Dietary protein and bone health across the life-course: an updated systematic review and meta-analysis over 40 years

Comprehensive review on collagen extraction from food by-products and waste as a value-added material

The consumption of animal products has witnessed a significant increase over the years, leading to a growing need for industries to adopt strict waste control measures to mitigate environmental impacts. The disposal of animal waste in landfill can result in diverse and potentially hazardous decomposition by-products. Animal by-products, derived from meat, poultry, seafood and fish industries, offer a substantial raw material source for collagen and gelatin production due to their high protein content. Collagen, being a major protein component of animal tissues, represents an abundant resource that finds application in various chemical and material industries. The demand for collagen-based products continues to grow, yet the availability of primary material remains limited and insufficient to meet projected needs. Consequently, repurposing waste materials that contain collagen provides an opportunity to meet this need while at the same time minimizing the amount of waste that is dumped. This review examines the potential to extract value from the collagen content present in animal-derived waste and by-products. It provides a systematic evaluation of different species groups and discusses various approaches for processing and fabricating repurposed collagen. This review specifically focuses on collagen-based research, encompassing an examination of its physical and chemical properties, as well as the potential for chemical modifications. We have detailed how the research and knowledge built on collagen structure and function will drive the new initiatives that will lead to the development of new products and opportunities in the future. Additionally, it highlights emerging approaches for extracting high-quality protein from waste and discusses efforts to fabricate collagen-based materials leading to the development of new and original products within the chemical, biomedical and physical science-based industries.

Nutrition and Osteoporosis Prevention

PURPOSE OF REVIEW

Osteoporosis affects 50% of women and 20% of men after the age of 50. Fractures are associated with significant morbidity, increased mortality and altered quality of life. Lifestyle measures for fragility fracture prevention include good nutrition including adequate protein and calcium intakes, vitamin D sufficiency, and regular weight bearing physical exercise.

RECENT FINDINGS

Dietary protein is one of the most important nutritional considerations as it affects bone mineral density, trabecular and cortical microstructure, and bone strength. When calcium intake is sufficient, higher dietary protein intake is associated with lower risk of fracture. Dairy products are a valuable source of calcium and high quality protein. Dairy product consumption, particularly fermented dairy products, are associated with a lower risk of hip fracture and vegan diets are associated with increased fracture risk. Other dietary factors associated with reduced fracture risk include at least 5 servings per day of fruits and vegetables, regular tea drinking, adherence to a Mediterranean diet and other dietary patterns which provide fibers, polyphenols and fermented dairy products. Such dietary patterns may confer health benefits through their effect on gut microbiota composition and/or function. A balanced diet including minerals, protein, fruits and vegetables is an important element in the prevention of osteoporosis and of fragility fracture.

Meat consumption and the risk of hip fracture in women and men: two prospective Swedish cohort studies

PURPOSE

To study the association between meat intake (predominantly red and processed meats) and the risk of hip fracture, as well as the association between meat intake and biomarkers of inflammation, oxidative stress, bone turnover, body composition, and bone mineral density (BMD).

METHODS

Data from the Swedish Mammography Cohort and the Cohort of Swedish men (n = 83,603, 54% men) with repeated investigations and their respective clinical sub-cohorts was utilised. Incident hip fractures were ascertained through individual linkage to registers. Associations were investigated using multivariable Cox and linear regression analyses.

RESULTS

During up to 23 years of follow-up (mean 18.2 years) and 1,538,627 person-years at risk, 7345 participants (2840 men) experienced a hip fracture. Each daily serving of meat intake conferred a hazard ratio (HR) of 1.03 (95% confidence interval [CI] 1.00; 1.06) for hip fracture. In quintile 5, compared to quintile 2, the HR was 1.11 (95% CI 1.01; 1.21) among all participants. In the sub-cohorts, meat intake was directly associated with circulating levels of interleukin-6, C-reactive protein, leptin, ferritin, parathyroid hormone, and calcium.

CONCLUSION

A modest linear association was found between a higher meat intake and the risk of hip fractures. Our results from the sub-cohorts further suggest that possible mechanisms linking meat intake and hip fracture risk may be related to the regulation of bone turnover, subclinical inflammation, and oxidative stress. Although estimates are modest, limiting red and processed meat intake in a healthy diet is advisable to prevent hip fractures.

High-Protein Diets during either Resistance or Concurrent Training Have No Detrimental Effect on Bone Parameters in Resistance-Trained Males

BACKGROUND

The effects of combining resistance training (RT) and concurrent training (CT; resistance + endurance training) with varied protein doses on bone measures remain poorly understood. Hence, we conducted a comparison of the impacts of two high-protein diets (1.6 or 3.2 g kg-1 d-1) over 16 weeks in resistance-trained males, either with CT or RT alone.

METHODS

A total of forty-eight males, all of whom were resistance-trained, had the following demographics: 26.6 ± 6 years, body mass index: 25.6 ± 2.9 kg m-2 administered either 3.2 g kg-1 d-1 protein (CT2; n = 12; RT2; n = 12) or 1.6 g kg-1 d-1 protein (CT1; n = 12; RT1; n = 12) during 16 weeks (four sessions·w-1). Bone parameters were assessed pre- and post-intervention.

RESULTS

There was no significant interaction between the intervention group and time for the legs, arms, ribs, or pelvis area BMC and BMD (p > 0.05). For the BMD of the pelvis and the BMC of the right ribs, however, there were significant time effects noted (p < 0.05). Furthermore, there was a significant interaction between the intervention group and time in the lumbar and thoracic spines, with a particular time effect noted for the thoracic spine region (p < 0.05). The regional differences in skeletal responses to the intervention are highlighted by these data.

