Quantitative and qualitative evaluations of protein intake in a geriatric subpopulations from a southern Swedish...

The daily intake of protein and the amino acid content of food samples collected in association with a dietary survey of male and female Swedish pensioners, were determined. Duplicate portions of 1-day, mixed food samples were collected. The samples were homogenized and the fat was extracted before lyophilization. Protein content was determined by a modified Kjeldahl method. Cysteine and methionine were determined by ion-exchange chromatography after performic acid oxidation follow by acid hydrolysis, whereas tryptophan was determined by a spectrofluorometric method. All other amino acids were analyzed by gas-liquid chromatography. Median protein intake was 0.69 g per person per kilograms of body weight per day for the male pensioners and 0.67 g per person per kilograms of body weight per day for the female pensioners and 0.67 g per person per kilograms of body weight per day for the female pensioners. The quality of protein consumed by the participants, determined by amino acid analysis, showed that lysine, threonine, and tryptophan were the limiting amino acids. The chemical score, when compared with the FAO reference protein, varied between 35 and 100 (mean = 77).