Optimal protein intake in the elderly

Protein and healthy aging

Our understanding of the potential benefits and challenges of optimizing dietary protein intake in older adults continues to evolve. An overarching hypothesis generated during Protein Summit 2.0 was that consuming an adequate amount of high-quality protein at each meal, in combination with physical activity, may delay the onset of sarcopenia, slow its progression, reduce the magnitude of its functional consequences, or all of these. The potential benefits of young and middle-aged adults adopting a diet pattern whereby adequate protein is consumed at each meal as a countermeasure to sarcopenia are presented and discussed. For example, meeting a protein threshold (∼25-30 g/meal) represents a promising, yet still largely unexplored dietary strategy to help maintain muscle mass and function. For many older adults, breakfast is a carbohydrate-dominated lower-protein meal and represents an opportunity to improve and more evenly distribute daily protein intake. Although both animal and plant-based proteins can provide the required essential amino acids for health, animal proteins generally have a higher proportion of the amino acid leucine. Leucine plays a key role in stimulating translation initiation and muscle protein anabolism and is the focus of ongoing research. Protein requirements should be assessed in the light of habitual physical activity. An evenly distributed protein diet provides a framework that allows older adults to benefit from the synergistic anabolic effect of protein and physical activity. To fully understand the role of dietary protein intake in healthy aging, greater efforts are needed to coordinate and integrate research design and data acquisition and interpretation from a variety of disciplines.

Promoting health and longevity through diet: from model organisms to humans

Reduced food intake, avoiding malnutrition, can ameliorate aging and aging-associated diseases in invertebrate model organisms, rodents, primates, and humans. Recent findings indicate that meal timing is crucial, with both intermittent fasting and adjusted diurnal rhythm of feeding improving health and function, in the absence of changes in overall intake. Lowered intake of particular nutrients rather than of overall calories is also key, with protein and specific amino acids playing prominent roles. Nutritional modulation of the microbiome can also be important, and there are long-term, including inter-generational, effects of diet. The metabolic, molecular, and cellular mechanisms that mediate both improvement in health during aging to diet and genetic variation in the response to diet are being identified. These new findings are opening the way to specific dietary and pharmacological interventions to recapture the full potential benefits of dietary restriction, which humans can find difficult to maintain voluntarily.

Exploration of the protein requirement during weight loss in obese older adults

RATIONALE

Currently there is no consensus on protein requirements for obese older adults during weight loss. Here we explore the potential use of a new method for assessment of protein requirements based on changes in appendicular muscle mass during weight loss.

METHODS

60 obese older adults were subjected to 13 wk weight loss program, including hypocaloric diet and resistance training. Assessment of appendicular muscle mass was performed by DXA at baseline and after 13 wk challenge period, and the difference calculated as muscle mass change. Protein intake (g/kg body weight and g/kg fat free mass (FFM)) at 13wks was used as marker of protein intake during 13 wk period. 30 subjects received 10 times weekly 20 g protein supplement throughout the 13 week hypocaloric phase which is included in the calculation of total protein intake. Receiver operating characteristic (ROC) curve analysis was used to explore the optimal cutoff point for protein intake (g/kg) versus increase in appendicular muscle mass of more than 250 g over 13 wks (y/n). Subsequently, logistic regression analysis was performed for protein intake cutoff and muscle mass accretion, adjusted for sex, age, baseline BMI, and training compliance.

RESULTS

ROC curve analysis provided a protein intake level per day of 1.2 g/kg bw and 1.9 g/kg FFM as cutoff point. Presence of muscle mass accretion during 13 wk challenge period was significantly higher with protein intake higher than 1.2 g/kg bw (OR 5.4, 95%CI 1.4-20.6, p = 0.013) or higher than 1.9 g/kg FFM (OR 8.1, 95%CI 2.1-31.9, p = 0.003). Subjects with a protein intake higher than 1.2 g/kg had significantly more often muscle mass accretion, compared to subjects with less protein intake (10/14 (72%) vs 15/46 (33%), p = 0.010). For 1.9 g/kg FFM this was 70% vs 28% (p = 0.002).

CONCLUSION

This exploratory study provided a level of at least 1.2 g/kg body weight or 1.9 g/kg fat free mass as optimal daily protein intake for obese older adults under these challenged conditions of weight loss, based on muscle mass accretion during the challenge.

TRIAL REGISTRATION

Dutch Trial Register under number NTR2751.

A nutritional formula enriched with arginine, zinc, and antioxidants for the healing of pressure ulcers: a randomized trial

BACKGROUND

Trials on specific nutritional supplements for the treatment of pressure ulcers (PUs) have been small, inconsistent in their formulations, or unsuccessful in controlling for total supplement calorie or protein content.

OBJECTIVE

To evaluate whether supplementation with arginine, zinc, and antioxidants within a high-calorie, high-protein formula improves PU healing.

DESIGN

Multicenter, randomized, controlled, blinded trial. (ClinicalTrials.gov: NCT01107197).

SETTING

Long-term care and home care services.

PATIENTS

200 adult malnourished patients with stage II, III, and IV PUs.

INTERVENTIONS

An energy-dense, protein-rich oral formula enriched with arginine, zinc, and antioxidants (400 mL/d) or an equal volume of an isocaloric, isonitrogenous formula for 8 weeks.

MEASUREMENTS

The primary end point was the percentage of change in PU area at 8 weeks. Secondary end points included complete healing, reduction in the PU area of 40% or greater, incidence of wound infections, the total number of dressings at 8 weeks, and the percentage of change in area at 4 weeks.

RESULTS

Supplementation with the enriched formula (n = 101) resulted in a greater reduction in PU area (mean reduction, 60.9% [95% CI, 54.3% to 67.5%]) than with the control formula (n = 99) (45.2% [CI, 38.4% to 52.0%]) (adjusted mean difference, 18.7% [CI, 5.7% to 31.8%]; P = 0.017). A more frequent reduction in area of 40% or greater at 8 weeks was also seen (odds ratio, 1.98 [CI, 1.12 to 3.48]; P = 0.018). No difference was found in terms of the other secondary end points.

