Authors' Response to Commentary

Abstract

HE aging of the world's population due to (a) an increasing absolute number of elderly people and (b) an increased expectancy is well established (1). However, in what way pro­ portional healthy expectancy or perhaps, in other words, satisfactory quality of elderly life can be achieved, is still an important topic of multiple research. Because sensory proper­ ties of food are almost exclusive factors that remain important until the very last end (2), it is of great value to investigate the decline in taste and smell perception and its impact on food en­ joyment and total food intake. In her comment, Schiffman ad­ vocates a greater understanding of the impact of especially dif­ ferent types of taste and smell dysfunction on appetite in relation to developing and providing cost-effective health care systems for the elderly population. Different types of chemo­ sensory losses may have divergent effects on food intake and nutritional and health status. Schiffman argues that poor appetite is one cause of decreased energy intake. Consequently, effects on macro- and micronutri­ ent status, clinical nutritional parameters, and finally overall functioning are induced. We fully agree that this may be espe­ cially the case in critically ill patients and perhaps frail elders, who accordingly have a high risk of developing deficiencies. We, however, could not confirm this premise in our study (3). We were able to demonstrate a firm relationship between sen­ sory perception and appetite, but low scores on the appetite questionnaire were not significantly related to low dietary in­ take, adverse quality of dietary intake, or low body mass index (BMI) in our elderly population. A possible explanation may be that institutionalized elders eat because they understand that they simply have to eat. Another reason may be that they do not have to prepare the hot meal themselves anymore. If the hot meal is served, they may eat it because this older generation will not throw food away. Free-living elders with a poor appetite may be reluctant to prepare something regularly. It may just be too big an effort to overcome, and when there is no control by a central kitchen or staff, they may end up with only a sandwich. To our knowledge, there is no available uniform, validated approach of measuring appetite and feelings of hunger. The questionnaire developed for our study was the first attempt to expand the concept of appetite in a direction that is more than one question only. The internal validity was satisfactory, but still a lot of work has to be done with respect to the external va­ lidity. In our department, we are currently trying to validate the questionnaire with objective measures such as hormone levels, as leptine or cholecystokinine. In an earlier study by Schiffman and Warwick (4) it was ob­ served that flavor enhancement could improve palatability and intake. We, likewise, attempted to increase pleasantness and inB334 take of foods for elders by increasing sucrose concentrations in breakfast items in a trial published in 1996 (5). The preferred concentration of sucrose in these foods was determined initially in our laboratory. We were unfortunately not able to reproduce the results that were found by Schiffman. No increase in pleas­ antness occurred, whereas the increase in energy intake was at­ tributable to the increase of sucrose concentration. One of the explanations may be that results obtained from lab studies do not necessarily predict behavior in the free-living situation. From this point of view, it can be argued that more research should be done in elders' actual living situations, and taste­ and-spit methods should be left to the laboratory. Perhaps, as has been hypothesized by Schiffman, different types of chemosensory losses provoke different effects on food intake. In this light the results of Duffy and colleagues (6), that olfactory dysfunction correlates with a higher intake of fats and sweets, should be interpreted. The increased preference for sweeter, saltier, and fatter foods may indeed interfere with the current diet recommendations for elderly people and may influ­ ence the occurence of chronic diseases. The intake of high- fat foods, together with reduced physical activity and disuse of muscles, may induce adverse changes in body composition. On the other hand, in the very old in contrast to the younger old, a further decline in activity pattern and energy expenditure may consequently hamper appetite and total dietary intake. This, in tum, may cause (micro)nutrient deficiencies. It is assumed that this can happen not only to ill patients but also to a group of el­ ders who may be referred to as ''frail'' or at risk.