| By Dr. Beth Gruber
A Quick Review
Let's have a quick review of where we are in our study of carbohydrates. From our previous discussions, you now understand that everything we eat is one, or a combination of, five substances: carbohydrate, protein, fat, vitamin, or mineral. You now know that ‘carbohydrate’ means 'one of many different combinations of carbon, hydrogen, and oxygen, whose various sections join and break apart by taking on, or releasing water,' and that this is done in a process called 'hydrolysis'.
We have discussed that sugars and starches are the major categories of carbohydrates that we are concerned with, and that starches are really just complex forms of sugar. You now know not to be led down the primrose path with talk of high or low glycemic index, since complex sugars break down into simple sugars. And, we discussed that foods that are full of sugar can be called 'sugar-free' if they don't contain table sugar (sucrose).
In the last article, we discussed fiber, those carbohydrates that cannot be digested, and we started our discussion about how the body digests carbohydrates with the help of enzymes. Now we are ready for a further look into enzymes and what happens to carbohydrates once they enter the digestion.
What Is Digestion?
Those of us who are concerned with limiting nutrients in order to drop pounds often forget that the body is in the business of taking in food and using it to its own best advantage. We must remember that the body wants to take in the nutrients in food. Very few foods, however, are ready for use by the body in the state in which we eat them. Water, a few of the simple sugars, vitamins, and some minerals make up almost the entire list of such substances. Everything else must be digested, that is, converted by the body into products suitable for absorption and utilization. We have taste buds so we will enjoy the food, and luckily, the mechanisms for getting the foods to a usable condition has been made easy for us. Digestion is the way.
What Are Enzymes?
The prime movers in the breakdown of foods are called enzymes. In fact, it has been said that enzymes are the mediators of most, if not all, life processes. Enzymes are protein substances that are normally produced by the body to cause or allow specific actions.
The enzymes for food digestion are often named for the food they act upon with the use of the letters ‘-ase’ added to the end of the word. Thus, we produce 'sucrase' to act on sucrose, 'lipase' to act on fat (‘lipo’ = fat), and 'amylase' to act on starch (‘amylose’ = starch). Often the source of the enzyme is part of the name too, such as 'pancreatic lipase,' the fat-digesting enzyme that is produced in the pancreas. Sometimes the letters '-lytic' or '-lysis' are used with the name of the enzyme to signify a breaking apart. (Remember 'hydrolysis', breaking down in the presence of water?) Thus, we have the 'gastric proteolytic enzyme,' pepsin, which is produced in the stomach (‘gastric’ = stomach), and breaks down protein (‘proteo’ = protein).
Enzymes are partially destroyed while performing their digestive function, so the body must continually make more. Any decrease or increase in enzyme production or enzyme activity results in malfunctions and disease. If the enzyme to break down a particular food type is not produced by a person's body, that person is said to be 'intolerant' of that particular food.
People who do not manufacture 'lactase,' for example, are said to be 'lactose intolerant,' and they cannot break down foods containing the milk sugar, lactose. (As unpleasant as lactose intolerance is for the sufferer, it is a relatively mild result of enzymatic problems. Some enzyme deficiencies can cause very serious diseases and mental retardation.)
How Do Enzymes Aid In Digestion?
As a rule, digestion is aided by cooking because the heat causes some foods to begin breaking down. This is especially true of starch, the connective tissue in meat, and other protein foods such as eggs. But most digestion takes place once the food has been eaten.
Enzymes are produced in various parts of the digestive system, and the digestion of carbohydrates begins right in the mouth with the saliva. Saliva contains, and mixes into the food, the amylase enzyme (specifically, ptyalin), which is used for the digestion of starches. The chewing process is also important because it breaks the food into smaller pieces, thereby producing more surfaces for the enzyme actions to take place upon.
In the stomach, digestion continues under the action of hydrochloric acid and enzymes for the break down of protein, sugars, and fats. Hydrochloric acid is necessary, and digestion is harmed by taking antacids. The further digestion of carbohydrates, and some digestion of fats, takes place both in the stomach and beyond the stomach, in the small intestine (the upper part of the bowel). We will talk more about the digestion of protein and fats as we go along, but for now, we are still focusing on carbohydrates.
By the time the food has reached the end of the small intestine, all the usable carbohydrates have been broken down into simple sugars, and the body can begin to absorb and use them. This brings us to the next chapter in our fascinating story: What happens when sugars are absorbed into the body? That is where we will begin when we get together again.
I hope you'll be here with me.
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Dr. Gruber is a graduate of the Southern California University of Health Sciences, and has been in private chiropractic practice in Long Beach, California since 1964. She also received a Bachelor's Degree and a Master's Degree from California State University at Long Beach. She has written on health-related subjects for over 30 years, for several different publications. She lives in Southern California with her husband of 33 years. Both she and her husband follow and live the low carb lifestyle, full time.
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