CONCLUSION

Our findings show that the intake of two high-protein diets combined with RT and CT during 16 weeks had no adverse effects on bone tissue parameters. While these findings indicate that protein intake between 2 and 3 times the current RDI does not promote bone demineralization when consumed in conjunction with exercise, future studies investigating the long-term effects of chronic high protein intake on bone tissue health are warranted.

Effects of partial replacement of red and processed meat with non-soya legumes on bone and mineral metabolism and amino acid intakes in BeanMan randomised clinical trial

The transition towards more plant-based diets may pose risks for bone health such as low vitamin D and Ca intakes. Findings for the contribution of animal and plant proteins and their amino acids (AA) to bone health are contradictory. This 6-week clinical trial aimed to investigate whether partial replacement of red and processed meat (RPM) with non-soya legumes affects AA intakes and bone turnover and mineral metabolism in 102 healthy 20-65-year-old men. Participants were randomly assigned to diet groups controlled for RPM and legume intake (designed total protein intake (TPI) 18 E%): the meat group consumed 760 g RPM per week (25 % TPI) and the legume group consumed non-soya legume-based products (20 % TPI) and 200 g RPM per week, the upper limit of the Planetary Health Diet (5 % TPI). No differences in bone (bone-specific alkaline phosphatase; tartrate-resistant acid phosphatase 5b) or mineral metabolism (25-hydroxyvitamin D; parathyroid hormone; fibroblast growth factor 23; phosphate and Ca) markers or Ca and vitamin D intakes were observed between the groups (P > 0·05). Methionine and histidine intakes were higher in the meat group (P ≤ 0·042), whereas the legume group had higher intakes of arginine, asparagine and phenylalanine (P ≤ 0·013). Mean essential AA intakes in both groups met the requirements. Increasing the proportion of non-soya legumes by reducing the amount of RPM in the diet for 6 weeks did not compromise bone turnover and provided on average adequate amounts of AA in healthy men, indicating that this ecologically sustainable dietary change is safe and relatively easy to implement.

Association between total and animal proteins with risk of fracture: A systematic review and dose-response meta-analysis of cohort studies

Previous cohort studies have indicated that consumption of total and animal proteins are related to fracture risk; however, results were inconclusive. This dose-dependent review sought to summarize the earlier evidence regarding the relation between total and animal proteins and fracture risk. We searched Scopus, PubMed, and Web of Science until July 2023 for original research articles examining the association of certain types of proteins and the incidence of all fractures in general adults. Summary relative risks (RRs) were calculated using random effects analysis to examine the relation between each certain amount (g/day) increment of total and animal protein and fracture risk. Twenty cohort studies with serious to moderate risk of bias involving 780,322 individuals were included. There was a non-statistically significant relation between intake of animal proteins and dairy products and all fracture risk. However, 43% and 5% decreased incidence of fracture was obtained with total protein (RR, 0.57; 95%CI, 0.36 to 0.93; per 100 g/day) and fish (RR, 0.95; 95%CI, 0.91 to 0.99; per 15 g/day) intake. Every 100 g/day total and animal protein consumption and every 15 g/day fish consumption were linked to 48%, 50%, and 5% lower hip fracture risk. Greater dietary animal protein intake might reduce risk of hip but not fracture at any site. We obtained a lower risk of any or hip fracture with greater total protein (per 100 g/day) and fish (per 15 g/day) intake. No evidence was obtained that higher intake of dairy could decrease risk of fracture.

Nutritional strategies to optimise musculoskeletal health for fall and fracture prevention: Looking beyond calcium, vitamin D and protein

Falls and osteoporotic fractures are a major public health problem, particularly among older adults. A third of individuals aged 65 years and over fall at least once each year, with up to 20 % of these resulting in serious injury, including fracture. In conjunction with regular exercise, the importance of diet for musculoskeletal health has largely focused upon calcium, vitamin D, and protein, particularly in the context of preventing falls and fractures. Whilst there is evidence for the benefits of these nutrients for musculoskeletal health, other aspects of the diet remain largely underexplored. For example, vegetables are rich sources of macro- and micronutrients that are essential for muscle function and bone health, which are key factors in the prevention of falls and fractures. Recent work has highlighted the importance of nutrients such as vegetable-derived nitrate and vitamin K1 in optimising muscle strength, physical function, and bone quality. In the context of dietary patterns, vegan/plant-based diets have recently gained popularity due to perceived health benefits, animal welfare, or to tackle climate change. The elimination and/or substitution of animal-based products for plant foods (without careful planning and/or expert dietary guidance) could, however, have long-term negative musculoskeletal consequences; a trend uncovered by recent evidence. Within the overarching theme of nutrition for fall and fracture prevention in older populations, the aim of this review is to (i) summarise the current evidence for calcium, vitamin D and protein; (ii) describe the importance of vegetables and selected nutrients, such as nitrate and vitamin K1, for muscle function and bone structural integrity; and (iii) highlight current evidence around different dietary patterns (e.g., plant-based, diet quality, data driven approaches) and their impact on musculoskeletal health.

