Mealtime Physiology

Through the years the Spirit of prophecy gave much instruction on diet and health. Included among the many major details of dietary instruction are a number of smaller points which have been largely overlooked. I would like to review a few of these in the light of present-day concepts in physiology.

Some food faddists have advised the pro­longed chewing of food for health, but the Spirit of prophecy has prescribed a middle-of­the road course. While advising that food should be chewed thoroughly to be mixed with saliva,' it.has at the same time warned against the use of porridgelike food.'

The incorporation of dry food is advised in place of porridge.' The reasoning for this is clear. First, dry food excites a much greater flow of saliva than does liquid or soft food. Second, the taking of much soft food makes the digestive process much less efficient. Normally, solid food is mixed with saliva in the mouth and enters the stomach to form a bolus, or ball. As more food enters the stomach, it is deposited in the center of the mass. For _s some time the acid gastric juice comes in con­tact with only the exterior of this bolus of food, so that the alkaline saliva is permitted to act for thirty or forty minutes. Saliva was for­merly thought to have little digestive function, yet it is now considered to have definite value in starch digestion. If the swallowed food is too fine or liquid, it will not form a bolus, but is at once mixed with gastric juice, neutralizing the alkaline saliva and stopping its function.

As the food enters the stomach and stretches the walls, the muscle is stimulated to contract and carry the food to the pylorus, or lower end. Usually there are some coarse particles present in the food which will irritate the pyloric mu­cosa (the lining of the lower end of the stom­ach) and cause it (the pylorus) to contract, thus closing the exit. The food is held in the stomach and churned with the digestive juice secreted until it becomes smooth and liquid. As soon as it becomes smooth enough not to scratch the pyloric mucosa, it is carried out of the stomach into the small intestine. However, if the food has been chewed or cooked very fine, it will be carried out of the stomach at once, and gastric digestion will not have a chance to occur. This chemical digestion by the gastric juice is quite important.

Another point stressed in the writings of Mrs. White is that food should be appetizing and palatable,' and that our individual cares and responsibilities are to be laid aside at meal­time, and that we should take adequate time to eat and enjoy our food.'

When studying digestion with dogs, the Rus­sian-physiologist Pavlov showed that the amount of saliva produced by a dog was in direct proportion to how well the dog liked the food. Thus, whereas most dogs produced more saliva with meat, one dog that preferred bread to meat, always produced more saliva when given bread than when given meat. Later studies in­dicate that the same is true for stomach secre­tion. Carlson, in applying these studies to a man with an opening from the stomach to the outside of the body (gastric fistula), has proved that man secretes more digestive juice when fed favorite, tasty foods. Because digestion is in proportion to the amount of digestive juice se­creted, palatable food will be more completely digested and utilized than tasteless food, al­though it may have the same nutritive value.

The need for a pleasant, attractive environ­ment while eating has been shown in demon­strating that emotional stress will inhibit the function of the digestive tract. A low-grade an­noyance (such as a nagging wife) will usually, on the other hand, overstimulate the digestive tract, causing spasm with an inhibition of move­ment, but with an excessive production of hy­drochloric acid and other secretions. Prepara­tion of a tasty, nourishing diet served in pleasant surroundings is good physiology.

Mechanisms Which Inhibit Digestion

There are two possible mechanisms which might inhibit digestion. First, water would make the meal into a much thinner, smoother paste, and thus unduly hasten the emptying of the stomach, and markedly lessen the duration of both salivary and gastric digestion. Second, water is not absorbed in the stomach, but stim­ulates the production of hydrochloric acid there.' This might be an undesirable action if too much acid is produced. An additional factor against drinking liquid with meals is that the liquid is usually taken extremely hot or ex­tremely cold. Either extreme of heat or cold alters the normal motility of the digestive tract.⁷ Both tend to cause a spasm of the mus­cles of the intestine with a decreasing of mo­tion. Warm food, on the other hand, stimulates the digestive tract to more efficient action.

The instruction relative to the taking of large amounts of sugar has, until recently, been difficult to substantiate from the scientific point of view. When high concentrations of sugar are taken into the stomach, the sugar is held there until it can absorb enough water from the lining of the stomach to dilute it. Gastric movements are inhibited, and the stomach is distended by the large volume of sugar solution for hours be­fore the stomach slowly empties itself.' This will slow digestion as well as be a source of irritation. Also, this delaying of the emptying of the stomach will be still further increased if there is a large amount of fat associated with the sugar, as in some candies and pastries.

When carbohydrates or sugars are taken in excess of what can be readily absorbed, they are liable to undergo acid fermentation from the intestinal bacteria and produce acetic acid, lactic acid, butyric acid, succinic acid, carbon dioxide, alcohol, and hydrogen. When sugars are in excess in the diet or when there is poor digestive absorption, the large production of these acids may lead to irritation of the intes­tine, giving rise to symptoms such as diarrhea.

Until very recently there has been no direct proof that diet had anything to do with the production of diabetes mellitus (sugar diabe­tes). Dohan and Lukens⁹ have reported that the prolonged administration of sugar solution by intraperitoneal injection can produce dia­betes in normal cats. Although this is very sug­gestive, more work will be required to prove the exact relationship of large amounts of sugar to human disease. It is true that large amounts of sweets diminish the appetite for more bal­anced types of foods, and thus may lead to a nutritional deficiency. We must remember, however, that the testimony is against excessive use of sugar. Sugars are good in reasonable amounts, and need to be included in the diet in normal amounts."

In conclusion, I wish to point out the har­mony of these statements, given years ago, with the results of recent research. "To the really wise, scientific research opens vast fields of thought and information. The ways of God as revealed in the natural world and in His deal­ings with man, constitute a treasury from which every student in the school of Christ may draw." "