Digestion and health
In nutritional therapy, we prioritize supporting the foundations of good health: diet, digestion, blood sugar regulation, mineral balance, and hydration because they support everything else - endocrine, immune, cardiovascular, detoxification and nervous systems, for example. Digestion, in particular, is a critical foundation that affects every aspect of our body by absorbing the nutrients from the food we eat. These nutrients are what keeps us healthy!
Let’s take a closer look at some examples.
Endocrine system:
The digestive system plays a critical role in supporting the endocrine system by breaking down food into its component nutrients, which are then used to build hormones.
For example, thyroid hormones are made up of iodine and tyrosine. That means we need foods containing iodine and high-quality proteins (Biga, et al).
We also need protein for amine hormones, as well as for our peptide and protein hormones, which are just chains of amino acids.
But protein digestion starts in a very acidic stomach, so we need to have proper pH in there. If we can't break the protein down into individual amino acids, we can't make thyroid, peptide or amine hormones, no matter how good our diet is.
Steroid hormones are derived from cholesterol, which is a type of fat, so we need to consume high-quality and not-too-lean animal foods.
Eicosanoid hormones, which are also derived from fatty acids, require healthy, high-quality dietary fats as well from both animal and plant sources.
Fatty acids require good gallbladder function to be broken down to be able to be absorbed in the small intestine and turned into eicosanoid hormones so we can manage inflammation properly. Low fat diets can negatively affect your gallbladder function.
So you can see how optimal digestion is essential for the proper functioning of the endocrine system, as it ensures that the body has a steady supply of nutrients for hormone synthesis. Any disruptions in digestion, such as poor gallbladder function and suboptimal stomach acidity, as well as an imbalanced microbiome, which can affect how we absorb nutrients in the small intestine, can have negative effects on endocrine function.
Immune system:
The digestive tract plays a significant role in the body's defense against pathogens. A healthy digestive tract is essential for preventing the proliferation of harmful microorganisms, such as viruses, bacteria, and fungi. The digestive tract contains several barriers that prevent these pathogens from entering the bloodstream and causing infections. For example, the acidic environment of the stomach helps to kill off harmful bacteria, while the lining of the intestine is coated with mucus that traps and eliminates pathogens.
The large intestine is home to a vast array of microorganisms, collectively known as the gut microbiota. These microorganisms play an important role in maintaining the balance between the immune system and the gut environment. A healthy gut microbiota can stimulate the immune system to produce antibodies and immune cells that can fight off infections.
Nutrients obtained through digestion are essential for building and maintaining a strong immune system, as they provide the energy and resources that immune cells need to function properly. For example, certain nutrients such as vitamin C, vitamin D, and zinc are essential for the development and function of immune cells.
On the other hand, poor digestion can lead to nutrient deficiencies, which can compromise immune function.
Some foods are more resistant to digestion than others. Gluten, for instance, contains proteins that are notoriously difficult to digest and this will irritate the gut lining, causing the tight junctions in the mucosal epithelium to become more permeable, causing inflammation and triggering the immune system. A healthy mucosal lining should produce lots of secretory IgA, which will bind with the antigens and prevent them from being absorbed. A healthy microbiome living within the mucus produced by the mucosal epithelium should protect the integrity of the tight cellular junctions. This is a huge part of our gut’s barrier defenses against invaders.
Chewing your food well matters, too! If a food is not properly broken down and in the scenario described above, it is capable of becoming an allergen or an antigen. Excessive triggering of the immune system can result in auto-immunity.
Cardiovascular system:
Good protein digestion (think stomach pH first and foremost!) is critical to make amino acids needed by the heart, such as taurine and carnitine. Proper stomach pH is also necessary to absorb calcium, digest the B vitamins, and absorb the amino acids. Furthermore, proper bowel flora is needed to produce vitamins B1, B2, B12, and K2.
Since fatty acids are the preferred fuel for the heart muscle, proper digestion and gallbladder function are essential to digest fats effectively.
In addition, the digestive system regulates blood sugar levels, which, when combined with insulin resistance, is a significant precursor to cardiovascular disease. After a meal, pancreas releases insulin, a hormone that signals the body's cells to absorb glucose from the bloodstream. This process helps maintain normal blood sugar levels and prevent the development of conditions such as diabetes.