LIMITATION

Participation was restricted to patients who were malnourished, were able to drink oral supplements, and were living in long-term care institutions or receiving home care services.

CONCLUSION

Among malnourished patients with PU, 8 weeks of supplementation with an oral nutritional formula enriched with arginine, zinc, and antioxidants improved PU healing.

PRIMARY FUNDING SOURCE

Azienda Ospedaliera Universitaria Maggiore della Carità.

A high whey protein-, leucine-, and vitamin D-enriched supplement preserves muscle mass during intentional weight loss in obese older adults: a double-blind randomized controlled trial

BACKGROUND

Intentional weight loss in obese older adults is a risk factor for muscle loss and sarcopenia.

OBJECTIVE

The objective was to examine the effect of a high whey protein-, leucine-, and vitamin D-enriched supplement on muscle mass preservation during intentional weight loss in obese older adults.

DESIGN

We included 80 obese older adults in a double-blind randomized controlled trial. During a 13-wk weight loss program, all subjects followed a hypocaloric diet (-600 kcal/d) and performed resistance training 3×/wk. Subjects were randomly allocated to a high whey protein-, leucine-, and vitamin D-enriched supplement including a mix of other macro- and micronutrients (150 kcal, 21 g protein; 10×/wk, intervention group) or an isocaloric control. The primary outcome was change in appendicular muscle mass. The secondary outcomes were body composition, handgrip strength, and physical performance. Data were analyzed by using ANCOVA and mixed linear models with sex and baseline value as covariates.

RESULTS

At baseline, mean ± SD age was 63 ± 5.6 y, and body mass index (in kg/m(2)) was 33 ± 4.4. During the trial, protein intake was 1.11 ± 0.28 g · kg body weight(-1) · d(-1) in the intervention group compared with 0.85 ± 0.24 g · kg body weight(-1) · d(-1) in the control group (P < 0.001). Both intervention and control groups decreased in body weight (-3.4 ± 3.6 kg and -2.8 ± 2.8 kg; both P < 0.001) and fat mass (-3.2 ± 3.1 kg and -2.5 ± 2.4 kg; both P < 0.001), with no differences between groups. The 13-wk change in appendicular muscle mass, however, was different in the intervention and control groups [+0.4 ± 1.2 kg and -0.5 ± 2.1 kg, respectively; β = 0.95 kg (95% CI: 0.09, 1.81); P = 0.03]. Muscle strength and function improved over time without significant differences between groups.

CONCLUSION

A high whey protein-, leucine-, and vitamin D-enriched supplement compared with isocaloric control preserves appendicular muscle mass in obese older adults during a hypocaloric diet and resistance exercise program and might therefore reduce the risk of sarcopenia. This trial was registered at the Dutch Trial Register (http://www.trialregister.nl) as NTR2751.

Nutritional guidelines for older people in Finland

BACKGROUND

Ageing is associated with an increased risk of malnutrition, decreased nutrient intake, unintentional weight loss and sarcopenia, which lead to frailty, functional disabilities and increased mortality. Nutrition combined with exercise is important in supporting older people's health, functional capacity and quality of life.

OBJECTIVE

To identify nutritional needs in various groups of older individuals and to present the nutritional guidelines for older people in Finland.

DESIGN

A review of the existing literature on older people's nutritional needs and problems. The draft guidelines were written by a multidisciplinary expert panel; they were then revised, based on comments by expert organisations. The guidelines were approved by the National Nutritional Council in Finland.

RESULTS

The heterogeneity of the older population is highlighted. The five key guidelines are: 1. The nutritional needs in different age and disability groups should be considered. 2. The nutritional status and food intake of older individuals should be assessed regularly. 3. An adequate intake of energy, protein, fiber, other nutrients and fluids should be guaranteed. 4. The use of a vitamin D supplement (20 μg per day) recommended. 5. The importance of physical activity is highlighted. In addition, weight changes, oral health, constipation, obesity, implementing nutritional care are highlighted.

CONCLUSIONS

Owing to the impact that good nutrition has on health and well-being in later life, nutrition among older people should be given more attention. These nutritional guidelines are intended to improve the nutrition and nutritional care of the older population.

Muscular strength and physical function in elderly adults 6-18 months after a 12-week resistance exercise program

AIMS

Benefits of resistance exercise in elderly people are well documented; however, sustaining these benefits can be difficult and adherence is often poor. Muscular strength and physical function usually decline after a supervised resistance exercise program (REP). We investigated these changes in older adults during an observational follow-up and whether leisure time physical activity (LTPA) or unsupervised resistance exercise (RE) limit these changes.

METHODS

Subjects (N = 236, 73.7 ± 5.7 years, 58.2% female) had participated in a supervised 12-week REP. Quadriceps strength and timed-up-and-go performance (TUG) at follow-up were compared to values before and after REP. Multivariate statistics were used to predict changes in strength or function.

RESULTS

Two hundred and eleven (90.3%) participants completed REP and 149 (63.1%) completed follow-up (11.4 ± 2.9 months). Quadriceps strength at follow-up decreased significantly compared to after REP (-27N), but was higher than before REP (+ 30N). TUG did not decrease during follow-up and was better than before REP (-0.9 seconds). LTPA (+ 38.0N, p < 0.001) and RE (+31.6N, p = 0.006) predicted strength at follow-up, although they did not completely prevent loss of strength during follow-up.

CONCLUSIONS

quadriceps strength declines after a 12-week resistance exercise program in older adults. Neither LTPA nor RE completely prevents loss of quadriceps strength during follow-up, although they limited the loss. TUG did not change during follow-up and was better at follow-up than before the start of the resistance exercise program.

Dietary protein intake in elderly women: association with muscle and bone mass

BACKGROUND

An inadequate food intake, mainly with regard to protein intake, seems to contribute to a reduction of skeletal muscle and bone mass in the elderly. This study was undertaken to evaluate differences in protein intake in women with or without sarcopenia and verify the intake level that is related to a better bone and muscle mass.

