American Journal of Clinical Nutrition, Vol 11, 368-376, Copyright © 1962 by The American Society for Clinical Nutrition, Inc.

Variations in the Nutritive Values of Foods

¹ From the Department of Biochemistry and Nutrition, School of Medicine, University of Puerto Rico, San Juan, Puerto Rico

In conclusion, it can be stated that the variations observed in the nutritive value of foods are the result of two radically different types of modifications—those due to genetic factors, and those due to environmental and processing agencies. Therefore, it is possible by careful and painstaking selection to establish pure lines and check heredity as a cause of variations.

On the other hand, the soil as a source of mineral elements for plants and indirectly for animals, can be conditioned and modified to a certain extent only as it is affected by weather factors which, so far, we are incapable of regulating.

Harvesting, handling and processing, including storage, are operations which, if not carefully conducted, can introduce large variations in the nutritive values of foods. They are, however, more amenable to control by the application of scientific principles and practices than are the environmental factors.

The soil-weather complex, therefore, remains the most formidable problem when variations in the nutritive values of foods are considered. This problem will remain unsolved until we learn how to control climatic conditions.