for a great part of my culinary adventures, for she inspires me infinitely and, after I met her, cooking became so much more fun and tasty. Thank you Jo!

So, let's talk about this organ which I oftentimes call "our root": the intestine.

Have you ever heard that saying "All disease begin in the gut"? Researching just a little, we discover it has been said over 2000 years ago by Hippocrates, the Greek doctor who, for the first time, has systematized the study of Medicine, and who is called "the Founder of the Western Medicine".

After a couple of years studying the area of Ancestral Health of Functional Medicine (which is a branch of Medicine that prioritizes the treatment of causes of imbalance, rather than the symptoms), and started to observe that the professionals who stood out for having a larger number of successfully resolved cases, were the ones who emphasized gastro-intestinal health and that, oftentimes would put it in the first place in their protocols and treatments. I noticed that many patients who had success and resolution of their cases had rather dramatic history of serious health disorders, such as Irritable Bowel Syndrome and allergies that debilitated several aspects of their lives, not allowing them to have full social or professional life. These people seeked help and did not find solutions, even after having followed protocols given by several doctors and healthcare professionals for a long time, some for more than 20 years.

This has drawn my attention greatly. So I have been dedicating part of my time to study the mysteries of the microbiome, the combination of gatherings of populations of micro-organisms present in the instestines and their funcions, including some functions that for me are surprising and mysterious. Here I will expose a few of my most precious findings, the ones that caused the most impact on me, and that I have been collecting over the years.

So, let's start from the beginning. The organ itself, the intestine:



Intestine - It's Structure and What it Does

In the image above we see, in orange, the first portion of the intestine, the small intestine. This area receives food from the stomach. A healthy small intestine has a relatively neutral environment; there are about 10 Thousand bacteria by a millimiter of fluid, compared to the large intestine, in green, which contains around 1 Billion bateria by by a millimiter of fluid.

The small intestine is divided in three parts: The first one is the duodenum, about 25cm long. There is where food is received from the stomach. Within the duodenum most of the digestion occurs. Chloridric acid is injected from the stomach, as are enzymes from the pancreas, biliary gland and liver. In the duodenum are also present the enzymes that are produced within it's own mucous membrane, that are crucial to digesting food.

The second part is the jejunum, about 2,5m long. This area is responsible for the largest part of assimilation and absorption of nutrients in food.

The third part is the ileum, about 3,5m long. The ileum plays a crucial role in the absorption of Vitamin B12, and in the operation of the liver, by making it possible for the bile to return to it. The ileum also has the immune system integrated within itself, taking the task of monitoring the baterial populations in the intestines, as well as avoiding the growth of harmful bacteria.

The internal membrane of all three parts of the small intestine has a structure similar to our tongue, with papillae or microvilli, which enlarge the surface that absorbs nutrients. This membrane, in the duodenum digests food, and in the jejunum and ileum, it filters beneficial nutrients allowing them to flow into the blood stream. 

The microvilli walls are only ONE cell thick! They are directly connected to the blood capillaries, which enter each one of them, and their structure is extremely sophisticated and delicate. The fact that this mucous membrane is structured by these microvilli is a very efficient way of enlarging the contact surface with nutrients in all three areas of the small intestine. Nature has created such a perfect system, and focus on concentrating as much contact surface as possible, in as little space as possible. If we stretched out the microvilli of the small intestine on the ground, for example, it would cover the area of an entire tennis court!

The part in green in the image is the large intestine, around 1,5m long. Generally speaking, it is composed of: caecum, where is the appendix which, we will soon see, is not just a useless heritage from our evolution; ascending colon, transverse colon, and sigmoid colon, where faeces are kept until elimination.

The internal walls of the large intestine have the single cell layer mucosa, besides cells which produce mucus. In these walls there is also a great quantity of muscles which perform a wave-like movement (peristaltic) to move food foward with the goal of eliminating it. There are also found blood vessels too, to absorb nutrients with maximum efficiency. Yes, the large intestine also absorbs nutrients, besides eliminating them! There happens a process of absorbing vitamins, such as B and K, that areproduced by the large intestine bacteria.

 The bacteria populations in the large intestine digest nutrients that have not been digested in the disgestive tract until that point, mostly carbohydrates. Another function of the large intestine is to remove water from the nutrients and turn them into faeces, then, speaking simply, this faecal matter is taken to the sigmoid colon by peristaltic muscular actions and eliminated by the anus.