METHODS

Elderly women older than 65 years with sarcopenia (n = 35) and without sarcopenia (n = 165) participated in the study. Assessment of bone mineral density of the lumbar spine and femur was taken, body composition was evaluated by dual-energy x-ray absorptiometry, and an evaluation of protein intake was performed through 3-day dietary records.

RESULTS

Muscle, bone, and fat mass was significantly higher in women who had protein intake >1.2 g/kg/d. A lower intake of essential amino acids in women with sarcopenia was also observed. Protein and energy intake were significant predictors of muscle mass. The presence of osteoporosis was a predictor of muscle strength. In conclusion, the present study demonstrated that in elderly women, an adequate protein intake in terms of quality and quantity, without need of supplementation, could have a positive impact on bone mineral density, lean mass, and skeletal muscle mass.

Dietary protein distribution positively influences 24-h muscle protein synthesis in healthy adults

The RDA for protein describes the quantity that should be consumed daily to meet population needs and to prevent deficiency. Protein consumption in many countries exceeds the RDA; however, intake is often skewed toward the evening meal, whereas breakfast is typically carbohydrate rich and low in protein. We examined the effects of protein distribution on 24-h skeletal muscle protein synthesis in healthy adult men and women (n = 8; age: 36.9 ± 3.1 y; BMI: 25.7 ± 0.8 kg/m2). By using a 7-d crossover feeding design with a 30-d washout period, we measured changes in muscle protein synthesis in response to isoenergetic and isonitrogenous diets with protein at breakfast, lunch, and dinner distributed evenly (EVEN; 31.5 ± 1.3, 29.9 ± 1.6, and 32.7 ± 1.6 g protein, respectively) or skewed (SKEW; 10.7 ± 0.8, 16.0 ± 0.5, and 63.4 ± 3.7 g protein, respectively). Over 24-h periods on days 1 and 7, venous blood samples and vastus lateralis muscle biopsy samples were obtained during primed (2.0 μmol/kg) constant infusion [0.06 μmol/(kg⋅min)] of l-[ring-(13)C6]phenylalanine. The 24-h mixed muscle protein fractional synthesis rate was 25% higher in the EVEN (0.075 ± 0.006%/h) vs. the SKEW (0.056 ± 0.006%/h) protein distribution groups (P = 0.003). This pattern was maintained after 7 d of habituation to each diet (EVEN vs. SKEW: 0.077 ± 0.006 vs. 0.056 ± 0.006%/h; P = 0.001). The consumption of a moderate amount of protein at each meal stimulated 24-h muscle protein synthesis more effectively than skewing protein intake toward the evening meal.

Early body weight loss during concurrent chemo-radiotherapy for non-small cell lung cancer

BACKGROUND AND PURPOSE

Radiation-esophagitis and weight loss are frequently observed toxicities in patients treated with concurrent chemo-radiotherapy (CT-RT) for non-small cell lung cancer (NSCLC) and might be related. The purpose was to investigate whether weight loss already starts early after initiation of CT-RT and precedes radiation-esophagitis.

MATERIALS AND METHODS

In a retrospective cohort, weight and esophagitis grade ≥2 were assessed during the first weeks of (CT-)RT in patients treated with concurrent (n = 102) or sequential (n = 92) therapy. In a prospective validation study, data on body weight, esophagitis grade ≥2, nutritional intake and muscle strength were obtained before, during and following CT-RT.

RESULTS

In the retrospective cohort, early weight loss was observed in concurrently treated patients (p = 0.002), independent of esophagitis ≥ grade 2. Early weight loss was also observed in the prospective cohort (p = 0.003) and was not accompanied by decreases in nutritional intake. In addition lower limb muscle strength rapidly declined (p = 0.042). In the later weeks of treatment, further body weight loss occurred (p < 0.001) despite increased nutritional supplementation and body weight was only partly recovered after 4 weeks post CT-RT (p = 0.003).

CONCLUSIONS

Weight loss during concurrent CT-RT for NSCLC starts early and prior to onset of esophagitis, requiring timely and intense nutritional rehabilitation.

Obesity-related inflammation: implications for older adults

The combination of age-related increases in obesity and inflammation can lead to chronic disease, decreased strength, and physical disability. Lifestyle interventions that include moderate caloric restriction along with aerobic and resistance exercise have shown improvements in metabolic outcomes, strength, and physical function in obese older adults. Although few weight loss studies have addressed diet quality, evidence summarized in this review suggests that encouraging intake of antioxidant-rich fruits and vegetables, high-quality protein, low-glycemic index carbohydrates, and omega-3 fatty acids may further ameliorate obesity-related inflammation. Future controlled trials are indicated to examine the effects of incorporating these foods into multimodal weight loss interventions.

Protein-enriched diet, with the use of lean red meat, combined with progressive resistance training enhances lean tissue mass and muscle strength and reduces circulating IL-6 concentrations in elderly women: a cluster randomized controlled trial

BACKGROUND

Physical inactivity, inadequate dietary protein, and low-grade systemic inflammation contribute to age-related muscle loss, impaired function, and disability.

OBJECTIVE

We assessed the effects of progressive resistance training (PRT) combined with a protein-enriched diet facilitated through lean red meat on lean tissue mass (LTM), muscle size, strength and function, circulating inflammatory markers, blood pressure, and lipids in elderly women.

DESIGN

In a 4-mo cluster randomized controlled trial, 100 women aged 60-90 y who were residing in 15 retirement villages were allocated to receive PRT with lean red meat (∼160 g cooked) to be consumed 6 d/wk [resistance training plus lean red meat (RT+Meat) group; n = 53] or control PRT [1 serving pasta or rice/d; control resistance training (CRT) group; n = 47)]. All women undertook PRT 2 times/wk and received 1000 IU vitamin D3/d.