The skeletal safety of milk-derived proteins: A meta-analysis of randomized controlled trials

PURPOSE

There has been a persistent claim that dairy products contain calcium-leaching proteins, although the soundness of such a claim has been challenged. A meta-analysis of randomized controlled trials (RCTs) on the effects of milk-derived protein supplementation on bone health indices in adults was performed to reconcile the controversy surrounding the potential skeletal safety concerns of proteins of dairy origin.

METHODS

The PubMed and Web of Science databases were searched for relevant RCTs. A random-effects model was used to generate pooled effect sizes and 95% confidence intervals.

RESULTS

Milk-derived protein supplementation did not significantly affect whole-body BMD (n = 7 RCTs) and BMD at the lumbar spine (n = 10), hip (n = 8), femoral neck (n = 9), trochanter (n = 5), intertrochanter (n = 2), and ultradistal radius (n = 2). The concentrations of bone formation markers (bone-specific alkaline phosphatase [n = 11], osteocalcin [n = 6], procollagen type 1 amino-terminal propeptide [n = 5]), bone resorption markers (N-terminal telopeptide of type 1 collagen [n = 7], C-terminal telopeptide of type 1 collagen [n = 7], deoxypyridinoline [n = 4]), and parathyroid hormone (n = 7) were not significantly affected. However, increased insulin-like growth factor-1 (IGF-1) concentrations (n = 13) were observed. Reduced IGF-1 concentrations were observed when soy protein was used as a comparator, and increased IGF-1 concentrations were observed when carbohydrate was used.

CONCLUSION

Our findings do not support the claim that proteins of dairy origin are detrimental to bone health.

The Influences of Macronutrients on Bone Mineral Density, Bone Turnover Markers, and Fracture Risk in Elderly People: A Review of Human Studies

Osteoporosis is a health condition that involves weak bone mass and a deteriorated microstructure, which consequently lead to an increased risk of bone fractures with age. In elderly people, a fracture attributable to osteoporosis elevates mortality. The objective of this review was to examine the effects of macronutrients on bone mineral density (BMD), bone turnover markers (BTMs), and bone fracture in elderly people based on human studies. A systematic search was conducted in the PubMed®/MEDLINE® database. We included human studies published up to April 2023 that investigated the association between macronutrient intake and bone health outcomes. A total of 11 meta-analyses and 127 individual human studies were included after screening the records. Carbohydrate consumption seemed to have neutral effects on bone fracture in limited studies, but human studies on carbohydrates' effects on BMD or/and BTMs are needed. The human studies analyzed herein did not clearly show whether the intake of animal, vegetable, soy, or milk basic proteins has beneficial effects on bone health due to inconsistent results. Moreover, several individual human studies indicated an association between eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and osteocalcin. Further studies are required to draw a clear association between macronutrients and bone health in elderly people.

Sarcopenia, osteoporosis and frailty

Muscles and bones are intricately connected tissues displaying marked co-variation during development, growth, aging, and in many diseases. While the diagnosis and treatment of osteoporosis are well established in clinical practice, sarcopenia has only been classified internationally as a disease in 2016. Both conditions are associated with an increased risk of adverse health outcomes such as fractures, dysmobility and mortality. Rather than focusing on one dimension of bone or muscle mass or weakness, the concept of musculoskeletal frailty captures the overall loss of physiological reserves in the locomotor system with age. The term osteosarcopenia in particular refers to the double jeopardy of osteoporosis and sarcopenia. Muscle-bone interactions at the biomechanical, cellular, paracrine, endocrine, neuronal or nutritional level may contribute to the pathophysiology of osteosarcopenia. The paradigm wherein muscle force controls bone strength is increasingly facing competition from a model centering on the exchange of myokines, osteokines and adipokines. The most promising results have been obtained in preclinical models where common drug targets have been identified to treat these conditions simultaneously. In this narrative review, we critically summarize the current understanding of the definitions, epidemiology, pathophysiology, and treatment of osteosarcopenia as part of an integrative approach to musculoskeletal frailty.

Protein intake and bone health: an umbrella review of systematic reviews for the evidence-based guideline of the German Nutrition Society

This umbrella review aimed at assessing whether a protein intake exceeding the current recommendation for younger (0.8 g/kg body weight [BW]/day) and older (1.0 g/kg BW/day) adults affects bone mineral density and fracture risk. Moreover, the effect of animal or plant protein was evaluated. A systematic literature search was conducted in PubMed, Embase, and Cochrane Database of Systematic Reviews for systematic reviews (SRs) with or without meta-analysis of prospective studies published between 11/2008 and 08/2021. Methodological quality, outcome-specific certainty of evidence, and overall certainty of evidence of the retrieved SRs were assessed using established tools and predefined criteria. Eleven SRs of randomized controlled trials (RCTs) and/or cohort studies were included. In SRs of cohort studies and RCTs, protein intake/kg BW/day ranged between 0.21-0.95 g (low intake) and > 1.24 g (high intake), respectively, and between 0.67-1.1 g (control groups) and 1.01-1.69 g (intervention groups), respectively. The vast majority of outcome-specific certainty of evidence was rated "low" or "very low." The overall certainty of evidence for an association (cohort studies) or effect (RCTs) of total, animal or plant protein intake on each of the investigated outcomes was rated "insufficient," with the exception of possible evidence for a reduced hip fracture risk by high vs. low protein intake. Since protein intakes in low/control and high/intervention groups were very heterogeneous and with low certainty of evidence, it remains unclear whether a dose above the current recommendation or type of protein intake (animal or plant protein) affects bone health overall. However, there is possible evidence for reduced hip fracture risk with high versus low protein intake.

