Water balance, hydration status, and fat-free mass hydration in young and older adults

Department of Foods and Nutrition, Purdue University, West Lafayette, IN 47907, USA.
American Journal of Clinical Nutrition (Impact Factor: 6.77). 07/2005; 81(6):1342-50.
Source: PubMed


Older adults are at increased risk of dehydration, yet water balance is understudied in this population.
This controlled diet study assessed the effect of age on water input, output, and balance in healthy adults. Hydration status (plasma osmolality and urine specific gravity) and body composition were also measured.
Eleven men and 14 women aged 23-46 y and 10 men and 11 women aged 63-81 y were subjects. Water balance was assessed during days 7-10 of three 18-d controlled feeding trials with protein intakes of 0.50, 0.75, and 1.00 g . kg(-1) . d(-1). Total water input included water from the provided foods and beverages, ad libitum intake, and metabolic production. Water output included the losses in urine and stool and the insensible losses from respiration and nonsweating perspiration.
Ad libitum water consumption, total water intake, water output through urine, total water output, and net water balance were not different in the older subjects than in the younger subjects. Markers of hydration status were within the range of clinical normalcy for all groups. Total body water (TBW) was not significantly different, fat-free mass (FFM) was significantly lower (P < 0.05), and FFM hydration (TBW:FFM) was significantly higher (P < 0.05) in the older subjects than in the younger subjects. Dietary protein intake did not influence any of these results.
These results show that healthy older adults maintain water input, output, and balance comparable to those of younger adults and have no apparent changes in hydration status. The results support that the hydration of FFM is increased in older men and women.

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    • "Each urine collection started at 07:00 am and was performed for the ensuing 24 h. Insensible water loss was estimated by assuming that for every 1,000 kcal of energy consumed, 430 ml of water is lost as a consequence of respiration and skin perspiration (Bossingham et al. 2005). "
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    ABSTRACT: Purpose This study tested the hypothesis that hypoxia exacerbates reductions in body mass observed during unloading. Methods To discern the separate and combined effects of simulated microgravity and hypoxia, 11 healthy males underwent three 21-day campaigns in a counterbalanced fashion: (1) normoxic bed rest (NBR; FiO2 = 0.209; PiO2 = 133.1 ± 0.3); (2) hypoxic ambulatory confinement (HAMB; FiO2 = 0.141 ± 0.004; PiO2 = 90.0 ± 0.4; ~4,000 m); and (3) hypoxic bed rest (HBR; FiO2 = 0.141 ± 0.004; PiO2 = 90.0 ± 0.4). The same dietary menu was applied in all campaigns. Targeted energy intakes were estimated individually using the Harris–Benedict equation taking into account whether the subjects were bedridden or ambulatory. Body mass and water balance were assessed throughout the campaigns. Whole body and regional body composition was determined before and after the campaigns using dual-energy X-ray absorptiometry. Before and during the campaigns, indirect calorimetry and visual analogue scores were employed to assess the resting energy expenditure (REE) and perceived appetite sensations, respectively. Results Energy intakes were lower than targeted in all campaigns (NBR: −5 %; HAMB: −14 %; HBR: −6 %; P < 0.01). Body mass significantly decreased following all campaigns (NBR: −3 %; HAMB: −4 %; HBR: −5 %; P < 0.01). While fat mass was not significantly altered, the whole body fat free mass was reduced (NBR: −4 %; HAMB: −5 %; HBR: −5 %; P < 0.01), secondary to lower limb fat-free mass reduction. Water balance was comparable between the campaigns. No changes were observed in REE and perceived appetite. Conclusions Exposure to simulated altitude of ~4,000 m does not seem to worsen the whole body mass and fat-free mass reductions or alter resting energy expenditure and appetite during a 21-day simulated microgravity.
    Arbeitsphysiologie 08/2014; DOI:10.1007/s00421-014-2963-1 · 2.19 Impact Factor
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    • "For instance, we found no association between students' DWI a nd gender variable (both chi-square test and regression confirms this), this is in line with findings of Kant et al. (2006), Park et al. (2011); though, the concept of association between water intake and gender remains controversial (Pintar et al., 2009). Our results suggest that students' DWI decline with age but increases with weight, consistent with our findings, though for older age groups (Volkert et al., 2005), Zizza et al. (2009) found that water intake declines with age; however, the findings by De Castro et al. (1992), Bossingham et al. (2005) are contrary as they found no differences in DWI and age. "
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    • "Bicca-Marques 1992). To corroborate the importance to howler monkeys of drinking for thermoregulation and water balance, future research could include measurement of physiological indicators of the hydration status of individuals, for example vasopressin hormone (Bossingham et al. 2005), which can be monitored noninvasively (Diederich et al. 2001). Water in food varies from less than 30 % of mass in some seeds to more than 80 % in some fruits (Barboza et al. 2009). "
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