RESULTS

The mean (± SD) protein intake was greater in the RT+Meat group than in the CRT group throughout the study (1.3 ± 0.3 compared with 1.1 ± 0.3 g · kg⁻¹ · d⁻¹, respectively; P < 0.05). The RT+Meat group experienced greater gains in total body LTM (0.45 kg; 95% CI: 0.07, 0.84 kg), leg LTM (0.22 kg; 95% CI: 0.02, 0.42 kg), and muscle strength (18%; 95% CI: 0.03, 0.34) than did the CRT group (all P < 0.05). The RT+Meat group also experienced a 10% greater increase in serum insulin-like growth factor I (P < 0.05) and a 16% greater reduction in the proinflammatory marker interleukin-6 (IL-6) (P < 0.05) after 4 mo. There were no between-group differences for the change in blood lipids or blood pressure.

CONCLUSION

A protein-enriched diet equivalent to ∼1.3 g · kg⁻¹ · d⁻¹ achieved through lean red meat is safe and effective for enhancing the effects of PRT on LTM and muscle strength and reducing circulating IL-6 concentrations in elderly women. This trial was registered at the Australian Clinical Trials Registry as ACTRN12609000223235.

Assessment of protein requirement in octogenarian women with use of the indicator amino acid oxidation technique

BACKGROUND

Data on the protein requirements of elderly adults are limited, because it is impractical to conduct repeated nitrogen balance protocols in these vulnerable humans.

OBJECTIVE

This study was designed to determine the dietary protein requirement of elderly women by using the recently developed minimally invasive indicator amino acid oxidation (IAAO) technique.

DESIGN

Six white women aged 80-87 y [mean ± SEM: 82 ± 1 y and body mass index (in kg/m²) 26 ± 2] completed a 3-d protocol 7 times. Each woman consumed an adaptation diet for 2 d and on day 3 consumed a complete test diet with a crystalline amino acid mixture containing 1 of 7 protein intakes (0.1, 0.3, 0.6, 0.9, 1.2, 1.5, or 1.8 g · kg⁻¹ · d⁻¹) tested randomly. A group-based protein requirement was assessed by using a nonlinear mixed model of protein intake and L-[1-¹³C]phenylalanine oxidation. The breakpoint, at which there was no further decline in the rate of appearance of ¹³C in the breath, was used as an index of the mean protein requirement.

RESULTS

The mean protein requirement (95% CI) was 0.85 (0.60, 1.09) g · kg⁻¹ · d⁻¹. This requirement is 29% higher than the current Estimated Average Requirement (EAR) for adults of 0.66 g · kg⁻¹ · d⁻¹ based on the nitrogen balance technique, although the 95% CI includes the current EAR. The corresponding adequate protein allowance of 1.15 (0.77, 1.54) g · kg⁻¹ · d⁻¹ is 44% higher, although the 95% CI includes the Recommended Dietary Allowance (RDA) of 0.80 g · kg⁻¹ · d⁻¹.

CONCLUSIONS

Notwithstanding uncertainty about the validity of the use of the IAAO technique to assess protein requirements, the results of this study with octogenarian women suggest that the current EAR and RDA for elderly women may be underestimated. The limitations of this short-term, noninvasive method underscore the need for new research that uses alternative experimental designs and measuring physiologic, morphologic, and health-related outcomes.

Developing a new treatment paradigm for disease prevention and healthy aging

An increasingly prevalent pattern of risk factors has emerged in middle-aged and older adults that includes the presence of type 2 diabetes or prediabetes, overweight or obese weight status with central obesity and very high body fat, low cardiorespiratory fitness (CRF), low strength, and a low lean-body-mass-to-body-fat ratio. Traditionally, these problems have been approached with a low-fat and low-calorie diet and with lower to moderate intensity activity such as walking. While the treatment has some clear benefits, this approach may no longer be optimal because it does not reflect more recent findings from nutrition and exercise sciences. Specifically, these fields have gained a greater understanding of the metabolic and functional importance of focusing on reducing body fat and central obesity while maintaining or even increasing lean body mass, a quality weight loss, and how to efficiently and effectively increase CRF and strength. Evidence is presented for shifting the treatment paradigm for disease prevention and healthy aging to include the DASH nutrition pattern but with additional protein, higher intensity, brief aerobic training, effort-based, brief resistance training, and structured physical activity. Recent interventions based on social cognitive theory for initiating and then maintaining health behavior changes show the feasibility and efficacy of the approach we are advocating especially within a multiple health behavior change format and the potential for translating the new treatment paradigm into practice.

Protein intake protects against weight loss in healthy community-dwelling older adults

Weight loss is prevalent in the elderly population, with deleterious health consequences, notably loss of lean body mass and subsequent functional decline. Protein intake below the current RDA [0.8 g/(kg · d)] is also common in older adults; however, the link between the 2 has received little attention. Our objective was to assess the relation between protein intake and incident 1-y weight loss ≥5% in community-dwelling older adults. We conducted a nested, prospective, case-control study in 1793 community-living elderly participants of the Quebec Longitudinal Study of Nutrition as a Determinant of Successful Aging (NuAge). We studied 211 incident cases of 1-y weight loss (≥5%) and 211 weight-stable controls (±2%) matched by sex and age category (70 ± 2, 75 ± 2, and 80 ± 2 y). Diet was measured by 3 nonconsecutive 24-h recalls. ORs (95% CIs) for the association between protein intake and weight loss were computed by using conditional logistic regression. After adjustment for body mass index, energy intake, appetite, smoking status, physical activity level, physical function, chronic diseases and medications, depressive symptoms, and serum albumin and ultrasensitive C-reactive protein, the ORs of weight loss in participants with low protein intakes [<0.8 g/(kg · d)] were 2.56 (95% CI: 1.01, 6.50) compared with participants with very high protein intakes [≥1.2 g/(kg · d)]. Corresponding numbers were 2.15 (95% CI: 1.02, 4.56) in participants with moderate protein intakes [0.8-<1.0 g/(kg · d)] and 1.33 (95% CI: 0.77, 2.28) in participants with high protein intakes [1.0-1.2 g/(kg · d)]. Our results suggest that protein intakes >1.0 g/(kg · d) are protective against weight loss in healthy older adults. These findings add epidemiologic evidence in support of higher optimal protein intakes than the current guidelines for healthy older adults.

