Food concerns often precede other google searches people make to solve digestive problems such as bloating, gas, or digestive discomfort. It’s a common concern I see in the clinic too, patients report, “I just have no idea what foods I’m eating cause these digestive problems.”
Often, the solution can lie within addressing the function of the organs of the digestive system—those same organs breaking the food down and absorbing the nutrients that eventually interact with the body.
To explain this within the clinic, I often frame the relationship between food and the digestive system as an equation missing a variable.
It’s start off as: FOOD = DIGESTIVE PROBLEMS
When most of the time it’s: FOOD/DIGESTIVE FUNCTION = DIGESTIVE PROBLEMS
That’s a significant variable that gets missed out. What do you think?
In this article, we’re going to look at the fundamentals of how the digestive system works and build an understanding of how things can go wrong, regardless of the food you might be eating—an essential preliminary step to take in solving any digestive problems.
Common frustrations from patients with a long history of IBS diagnoses from various specialists and practitioners is that they don’t have a clear insight into exactly how it happened and, worse still, a lack of precise tools to help get long-term relief of the symptoms. A quick teaser, SIBO may be the breakthrough that clears up this mystery of IBS and digestive problems for many people, including those people you know suffering today.
I’ve seen patients present with IBS diagnoses from their doctor and SIBO from their Dr Google consultation, often with some confusion about how they relate to each other. The answer is like the chicken and egg problem. One can cause the other, or vice versa. First, let’s deconstruct the nuance of both to understand better how they’re connected.
Food travels through the digestive system in a step-by-step fashion that relies on cues from its different components, similar to a train line.
The journey can also be referred to as a “north to south” type of system, a term popularized by Dr Datis Kharrazian; with the brain representing “north”, and the mouth, stomach, gall bladder, pancreas, small intestine each having a part to play with the journey “south” through the digestive process.
Understanding the processes in each of these organs, from the brain to the small intestine, can help you understand why you might be experiencing digestive problems after eating and how these functional issues can occur up to two to three hours after eating!
The vagus nerve helps the brain communicate with the digestive system creating the brain-gut axis.
You might have heard of the digestive system labelled as the “second brain.” This definition is largely down to the highly concentrated amounts of neurons that can, independently of the brain, affect motility (the journey your food takes from your plate to the toilet) and a host of other functions.
The vagus nerve is a critical mediator here, handling the bidirectional messages between the brain and the digestive system, making it the first component of the north to south principle. For example, when food enters the body via the mouth, it sends a host of interacting signals via the vagal nerve to the brain loaded with information covering, amongst other things, sensation and nutrition. [1]
Whilst our focus here is the journey of the food you eat travelling south, the ascending conversation that travels north up the vagal nerve from the digestive system to the brain plays an essential role and could be a part of how things go wrong. Correcting low vagal tone, as referred to in the literature, is often a goal in functional digestive disorders such as IBS and inflammatory bowel conditions (IBD). [2]
Deep breathing, meditation, and physical exercise, amongst other things, can all have a positive effect on this vagal tone, with preliminary research showing that probiotics may positively affect the brain via their activity on the vagal nerve. [3] This positive effect on the brain may also extend to mood and anxiety regulation and decrease cytokines, the chemicals in the body that can cause inflammation. [4]
Chewing your food makes a more significant difference to your body’s interaction with food than you think
The next station on the train line is the mouth, the first stop in mechanical digestion. Just like many people don’t go to the dentist as regularly as they should (is this you?), the role of the mouth in the digestive process can be one we take for granted.
Chewing and saliva are vital components of the digestive and immune processes when it comes to food. The mouth may also be the first place that we lose our “oral tolerance” to food. After years of seeing vegetable fibres in people’s digestive exams, it’s clear we all (including me) need to chew our food more, but why?
Chewing helps increase your meal’s surface area to volume, making it easier to digest and swallow. The more you chew your food, the better chance you can absorb the maximum amount of nutrients. Studies have shown that people who chew less consume more calories. The difference seems to be between 15 to 50 chews; the closer to 50 you get, the better it is. [5]
The mouth, more precisely the saliva, is the location of secretory IgA, one of the most critical first responders when it comes to your immune system.
Simply, secretory IgA helps protect the digestive lining, the lungs and the urinary tract from invaders that can cause irritation or infection. [6]
Whilst numerous factors influence how much secretory IgA is available in your saliva (stress can inhibit it, for example), the more you chew, the higher level of exposure there is to this vital part of the immune system to whatever you’re eating. Chewing also makes sure the antigens that might be tagging along for the ride get exposed simultaneously.