The elimination function is fundamental! For when food is not eliminated, there might happen a pH change in the intestinal environment, and this may facilitate the growth of pathogenic microorganisms and free radicals. This includes the case when the intestinal flora is unbalanced due to antibiotics, a diet poor in insoluble fibers, or lack of carbohydrates in general, contributing to decreased fermentation, leaving the environment less acidic and thus vulnerable to harmful bacteria.

The unbalance of intestinal flora, as we will soon enlighten, has immediate effects over the brain and our hormones, which regulate homeostasis (balance, or that state of well being where everything works with vitality and harmony, when the body can experiment wholly its power of well-being) of all the other organs.

The large intestine is designed to work optimally with a constant balance of probiotics and prebiotics. When this does not happen, the consequences in general cause an impact in all systems within the body in different levels. Speaking simply, probiotics are actual bacteria, and prebiotics are the nutrients that feed these bacteria, and support them to multiply and strengthen.

Our microbiota, or intestinal flora, is composed of populations, or colonies of probiotics, that have been primarily transmitted to us through the contact with our mother's microorganisms during birth and breastfeeding. From there, we also acquire other colonies of microorganisms throughout our lives. However, there is evidence that the intestinal flora acquired in the childhood will determine several aspects of our health, including the protection against infections, if we will or not be susceptible to obesity, as well as psycho-emotional patterns.

Unbalanced flora, for example, is closely correlated to diabetes, and inflammatory brain processes such as autism, and also auto-immune deseases.
Around 75% of out immunological system is located in the intestine, because the lymphatic tissue is, like a net, interlaced within our intestinal membrane. Like this, it becomes easy to understand that each piece of food we see and choose to ingest, will follow a route leading to direct contact with our immune system.

Besides that, around 80% of the serotonin in the body, which has effect over mood and social behavior, appetite and digestion, sleep, memory and sexual desire, is produced in the intestine.
Summing up the functions of the small and large intestine: we transform the nutrients offered by earth right there at there in the intestinal mucosa, from there the nutrients are injected into the blood vessels promoting the impeccable balance of vitamins, minerals, amino acids and other nutrients that the brain and each organ needs to give us life.

In the second part of this article, to be published at the end of April, we will explore in detail the topic of probiotics and prebiotics, in which foods they are found, and how to acknowledge if we are ingesting the amount and quality proper for our body.

Our Second Brain?

Think of a net of interlaced strings. This net permeates the digestive membranes from the mouth to the anus. It is composed of neurons and is named Enteric Nervous System. This nervous system has started existing way before the brain was developed, and long before the human race came into existence. Our species is about 2 million years old, while the Enteric circuits, which compose the Enteric Nervous System, already existed since 500 million years ago, even in the invertebrates! This gives plenty of room to contemplate how sophisticated and advanced this system is. The ENS communicates to the Central Nervous System through the vagus nerve. In the picture below, see the vagus nerve in yellow:



The vagus nerve is originated in the medulla oblongata area, just above our nape, and controls the involuntary movements of our vital organs, such as heart, lungs, liver, and intestines. To give an idea of how much nature emphasizes the importance of this nerve: it's been documented that around 80% to 90% of the energy produced by the brain is sent to the region where the vagus nerve originates.

In the last ten years, people have started to refer to the Enteric Nervous System as the "second brain". One of the facts that has determined that was the discovery that about 90% of the signals passing through the vagus nerve are coming from the intestine and going to the brain, and not the opposite! This has opened a new paradigm of scientific investigation, and an alert to the healthcare professionals to reorganize their priorities and start to pay greater attention to the intestinal health. This article 1 and this study 2 illustrate that.

But how exactly does this connection happen between brain and intestine? In sum, all of the nutrients that pass through the highly sophisticated selection made by the one-cell-layer wall, named microvilli, go into the blood stream. These nutrients are taken to the brain through our blood vessels, and once in the brain, they are prepared to pass the barrier between the blood and the brain to be used by the brain. 

So we understand, in a direct language, that the intestine prepares the food for the brain. Simultaneously, as we have seen before, the vagus nerve uses most of the brain's energy to transmit signals to it generated in the intestines, also taking messages of balance, strenght, harmony, or stress, distention, inflammation to the brain. Like this, the brain receives not only the nutritious or inflammatory molecules (inflammatory cytokines) directly from the blood, but also the nervous impulses, coming from the vagus nerve, that can bring harmony, vitality, homeostasis, or stress, agitation, inflammation.

Finally, the brain responds, creating a vicious cycle, similar to a snow ball rolling down a mountain and growing in volume. A low grade inflammation is created in the brain, than it is retransmitted by the vagus nerve back to the intestines. That is why, as we will see in the studies soon, so many psychiatric diseases occur simultaneously with digestive problems and vice-versa.