Increased Dietary Intakes of Total Protein, Animal Protein and White Meat Protein Were Associated with Reduced Bone Loss—A Prospective Analysis Based on Guangzhou Health and Nutrition Cohort, South China

In this study, we aimed to prospectively investigate the relationships between different types of dietary protein and changes in bone mass in Chinese middle-aged and elderly people. Dietary intakes were evaluated by means of a validated food frequency questionnaire. Bone mineral density (BMD) was measured using a dual-energy bone densitometer at multiple bone sites. Multivariable regression models were applied to investigate the associations of the participants’ dietary intakes of total protein, intakes of protein from various sources, and amino acid intakes with the annualized changes in BMD during a 3-year follow-up. A total of 1987 participants aged 60.3 ± 4.9 years were included in the analyses. Multivariable linear regression results showed that dietary intakes of total protein, animal protein, and protein from white meat were positively correlated with BMD changes, with standardized coefficients (β) of 0.104, 0.073, and 0.074 at the femur neck (p < 0.01) and 0.118, 0.067, and 0.067 at the trochanter (p < 0.01), respectively. With each increase of 0.1g·kg−1·d−1 in animal protein and white meat protein intakes, the BMD losses were reduced by 5.40 and 9.24 mg/cm2 at the femur neck (p < 0.05) and 1.11 and 1.84 mg/cm2 at the trochanter (p < 0.01), respectively. Our prospective data, obtained from Chinese adults, showed that dietary total and animal protein, especially protein from white meat, could significantly reduce bone loss at the femur neck and trochanter.

The Metabolic Features of Osteoblasts: Implications for Multiple Myeloma (MM) Bone Disease

The study of osteoblast (OB) metabolism has recently received increased attention due to the considerable amount of energy used during the bone remodeling process. In addition to glucose, the main nutrient for the osteoblast lineages, recent data highlight the importance of amino acid and fatty acid metabolism in providing the fuel necessary for the proper functioning of OBs. Among the amino acids, it has been reported that OBs are largely dependent on glutamine (Gln) for their differentiation and activity. In this review, we describe the main metabolic pathways governing OBs' fate and functions, both in physiological and pathological malignant conditions. In particular, we focus on multiple myeloma (MM) bone disease, which is characterized by a severe imbalance in OB differentiation due to the presence of malignant plasma cells into the bone microenvironment. Here, we describe the most important metabolic alterations involved in the inhibition of OB formation and activity in MM patients.

Bone fragility during the COVID-19 pandemic: the role of macro- and micronutrients

Bone fragility is the susceptibility to fracture due to poor bone strength. This condition is usually associated with aging, comorbidities, disability, poor quality of life, and increased mortality. International guidelines for the management of patients with bone fragility include a nutritional approach, mainly aiming at optimal protein, calcium, and vitamin D intakes. Several biomechanical features of the skeleton, such as bone mineral density (BMD), trabecular and cortical microarchitecture, seem to be positively influenced by micro- and macronutrient intake. Patients with major fragility fractures are usually poor consumers of dairy products, fruit, and vegetables as well as of nutrients modulating gut microbiota. The COVID-19 pandemic has further aggravated the health status of patients with skeletal fragility, also in terms of unhealthy dietary patterns that might adversely affect bone health. In this narrative review, we discuss the role of macro- and micronutrients in patients with bone fragility during the COVID-19 pandemic.

Dietary recommendations in the prevention and treatment of osteoporosis

INTRODUCTION

This article presents the initial recommendations of the French Rheumatology Society (Société Française de Rhumatologie - SFR) and the Osteoporosis Research and Information Group (Groupe de Recherche et d'Informations sur les Ostéoporoses - GRIO) on the role of diet in the prevention and treatment of osteoporosis.

METHODS

The recommendations were produced by a working group composed of rheumatologists, physician nutrition specialists and a geriatrician. Fifteen (15) questions pertaining to "daily practices" were preselected by the working group. For the literature review, the working group focussed mainly on the effects of diet on bone mineral density (BMD) and fractures, and primarily on meta-analyses of longitudinal studies and dietary intervention studies.

RESULTS

A Mediterranean-type diet and the daily consumption of 2 to 3 dairy products are recommended. Together, these provide the calcium and "high quality" protein required to maintain a normal calcium-phosphorus balance and bone metabolism, and are associated with lower fracture risk. Conversely, unbalanced Western diets, vegan diets, weight-loss diets in non-overweight individuals, alcohol consumption and daily consumption of sodas are advised against. In terms of the beneficial effects on bone mineral density and fracture risk, current scientific data are either insufficient or too divergent to recommend increasing or restricting the consumption of tea or coffee, vitamins other than vitamin D, vitamin D-enriched or phytoestrogen-rich foods, calcium-enriched plant-based beverages, oral nutritional supplements, or dietary sources of prebiotics and probiotics.

CONCLUSIONS

These are the first set of recommendations addressing the role of diet in the prevention and treatment of osteoporosis. More research is necessary to direct and support guidelines.

Fracture Risk in Vegetarians and Vegans: the Role of Diet and Metabolic Factors

PURPOSE OF REVIEW

There is strong evidence that poor dietary intake of certain micro- and macro-nutrients can negatively affect bone health. It is unclear if diet is the primary culprit for poor bone health in the vegan population.

