Our study is one of the first to look at the impact of diet quality jointly with measured energy expenditure using doubly labeled water on mortality among the elderly. The caloric intake of participants in the highest tertile of daily activity energy expenditure (DAEE) was significantly higher, they reported having a better appetite and finding their meals more enjoyable. Participants who reported improvement in their appetite as well as participants who reported a good appetite were at lower risk for mortality even after adjusting for DAEE, demographic, nutritional and health indices.
It is interesting to note that an objective measure of energy expenditure using doubly labeled water remained significant even after adjusting for diet quality. In a previous analysis of the Health ABC cohort (24
), DAEE was a strong predictor for mortality after adjusting for several health conditions.
Physical activity measured by DLW was shown to be associated with better appetite among our group and with lower CRP and IL-6 levels. Lower IL-6 levels were shown among Health ABC participants with better appetite in a previous analysis performed for the entire group (42
). A fall in the level of cytokines may be one of the mechanisms through which physical activity enhances appetite in elderly persons. In a small study among nursing home patients, inactive patients were at increased risk for malnutrition and loss of appetite (19
). Fiatarone (43
) and Gray-Donald (44
) have both suggested that physical exercise increases energy expenditure and, thereby, appetite, total energy intake and diet quality, and, thus, slows the process of frailty. Likewise, high energy expenditure is a characteristic of higher activity level and a higher lean body mass, both more typical of the fit, rather than the frail elderly (18
The association between poor appetite and mortality has not been deeply investigated. It has often been thought that decreased appetite may be an indicator or a result of other health problems, and that malnutrition, rather than low appetite, was associated with mortality. Interestingly, in this Health ABC sub-study, poor appetite remained an independent predictor for mortality even after adjusting for several health and functional measurements. To the best of our knowledge, this is the first time that this direct association has been shown among a relatively independent group of elderly people.
The Healthy Eating Index that was used in our study to capture diet quality did not differ by DAEE tertiles and did not predict mortality in this Health ABC sub-study. Previous studies in different population groups showed a decreased risk for mortality among people consuming a Mediterranean diet (2
). Other dietary patterns have also shown a positive impact on mortality (1
). The HEI is a measure of compliance with the general dietary guidelines for the public (30
). It was shown to be negatively associated with obesity (45
) and major chronic diseases (46
) as well as with mobility limitation (47
); however, we did not find any studies that suggested an association with mortality.
The version of the HEI that we used did not take into account several health-related food groups and food items such as trans fatty acids, mono and omega 3 fatty acids and nuts. In addition, whole grains are included as part of the grain food group and legumes are included as part of the meat or vegetable food groups, but neither is considered as a separate food group. These changes are taken into account in the HEI-2005 (48
) and in the Mediterranean diet score. Since our questionnaire was administered in 1998–1999, it was analyzed according to the “older” version of the HEI. Application of the newer HEI-2005 version using the Health ABC cohort was not technically feasible at this time. Moreover a recent study that was conducted as part of the EPIC study among elderly people in Italy identified four major dietary patterns by using an exploratory factor analysis. ‘Olive Oil & Salad’ pattern, characterized by a high consumption of olive oil, raw vegetables, soups and poultry, emerged as being inversely associated with overall mortality in both crude and adjusted models (49
). These findings may suggest the need to develop more specific and objective measures of dietary exposure for the elderly population.
In conclusion we showed an interesting association between DAEE and appetite and mortality rates among a group of 298 elderly people participating in the Health ABC study. These findings may have some practical use for the health providers. Inclusion of a question regarding appetite as part of the medical assessment of an elderly patient may provide important information regarding risk for health deterioration and mortality.