Northern Nut Growers Association, Report Of The Proceedings At The Tenth Annual Meeting. / Battle Creek, Michigan, December 9 and 10, 1919

by Unknown

Nuts have had a reputation for indigestibility that was wide spread, not only among people in general, but also among physicians and dieticians, and even Prof Jaffa's clear cut experiments failed to dispell this idea of indigestibility that had been empirically assigned to nuts. A few years ago, a rather extensive series of digestion experiments were inaugurated at Yale University in an effort to settle this question of the indigestibility of nuts and also to test out some of the commercial nut products to find what effect roasting, boiling, and other processes that nuts are subjected to, had to do with the digestibility. Through the courtesy of Dr Kellogg of Battle Creek, it was possible to follow up these experiments with a series here at Battle Creek. It is the result of these tests that I wish to speak of today. One word regarding the method which is the conventional one for such experiments. The amount of food eaten by the individual or animal is weighed at each meal and the composition determined by chemical analysis. The intestinal output is collected, weighed and analysed. From the difference in any substance such as protein in the food and the protein which appears in the body refuse, the amount digested and absorbed or utilized by the body is easily determined. For example; if 10gms. of nitrogen were eaten in the food and one gm appears in the feces, we say that the coefficient of digestibility of that nitrogen is 90%, that is 9 of the 10 gms. eaten were absorbed by the body. The average of a great many such tests on mixed diets has the following standard coefficient: protein 93%, fat 95%, and carbohydrates 98%.

Our digestion experiments show the following results: for protein digestion of nuts, almond 89%, peanut 84%, pine nut 89%, Eng. walnut, 83%, Brazil 88%, and coconut 88%. In all cases the carbohydrate coefficients are 98 or 99%, and in the case of the carbohydrate rich chestnut, normal digestion took place after the nut was heated so as to rupture the starch granules. In all of these cases the nut made up a substantial part of each meal and was eaten in large amounts. The experimental subject, experienced no digestive troubles or discomforture whatsoever except in the case of the English walnut, which evidently contains some irritating substance that causes diarrhea. Except for the pecan which gave rather low utilization, the protein of nuts was digested to a high degree that compares most favorably with our ordinary foodstuffs.

How then explain the undoubted discomforture that many people experience after eating nuts? I believe that the explanation rests on the fact that our common American way of eating nuts, is not the rational way. We would not consider topping off a heavy meal with eggs, meats or cereals or to eat these in large quantities between meals realizing that we are exposing ourselves to possible digestive discomfort. No more then, can we expect to so eat nuts which are even more concentrated or "heavy" than meat or eggs without occasional discomfort. Unpleasant results from so eating does not condemn the nuts as indigestible, rather it condemns our mode of using that nut. Further, we must recognize that the nut is a hard, compact substance and that unless completely masticated, is not readily penetrated by the digestive juices of the alimentary canal. This was very well brought out in our experiment with dogs. The dog bolts his food and where there were large fragments of the nut in the food, they appeared almost unchanged in the feces, while if the nut is ground fine before feeding, it was readily digested. Comparisons of nut butters and nut pastes with the whole nut also brought out this point. The completely commuted nut butters showed consistently higher degrees of digestion than the whole nut.

With the exception of the starch rich chestnut, the heating of the nut did not seem to effect the digestibility whether this heat was boiling, steaming or roasting. The raw nut apparently is as well digested as the heated products. No differences were found between nut butters whether the process involved steaming or roasting of the nut. I am not speaking of the enhancing of the flavor that heating may bring about, but only of the digestibility.

Dr. Longworthy and his co-workers in the Dept. of Agriculture have investigated in recent years the digestibility of many vegetable oils, among them nut oils, and have found as high a percent of utilization with these as with butter and our other common animal food fats.

I believe that we are fully justified in the conclusion that nuts and nut products, if rationally used in our diets, are as digestible and fully as valuable from a nutritional point of view as our other foodstuffs.

While we can now definitely speak of the high digestibility of nuts, it is necessary to consider other phases of the part played by foods in nutrition. The fact that a food after being taken into the body can be broken up by the digestive juices of the alimentary tract, and the products absorbed, as we have found, to be the case with the nuts, is not the end of the story of the function of that food.

About fifteen years ago, it was discovered that during the progress of digestion, the protein materials are reduced by the digestive juices of our stomachs and intestines to smaller chemical compounds, and that it is these smaller fragments of the protein molecule that are absorbed into the blood and are used to build up our muscles and tissues. These fragments or "building stones" as they have been fancifully called, are all of a distant class of chemical compounds known to chemists as amino acids. Eighteen of these acids have been found as the products of protein digestion.

We may conceive of our bodies as being continually supplied with a mass of these 18 building stones from which it selects the kind and number that it needs to repair the everyday wear and tear of the tissues and in the case of the growing child builds new structures.

Since the date of this important discovery regarding the fate of indigested protein, it has been found that with few exceptions, the body is not able to manufacture these amino acids or to change one kind into another, and must depend on the protein eaten, for a supply of the various kinds that go to make up the body protein. Further it has been found, that many of our commonly used food proteins do not contain all 18 of these amino acids components. In some foods one, two, and sometimes more are lacking, or if present are in very small amounts. If our diet contained only proteins of an inferior grade, we can picture our body requiring building stones of various kinds to maintain the structure of the body and unable to obtain them due to the poor quality of the food, protein. Nutritional failure would be the result. The proteins then must be of the right quality as well as present in the proper quantities, to prevent mal-nutrition. Bearing in mind these facts, it is necessary in studying a food such as our nuts, to determine the kind of protein the individual nut contains as well as to know whether or not it can be digested by the body.