The Not So Surprising Surprises:

Let's now expose another series of facts that exemplify the points shown above. These discoveries also serve as invitation for us to consider intestinal health beyond simple digestion and elimination of food, but maybe, as a key factor for the individual as he or she relates with the world, including the health of bones, skin, brain, the quality of emotions, mental and psychological processes, professional performance, socialization, among many others.

  • In this study 3, it's been documented that between 50 and 90% of the patients with Irritable Bowel Syndrome also suffer from psychiatric disorders.

  • This study 4 is one more in the rising number of studies observing the efficacy of "anti-depressant" drugs in the improvement of the Irritable Bowel Syndrome.

  •  This study 5 has monitored individuals for 5 to 12 years, and brings more evidences that psychological stress can predict the start of a gastrointestinal functional disorder and vice-versa. It is remarked that psychological treatment improves symptoms of gastrointestinal disorders.

  • In this study 6, for example, the conclusion is that the unbalanced intestinal microbiota present in children is a key factor to predict if these children will be obese when adults.

  • This study 7 about the appendix can illustrate the fact that so many people suffer from digestive problems and consequently, some present low grade inflammation in the brain, such as psychological and/or mental disorders, before and/or after surgical removal of the appendix. In this study, it's observed that the appendix is not purely an organ kept as evolutionary trace, as it was believed before. In the appendix area, there is a confluence of several lymphatic tissues, closely related to the immune system. The function of the appendix involves the immune-mediated maintenance of the normal intestinal flora, especially during bouts of intestinal distress. Additionally, the appendix also offers some degree of protection against any potentially pathologic contaminants found in the faecal stream.

  • This study 8 shows that small amounts of gluten aggravate symptoms such as lack of memory, mental confusion, depression, abdominal distention, and stomatitis, in a group of people that were not diagnosed as suffering from celiac disease nor allergic to gluten, meaning they were just like most of us!

  • This study 9 illustrates the importance of elimination, and is one of several alerts for those who consume insufficient amounts of carbohydrates, and/or do not consume adequate insoluble fibers to feed the microbiome. The text illustrates how an environment with less fermentation, or less acidic, leaves us vulnerable to the harmful bacteria. 

Before ending this text, I will bring up two of several dysbioses or intestinal dysfunctions, which are increasing in incidence and taking alarming proportions: Small Intestinal Bacterial Overgrowth and the Intestinal Permeability, or "Leaky Gut".

Small Intestinal Bacterial Overgrowth, or SIBO, is the increase in bacteria and/or changes in the types of bacteria in the small intestine. These bacteria frequently migrate from the large intestine back to the small intestine. Do you remember that, in comparison to the large intestine, the environment of the small intestine is almost neutral? (Ten thousand bacteria by millimeter of fluid as compared to the large intestine where there are 1 billion bacteria by millimeter of fluid). These misplaced bacteria cause unbalance at a physiological level and can cause even structural harm in the walls of the small intestine. They can absorb vitamin B, proteins and amino acids even before our own cells have a chance to absorb these nutrients, thus causing nutritional deficiencies. The most common symptoms of SIBO are: delayed transit of food in the intestine (constipation), although there might be diarrhea too (which is nowadays understood as another form of constipation), abdominal distention and excessive gas.

There are several causes for SIBO, some of them related to the consumption of antacids, consumption of antibiotics and gluten. More recently it has been observed that the moderate consumption of alcohol is an aggravating factor for SIBO, as illustrated in this study 10.

As for Intestinal Permeability, this is a disorder where the cells that compose the microvilli in the small intestine are harmed, causing holes in the walls. This "open" space in the intestinal mucosa is like a brick missing from a wall, or a cell missing from the membrane. Through this hole, undigested substances start to scape into the bloodstream, for example, large protein molecules, yeast and even toxins, which were destined to be transformed into faeces. From that moment on, it's like a great battle is taking place in the organism. First, the liver is overwhelmed "trying" to filter and digest what should have been digested in the intestinal mucosa. From then on, until these particles of unfiltered food reach the brain, affecting and harming several systems of the body on their way. Depending on the toxicity level of these particles, them arriving at the brain may be fatal. Intestinal Permeability symptoms are also varied, the most common are several allergies, abdominal distention, headaches, mental confusion, loss of memory, fatigue, craving sugar and carbohydrates and anxiety.

The causes of Intestinal Permeability are varied as well. Some of them are: untreated SIBO, chronic stress, consumption of antibiotics; diet composed of sugar, processed flours, hydrogenated and/or industrilized fats, rich in pro-inflammatory Omega-6, preservatives and zync deficiency. An agent that is efficient in causing harm to the integrity of intestinal mucosa, resulting also in permeability, is alcohol. Here is one of the numerous studies that exemplify that: study 11.