But the pathological state of being insulin resistant (or chronically overproducing insulin) damages blood vessels, promotes the formation of atherosclerotic plaque, alters nutrient delivery to the heart, and impairs the regulation of nutrient metabolism in the heart. (Ormazabal, et al, 2018)
Detoxification:
As we have seen, the digestive system is responsible for breaking down food into nutrients that the body can use for energy, growth, and repair, while also eliminating waste products and toxins from the body. It scans the food for invaders, filters food and intestinal bacteria, and eliminates toxins and other unsuitable substances from the body.
The liver is the primary organ responsible for detoxification. It receives nutrients and other substances from the digestive system, which it then metabolizes and eliminates from the body.
Optimal digestion ensures that the liver receives the nutrients it needs to carry out its detoxification functions effectively. For example, certain nutrients such as B vitamins, vitamin C, and specific amino acids, such as methionine, are essential for the production of enzymes that aid in detoxification.
After the liver neutralizes toxins in preparation for elimination, they get passed into the gallbladder via bile and are eventually excreted in the feces. Poor gallbladder function and fat digestion clogs the lymph and, therefore, the liver.
The digestive tract contains several barriers that prevent harmful substances from entering the bloodstream and causing damage to the body. For example, the lining of the intestine is coated with mucus that traps and eliminates toxins, while beneficial bacteria in the gut can help to break down harmful substances and prevent their absorption. The intestines also contain probiotic bacteria that assist in the detoxification of many substances.
On the other hand, poor digestion can lead to the accumulation of toxins in the body, which can have negative effects on health. For example, a sluggish digestive system and bile stasis can lead to constipation, which can cause the buildup and reabsorption of waste products and toxins in the colon. An imbalance in the intestinal flora can injure the intestinal walls, allowing undigested food and other contaminants to leak into the bloodstream. This can contribute to candida overgrowth and autoimmune responses.
Overall, optimal digestion is essential for supporting the body's natural detoxification processes, as it provides the nutrients it needs to function effectively and helps to prevent the accumulation of harmful substances in the body. (Phang-Lyn & Llerena, 2022)
Nervous system:
The gut and brain are connected through a complex network of nerves, hormones, and signaling molecules called the gut-brain axis. This axis enables communication in both directions, meaning that changes in the gut can affect the brain, and vice versa.
Maintaining good gut health is crucial for the proper functioning of the nervous system because the gut is home to the microbiota, which plays a crucial role in regulating the immune system, producing neurotransmitters, and modulating the gut-brain axis.
Studies have demonstrated that a healthy gut microbiota is necessary for the proper functioning of the nervous system (Ma, et al., 2019). Certain species of gut bacteria have been found to produce neurotransmitters such as serotonin and dopamine, which are essential for mood regulation, cognitive function, and the regulation of the stress response.
Conversely, disruptions in the gut microbiota, such as those caused by a poor diet, stress, or antibiotic use, have been linked to various neurological disorders, including anxiety, depression, and autism.
The gut-brain connection operates through several different mechanisms, with one of the most significant being the vagus nerve, a large nerve that runs from the brainstem to the gut. The vagus nerve carries signals between the gut and the brain, allowing the two organs to communicate and coordinate their activities.
Another crucial mechanism is the production of neurotransmitters and hormones in the gut. For instance, the gut generates hormones such as ghrelin, which control our hunger, as well as neurotransmitters such as serotonin and gamma-aminobutyric acid (GABA), which are involved in mood regulation and stress response.
In conclusion, maintaining a healthy gut is crucial for the proper functioning of the nervous system, and the gut-brain axis is a crucial area of research with the potential to yield new treatments for various neurological and psychiatric disorders.
References:
Biga, Lindsay M. et al. Anatomy & Physiology. Chapter 17.2, Hormones., Retrieved from: https://open.oregonstate.education/aandp/chapter/17-2-hormones/
Ormazabal V. et al., (2018). Association between insulin resistance and the development of cardiovascular disease. Retrieved from: https://cardiab.biomedcentral.com/articles/10.1186/s12933-018-0762-4
Phang-Lyn, S., Llerena V.A. (2022) Biochemistry, biotransformation. Retrieved from: https://www.ncbi.nlm.nih.gov/books/NBK544353/
Ma, Q. et al., (2019). Impact of microbiota on central nervous system and neurological diseases: the gut-brain axis. Journal of Neuroinflammation. Retrieved from: https://jneuroinflammation.biomedcentral.com/articles/10.1186/s12974-019-1434-3