Theory about interrelationships between macromineral nutrients and growth rate during recovery from undernutrition

Uptake Kinetics and Absorption of Calcium in Apple Matrices

The purpose of this paper was to study the kinetics of calcium uptake of blanched and not blanched apple tissue during impregnation treatments under vacuum or/and at atmospheric pressure. The relative absorption of calcium in rats, regarding calcium carbonate as reference substance, was also analyzed as a first approach. Apple impregnation is conducted (with and without previous blanching in saturated vapor) in isotonic glucose aqueous solutions containing calcium gluconate and lactate. A 50 mm Hg vacuum pressure is applied for a time t1 (0—180 min) or atmospheric pressure is used for a process time t2 (0—7.5 h). Calcium uptake by apple tissue is influenced by system pressure, blanching, and impregnation time, reaching 500—4600 μg Ca/g according to process variables. Preliminary data of true calcium absorption ranges between 74 and 86% regarding calcium carbonate.

Influence of dietary calcium concentration on body size and bone composition in rats during recovery from malnutrition

OBJECTIVE

The purpose of our study was to assess the influence of different levels of calcium (Ca) in a diet containing 30% protein on the rehabilitated of the body size from protein-energy malnutrition (PEM) and to establish the optimal Ca/protein ratio for attaining a normal body composition.

METHODS

Weanling female Wistar rats were fed with protein-free diet up to a weight deficit of 20 +/- 1%. Then they were arranged in groups (TO) and fed diets with 30% protein and 0.0, 0.2, 0.4, 0.6, 0.9 or 1.2% Ca for 28 days (T28). Food and deionized water were given ad libitum. Body weight and length were recorded every 3 days. At T28, the animals were sacrificed to determine femur composition.

RESULTS

At T13, weight-for-age (W/A) was within the normal range for rats consuming > or = 0.6% Ca. At T28 all groups showed adequate W/A. Although length-for-age was adequate during rehabilitated period, rate of weight gain improved when Ca was > or = 0.6%. Femur length did not show significant difference between groups. Total femur Ca content and mg Ca/g of dry-weight tissue increased with increments in dietary Ca concentration and tended to plateau with 0.4% Ca. Ca/P ratio reached the highest value with 0.9% Ca.

CONCLUSIONS

Our findings indicate that at a dietary protein level of 30% the Ca/protein ratio is a limiting factor in attaining of normal body size; this is achievable when Ca concentration is 1.2% and the Ca/protein ratio is 0.04.