Wednesday, May 31, 2017
Wisdom Wednesday: Food Sensitivity Series
There appears to be a lot of confusion and misconception about food sensitivities. For the next several weeks the Wisdom Wednesday blogs will cover the most common reactive foods. In order they are wheat, dairy, soy, corn and the nightshades.
In general, any food sensitivity is the result of a trigger mechanism in the GALT (gut associated lymphoid tissue) that lines the digestive tract.
The GALT is a component of the mucosa associated lymphoid tissue (MALT). It lays throughout the intestine and is about 300 square meters in size. This large surface area is achieved by finger-like projections (villi) creating folds in the lining. A single layer of epithelial cells covers the GALT separating it from the lumen of the intestine and its contents. The epithelial cells are covered in mucus to protect them from the harsh environment of the digestive tract.
The epithelial cells are constantly being replaced with a complete turnover every 24-36 hours. That’s by far the fastest cell turnover of any tissue in the human body. Inflammation, disease, and even nutritional deficiencies can reduce the replication rate resulting in gaps in the epithelial cell layer. This is the origin of “leaky gut” in which partially digested foods, bacteria, viral particles or other irritants can enter the blood stream to trigger an immune response.
The GALT is constantly analyzing the contents of the gut. Dendrites (a crane-like immune cell) can actually reach into the lumen to test a potential foreign object. On occasion, they will actually carry the foreign object back into the GALT for further evaluation.
The information gleaned by the GALT then stimulates the thymus. The thymus in turn produces either a Th1 cell or a Th2 cell. If the immune system identifies the foreign body as “living”, then Th1 cells are produced. This is the normal response to a virus or bacteria. However, if the foreign body is deemed “non-living”, like gluten or lactose, then Th2 cells are produced. The total number of Th cells doesn’t really fluctuate much, just the ratio of Th1:Th2. So patients will have a high ratio of Th1 with infection and a high ratio of Th2 with allergy or food sensitivity.
Food sensitivities, the focus of this series, are reactions to either protein or carbohydrate. Although fat can be an irritant to the gut and feed unfriendly bacteria in the colon, the immune system does not react to the presence of fat.
Protein is comprised of chains of amino acids. Under normal circumstances only single amino acids are transported across the epithelial lining of the gut. However, if the gut lining is compromised, then short chains of amino acids can “leak” through the lining. As little as five amino acids linked together will create an immune response.
Carbohydrates are formed from various sugars. Lactose, the sugar found in milk is a disaccharide, meaning it is two sugars linked together – one molecule of glucose and one of galactose. Single sugars (monosaccharides) are normally the only form of sugar transported across the gut. Disaccharides will cause an immune response, just like five linked amino acids.
The Bottom Line:
food sensitivities arise from incomplete digestion, leaky gut and an immune response from the GALT and thymus.
Next week, I will cover wheat, the most common food sensitivity in the world today.