Stay with us for the second part of this article, which will bring practical everyday details of how to be more connected to our intestinal health, and what to do to have a microbiome that is a source of nutrition to the brain and the whole body.
Who knows, maybe we can even collaborate with Hippocrates through our own experience, and complement his saying of "All diseases begin in the gut", with our own version: "And health can also begin in the gut!" What do you think?

16/08/2016 16:05:32


Olá gostaria de ver a segunda parte do material sobre intestino. aonde consigo??

Response from Flora
Oi Cintia! Tudo certo? A parte dois está neste link >> Ainda temos mais dois artigos para publicar sobre a saúde intestinal, falando de dieta e suplementação, mas não estamos com o texto pronto para publicar ainda. Vou mandar um email pra te dizer quando estiver no ar, ok? Qualquer dúvida, é só escrever pra nós! Um beijo.

08/06/2016 16:51:41


Primeiramente, parabéns pela matéria, excelente! Gostaria de saber se a síncope do vasovagal (onde há uma hiperestimulação do nervo vago, que causa desmaios) tem relação com a SIBID. Vi que o nervo vago tem muita comunicação com o intestino, será que o desiquilíbrio nesse nervo pode levar ao aumento de bactérias ruins no intestino? Obrigada! Abraços

19/04/2015 21:56:54

Laura Leite

Obrigada Thais pelas perguntas. Quanto ao apendice, a manutenção de uma flora saudável e portanto a diminuicao e dos sintomas inflamatórios é desejavel. O apendice proteje quando as crises inflamatórias ou patogenicas acontecem, entao evitar esses cenarios é aconselhavel. Na parte dois do artigo descreveremos alguns aspectos de como identificar os sintomas inflamatórios e algumas evidencias de como eles podem ser remediados e/ou prevenidos. A questao da ingestao dos carboidratos diaria e’ dependente do perfil de saude e de atividade fisica de cada pessoa. Mais detalhes sobre isso tambem sera incluído na parte dois do artigo. Sobre sua questao tres, em geral isso é constatável sim. A relação existe entre gluten e SBID, e é mencionada em varios estudos. Existe evidencia que, em geral, como você diz: “a digestao do gluten” (originalmente do Latin: “Glutin”, ou “cola”) e suas proteinas gliadinas e glutenina, nao é um processo simples para o corpo executar. Essas proteinas tem o proposito original de nutrir o embriao do grão para que ele possa germinar. Sendo assim um principio comum dentre vários outros anti-nutrientes contidos nos graos, pois a força nata que eles possuem de querer se transforma numa planta, que interrompemos com a colheita, processamento e consumo, nao é para ser substimada. Portanto, muito embora um grao possa ter sido, germinado, fermentado, transformado em farinha, ainda existe nele esse proposito basico evolutivo que é de transformar-se numa planta. Espero que as respostas tenham ajudado.

08/04/2015 19:35:26


Fico muito bem impressionada com o conjunto de conhecimentos que o site apresenta e a conexão estreita com a realidade do dia. A interação dos assuntos, das abordagens sobre eles e até das formas de escrever é muito interessante também. Também acredito em alimento como um remédio poderoso, fonte de vitalidade. Parabéns, esperando pela continuação do texto da Laura e pelas sugestões de nutrição e delicias, que deverão vir a seguir, por que além de tudo, comer bem é muito bom!

31/03/2015 16:17:38


Oi laura! Gostei muito do texto e a clareza com que descreveu as partes do intestino e a importancia das respectivas floras bacterianas. Estou curiosa por saber mais, as causas do desequilibrio da flora intestinal, o efeito hormonal homeostatico e a alteração na produção de serotonina. Muito bom tambem a elucidação sobre a relação do sistema nervoso entérico - nervo vago - cérebro. 3 perguntas quando puderes responder: Como uma pessoa que já retirou o apêndice pode ajudar o organismo a suprir a função deste orgão? Qual é a ingestão diária adequada de carboidratos para manter um ph saudavel? E a relação da ingestão do gluten com SBID? Obrigada Laura!!!

31/03/2015 13:15:04

maria carmen bahia

Muito intessante o artigo, em linguagem clara e precisa. Achei muito legal saber como esse orgão está ligado a outras partes como o cérebro, enfim,sua conexão com outros aspectos do corpo.

29/03/2015 21:01:23


Muito bom o texto e o assunto escolhido! Ansiosa no aguardo da segunda parte pra saber um poquinho mais! ;)

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