American Journal of Clinical Nutrition, Vol 10, 231-239, Copyright © 1962 by The American Society for Clinical Nutrition, Inc.

The Nutritive Value of Human Diets as Affected by Extraction Rate of Flour and Its Supplementation with Soya Meal

¹ From the Laboratory of Nutrition, Department of Biochemistry, Hebrew University-Hadassah Medical School, Jerusalem, Israel

The effect of two kinds of bread, prepared from white (74 per cent extraction) and unsupplemented flour and from dark (87 per cent extraction) flour fortified with 5 per cent heat-processed soya meal, respectively, was studied in two groups of adolescents comprised of ninety-six and eighty-eight subjects, respectively. The subjects were pupils of two agricultural schools who were engaged in heavy physical work and consumed large amounts of bread in an otherwise adequate diet. The trial lasted eight months.

The white unsupplemented bread contained significantly less protein, lysine, iron, thiamine and nicotinic acid than the dark and fortified bread, but similar amounts of methionine and riboflavin. The diets of the subjects consuming the white unsupplemented bread supplied considerably less protein, iron, thiamine and nicotinic acid per 1,000 calories than that containing the dark and fortified bread.

At the end of the observation period there was no appreciable difference in increase in weight and height, change of skinfold thickness, general nutritional status and hematologic findings between the two groups which could be ascribed to the bread. Urine specimens were repeatedly examined during the trial period; excretion of riboflavin and N¹-methyl-nicotinamide per gram creatinine was similar in both groups; excretion of thiamine, however, was much higher in the subjects consuming the dark bread.

It was concluded that the failure to demonstrate an effect of the two kinds of bread despite the large difference in nutritive value was the result of an adequate intake of nutrients from other sources than bread.

Rat experiments are discussed showing that both extraction rate of flour and fortification with soya meal are of great importance in diets which are nutritionally inadequate.