Nutrition, energy metabolism and body composition in the frail elderly

Abstract

During aging a reduction of energy metabolism, energy intake and fat free mass can be seen. Some elderly patients experience more pronounced body weight loss that may lead to malnutrition states. The reasons for the unintentional body weight loss, that often accompanies chronic disease, are poorly understood. A combination of poor nutritional state and impaired physical function increases the risk for dependency in the daily living and further deterioration of health. Treatment needs to focus on the one hand of optimizing disease management and on the other on nutrition and physical function.

The aim of this thesis was to study several nutrition related parameters in frail elderly people and try to gain a deeper understanding of the mechanisms contributing to the nutritional problems in elderly patients, also focusing on treatment and follow-up. This was done by analyzing energy intake, body composition and energy metabolism in both nursing home patients and free-living, frail elderly individuals. Individualized nutritional treatments were applied and analyzed longitudinally. In the free-living group a three-month randomized controlled trial (RCT) with four arms was performed (nutritional treatment, physical training, both combined or control).

The results showed that energy intake was low (mean total intake below 1600 kcal/day, mean relative intake was 25-27 kcal/kg body weight/day). Individual nutritional intervention was difficult to manage and the effects difficult to analyze. Nutrient intake was low for about half of the nutrients analyzed. Nutrient density was also low, especially considering the low level of energy intake. Resting metabolic rate was related to fat free mass and was in accordance with previous studies. Mean body weight was stable. At an individual level there was no relation between changes in energy intake and body weight. In the RCT no evident treatment effects could be seen on any of the nutrition parameters analyzed. Of those in need of an increased energy intake, about one third managed to actually increase their intake, regardless of intervention. These individuals seemed to be protected against further weight loss.

As energy metabolism was normal and the physical activity low in these as in previous studies in the literature, future research needs to focus on the reasons for the poor energy and nutrient intake in the frail elderly. The relative contribution of diseases and/or injuries, effects of medication, low physical activity, social deprivation and mechanisms related to ageing are unclear and should be considered. There is a strong need for more treatment trials regarding malnutrition and frailty states. There is a large variety between individuals and therefore attention to the needs of the individual should be emphasized. The importance of preventing frailty will increase, as the number of very elderly people grows in society.