RECENT FINDINGS

Plant-based diets are gaining public interest since they may improve metabolic health. Studies that examine vegetarians and vegans together show a lower bone mineral density (BMD), but not always increased fracture risk compared to omnivores. However, vegans consistently have higher risk of fracture at multiple bone sites, especially at the hip. There is higher fracture risk in vegans which may be due to calcium and vitamin D intake, as well as amount of dietary protein and quality. Other nutrients (B vitamins, Se, Zn, Fe, iodine) or physiological factors (lower body mass index, microbiome, or endocrine profile) may also play a role but have not been examined and require further study.

Modifiable risk factors for bone health & fragility fractures

Osteoporosis is an ageing disorder characterised by poor microstructural architecture of the bone and an increase in the risk of fragility fractures, which often leads to hospitalisation and eventually a loss of mobility and independence. By 2050, it is estimated that more than 30 million people in Europe will be affected by bone diseases, and European hospitalisation alone can approximately cost up to 3.5 billion euros each year [1]. Although inherited variation in bone mineral density (BMD) is pre-determined by up to 85% [2], there is a window of opportunity to optimise BMD and reduce fracture risk through key modifiable lifestyle factors during the life course. An optimal diet rich in micronutrients, such as calcium, vitamin D, and potassium, has long been considered an important modifiable component of bone health, which is attributed to their direct roles within bone metabolism. Recently, there has been emerging evidence to suggest that protein and even an adequate intake of fruit and vegetables may also play an important role in improving BMD [3,4]. Maintaining a physically active lifestyle is not only protective from non-communicable diseases such as cardiovascular disease but it also has been shown to lessen the risk of fractures later in life, thereby making it an imperative modifiable factor for bone health, particularly as it also supports peak bone mass attainment during childhood/adolescence and can facilitate the maintenance of bone mass throughout adulthood [5]. Other key lifestyle factors that could be potentially modified to reduce the risk of osteoporosis or osteoporotic fractures later in life include smoking status, alcohol intake, and body composition [6]. Therefore, the principle aim of this review is to highlight the recent evidence pertaining to modifiable lifestyle factors that contribute to optimal bone health and the prevention of fragility fractures in later life.

Vegan nutrition: a preliminary guide for health professionals

Since the beginning of the 21st century, interest in vegan diets has been rapidly increasing in most countries. Misconceptions about vegan diets are widespread among the general population and health professionals. Vegan diets can be health-promoting and may offer certain important advantages compared to typical Western (and other mainstream) eating patterns. However, adequate dietary sources/supplements of nutrients of focus specific to vegan diets should be identified and communicated. Without supplements/fortified foods, severe vitamin B12 deficiency may occur. Other potential nutrients of focus are calcium, vitamin D, iodine, omega-3 fatty acids, iron, zinc, selenium, vitamin A, and protein. Ensuring adequate nutrient status is particularly important during pregnancy, lactation, infancy, and childhood. Health professionals are often expected to be able to provide advice on the topic of vegan nutrition, but a precise and practical vegan nutrition guide for health professionals is lacking. Consequently, it is important and urgent to provide such a set of dietary recommendations. It is the aim of this article to provide vegan nutrition guidelines, based on current evidence, which can easily be communicated to vegan patients/clients, with the goal of ensuring adequate nutrient status in vegans.

Benefits and Risks Associated with Meat Consumption during Key Life Processes and in Relation to the Risk of Chronic Diseases

Red meat has been an important part of the diet throughout human evolution. Overall, when included as part of a healthy and varied diet, red meat can provide a rich source of bioavailable essential nutrients and high biological value protein. The present paper discusses the dietary role/impact of red and processed meat, with some reference to the relative effect of white meat, in a range of chronic conditions including iron-deficiency anaemia, cardiovascular diseases (CVD), cancer and dementia. The role of red meat in relation to key physiological conditions such as maintaining skeletal muscle and bone health and during pregnancy is also discussed. The inclusion of lean red meat in a healthy, varied diet may be beneficial during these critical conditions. There is however increasing evidence that red meat and especially processed meat are associated with increased risks of CVD, cancer and dementia whereas white meat is neutral or associated with a lower risk. There now seems little doubt that processed and unprocessed meat should have separate public dietary guidance.

Dietary Acid Load and Bone Health: A Systematic Review and Meta-Analysis of Observational Studies

Findings on the association between dietary acid load (DAL) and bone health are conflicting. This study aimed to summarize available studies on the association between DAL and risk of fractures or bone mineral density (BMD) in adults. Online databases including PubMed, Scopus, and Embase were searched for relevant studies published up to June 2021, using pertinent keywords. We identified observational studies (cohort, case-control, and cross-sectional) investigating the association between DAL and risk of fractures or BMD, then selected studies following these reported criteria: RRs with corresponding 95% CIs for the relationship between DAL and fracture risk; correlation coefficients for the association between DAL and BMD; and mean ± SD of BMD values across the categories of DAL. Overall, 17 studies with 80545 individuals were included. There was no significant relationship between the PRAL and fracture risk (Pooled RR: 1.18; 95% confidence interval 0.98 to 1.41, I² = 60.6%). Moreover, a similar association was observed between the NEAP and fracture risk (Pooled RR: 1.41, 95% CI: 0.79 to 2.52, I² = 54.1%). The results of five studies from four publications revealed no significant association between dietary PRAL score and femoral and spinal BMD (WMD femoral = −0.01, 95% confidence interval: −0.02 to 0.01, I² = 76.5%; WMD spinal = −0.01, 95% CI: −0.03 to 0.01, I² = 56.7%). However, being in the highest category of NEAP was significantly associated with a lower femoral and spinal BMD (WMD femoral = −0.01, 95% CI: −0.02 to −0.00, I² = 82.1%; WMD spinal = −0.02, 95% CI: −0.03 to −0.01, I² = 93%). It was showed that adopting diets high in acidity was not associated with risk of fractures. We also found a significant negative relationship between NEAP and BMD. However, DAL based on PRAL was not associated with BMD.

