The Effect of Dietary Fat on Bone Calcification in the Growing Rat

Abstract

When cottonseed oil was included in a low-phosphorus, cereal-free rachitogenic ration for rats, calcification was decreased uniformly and in proportion to the amount of oil fed. This occurred whether the phosphorus of the ration was derived from phytic acid or from inorganic phosphates. It occurred on a diet with a high calcium/phosphorus ratio (6:1 and 3:1) and with a calcium/phosphorus ratio (1:1), and in the presence or absence of vitamin D. When fibrin, yeast and starch were substituted for egg white, rice bran concentrate, and glucose, respectively, the result was the same. The depressing action of cottonseed oil was in direct proportion to the amount of oil fed and paralleled the greater increments in weight produced by the fat rations as compared with the basal. However, the greater increments in weight were not due to an increase in either lipid-free soft tissues or lipid-free bone. When cottonseed oil was included in a diet “optimal” in phosphorus content, calcification was increased to a pronounced degree; when it was included in a diet containing more than “optimal” phosphorus it was likewise increased, though to a lesser degree. These effects were not negated by increases in the calcium/phosphorus ratios to a multiple of four.