Biomedical subjects

J F Reith

Publications and source records attributed to J F Reith.

At least 19 recordsLinked to original sources

PubMed1981

Determination of calcium intake of help of atomic absorption spectrophotometry.

In a dietary survey, large numbers of a wide variety of food samples have to be analyzed. The atomic absorption spectroscopy (AAS), with its simplicity, accuracy and rapidity, suggests itself for determination of many elements in such a case. In this investigation, calcium determination by AAS is reviewed. Analytical parameters, interferences and their control are studied. Food samples are dry ashed and treated so as to eliminate silicates. Most serious interference comes from phosphates and is successfully controlled by addition of lanthanum. Calcium is determined in the range 2-10 ppm with a sensitivity of 0.1 ppm. Single food samples and samples representing food mixtures are analyzed, and calcium intake of different population groups is computed. In most cases, results compare favourably well with those obtained from food composition tables. Calcium intake in the Netherlands both of the average per caput and of chosen population groups is found to cover the recommendations except for infants. Differences do exist between intakes of different groups and in different seasons.

Age Factors↗

PubMed1976

On the phosphate problem.

Acceptable Daily Intakes (ADI) of phosphorus set by the FAO/WHO Committee are fixed at 70 and 30 mg P/kg body weight, for conditional (C) (where Ca intake is high) and unconditional (UC) intake, respectively. In light of the increasing application of phosphates in food industries, the question arises whether these permissible limits are not exceeded by certain population group (s). The groups studied in this paper included: children, nursing mothers, farmers and town's men, and students. Average per capita and excessive consumptions were also estimated. Spectrometric techniques were used for analysis of both phosphorus and calcium. Unless for few items, Dutch Food Composition Tables were found accurate enough to use for calculations. Intake of P was found to exceed the UC ADI in most groups, and even the C ADI in infants (1 year). Food intakes of all groups resulted in P/Ca ratios higher than the recommended dietary allowances of U.S.A. Milk and dairy products proved important items for lowering this ratio in the Dutch diet. It is concluded that more investigation for the toxicological evaluation of phosphates is required, and a more clear ADI need be set. Food laws must take into account addition of phosphates during food processing. Estimation of P intake should be carried out particularly in countries of low calcium intake or high consumption of phosphate-treated or phosphate-rich foods (e.g. wholemeal bread and nut consumption in Iran).

Calcium↗

PubMed1972