It is, of course, a fact - but it is only a part of the story. Unless you digest your food thoroughly and absorb the nutrients it contains, the benefits of a healthy diet will be lost.
The process of digestion begins before you put anything into your mouth. Think about what happens when you smell bread baking or a meal cooking... production of saliva increases. Apart from providing lubrication which enables you to swallow the food comfortably, saliva contains an enzyme - amylase - which breaks down carbohydrates into smaller molecules (known as polysaccharides), ready for their eventual conversion into glucose which is the fuel for your body and brain.
Try leaving a small piece of bread or plain cracker in your mouth until it begins to turn sweet, a sure sign it is breaking down. Different enzymes break down different forms of carbohydrate. For example lactase is needed for milk sugar (lactose); sucrase for sugar (sucrose); and maltase for malt (maltose), which is a double glucose. You do not start to digest protein or fat in your mouth.
Into the stomach
The next port of call in the digestive process is the stomach. Provided that you have adequate amounts of zinc, vitamin B6, and water, the parietal cells in the stomach wall will release hydrochloric acid which breaks protein foods down into amino acids. Acid production often declines as we get older, along with zinc status, and this may result in indigestion.
When you have indigestion, it is commonly assumed that this is because you have an excess of acid in the stomach, and the remedy is an antacid tablet. It is much more common for indigestion to be the result of low levels of stomach acid and, if this is the case, food can remain in the stomach for longer than necessary.
This can cause carbohydrates to ferment, producing gas and wind. Ironically, taking an antacid will provide some relief because, if stomach acid levels are already low and you take a remedy which lowers them still further, the body goes into emergency mode and produces hormones to stimulate acid production.
When the semi-digested food, known as chyme, is ready to leave the stomach it is in a very acid state. he liver manufactures bile, which contains alkaline salts and is stored and concentrated in the gall bladder. As the chyme passes the gall bladder on its way to the small intestine, bile is released. Bile emulsifies dietary fats and neutralises it ready for the addition of yet more enzymes - this time from the pancreas.
Enzymes
These include amylases to complete the digestion of carbohydrates; proteases and peptidases to complete protein digestion; and lipase to deal with the further breakdown of fats. Enzymes are found in fresh, unprocessed foods such as pineapple, papaya, avocado, banana, mango and sprouted seeds. In fact all raw foods contain some enzymes, so beginning a meal with something raw can be helpful.
Another important factor in the digestive process is water. Ideally this should mainly be drunk between meals - always at room temperature - with no more than two glasses with a meal.
Stress and digestion
Stress can play an important part in the digestion of food. When we are anxious, our bodies go into fight-or-flight mode by releasing adrenaline. As part of this mechanism, digestion slows or even stops completely, so it is better not to eat during a period of acute stress, or at least to have a very light meal.
03/06/2009