Protein requirements in healthy adults: a meta-analysis of nitrogen balance studies

Rational Use of Protein Supplements in the Elderly-Relevance of Gastrointestinal Mechanisms

Protein supplements are increasingly used by older people to maintain nutrition and prevent or treat loss of muscle function. Daily protein requirements in older people are in the range of 1.2 gm/kg/day or higher. Many older adults do not consume this much protein and are likely to benefit from higher consumption. Protein supplements are probably best taken twice daily, if possible soon after exercise, in doses that achieve protein intakes of 30 gm or more per episode. It is probably not important to give these supplements between meals, as we have shown no suppressive effects of 30 gm whey drinks, and little if any suppression of 70 gm given to older subjects at varying time intervals from meals. Many gastrointestinal mechanisms controlling food intake change with age, but their contributions to changes in responses to protein are not yet well understood. There may be benefits in giving the supplement with rather than between meals, to achieve protein intakes above the effective anabolic threshold with lower supplement doses, and have favourable effects on food-induced blood glucose increases in older people with, or at risk of developing, type 2 diabetes mellitus; combined protein and glucose drinks lower blood glucose compared with glucose alone in older people.

Dose-response relationship between protein intake and muscle mass increase: a systematic review and meta-analysis of randomized controlled trials

CONTEXT

Lean body mass is essential for health, yet consensus regarding the effectiveness of protein interventions in increasing lean body mass is lacking.

OBJECTIVE

The aim of this systematic review was to evaluate the dose-response relationship of the effects of protein intake on lean body mass.

DATA SOURCES

The PubMed and Ichushi-Web databases were searched electronically, and reference lists of the literature included here and in other meta-analyses were searched manually.

STUDY SELECTION

Randomized controlled trials evaluating the effects of protein intake on lean body mass were included.

DATA EXTRACTION

Two authors independently screened the abstracts; 5 reviewed the full texts.

RESULTS

A total of 5402 study participants from 105 articles were included. In the multivariate spline model, the mean increase in lean body mass associated with an increase in protein intake of 0.1 g/kg of body weight per day was 0.39 kg (95%CI, 0.36-0.41) and 0.12 kg (95%CI, 0.11-0.14) below and above the total protein intake of 1.3 g/kg/d, respectively.

CONCLUSIONS

These findings suggest that slightly increasing current protein intake for several months by 0.1 g/kg/d in a dose-dependent manner over a range of doses from 0.5 to 3.5 g/kg/d may increase or maintain lean body mass.

SYSTEMATIC REVIEW REGISTRATION

UMIN registration number UMIN000039285.

Issues in Measuring and Interpreting Energy Balance and Its Contribution to Obesity

PURPOSE OF REVIEW

Obesogenic environment challenges individuals' ability to preserve energy homeostasis, leading to weight gain. To understand how this energy imbalance proceeds, several methods and analytical procedures to determine energy intake and expenditure are currently available. However, these methods and procedures are not exempt from issues that may lead to equivocal conclusions. Our purpose herein is to discuss major issues involved in energy balance assessment.

RECENT FINDINGS

Measurement of energy intake mostly relies on self-report methods that provide inaccurate data. In contrast, determination of energy expenditure is more accurate as long as methodological and analytical issues are correctly addressed. Accurate measurements of energy expenditure can be obtained with the current methods once issues in measuring and interpreting data are correctly addressed. However, development of new technologies to measure energy intake is imperative to further understand the small and chronic energy imbalance leading to obesity.

Revised Reference Values for the Intake of Protein

BACKGROUND

Following a timely update process, the nutrition societies of Germany, Austria, and Switzerland (D-A-CH) revised the reference values for the intake of protein in 2017. The Working Group conducted a structured literature search in PubMed considering newly published papers (2000- 2017).

SUMMARY

For infants < 4 months, the estimated values were set based on the protein intake via breast milk. Reference values for infants > 4 months, children, adolescents, pregnant, and lactating women were calculated using the factorial method considering both requirement for growth and maintenance. For adults, reference values were derived from nitrogen balance studies; for seniors (> 65 years), reports on metabolic and functional parameters under various protein intakes were additionally considered. Reference -values (g protein/kg body weight per day) were set as follows: infants  < 4 months: 2.5-1.4, children: 1.3-0.8, adults < 65 years: 0.8, adults > 65 years: 1.0. Key Messages: The reference values for infants, children, adolescents, and adults < 65 years are essentially unchanged compared to recently published values. Scientifically reliable data published between 2000 and 2017 guided the D-A-CH Working Group to set a higher estimated value for adults > 65 years. Since the energy consumption continuously decreases with age, this new estimated protein intake value might be a challenge for the introduction of food-based nutrition concepts for older people.