Calcium homeostasis and bone metabolic responses to high-protein diets during energy deficit in healthy young adults: a randomized controlled trial

BACKGROUND

Although consuming dietary protein above current recommendations during energy deficit (ED) preserves lean body mass, concerns have been raised regarding the effects of high-protein diets on bone health.

OBJECTIVE

The objective was to determine whether calcium homeostasis and bone turnover are affected by high-protein diets during weight maintenance (WM) and ED.

DESIGN

In a randomized, parallel-design, controlled trial of 32 men and 7 women, volunteers were assigned diets providing protein at 0.8 [Recommended Dietary Allowance (RDA)], 1.6 (2 × RDA), or 2.4 (3 × RDA) g · kg(-1) · d(-1) for 31 d. Ten days of WM preceded 21 d of ED, during which total daily ED was 40%, achieved by reduced dietary energy intake (∼30%) and increased physical activity (∼10%). The macronutrient composition (protein g · kg(-1) · d(-1) and % fat) was held constant from WM to ED. Calcium absorption (ratio of (44)Ca to (42)Ca) and circulating indexes of bone turnover were determined at day 8 (WM) and day 29 (ED).

RESULTS

Regardless of energy state, mean (±SEM) urinary pH was lower (P < 0.05) at 2 × RDA (6.28 ± 0.05) and 3 × RDA (6.23 ± 0.06) than at the RDA (6.54 ± 0.06). However, protein had no effect on either urinary calcium excretion (P > 0.05) or the amount of calcium retained (P > 0.05). ED decreased serum insulin-like growth factor I concentrations and increased serum tartrate-resistant acid phosphatase and 25-hydroxyvitamin D concentrations (P < 0.01). Remaining markers of bone turnover and whole-body bone mineral density and content were not affected by either the protein level or ED (P > 0.05).

CONCLUSION

These data demonstrate that short-term consumption of high-protein diets does not disrupt calcium homeostasis and is not detrimental to skeletal integrity. This trial was registered at www.clinicaltrials.gov as NCT01292395.

Nutrition and protein energy homeostasis in elderly

Protein-energy homeostasis is a major determinant of healthy aging. Inadequate nutritional intakes and physical activity, together with endocrine disturbances are associated with of sarcopenia and frailty. Guidelines from scientific societies mainly address the quantitative aspects of protein and energy nutrition in elderly. Besides these quantitative aspects of protein load, perspective strategies to promote muscle protein synthesis and prevent sarcopenia include pulse feeding, the use of fast proteins and the addition of leucine or citrulline to dietary protein. An integrated management of sarcopenia, taking into account the determinants of muscle wasting, i.e. nutrition, physical activity, anabolic factors such as androgens, vitamin D and n-3 polyunsaturated fatty acids status, needs to be tested in the prevention and treatment of sarcopenia. The importance of physical activity, specifically resistance training, is emphasized, not only in order to facilitate muscle protein anabolism but also to increase appetite and food intake in elderly people at risk of malnutrition. According to present data, healthy nutrition in elderly should respect the guidelines for protein and energy requirement, privilege a Mediterranean way of alimentation, and be associated with a regular physical activity. Further issues relate to the identification of the genetics determinants of protein energy wasting in elderly.

Heat-induced aggregation of whey proteins in aqueous solutions below their isoelectric point

Processing beverages containing high concentrations of globular proteins represents a technological challenge due to their instability during heating caused by protein aggregation and gelation. Aggregation of whey protein mixtures was investigated in aqueous model systems at pH 3.5, 4.0, and 4.5 at heating conditions resembling conventional industrial treatment (90 °C for 30 s). The extent of aggregation progressively decreased moving away from the pI. Protein aggregates became smaller and had a more open structure compared to higher pH values. Significant loss of protein dispersibility occurred at pH 4.0 and 4.5 above the denaturation T of whey protein (∼70 °C), at which aggregation was caused by intermolecular hydrophobic interactions. Accessible thiol groups were detected in the heat-treated systems, with a higher intensity at higher pH and increasing extent of aggregation. Intermolecular -S-S- bonding played only a minor role in the aggregation at all conditions studied.

Associations of dietary protein intake on subsequent decline in muscle mass and physical functions over four years in ambulant older Chinese people

OBJECTIVE

To examine the association of dietary protein intake with 4-year change in physical performance measures and muscle mass in Chinese community-dwelling older people aged 65 and older in Hong Kong.

DESIGN

Prospective cohort study design.

SETTING

Hong Kong, People's of Republic of China.

PARTICIPANTS

There were 2,726 (1411 male, 1315 female) community-dwelling older people aged 65 and older.

MEASUREMENTS

Baseline total, animal and vegetable protein intakes were collected using a validated food frequency questionnaire. Relative protein intake expressed as g/kg body weight was calculated and divided into quartiles for data analysis. Baseline and 4-year physical performance measures (normal and narrow 6-meters walking speed and step length in a 6-meters walk) were measured and 4-year change in appendicular skeletal muscle mass (ASM) from baseline was assessed by dual-energy X-ray absorptiometry. Univariate analysis identified age and sex as significant factors associated with change in physical performance measures or ASM, thus adjustments for these factors were made for subsequent analysis of covariance.

RESULTS

Median relative total protein intake was 1.3 g/kg body weight in men and 1.1 g/kg body weight in women. After adjustment for age and sex, relative total protein intake and animal protein intake were not associated with change in physical performance measures and ASM. In contrast, participants in the highest quartile (>0.72 g/kg body weight) of relative vegetable protein intake lost significantly less ASM over 4-year than those in the lowest quartile of relative vegetable protein intake (<=0.40 g/kg body weight) (adjusted mean ± SE: 0.270 ± 0.029 vs. 0.349 ± 0.030 kg, ptrend=0.025). There was no association between relative vegetable protein intake and change in physical performance measures.

CONCLUSIONS

Higher protein intake from vegetable source was associated with reduced muscle loss in Chinese community-dwelling older people in Hong Kong whereas no association between total and animal protein intake and subsequent decline in muscle mass or physical performance measures was observed in this sample.

Dietary protein and muscle in older persons

PURPOSE OF REVIEW

The purpose of this study is to highlight recent advances in nutrition and protein research that have the potential to improve health outcomes and status in ageing adults.

