Assessment of protein energy malnutrition in older persons, Part II: Laboratory evaluation

A large proportion of chronic diseases affecting older persons can be either prevented or significantly improved by improving nutrition. This places an increased burden on health care professionals caring for older persons. Screening for malnutrition at an early stage allows the intervention to be most successful. History, physical examination, and anthropometric measurements are essential parts of any nutritional evaluation. However, these tools can be highly subjective and rely heavily on the knowledge and experience of the evaluator. Incorporating biochemical measurements in the routine nutritional assessment provides an often-needed objective dimension. Interpreting these measurements must take into consideration the normal biological changes seen with aging. In this article, we review many of the biochemical parameters used in nutritional assessment and their relation to morbidity and mortality, with a special focus on normal changes seen with aging.     

Dietary protein and resistance training effects on muscle and body composition in older persons

The regular performance of resistance exercises and the habitual ingestion of adequate amounts of dietary protein from high-quality sources are two important ways for older persons to slow the progression of and treat sarcopenia, the age-related loss of skeletal muscle mass and function. Resistance training can help older people gain muscle strength, hypertrophy muscle, and increase whole body fat-free mass. It can also help frail elderly people improve balance and physical functioning capabilities. Inadequate protein intake will cause adverse metabolic and physiological accommodation responses that include the loss of fat-free mass and muscle strength and size. Findings from controlled feeding studies show that older persons retain the capacity to metabolically adjust to lower protein intakes by increasing the efficiency of nitrogen retention and amino acid utilization. However, they also suggest that the recommended dietary allowance of 0.8 g protein x kg(-1) x d(-1) might not be sufficient to prevent subtle accommodations and blunt desired changes in body composition and muscle size with resistance training. Most of the limited research suggests that resistance training-induced improvements in body composition, muscle strength and size, and physical functioning are not enhanced when older people who habitually consume adequate protein (modestly above the RDA) increase their protein intake by either increasing the ingestion of higher-protein foods or consuming protein-enriched nutritional supplements.     

评定外科病人蛋白质热量营养不良发病率

目的调查外科住院病人蛋白质-热量营养不良(PEM)发病率,评定并比较中青年及老年患者人体组成差异。方法随机抽取北京协和医院1998～1999年度外科择期手术病人378例(老年病例152例)术前进行(1)人体测量(体重、体重指数BMI、上臂围、上臂肌围、三头肌皮褶厚度、握力);(2)人体组成分析(生物电阻抗法,测定瘦体组织LBM、总体脂肪TBF和总体TBW);(3)血清前白蛋白测定(速率透射比浊法)及(4)膳食调查(24小时回顾法,测定5天)等。结果(1)术前PEM总发病率为33.4%,外科老年患者显著高于中青年患者(41.6%vs27.9%,P<0.05);(2)营养正常与营养不良病人的人体测量及血清前白蛋白测定结果有显著性差异(P<0.05);(3)与中青年相比,老年患者LBM显著降低(男性46.1±6.3kgvs51.3±6.1kg,P<0.05;女性34.2±4.5kgvs38.2±4.1kg,P<0.05);老年女性LBM%显著降低(62.2±8.7%vs68.4±7.9%,P<0.05),TBF%显著升高(38.0±5.8%vs31.2±7.5%,P<0.05)。结论应考虑对外科病人术前术后进行肠内与肠外营养支持;老年外科病人PEM发病率高,且易发生LBM丢失,故对其更应注意补充能量及氮源。     

膳食蛋白质与老年肌肉衰减综合征

随着人类寿命的日趋延长,伴随增龄而发生的人体脏器功能衰退和多种增龄性疾病明显增多,骨质疏松、骨关节炎等骨骼疾病严重地影响着老年人的生活质量。虽然这些代谢性骨病已引起人们的广泛关注,但对骨骼肌在增龄过程中的变化的有关研究较少。     

Rheumatoid cachexia,central obesity and malnutrition in patients with low-active rheumatoid arthritis: feasibility of anthropometry,Mini Nutritional Assessment and body composition techniques

Background and aims  The concurrent decrease in fat free mass (FFM) and increase in fat mass (FM), including central obesity, in patients with rheumatoid arthritis (RA) may be related to increased cardiovascular morbidity as well as to functional decline. The objectives of this study were to evaluate body composition and nutritional status in patients with RA and the feasibility of bioelectrical impedance (BIA) to detect rheumatoid cachexia. Methods  Eighty RA outpatients (76% women), mean age 61 (range 22–80) years and with mean disease duration of 6 (range 1–52) years, were assessed by body mass index (BMI), waist circumference (WC), whole-body dual-energy X-ray absorptiometry (DXA), BIA and the Mini Nutritional Assessment (MNA). Results  Fat free mass index (FFMI; kg/m²) was low in 26% of the women and in 21% of the men. About every fifth patient displayed concomitant low FFMI and elevated fat mass index (FMI; kg/m²), i.e. rheumatoid cachexia. BMI and MNA were not able to detect this condition. Sixty-seven percent had increased WC. Reduced FFM was independently related to age (p = 0.022), disease duration (p = 0.027), ESR (p = 0.011) and function trendwise (p = 0.058). There was a good relative agreement between DXA and BIA (FM r ² = 0.94, FFM r ² = 0.92; both p < 0.001), but the limits of agreement were wide for each variable, i.e. for FM −3.3 to 7.8 kg; and for FFM −7.9 to 3.7 kg. Conclusion  Rheumatoid cachexia and central obesity were common in patients with RA. Neither BMI nor MNA could detect this properly. There was a good relative agreement between DXA and BIA, but the limits of agreement were wide, which may restrict the utility of BIA in clinical practice. This work has in part been presented at the Congress of American College of Rheumatology in San Francisco, October 2008.     

