Objective: Lactose absence implies a decrease in calcium absorption. If not absorbed, calcium soaps can be produced with the intestinal fatty acids. Absorption and retention of total fat, individual fatty acids, calcium, magnesium and phosphate have been compared between two groups of children, one fed with lactose free formula and higher levels of calcium (FSL) and the other with standard starting formula (FI). None of them had additional arachidonic or docosahexaenoic acids.
Patients and methods: A randomized prospective study was made on 19 term newborn babies by means of metabolic balance measurement during an 8 day period (four days of a stabilization period on the formula, 3 days of the balance period and the final day for feces collection). Both groups were selected following the same criteria for gestational age, balance age, and weight and length at both time periods. Aliquos from the formula were collected daily, as well as all feces and urine during the balance period. Calcium and magnesium quantification of the corresponding ashed products was performed by means of atomic absorption, while Pi was with a colorimetric assay. Total fat was extracted by organic solvents and quantified by gravimetry. Lipid phase fatty acids were methylated, extracted and quantified by means of gas chromatography with a detector of flame ionization.
Results: Total fat content and the percentages of each fatty acid did not differ, only calcium concentration in FSL was slightly higher (64.9 +/- 6.9 vs 58.9 +/- 7.0 mg/100 g). No differences were found between groups in relation to ingestion, excretion and retention. The percentages of calcium and total fat retention, however, were slightly superior in the FI in relation to the FSL group. Ca: 68 +/- 22 mg/kg/d, 49 +/- 14% vs 56 +/- 23 mg/kg/d, 48 +/- 17% and total fat: 6.6 +/- 1.2 g/kg/d, 92 +/- 8% vs 6.8 +/- 1.5 g/kg/d, 90 +/- 9%. Absorption of MC fatty acids was 99% for C8. Linoleic and alfalinolenic acid showed an absorption of around 90% despite the big differences in their intake (10/1). Net retention of linoleic acid was 933 +/- 168 mg/kg/d (FI) and 963 +/- 190 mg/kg/d (FSL) and the amount of alpha-linolenic acid was 95 +/- 16 (FI) and 100 +/- 22 mg/kg/d (FSL). No correlation could be found between the amount of excreted calcium and the total amount of fat in feces or with any of the fatty acids studied. This was true for each group studied separately or when considered as a single group.
Conclusions: The absorptive pattern of fatty acids in full term babies, when quantified did not show any conspicous alterations in relation to the accepted values of other ages. The absence of lactose (FSL) in a formula does not make any change in the absorption of total fat and the individual fatty acids when compared to lactose containing formula (FI), when these are present in the same proportions. Supplemented calcium in the formula without lactose could compensate for its lower absorbtion. The absorptive pattern of fatty acid in full term babies did not show any conspicuos alterations in relationship to the accepted values of other ages.