To really understand leaky gut you have to understand one principle;
The inside of your intestines is outside of your body.
Look at the picture above as an illustration of how this works. In the picture, there is a pipe passing through an old stone bridge. The stones in the bridge represent the cells in your body. The pipe represents your intestines. The contents of the pipe pass through the bridge but don't enter into the structure of the bridge.
Here's another example. Let's say your body is like a doughnut...by the way, if this rings true to you, you may want to clean up your diet a bit...but I digress. In this doughnut, the hole is your digestive tract. This nice young lady can poke her finger through the hole and never touch the doughnut. So the inside of the hole is actually outside of the doughnut. Make sense?
The intestines contain all kinds of things; some good, some bad. The cells lining the inside of the intestine form a barrier to prevent the bad things from entering the tissues of the body (poking the doughnut). In fact, when the intestine is healthy, the only way for anything to get past those cells lining its interior is to pass through the cells themselves via special receptors. So, your body likes glucose and fats and vitamins and amino acids and whatnot so there are specific receptors on the cell surfaces that bind with those things and draw them inside of the cells. They are then transferred into the blood stream and distributed to cells all over the body. All of the foods that we eat are digested by enzymes released into the intestinal contents. Starches are broken down into simple sugars, proteins are broken down into amino acids etc... The tissues of a healthy body have never seen gluten, starch, roast beef, strawberries, doughnuts or any other food. All of these things are broken down into their most essential elements prior to being permitted to pass into the cells.
Leaky Gut Syndrome
(Increased Intestinal Permeability)