madman
Super Moderator
The Effects of Cow-Milk Protein Supplementation in Elderly Population: Systematic Review and Narrative Synthesis
Abstract
Background
To review the currently available evidence on the effect of cow-milk protein supplementation (CPS) on health in the elderly.
Methods
Five electronic databases (Pubmed, Web of Science, Embase, Cochrane Library, ClinicalTrials.gov) were searched for studies about CPS among older people. All types of publications were included, with the exception of systematic reviews, meta-analyses, opinion letters, editorials, case reports, conference abstracts, and comments. An additional search in Google Scholar and a manual review of the reference lists were performed.
Results
Overall, 103 studies were included. Several studies explored the role of CPS in the preservation or improvement of muscle mass among healthy subjects (40 studies) and pre-frail, frail or sarcopenic patients (14), with evidence of beneficial effects. Other studies assessed the effect of CPS on bones (12), cardiovascular disease (8), inflame-aging (7), chronic pulmonary disease (4), neurocognitive function (4), and vaccines (2), with weak evidence of positive effects. Seven studies in the field of protein metabolism investigated the role of CPS as an important contributor to nutritional needs. Other investigational areas are considered in the last five studies.
Conclusions
The beneficial effects of CPS in achieving age-related nutritional goals, preserving muscle mass, and in recovering after hospitalization may be particularly relevant in the elderly.
Aging is a plastic process, and it may affect nutritional requirements [9,10]. For example, basic science studies demonstrated that protein metabolism in the elderly is characterized by a high splanchnic extraction and a declining anabolic response to ingested proteins [11]. Lifestyle factors, such as high-quality diet, physical activity, little or no alcohol consumption, and smoking avoidance, can influence the quality of aging, improving well-being throughout the life span [9]. Taking into account these findings, the European Union Geriatric Medicine Society (EUGMS), in cooperation with other scientific organizations, appointed an international study group to review dietary protein needs with aging (PROT-AGE Study Group) [11]. According to the PROT-AGE position paper, recommendations for dietary protein intake in healthy older adults are as follows:
• average protein intake for older people should range from 1.0 to 1.2 g/kg of body weight per day (while in young adults, the recommended intake is about 0.7–0.8 g/kg/day) [12];
• it must be taken into account that the feeding-associated anabolic threshold for dietary protein is higher in the elderly than in younger subjects, with the amount of protein required to reach it from a variety of foods being in the order of 25–30 g of protein per meal;
• dietary recommendations for protein intake in the elderly should consider, beyond quantity, also quality, protein source, and timing of intake;
• best protein sources are rich in leucine;
• oral supplementation should be considered when dietary protein intake does not reach the recommended goals [11].
Sources of animal proteins, such as meat, fish, and poultry, are excellent for their essential amino-acid content, but their consumption may be impaired in the elderly, because of poor dentition, reduced appetite, or even anorexia, solid dysphagia, taste alteration, cost, and, when mobility is reduced, barriers in shopping and cooking [13,14]. Legumes and pulses are even good protein sources but may enhance gastrointestinal functional disorders, such as slow gastric emptying, bloating, abdominal distention, and diarrhea [15]. Dairy foods are rich in leucine, and they are available in many different forms, even soft and enriched with probiotics, but the weekly amount is usually restricted to 2–3 servings (excluding milk and yogurt), due to their fat content [16].
There is a large variety of protein oral supplements, mainly based on soy or cow milk sources [17]. Among the latter, whey proteins (WP), a by-product of cheese making, should be regarded as one of the best sources for oral protein supplementation, for their high leucine content, fast digestibility, and amino-acid availability (demonstrated in both young and old subjects) [18,19].
5. Conclusions
Our systematic literature review supports the evidence of a beneficial effect of cow-milk protein supplementation among old people. Evidence of beneficial effects is stronger for whey protein supplementation. Several health outcomes are reported with respect to milk proteins: the achievement of nutritional age-related goals, muscle mass preservation, and functionality, prevention, and treatment of sarcopenia, modulation of inflammation, response to vaccinations, and rehabilitation after hospitalization.
