Valda W. Bunker

Nitrogen balance studies in apparently healthy elderly people and those who are housebound.

Metabolic balance studies (5 d) for nitrogen were carried out in twenty-four apparently healthy elderly people (age 69.7-85.6 years) and a heterogeneous group of twenty housebound elderly people (age 69.9-85.1 years) with chronic diseases. During the study all subjects ate self-selected diets, lived in their own homes and continued their normal daily activities. Seven of the housebound received meals-on-wheels 5 d/week. Healthy men and women had mean metabolizable energy intakes of 8.7 and 6.6 MJ/d respectively compared with 6.3 and 4.8 MJ/d in the housebound. The average energy content of the meals-on-wheels as delivered was 2.4 MJ per meal, of which 2.1 MJ were consumed. The healthy men and women had average daily protein intakes of 69.4 and 59.7 g respectively compared with 46.3 and 39.1 g in the housebound. Meals-on-wheels as supplied provided 19.4 g protein per meal, of which 16.2 g were consumed. Healthy subjects were in equilibrium for N balance (0 mmol/d) with a daily intake of 733 mmol, which was equivalent to 11.04 mmol N (0.97 g mixed protein)/kg body-weight per d. Housebound individuals were in negative N balance (-95 mmol/d) with an intake of 475 mmol/d, corresponding to 7.59 mmol N (0.67 g mixed protein)/kg body-weight per d. We were unable to determine in the present study whether the negative N balance observed in the housebound people was due to the relatively low N intake or the underlying disease condition.

Energy, protein, zinc and copper status of twenty-one elderly inpatients: analysed dietary intake and biochemical indices

1. Duplicate diet analysis for energy, protein, zinc and copper with estimates of biochemical status for Zn and Cu were undertaken in twenty-one elderly long-stay inpatients (mean age 82 (range 63-89) years) consuming their customary hospital diet and in a stable medical condition. Fourteen patients had a long-standing and significant healing problem, either a leg ulcer or pressure sore. 2. Mean daily intakes of energy (5.2 MJ), protein (45 g), Zn (85 mumol) and Cu (14 mumol) were low in comparison with both official recommendations and levels of intake at which metabolic equilibrium was observed in healthy elderly people studied by the same methods (Bunker et al. 1984a). 3. Mean leucocyte Zn (9 pmol/10(6) cells) and Cu (7.5 pmol/10(6) cells) were low in comparison with results from healthy elderly people (Bunker et al. 1984a), implying suboptimal status for these elements. Those patients with healing problems tended to have the lower values within the range. 4. Recommendations are made with respect to improving nutritional status in this disadvantaged group of people.

A system to minimise trace metal contamination of biological material during homogenisation.

A major problem in the analysis of trace elements in biological samples is the prevention of contamination during sample preparation. This is particularly severe for the analysis of food and faeces which have to be rendered homogenous before sampling for analysis. Such homogenisation is usually achieved using laboratory blenders and mixers, which are generally constructed from metal components and therefore could give rise to trace element contamination of the material. Previously used techniques for minimising contamination during homogenisation have been to coat the metal surfaces with plastic! or nickel-gold plating.P We have modified a commercially available blender and a laboratory mixer such that all the metal parts in contact with the samples are made from titanium or coated with plastic. This procedure has reduced the contamination of homogenised diets and faeces with trace elements to levels that are acceptable for studies of these elements in human nutrition. base plate, knurled nuts, disintegrating head, and pump head were manufactured using pure titanium, kindly donated by Imperial Metal Industries (Kynoch) Ltd, Birmingham, UK. A PTFE bearing was made to replace the original. All replacement parts described above were made by R Fautley, who will provide details of construction on request.