Effect of protein and energy intakes on body composition in non-diabetic maintenance-hemodialysis patients

This cross sectional study was performed to find the adequate amount and combination of dietary protein and energy for maintaining better nutritional status for stable non-diabetic maintenance hemodialysis (MHD) patients. The body composition including body fat, total body water, body cell mass and body protein were measured by multi-frequency bioelectrical impedance analysis in 200 stable MHD patients without diabetes (124 men, 76 women). Dietary energy intake (DEI) and dietary protein intake (DPI) were assessed by a brief self-administered diet history questionnaire (BDHQ), the DPI value being confirmed by calculating the normalized protein equivalent of total nitrogen appearance (nPNA). The nutritional status and the body composition were compared among 4 groups of patients in each gender that were divided by the combination of DEI and DPI; high energy (HE)/high protein (HP), HE/low protein (LP), low energy (LE)/HP and LE/LP groups. The mean DPI ranged between 1.17-1.23 and 0.89-0.95 g/kg IBW/d in the HP and LP groups, respectively for both genders, and the mean DEI was 35-37 and 24-25 kcal/kg IBW/d in HE and LE groups, respectively. BMI and serum albumin concentration were not different among the 4 groups. Body cell mass index (BCMI) was maintained in the HE groups regardless of DPI, and it was significantly higher in the HE/HP group than in the LE/LP group. Multiple regression analysis also showed that the BCMI was more greatly affected by DEI than DPI. These results indicated that a DPI of 0.89-0.95 g/kg IBW/d could be sufficient for maintaining BCMI, if DEI is kept over 35 kcal/kg IBW/d in stable non-diabetic MHD patients. This DPI level is lower than the recommended DPI proposed by dietary guidelines in the US and Japan.     

Total body water in malnutrition: the possible role of energy intake

1. Total body water (TBW) was measured using tritiated water in sixty-five children. The measurements were distributed throughout rehabilitation in order to define the effect of changing energy intakes. 2. Oedematous children had a high TBW which decreased to the normal range during loss of oedema providing they were not receiving more than maintenance amounts of energy during this period. 3. Marasmic children who had not received greater than maintenance amounts of energy had a normal TBW. 4. Treatment with a high-energy diet was associated with an initial increase in TBW. 5. The possible mechanisms for this phenomenon are discussed.     

Alternate-day fasting in nonobese subjects: effects on body weight, body composition, and energy metabolism

BACKGROUND: Prolonged dietary restriction increases the life span in rodents. Some evidence suggests that alternate-day fasting may also prolong the life span. OBJECTIVE: Our goal was to determine whether alternate-day fasting is a feasible method of dietary restriction in nonobese humans and whether it improves known biomarkers of longevity. DESIGN: Nonobese subjects (8 men and 8 women) fasted every other day for 22 d. Body weight, body composition, resting metabolic rate (RMR), respiratory quotient (RQ), temperature, fasting serum glucose, insulin, free fatty acids, and ghrelin were assessed at baseline and after 21 d (12-h fast) and 22 d (36-h fast) of alternate-day fasting. Visual analogue scales were used to assess hunger weekly. RESULTS: Subjects lost 2.5 +/- 0.5% of their initial body weight (P < 0.001) and 4 +/- 1% of their initial fat mass (P < 0.001). Hunger increased on the first day of fasting and remained elevated (P < 0.001). RMR and RQ did not change significantly from baseline to day 21, but RQ decreased on day 22 (P < 0.001), which resulted in an average daily increase in fat oxidation of > or =15 g. Glucose and ghrelin did not change significantly from baseline with alternate-day fasting, whereas fasting insulin decreased 57 +/- 4% (P < 0.001). CONCLUSIONS: Alternate-day fasting was feasible in nonobese subjects, and fat oxidation increased. However, hunger on fasting days did not decrease, perhaps indicating the unlikelihood of continuing this diet for extended periods of time. Adding one small meal on a fasting day may make this approach to dietary restriction more acceptable.     