Dietary Protein Intake in Relation to the Risk of Osteoporosis in Middle-Aged and Older Individuals: A Cross-Sectional Study

OBJECTIVES

Dietary protein intake is of great significance for the bone health of middle-aged and elderly people. This study is aimed to explore the relationships between dietary protein intake and the risk of osteoporosis in middle-aged and older individuals among US population.

METHODS

Based on the National Health and Nutrition Examination Survey (NHANES), this study includes a total of 20497 participants during 2005-2008, and identify 4707 middle-aged and older people aged 45 years or above. Demographic data and relevant dietary intake information are acquired through in-home management questionnaires. The logistic regression models are established to identify the odds ratio (OR) and 95% confidence interval (CI) of OP in each quartile category of energy-adjusted dietary protein intake. The receiver operating characteristic (ROC) curve is applied to explore the optimal cut-off value of daily dietary protein intake for predicting risk of OP.

RESULTS

442 participants with OP are identified among 4707 middle-aged and older people, and the dietary protein intake of OP group is significantly lower than that of non-OP group (P<0.001). The logistic regression analysis shows that with the increase of daily dietary protein intake, the prevalence of OP in each quartile category decreases gradually (P<0.001). This trend is not altered in univariate model (P<0.001), as well as the adjustments for the covariates of age and BMI (Model 1, P<0.001), the covariates of sex (Model 2, P=0.036), the covariates of smoking, drinking alcohol, education, ratio of family income to poverty, hypertension and diabetes (Model 3, P<0.001), and the covariates of dietary intake (Model 4, P=0.008). Moreover, we also identify that the daily dietary protein intake of 61.2g is the optimal cut-off value for predicting risk of OP.

CONCLUSION

In general, among US population, the lower daily dietary protein intake is positively related to the ascending risk of OP in middle-aged and older individuals.

UK clinical guideline for the prevention and treatment of osteoporosis

The National Osteoporosis Guideline Group (NOGG) has revised the UK guideline for the assessment and management of osteoporosis and the prevention of fragility fractures in postmenopausal women, and men age 50 years and older. Accredited by NICE, this guideline is relevant for all healthcare professionals involved in osteoporosis management.

INTRODUCTION

The UK National Osteoporosis Guideline Group (NOGG) first produced a guideline on the prevention and treatment of osteoporosis in 2008, with updates in 2013 and 2017. This paper presents a major update of the guideline, the scope of which is to review the assessment and management of osteoporosis and the prevention of fragility fractures in postmenopausal women, and men age 50 years and older.

METHODS

Where available, systematic reviews, meta-analyses and randomised controlled trials were used to provide the evidence base. Conclusions and recommendations were systematically graded according to the strength of the available evidence.

RESULTS

Review of the evidence and recommendations are provided for the diagnosis of osteoporosis, fracture-risk assessment and intervention thresholds, management of vertebral fractures, non-pharmacological and pharmacological treatments, including duration and monitoring of anti-resorptive therapy, glucocorticoid-induced osteoporosis, and models of care for fracture prevention. Recommendations are made for training; service leads and commissioners of healthcare; and for review criteria for audit and quality improvement.

CONCLUSION

The guideline, which has received accreditation from the National Institute of Health and Care Excellence (NICE), provides a comprehensive overview of the assessment and management of osteoporosis for all healthcare professionals involved in its management. This position paper has been endorsed by the International Osteoporosis Foundation and by the European Society for the Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases.

A 1:1 matched case-control study on dietary protein intakes and hip fracture risk in Chinese elderly men and women

The role of protein intake in bone has been controversial. Our case-control study among Chinese elderly concluded that a higher consumption of protein, even substituted for fat, is associated with lowered hip fracture risk. Differences in protein sources, amino acids composition, gender, and calcium sufficiency may explain the inconsistency.

PURPOSE

The aim of the study was to investigate the association of dietary protein intakes with hip fracture risk among Chinese elderly.

METHODS

This was a 1:1 age and sex matched cross-sectional study of case-control design among 1070 pairs of elderly Chinese people aged 55 to 80 years. Patients who were newly diagnosed (within 2-week) hip fracture by X-ray were recruited from four hospitals in Guangdong Province of China. Dietary intakes were evaluated by a validated food frequency questionnaire for total protein, protein from different sources, amino acids profiles, and estimated renal acid load in diet.

RESULTS

Daily average intakes of total protein were 58.1±27.0 (women) and 65.7±31.8 (men) g/d for cases, and 66.8±21.5 (women) and 72.1±24.4 (men) for controls (p<0.001). Multivariable regression indicated that, compared with the lowest quartile, the highest quartile of consumption of energy adjusted total protein [OR: 0.360 (0.206~0.630) for women and 0.381 (0.153~0.949) for men] and animal protein [0.326 (0.183, 0.560) for women and 0.335 (0.136~0.828) for men] was significantly associated with the lowered risk of hip fracture in a dose-response manner (all p for trend <0.05). A significant hip fracture risk reduction was observed in women with higher intakes of sulfur amino acids [OR: 0.464 (0.286~0.753)] and aromatic amino acids [0.537 (0.326~0.884)] but not in men. Subgroup analysis suggested that these associations were more evident in elderly with lower body mass index and dietary calcium intake less than 400 mg/d.