It sounds preposterous that chewing your food more may fix a lot of your long-standing digestive problems, but if you don’t try it, then how will you know if this is the easy solution that’s been eluding you?
The stomach holds the key to preparing the food you eat for absorption into the body
The next stop in mechanical digestion is the stomach. For most people, when thinking about their digestion, the stomach is the central component. Clinically, people point to where they think the stomach is when reporting on their digestive problems. The stomach is, without a doubt, a pillar of both the digestive and the immune systems.
The gastric juice created within the stomach comprises digestive enzymes, hydrochloric acid, and other substances, such as intrinsic factor (important for B12 absorption), that are essential for absorbing nutrients. Would you believe that about 3 to 4 litres of gastric juice are produced daily in the stomach?! [7]
Firstly, hydrochloric acid breaks down food due to its high acidity level. Secondly, the digestive enzymes deconstruct the protein whilst the musculature of the stomach acts as a cement mixer to churn the food together so that it can pass through the stomach and into the small intestine.
The level of acidity that the hydrochloric acid reaches plays a critical role in digestion and immune function.
The acidity of hydrochloric acid plays the role of barrier immunity by killing bacteria that it encounters in food and water. It’s important to note that if the pH of the gastric juice doesn’t reach a critical point (ideally a pH of 1.5 to 2), then the inactive enzymes released by the stomach lining have trouble activating and subsequently doing their job. [8] This acidity also stimulates motility, which helps move food to the different stations of digestion—something particularly pertinent for people experiencing constipation-like symptoms.
Medications such as Proton Pump Inhibitors (PPIs), Antacids and Non-Steroidal Anti-inflammatory drugs can cause changes in hydrochloric acid secretions and the process we discussed above, motility. A more important consideration in the case of long-term PPI use concerns poor absorption of calcium, vitamin B12, iron and magnesium. [9]
In a clinical setting, a large proportion of people have lower levels of hydrochloric acid originating from chronic, moderate exposure to stress.
This lowering of gastric acid production is a protective mechanism to mitigate the stressful situation and the action required to react and respond. [10] Thyroid conditions, such as hypothyroidism and Hashimoto’s disease, can also cause changes in gastric secretions. [11]
This connection between the brain and digestion is one of the critical points of interest when looking at our north to south treatment method. After going through how it works, is it easier to see how necessary the stomach and its actions are in both triggering cues in the small intestine, mechanically digesting food, deconstructing protein for absorption, and the vitamins and minerals absorbed via the stomach?
Often using Apple Cider Vinegar before meals or at least as a morning shot can be an excellent place to begin the process of correcting the hydrochloric acid. Supplementally, a popular beginning is a combination of Betaine HCL and Pepsin, one of the main digestive enzymes in the stomach.
Be careful if you suffer from a methane dominant small intestinal overgrowth (SIBO) or constipation dominant IBS, as betaine can sometimes aggravate these types of conditions.
The small intestine is where nutrients get off the train and absorb into the body
There are a few fun facts when it comes to the small intestine and its role in digestion. The first is a surprise to most of my patients in that the small intestine is the primary site of nutrient breakdown and absorption. Yes, that’s right, it’s not your stomach. The second fun fact is that the small intestine is the longest part of the digestion and can measure up to 15 feet long!
The small intestine comprises three parts. The duodenum receives the mechanically digested food from the stomach and bile from the liver to break down fats and pancreatic enzymes. The rest of the assimilation and absorption process occurs over the proceeding parts of the small intestine, the jejunum, which absorbs sugars, amino acids and fats and the ileum, which absorbs any of the nutrients not already assimilated earlier in the organ, in particular, Vitamin B12.
The small intestine has become a focus of research due to the potential of bacterial overgrowths in the ileum, the lower part of the small intestine.
A better understanding of the small intestine’s role in essential digestion makes it easier to appreciate how important it is to clear any obstacles to its ability to bring nutrients into the body from the food you eat.
Once again, though, this is where the north to south ideology becomes the most appropriate. The gall bladder and the pancreas rely on cues from the stomach’s acidity to release bile and pancreatic enzymes appropriately into the small intestine. So, if the correct level of acidity isn’t achieved in the stomach, this could immediately have a downstream effect on the effectiveness of the small intestine.
Significantly though, pH regulation of the pancreatic juice and the bile also affect the digestive process. Pancreatic pH plays an essential role in its anti-bacterial action as well. [12]
Let’s try and bring this together
At the beginning of this article, we touched on how often the function of digestion and the way it can break down food is overlooked when solving problems such as bloating, gas and digestive problems.