RECENT FINDINGS

The beneficial effects of dietary protein on muscle health in older adults continue to be refined. Recent research has bolstered support for moderately increasing protein consumption beyond the current Recommended Dietary Allowance by adopting a meal-based approach in lieu of a less specific daily recommendation. Results from muscle protein anabolism, appetite regulation and satiety research support the contention that meeting a protein threshold (approximately 30 g/meal) represents a promising strategy for middle-aged and older adults concerned with maintaining muscle mass while controlling body fat.

SUMMARY

Optimizing dietary protein intake to improve health requires a detailed consideration of topics including muscle protein anabolism, appetite control and satiety. Although each area of research continues to advance independently, recent collaborative and translational efforts have highlighted broad, translational consistencies related to the daily distribution and quantity of dietary protein.

A systematic review of malnutrition screening tools for the nursing home setting

RATIONALE

Malnutrition screening among nursing home residents is often performed with tools developed for use among older subjects, and sometimes with tools designed for an adult population. Only a few tools have been designed specifically for the nursing home setting. This systematic review assesses the criterion and predictive validity of malnutrition screening tools used in nursing homes.

METHODS

The databases MEDLINE, CINAHL, and EMBASE were searched on January 30, 2013, for manuscripts including search terms for malnutrition, screening or assessment tools, and setting. Articles were eligible for inclusion if they expressed criterion validity (how well can a tool assess nutritional status) or predictive validity (how well can a tool predict clinical outcome) of malnutrition screening tools in a nursing home population. Included were articles that had been published in the English, German, French, Dutch, Spanish, or Portuguese language.

RESULTS

The search yielded 8313 references. Of these, 24 met the inclusion criteria and were available; 2 extra manuscripts were retrieved by reference checking. Twenty tools were identified. Seventeen studies reported on criterion validity, and 9 on predictive validity. Four of the tools had been designed specifically for use in long term care. None of the tools, not even the ones specifically designed for the nursing home setting, performed (on average) better than "fair" in either assessing the residents' nutritional status or in predicting malnutrition-related outcomes.

CONCLUSION

The use of existing screening tools for the nursing home population carries limitations, as none performs better than "fair" in assessing nutritional status or in predicting outcome. Also, no superior tool can be pointed out. This systematic review implies that further considerations regarding malnutrition screening among nursing home residents are required.

Nutritional influences on age-related skeletal muscle loss

Age-related muscle loss impacts on whole-body metabolism and leads to frailty and sarcopenia, which are risk factors for fractures and mortality. Although nutrients are integral to muscle metabolism the relationship between nutrition and muscle loss has only been extensively investigated for protein and amino acids. The objective of the present paper is to describe other aspects of nutrition and their association with skeletal muscle mass. Mechanisms for muscle loss relate to imbalance in protein turnover with a number of anabolic pathways of which the mechanistic TOR pathway and the IGF-1–Akt–FoxO pathways are the most characterised. In terms of catabolism the ubiquitin proteasome system, apoptosis, autophagy, inflammation, oxidation and insulin resistance are among the major mechanisms proposed. The limited research associating vitamin D, alcohol, dietary acid–base load, dietary fat and anti-oxidant nutrients with age-related muscle loss is described. Vitamin D may be protective for muscle loss; a more alkalinogenic diet and diets higher in the anti-oxidant nutrients vitamin C and vitamin E may also prevent muscle loss. Although present recommendations for prevention of sarcopenia focus on protein, and to some extent on vitamin D, other aspects of the diet including fruits and vegetables should be considered. Clearly, more research into other aspects of nutrition and their role in prevention of muscle loss is required.

Patients requiring perioperative nutritional support

One of the most important factors affecting outcome and recovery from surgical trauma is preoperative nutritional status. Research in perioperative nutritional support has suffered from a lack of consensus as to the definition of malnutrition, no recognition of which nutrients are important to surgical healing, and a paucity of well-designed studies. In the past decade, there has been some activity to address this situation, recognizing the importance of nutrition as a therapy before surgery, after surgery, and possibly even during surgery.

The role of dietary protein intake in the prevention of sarcopenia of aging

Sarcopenia is defined as an age-related decrease in muscle mass and performance. Several consensus definitions of sarcopenia exist, each providing different cut points and methodologies for assessing muscle mass and muscle strength. Thus, wide variation in the prevalence of sarcopenia has been reported, generally ranging up to 45% for men and 26% for women. Risk factors for sarcopenia include age, malnutrition, and physical inactivity. Additional evidence suggests a protective role for protein supplementation in older adults to preserve lean body mass and prevent frailty, accepted intervention targets for reducing the risk of sarcopenia. Protein supplements vary widely in their composition, and small trials of heterogeneous study designs have made it difficult to extrapolate findings to develop data-driven, evidence-based recommendations for protein supplementation in sarcopenia prevention. Short-term randomized controlled trials of muscle protein synthesis have demonstrated that whey protein increases synthesis more so than casein or soy isolates. Studies also suggest that essential amino acids stimulate muscle protein synthesis to a greater extent than nonessential amino acids. This review summarizes the epidemiological and clinical trial evidence establishing the current definitions for sarcopenia and provides an overview of the state of the evidence for protein supplementation to prevent and/or mitigate sarcopenia.

Influence of aging on nitrogen accretion during critical illness

BACKGROUND

Aging adversely affects nitrogen accretion during health, but its effect during critical illness is unknown. Nitrogen balance (NB) response to varying protein intakes was compared between critically ill, older and younger patients.

METHODS

Adult patients admitted to the trauma intensive care unit, given enteral or parenteral nutrition, and who had a NB determination within 5-14 days after injury were evaluated. Patients with renal or hepatic disease were excluded. Patients were categorized as older (≥60 years) or younger (18-59 years of age). Data are given as mean ± SD or median [interquartile range].