CONCLUSIONS

A higher level of protein intake, even substituted for fat, is associated with lowered hip fracture risk.

Improved Healing after Non-Surgical Periodontal Therapy Is Associated with Higher Protein Intake in Patients Who Are Non-Smokers

The aim of this study was to determine whether a relationship between periodontal healing and protein intake exists in patients undergoing non-surgical treatment for periodontitis. Dietary protein intake was assessed using the 2005 Block food frequency questionnaire in patients with chronic generalized periodontitis undergoing scaling and root planing (n = 63 for non-smokers, n = 22 for smokers). Protein intake was correlated to post-treatment probing depth using multiple linear regression. Non-smoking patients who consumed ≥1 g protein/kg body weight/day had fewer sites with probing depth ≥ 4 mm after scaling and root planing compared to patients with intakes <1 g protein/kg body weight/day (11 ± 2 versus 16 ± 2, p = 0.05). This relationship was strengthened after controlling for baseline probing depth, hygienist and time between treatment and follow-up (10 ± 2 versus 16 ± 1, p = 0.018) and further strengthened after controlling for potential confounders including age, sex, body mass index, flossing frequency, and bleeding on probing (8 ± 2 versus 18 ± 2, p < 0.001). No associations were seen in patients who smoked. Consuming ≥1 g protein/kg body weight/day was associated with reductions in periodontal disease burden following scaling and root planing in patients who were non-smokers. Further studies are needed to differentiate between animal and plant proteins.

Nutrients with anabolic/anticatabolic, antioxidant, and anti-inflammatory properties: Targeting the biological mechanisms of aging to support musculoskeletal health

Old age is associated with declines in bone density and muscle mass and function, which predisposes to mobility disability, falls, and fractures. Poor nutritional status, a risk factor for several age-related pathologies, becomes prevalent in old age and contributes to the structural and functional changes of the musculoskeletal system that increases the risk of osteoporosis, sarcopenia, osteosarcopenia, and physical frailty. The biological mechanisms underpinning these pathologies often overlap and include loss of proteostasis, impaired redox functioning, and chronic low-grade inflammation. Thus, provision of nutrients with anabolic/anticatabolic, antioxidant, and anti-inflammatory properties may be an effective strategy to offset these age-related pathologies. We searched PUBMED for pre-clinical and clinical work examining the effects of nutrients with a combined effect on muscle and bone. This review summarizes recent evidence on the mechanisms of action and potential clinical use of nutrients that concomitantly improve muscle and bone health in older persons.

Nutritional intake and bone health

Osteoporotic or fragility fractures affect one in two women and one in five men who are older than 50. These events are associated with substantial morbidity, increased mortality, and an impaired quality of life. Recommended general measures for fragility fracture prevention include a balanced diet with an optimal protein and calcium intake and vitamin D sufficiency, together with regular weight-bearing physical exercise. In this narrative Review, we discuss the role of nutrients, foods, and dietary patterns in maintaining bone health. Much of this information comes from observational studies. Bone mineral density, microstructure-estimated bone strength, and trabecular and cortical microstructure are positively associated with total protein intake. Several studies indicate that fracture risk might be lower with a higher dietary protein intake, provided that the calcium supply is sufficient. Dairy products are a valuable source of these two nutrients. Hip fracture risk appears to be lower in consumers of dairy products, particularly fermented dairy products. Consuming less than five servings per day of fruit and vegetables is associated with a higher hip fracture risk. Adherence to a Mediterranean diet or to a prudent diet is associated with a lower fracture risk. These various nutrients and dietary patterns influence gut microbiota composition or function, or both. The conclusions of this Review emphasise the importance of a balanced diet including minerals, protein, and fruit and vegetables for bone health and in the prevention of fragility fractures.

Bone-friendly lifestyle and the role of calcium or vitamin D supplementation

Bone health can be optimized by not smoking, limiting alcohol intake to ≤2 drinks/day and maintaining a healthy body weight (i.e. body mass index of about 25 kg/m²). A balanced diet with a protein content of about 1 g/kg/day and a calcium content >500 mg/day (e.g. two servings of dairy products or equivalent) is recommended. In those with poor sunlight exposure, use of a vitamin D supplement of 400-1000 IU/day should be considered. Calcium supplements cause side effects and are of unproven value. Their use is discouraged.

Early Nutrition during Hospitalization in Relation to Bone Health in Preterm Infants at Term Age and Six Months Corrected Age

Aim: to evaluate the potential association of macronutrient intake in the first postnatal weeks on bone mineral content (BMC) and bone mineral density (BMD) in extremely and very preterm infants. Methods: fifty-eight extremely and very preterm infants were included. Daily macronutrient intake was calculated in g kg⁻¹ day⁻¹ from birth up to 36 weeks postmenstrual age. A dual-energy X-ray absorptiometry whole body scan was used to assess BMC and BMD in preterm infants at term corrected age (TCA) and six months corrected age (CA). Results: fat intake (g kg⁻¹ day⁻¹) in the first four postnatal weeks was positively associated with BMC and BMD at TCA. At six months CA, protein and fat intake (g kg⁻¹ day⁻¹) in the first weeks of life were both individual predictors for BMD. Fat intake (g kg⁻¹ day⁻¹) in the first four postnatal weeks was significantly associated with BMC at six months CA. Conclusion: the association of macronutrient intake in the first postnatal weeks on BMC or BMD, at TCA and six months CA, suggest that early nutritional intervention immediately after birth and during early infancy is important for bone health in the first months of life.