Effects of dietary protein, fat and restriction on body composition and energy balance in lactating rats

Isoenergetic diets formulated at three levels of dietary protein using 12,24 and 40% casein and at two levels of fat using 2.26 and 13.82% corn oil were fed at five levels of intake, ad libitum, 75, 62.5, 50 and 37.5% of average ad libitum intake, to 90 lactating rats from d 7 to 14 of lactation. Regression equations developed from lactating rats killed on d 7 of lactation were used to calculate initial body composition and energy of rats killed on d 14 of lactation. Changes in body weight and body water were significantly (P less than 0.05) affected by dietary fat and protein, but change in dry lean body mass was affected only by level of dietary fat, whereas body nitrogen and fat and lean body energy were not affected by level of dietary fat or protein. However, restricted intake significantly increased loss of all these. Likewise, restricted intake decreased milk production. Changes in weights of heart and liver were not affected by diet or intake, whereas intestinal weight decreased with intake restriction. Liver enzyme activities were markedly affected by intake restriction, whereas responses to dietary protein and fat were marginal.     

Effect of protein source on resistive-training-induced changes in body composition and muscle size in older men

BACKGROUND: Aging is associated with reductions in muscle mass and strength, but nutrition and exercise interventions can delay this progression and enhance the quality of life. OBJECTIVE: We examined whether the predominant source of protein consumed by older men influenced measures of muscle size and strength, body composition, resting energy expenditure, and skeletal muscle creatine concentrations in response to 12 wk of resistive training. DESIGN: After consuming a lactoovovegetarian (LOV) diet for 2 wk, 21 men aged 65 +/- 5 y were randomly assigned to either consume a beef-containing (BC) diet (n = 10) or to continue the LOV diet (n = 11) throughout resistive training. The BC diet included 0.6 g protein. kg(-1). d(-1) from beef and the LOV diet included 0.6 g protein. kg(-1). d(-1) from textured vegetable protein (soy) sources. The remaining protein in the diets came from self-selected LOV sources. RESULTS: The mean total protein intake for both groups ranged from 1.03 to 1.17 g. kg(-1). d(-1) during the intervention. Men in both groups had improvements (14-38%) in maximal dynamic strength of all the muscle groups trained with no significant difference between groups. With resistive training, cross-sectional muscle area of the vastus lateralis increased in both groups (4.2 +/- 3.0% and 6.0 +/- 2.6% for the LOV and BC groups, respectively) with no significant difference between groups. Body composition, resting energy expenditure, and concentrations of muscle creatine, phosphocreatine, and total creatine did not differ significantly between groups or change over time. CONCLUSIONS: These data suggest that increases in muscle strength and size were not influenced by the predominant source of protein consumed by older men with adequate total protein intake.     

C-Reactive protein and lipid parameters in older persons aged 80 years and older

Objectives  Aims of the study were 1) to investigate the association of C-reactive protein (CRP) with lipid (i.e. total, LDL, and HDL cholesterol, triglycerides) concentrations, and to evaluate their predictive value for mortality in very old subjects. Design  Cross-sectional and longitudinal analyses in a prospective cohort study. Setting  Participants. Data are from 336 community-dwelling subjects aged ≥80 years old enrolled in the “Invecchiamento e Longevità nel Sirente” (ilSIRENTE) study. Measurements  High sensitivity CRP and lipid concentrations were measured at the baseline clinical visit. High sensitivity CRP concentrations were measured by ELISA assessment. Mortality outcome was evaluated over a 24-month follow-up. Results  Participants had a mean age of 85.8 (SD 4.8) years old. Spearman’s correlations showed significant (p values <0.01) inverse correlations between CRP and lipid parameters (except triglycerides). Adjusted linear regressions between CRP and lipid parameters concentrations showed no significant association in participants aged lower than 85 years old (all p values >0.5). In the older age group, significant inverse associations of CRP with total (p=0.002), LDL (p=0.007), and HDL cholesterol (p=0.002) were found, even after adjustment for potential confounders. Adjusted Cox proportional hazard models demonstrated that CRP was the only biomarker significantly predictive of mortality, independently of age and lipid parameters. Conclusion  An inverse relationship of total, LDL, and HDL cholesterol with CRP is present in very old persons. The prognostic value of CRP is particularly important among very old persons whereas lipid parameters tend to lose their capacity to predict events.     

Response of body protein and energy gain in growing chicks to differences in energy intake and composition of diet

Responses of metabolized energy, body protein gain and body energy gain of growing chicks to planes of energy intake and dietary composition of energy-yielding nutrients were studied. Ten diets were formulated to cover the entire range of composition (0-100%) of protein, fat and carbohydrate on the basis of gross energy (GE) and three sets of 10 groups of chicks were force-fed these diets at planes of 1380, 1076 and 773 kcal GE/chick per 10 d. The response surfaces of metabolized energy at each plane of GE intake were convex, and the upper two surfaces contacted in the field of 0% GE of dietary protein (PGE). The response surface of body energy gain was almost parallel to that of metabolized energy at each plane of GE intake, but the slopes of the body energy gain upward to the peak from the foot on the 100% PGE field were steep compared with those of the metabolized energy. On the other hand, the response surfaces of body protein gain at any plane of GE intake were also convex, and sloped down from the field of about 60% PGE to the higher PGE field and to the 0% PGE field. Regardless of the plane of GE intake, the body energy gain reached a plateau at about 25% PGE and the body protein gain at about 60% PGE. That body protein gain depends on both protein intake and plane of GE intake was clearly shown. On the basis of these results we calculated partial efficiency of metabolized energy utilization, and discussed validity of the classical definition of a "balanced ration."