RESULTS

Fifty-four older (69 [65, 77] years) and 195 younger (35 [27, 47] years) patients were evaluated. NB was blunted for the older patients with an observed trending improvement in NB from -13.5 ± 5.5 to -5.6 ± 8.8 g/d (P = NS) noted at 1.5-1.99 g/kg/d. NB improved from -22.2 ± 8.2 to -11.8 ± 9.9 g/d (P = .05) at 1-1.49 g/kg/d and modestly thereafter for each 0.5-g/kg/d increase in protein intake for the younger patients. Serum urea nitrogen concentration during the NB was highly variable but overall greater for the older patients (20 [14, 33] vs 15 [10, 20] mg/dL, P = .001).

CONCLUSIONS

Improvement in nitrogen accretion was blunted at lower protein intakes in critically ill, older patients compared with younger patients. Individualization of protein intake is warranted.

Effectiveness of exercise and protein supplementation intervention on body composition, functional fitness, and oxidative stress among elderly Malays with sarcopenia

Sarcopenia, characterized as muscle loss that occurs with aging, is a major health problem in an aging population, due to its implications on mobility, quality of life, and fall risk. Protein supplementation could improve the physical fitness by increasing protein anabolism, and exercise has a documented evidence of positive effect on functional status among the elderly. However, the combined effect of both protein supplementation and exercise has not been investigated among sarcopenic elderly in the Asian population. Thus, this study aimed to determine the effectiveness of exercise intervention and protein supplementation either alone or in combination for 12 weeks, on body composition, functional fitness, and oxidative stress among elderly Malays with sarcopenia. Sixty five sarcopenic elderly Malays aged 60–74 years were assigned to the control group, exercise group (ExG), protein supplementation group (PrG), or the combination of exercise and protein supplementation group. A significant interaction effect between body weight and body mass index (BMI) was observed, with the PrG (−2.1% body weight, −1.8% BMI) showing the highest reductions. Further, there was a decrease in % body fat (−4.5%) and an increase in fat-free mass (kg) (+5.7%) in the ExG after 12 weeks (P < 0.05). The highest increments in lower and upper body strength were observed in the PrG (73.2%) and ExG (47.6%), respectively. In addition, the ExG showed a reduction in superoxide dismutase (SOD) levels, and both interventions did not alter either lipid or protein oxidation. In conclusion, the exercise program was found to improve muscle strength and body composition, while protein supplementation reduced body weight and increased upper body strength, among sarcopenic elderly in Malaysia.

Muscle atrophy in aging and chronic diseases: is it sarcopenia or cachexia?

Cachexia and sarcopenia present several analogies in both the pathogenic mechanisms and the clinical picture. The loss of muscle mass and strength is a hallmark of these two clinical conditions. Although frequently overlapping and often indistinguishable, especially in old individuals, these two conditions should be considered distinct clinical entities. A prompt and accurate patient evaluation, guiding the physician through a proper differential diagnostic procedure and providing the best therapeutic options, is recommended. Given the several commonalities between cachexia and sarcopenia, it is likely that the therapeutic approaches may prove effective in both conditions. This review focuses on the most recent available literature and aims at providing physicians with the correct tools that are available to aid in diagnosing these two different entities that often clinically overlap. Currently available or proposed therapeutic strategies for pre-cachexia, cachexia and sarcopenia are also briefly described.

Management of protein-energy wasting in non-dialysis-dependent chronic kidney disease: reconciling low protein intake with nutritional therapy

Protein-energy wasting (PEW), characterized by a decline in body protein mass and energy reserves, including muscle and fat wasting and visceral protein pool contraction, is an underappreciated condition in early to moderate stages of chronic kidney disease (CKD) and a strong predictor of adverse outcomes. The prevalence of PEW in early to moderate CKD is ≥20-25% and increases as CKD progresses, in part because of activation of proinflammatory cytokines combined with superimposed hypercatabolic states and declines in appetite. This anorexia leads to inadequate protein and energy intake, which may be reinforced by prescribed dietary restrictions and inadequate monitoring of the patient's nutritional status. Worsening uremia also renders CKD patients vulnerable to potentially deleterious effects of uncontrolled diets, including higher phosphorus and potassium burden. Uremic metabolites, some of which are anorexigenic and many of which are products of protein metabolism, can exert harmful effects, ranging from oxidative stress to endothelial dysfunction, nitric oxide disarrays, renal interstitial fibrosis, sarcopenia, and worsening proteinuria and kidney function. Given such complex pathways, nutritional interventions in CKD, when applied in concert with nonnutritional therapeutic approaches, encompass an array of strategies (such as dietary restrictions and supplementations) aimed at optimizing both patients' biochemical variables and their clinical outcomes. The applicability of many nutritional interventions and their effects on outcomes in patients with CKD with PEW has not been well studied. This article reviews the definitions and pathophysiology of PEW in patients with non-dialysis-dependent CKD, examines the current indications for various dietary modification strategies in patients with CKD (eg, manufactured protein-based supplements, amino acids and their keto acid or hydroxyacid analogues), discusses the rationale behind their potential use in patients with PEW, and highlights areas in need of further research.

Percutaneous endoscopic gastrostomy (PEG) tube feeding of nursing home residents is not associated with improved body composition parameters

OBJECTIVES

To study differences in nutritional status and body composition, by feeding modality, among disabled nursing home residents.

DESIGN

A retrospective chart-review study.

SETTING

A nursing wing of a public urban geriatric center.

PARTICIPANTS

Three groups of patients: non-dysphagic, orally-fed dysphagic and percutaneous endoscopic gastrostomy -fed dysphagic patients.

INTERVENTION

Standard nursing care.

MEASUREMENTS

Basal metabolic rate, total energy expenditure and nitrogen balance under oral or percutaneous endoscopic gastrostomy feeding. Dietary intake was assessed during a 3-days period by daily-food intake protocols and a 24-hours urinary creatinine excretion to detect nitrogen balance and calculate body composition parameters.