Abstract
Background
To review the currently available evidence on the effect of cow-milk protein supplementation (CPS) on health in the elderly.
Methods
Five electronic databases (Pubmed, Web of Science, Embase, Cochrane Library, ClinicalTrials.gov) were searched for studies about CPS among older people. All types of publications were included, with the exception of systematic reviews, meta-analyses, opinion letters, editorials, case reports, conference abstracts, and comments. An additional search in Google Scholar and a manual review of the reference lists were performed.
Results
Overall, 103 studies were included. Several studies explored the role of CPS in the preservation or improvement of muscle mass among healthy subjects (40 studies) and pre-frail, frail or sarcopenic patients (14), with evidence of beneficial effects. Other studies assessed the effect of CPS on bones (12), cardiovascular disease (8), inflame-aging (7), chronic pulmonary disease (4), neurocognitive function (4), and vaccines (2), with weak evidence of positive effects. Seven studies in the field of protein metabolism investigated the role of CPS as an important contributor to nutritional needs. Other investigational areas are considered in the last five studies.
Conclusions
The beneficial effects of CPS in achieving age-related nutritional goals, preserving muscle mass, and in recovering after hospitalization may be particularly relevant in the elderly.
Aging is a plastic process, and it may affect nutritional requirements [9,10]. For example, basic science studies demonstrated that protein metabolism in the elderly is characterized by a high splanchnic extraction and a declining anabolic response to ingested proteins [11]. Lifestyle factors, such as high-quality diet, physical activity, little or no alcohol consumption, and smoking avoidance, can influence the quality of aging, improving well-being throughout the life span [9]. Taking into account these findings, the European Union Geriatric Medicine Society (EUGMS), in cooperation with other scientific organizations, appointed an international study group to review dietary protein needs with aging (PROT-AGE Study Group) [11]. According to the PROT-AGE position paper, recommendations for dietary protein intake in healthy older adults are as follows:
• average protein intake for older people should range from 1.0 to 1.2 g/kg of body weight per day (while in young adults, the recommended intake is about 0.7–0.8 g/kg/day) [12];
• it must be taken into account that the feeding-associated anabolic threshold for dietary protein is higher in the elderly than in younger subjects, with the amount of protein required to reach it from a variety of foods being in the order of 25–30 g of protein per meal;
• dietary recommendations for protein intake in the elderly should consider, beyond quantity, also quality, protein source, and timing of intake;
• best protein sources are rich in leucine;
• oral supplementation should be considered when dietary protein intake does not reach the recommended goals [11].
Sources of animal proteins, such as meat, fish, and poultry, are excellent for their essential amino-acid content, but their consumption may be impaired in the elderly, because of poor dentition, reduced appetite, or even anorexia, solid dysphagia, taste alteration, cost, and, when mobility is reduced, barriers in shopping and cooking [13,14]. Legumes and pulses are even good protein sources but may enhance gastrointestinal functional disorders, such as slow gastric emptying, bloating, abdominal distention, and diarrhea [15]. Dairy foods are rich in leucine, and they are available in many different forms, even soft and enriched with probiotics, but the weekly amount is usually restricted to 2–3 servings (excluding milk and yogurt), due to their fat content [16].
There is a large variety of protein oral supplements, mainly based on soy or cow milk sources [17]. Among the latter, whey proteins (WP), a by-product of cheese making, should be regarded as one of the best sources for oral protein supplementation, for their high leucine content, fast digestibility, and amino-acid availability (demonstrated in both young and old subjects) [18,19].
5. Conclusions
Our systematic literature review supports the evidence of a beneficial effect of cow-milk protein supplementation among old people. Evidence of beneficial effects is stronger for whey protein supplementation. Several health outcomes are reported with respect to milk proteins: the achievement of nutritional age-related goals, muscle mass preservation, and functionality, prevention, and treatment of sarcopenia, modulation of inflammation, response to vaccinations, and rehabilitation after hospitalization.
