How Do Food Sensitivities Cause Symptoms?
Translation: Tiana Thich, HK BioTek Intern
The moment we put food in our mouth, the body has already started to react to it. Once it has entered the mouth and gone down the digestive tract, muscle activity in the stomach (physical digestion) and digestive enzymes (chemical digestion) break down large pieces of food into smaller pieces. The food is further broken down into simple molecules that can be absorbed into the bloodstream through the small intestines. These molecules can be used by the body as nutrients for sustaining bodily functions. When food is broken down into simple molecules that enter the bloodstream during digestion, this generally does not trigger an immune response.
When digestion is poor and there are not enough digestive enzymes, the body fails to quickly break down food into simple molecules necessary for absorption. The undigested macromolecules from the food are easily detected by the immune system which triggers an immune response. From this, we know that the immune system and intestines are connected in relation to food sensitivities.
Key Point 1: An Incompletely Damaged Intestinal Wall
In a healthy and strong intestinal wall, the top layer has an intact mucous membrane and the bottom layer contains intestinal cells. These cells, like bricks, are placed tightly against each other to form a wall; the mucous layer acts as a cement and fills in the gaps of this “wall” as well as coats the intestinal cell “bricks” to prevent the intestinal wall structure from being damaged. This complete intestinal mucous membrane can absorb nutrients and prevent foreign pathogens from invading.
When we encounter food and drugs that cause inflammation, intestinal imbalance, and/or intestinal infections, these damages cause the intestinal mucous to lose its integrity. This results in a loss of protection of the mucous membrane as well as a degradation in the tight structure of the intestinal cells. The gap between cells gradually disintegrates, making the intestines easily to penetrate. This is also referred to as “Leaky Gut Syndrome.” If there are food macromolecules, metabolic waste, or microbial toxins that are not completely digested in the intestines, they can enter blood circulation through the leaking intestinal wall, ultimately stimulating the immune system and potentially harming different organs and causing disease.
Key Point 2: Medium-Sized Immune Complexes
Our immune system is a powerful and intelligent system that not only recognizes foreign invaders (eg. viruses, bacteria, pathogens, allergens), but also “mobilizes forces” by releasing different compounds and cells into the body that act as defence mechanisms to protect the body.
When food debris enters the bloodstream, the immune system recognizes that it is a foreign material and releases antibody immunoglobulin G (IgG) against the food particle. IgG sticks to the food proteins and forms an immune complex called an antigen-antibody complex. Large complexes are cleared by macrophages that are responsible for patrolling the immune system; small complexes are excreted by glomerular (kidney) filtration; only medium sized complexes are able to stay in the body and flow through the circulatory system in the blood, depositing mucous membranes in different parts of the body and triggering local inflammation and damage. The effects of IgG antibodies and food allergens reacting takes time and various symptoms may not always be the same each time a reaction occurs.
Original excerpt is from the “Food Sensitivity Handbook”, 2018, Published by Hong Kong Preventive Medicine Association