RESULTS

Data of 117 patients (55.5% females), mean age 84.6±7.5 (range 66-98 years) was analyzed. Dysphagic patients (60) differed from non-dysphagic patients (57) by lower body mass index (p=0.020), fat mass index (p=0.017), daily protein intake (p<0.0001), daily energy intake (p<0.001), protein related energy intake (p<0.001) and a negative nitrogen balance (p<0.001). In regression analyses, dysphagia was associated with increased risk of having a body mass index lower than 22.0kg/m2 (OR=2.60, 95% CI 1.135-5.943), a negative nitrogen balance (OR=2.33, 95% CI 1.063-4.669), a low fat mass index (OR=2.53, 95% CI 1.066-6.007), and low daily protein and energy intakes per body weight (OR=2.87, 95% CI 1.316-6.268 and OR=2.99, 95% CI 1.297-6.880). Compared with orally-fed dysphagic patients (21pts.), percutaneous endoscopic gastrostomy -fed patients (39pts.) received an additional mean energy intake of 30.5% kcal per day and mean protein intake of 26.0%. This additional intake was not associated with improved body composition parameters (such as fat free mass, skeletal mass or body mass index).

CONCLUSION

Dysphagic nursing home residents are characterized by worse nutritional, metabolic and body composition parameters, compared with non-dysphagic residents. Body composition parameters did not differ between orally-fed and percutaneous endoscopic gastrostomy-fed dysphagic patients, despite significantly better nutritional and metabolic parameters in PEG-fed patients. Other approaches (perhaps physical training, pharmacological etc.) should be sought to improve body composition of such patients.

Glomerular filtration rate after a 12-wk resistance exercise program with post-exercise protein ingestion in community dwelling elderly

OBJECTIVE

Increased protein intake and resistance exercise can be beneficial for maintenance of lean body mass (LBM) in older adults. However, these factors could also negatively affect renal function. We investigated changes in renal function after a 12-wk resistance exercise program combined with protein supplementation in community dwelling older adults.

METHODS

Patients (N = 237, 73.7 ± 5.7 y, 58.2% female) participated in a 12-wk resistance exercise program (3 times/wk) designed to increase strength and muscle mass of major muscle groups. Participants were randomly assigned to one of three dietary supplements consumed directly after training: whey protein drink (20 g whey protein, 20 g carbohydrates), milk protein drink (20 g milk protein, 20 g carbohydrates), or carbohydrate drink (40 g carbohydrates). Renal function was estimated as glomerular filtration rate (GFR, Cockcroft-Gault formula), and dietary intake was measured as 3-d-weighed food record at baseline and endpoint.

RESULTS

During the intervention, energy intake did not increase. Carbohydrate intake increased in the carbohydrate group and protein intake increased in the milk group, both approximately in accordance with the supplementation. In the whey group, protein intake did not increase, but carbohydrate intake did. GFR increased after the intervention (+4.4 mL/min/1.73 m2; P < 0.001), and the changes were similar in men and women or in the age quartiles. Changes in GFR at endpoint were not associated with LBM, dietary supplements, or total protein intake.

CONCLUSIONS

A 12-wk resistance exercise program combined with protein supplementation in community dwelling older adults does not negatively affect GFR. The supplementation had only minor effects on total dietary intake.

Role of specific dietary amino acids in clinical conditions

In a variety of chronic and acute disease states, alterations in protein synthesis, breakdown and protein turnover rates occur that are related to the loss of body protein and skeletal muscle wasting. A key observation is the stimulation of protein breakdown in muscle and the stimulation of protein synthesis in the splanchnic area; mainly liver. An altered splanchnic extraction of amino acids as well as an anabolic resistance to dietary protein, related to stress, disuse and aging play a key role in the pathogenesis of muscle wasting in these conditions. To overcome these factors, specific dietary protein and amino acid diets have been introduced. The main focus of these diets is the quantity and quality of dietary proteins and whether a balanced mixture or solely dietary essential amino acids are required with or without higher intake levels of specific amino acids. Specifically in cancer patients, stimulated muscle protein synthesis has been obtained by increasing the amount of protein in a meal and by providing additional leucine. Also in other chronic diseases such as chronic obstructive pulmonary disease and cystic fibrosis, meals with specific dietary proteins and specific combinations of dietary essential amino acids are able to stimulate anabolism. In acute diseases, a special role for the amino acid arginine and its precursor citrulline as anabolic drivers has been observed. Thus, there is growing evidence that modifying the dietary amino acid composition of a meal will positively influence the net balance between muscle protein synthesis and breakdown, leading to muscle protein anabolism in a variety of chronic and acute disease states. Specific amino acids with anabolic potential are leucine, arginine and citrulline.

Dietary intake and physical performance in healthy elderly women: a 3-year follow-up

BACKGROUND

Aging is generally accompanied by changes in body composition, muscle mass and strength, leading to a decline in motor and functional performance. Physical activity and eating habits could be involved in modulating this paraphysiological deterioration. Aim of our study was to investigate changes in body composition, diet and physical performance in healthy, elderly females over a 3-year follow-up.

METHODS

92 healthy elderly females (70.9±4.0 years) attending a twice-weekly mild fitness program were eligible for the study. They were assessed at baseline and again after 3 years in terms of clinical history, diet, body composition by DEXA, resting energy expenditure, handgrip strength, knee extensor isometric/isotonic strength, and functional performance measured using the Short Physical Performance Battery (SPPB).

RESULTS

After 3 years, women had a significant decline in muscle strength (∆ isotonic: -1.4±4.3 kg, ∆ isokinetic: -2.0±6.3 kg, ∆ handgrip: -3.2±5.0 kg; p<0.001) and physical performance (∆ walking time: 0.71±0.9 s, ∆ walking speed: -0.25±0.35 m/s; p<0.001), while their weight and body composition parameters did not change, except for a small decrease in appendicular skeletal muscle mass (-0.4±1.4 kg). There was a significant drop in calorie (∆:-345.7±533.1 kcal/d; p<0.001) and protein intake (∆:-0.14±0.23 g/d; p<0.001), while resting energy expenditure remained stable. ∆ calorie intake correlated with the variation in 4-meter walking time (r: 0.34; p<0.01).

CONCLUSIONS

With advancing age, physical performance declines even in healthy, fit females despite a spare of weight and body composition. This decline in physical activity could lead to a lower calorie intake, which would explain why there is no variation in body weight.