Whilst the bacterial environment in the large intestine also plays a different role in digestion, let’s keep our focus on our north to south train line, with the train stopping at the brain, mouth, stomach and small intestine.
How a breakdown in function can be the origin of bloating discomfort
Let’s use stress as a common trigger to explain how things can go wrong down the line. We already know that the brain can reduce gastric secretions in the stomach by simply sending a message. It does so in a protective fashion. But what about up the line with the mouth?
Yep, as soon as your brain perceives a threat in the environment that requires you to react and respond, the response initiated by your stress hormone, cortisol, inhibits the salivary glands (think about getting a dry mouth before that public speaking gig) and the pancreas’s ability to secrete enzymes.
Your whole mechanical digestive line gets diluted by the brain and its relationship to your environment. It’s no wonder that poorly digested food gets to the small intestine and ferments—the product of this fermentation, gas, bloating and discomfort. The small intestine never really has a chance because the mouth and stomach aren’t effectively covering their jobs properly.
Sure, if you have an overgrowth within the small intestine, it’s prudent to deal with it. Still, maybe first, it might be best to look at supplements that contain Betaine HCL, Pepsin, Ox Bile and some other pancreatic enzymes to support the function that may be letting you down in the first place. From there, you can assess whether the problem is your digestive system or the food.
Hope this helps.
References
[1] Food Forum; Food and Nutrition Board; Institute of Medicine. Relationships Among the Brain, the Digestive System, and Eating Behavior: Workshop Summary. Washington (DC): National Academies Press (US); 2015 Feb 27. 2, Interaction Between the Brain and the Digestive System. Available from: https://www.ncbi.nlm.nih.gov/books/NBK279994/
[2] Bonaz B, Sinniger V, Pellissier S. Vagal tone: effects on sensitivity, motility, and inflammation. Neurogastroenterol Motil. 2016;28(4):455-462. doi:10.1111/nmo.12817
[3] Hemarajata P, Versalovic J. Effects of probiotics on gut microbiota: mechanisms of intestinal immunomodulation and neuromodulation. Therap Adv Gastroenterol. 2013;6(1):39-51. doi:10.1177/1756283X12459294
[4] Breit S, Kupferberg A, Rogler G, Hasler G. Vagus Nerve as Modulator of the Brain-Gut Axis in Psychiatric and Inflammatory Disorders. Front Psychiatry. 2018;9:44. Published 2018 Mar 13. doi:10.3389/fpsyt.2018.00044
[5] Borvornparadorn M, Sapampai V, Champakerdsap C, Kurupakorn W, Sapwarobol S. Increased chewing reduces energy intake, but not postprandial glucose and insulin, in healthy weight and overweight young adults. Nutr Diet. 2019;76(1):89-94. doi:10.1111/1747-0080.12433
[6] Corthésy B. Multi-faceted functions of secretory IgA at mucosal surfaces. Front Immunol. 2013;4:185. Published 2013 Jul 12. doi:10.3389/fimmu.2013.00185
[7] InformedHealth.org [Internet]. Cologne, Germany: Institute for Quality and Efficiency in Health Care (IQWiG); 2006-. How does the stomach work? 2009 Dec 31 [Updated 2016 Aug 21]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK279304/
[8] Heda R, Toro F, Tombazzi CR. Physiology, Pepsin. [Updated 2021 May 9]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK537005/
[9] Ito T, Jensen RT. Association of long-term proton pump inhibitor therapy with bone fractures and effects on absorption of calcium, vitamin B12, iron, and magnesium. Curr Gastroenterol Rep. 2010;12(6):448-457. doi:10.1007/s11894-010-0141-0
[10] Esplugues JV, Barrachina MD, Beltrán B, Calatayud S, Whittle BJ, Moncada S. Inhibition of gastric acid secretion by stress: a protective reflex mediated by cerebral nitric oxide. Proc Natl Acad Sci U S A. 1996;93(25):14839-14844. doi:10.1073/pnas.93.25.14839
[11] Ebert EC. The thyroid and the gut. J Clin Gastroenterol. 2010;44(6):402-406. doi:10.1097/MCG.0b013e3181d6bc3e
[12] Melamed P, Melamed F. Chronic metabolic acidosis destroys pancreas. JOP. 2014;15(6):552-560. Published 2014 Nov 28. doi:10.6092/1590-8577/2854