Effect of Acid or Base Interventions on Bone Health: A Systematic Review, Meta-Analysis, and Meta-Regression

Osteoporosis is a global health issue among the aging population. The effect of the acid or base interventions on bone health remains controversial. This study performed a systematic review and meta-analysis to investigate effects of acidic diets and alkaline supplements on bone health simultaneously. We conducted a comprehensive literature search in 5 available databases and 1 registered clinical trial system to identify randomized controlled trials (RCTs) that assessed effects of the acid-base intervention on bone health. Depending on heterogeneity across studies, the pooled effects were calculated by fixed-effects or random-effects models. The present study included 13 acidic diet intervention studies and 13 alkaline supplement studies for final quantitative assessments. The meta-analysis showed that acidic diets significantly increased net acid excretion [NAE; standardized mean difference (SMD) = 2.99; P = 0.003] and urinary calcium excretion (SMD = 0.47, P < 0.00001) but had no significant effect on bone turnover markers and bone mineral density (BMD). On the other hand, alkaline supplement intervention significantly reduced NAE (SMD = -1.29, P < 0.00001), urinary calcium excretion (SMD = -0.44, P = 0.007), bone resorption marker aminoterminal cross-linking telopeptide (NTX; SMD = -0.29, P = 0.003), and bone formation marker osteocalcin (OC; SMD = -0.23, P = 0.02), but did not affect the other bone turnover markers. Furthermore, alkaline supplements significantly increased BMD in femoral neck [mean difference (MD) = 1.62, P < 0.00001, I2 = 0%], lumbar spine (MD = 1.66, P < 0.00001, I2 = 87%), and total hip (MD = 0.98, P = 0.02, I2 = 99%). Subsequently, meta-regression analyses identified 1 study that substantially contributed to the high heterogeneity of BMD in the latter 2 sites, but sensitivity analysis suggested that this study did not affect the significant pooled effects. Despite that, the results should be interpreted with caution and need to be further validated by a larger RCT. In summary, through integrating evidence from RCTs, the present meta-analysis initially suggests that alkaline supplements may be beneficial to bone metabolism and acidic diets may not be harmful to bone health. This work may be clinically useful for both clinicians and patients with osteoporosis.

Dietary patterns and intrinsic capacity among community-dwelling older adults: a 3-year prospective cohort study

PURPOSE

The WHO has proposed a novel model of healthy aging called intrinsic capacity (IC). However, the association between dietary patterns and IC is unclear. We aimed to investigate the prospective associations between dietary patterns and IC trajectories over a 3-year period in community-dwelling Japanese adults aged ≥ 60 years.

METHODS

A prospective cohort study which contained nutritional status, mental status, and physical function was used. A validated 34-item food frequency questionnaire was used to determine dietary intake and to derive five dietary patterns ("fruits and vegetables", "sugar and fat", "salt and pickles", "noodle and alcohol", and "protein-rich") using principal component analysis. The composite IC score was calculated as the mean of the locomotion Z-score, cognition Z-score, psychological Z-score, vitality Z-score, and sensory regression score. A generalized estimating equation was applied for longitudinal analysis.

RESULTS

A total of 666 enrollees were included in the analysis. The mean baseline IC was 0.07 ± 0.47. The "fruits and vegetables" dietary pattern was positively associated with composite IC score changes after adjusting for confounders (Q4 vs. Q1: mean difference [0.069], P = 0.019). Similarly, a positive correlation was observed for the "protein-rich" dietary pattern with the composite IC score changes (Q4 vs. Q1: mean difference [0.092], Q3 vs. Q1: mean difference [0.101], Q2 vs. Q1: mean difference [0.083]; all P < 0.01). However, adherence to the "sugar and fat" dietary pattern was negatively associated with composite IC score changes (Q4 vs. Q1: mean difference [- 0.072], P = 0.026). Furthermore, the percentage of animal protein to total protein intake showed a significant incremental trend in the "protein-rich" dietary pattern (P for trend < 0.001).

CONCLUSION

The "fruits and vegetables" and "protein-rich" (animal-based protein in particular) dietary patterns were positively associated with IC changes, whereas the "sugar and fat" dietary pattern was negatively associated with IC changes. Identification and promotion of healthy dietary patterns in older adults may inform future health policies and research.

Nutritional Supplements and Skeletal Health

PURPOSE OF REVIEW

Nutrition influences skeletal health throughout the lifespan, from the impact of maternal intakes during development, through the development of peak bone mass, to the rate of bone loss during aging. However, there are limited data available on the effects of nutritional supplements on bone density, let alone fracture risk. This review will assess the current literature, focusing on human studies, and emphasizing nutrients where bone density or fracture data are available.

RECENT FINDINGS

Calcium and vitamin D supplements, in combination, reduce fracture risk, particularly in populations with low intakes. Extensive recent analyses have supported the safety of these interventions at recommended intakes. There is growing evidence that specific isoflavones may improve bone density although fracture data are lacking. Multiple other nutrient supplements may benefit skeletal health, but data are limited. The effect size of nutrient interventions are relatively small, requiring large sample sizes for trials with bone outcomes, may be difficult to blind, and the impact of supplementation may depend on baseline intake. However, nutrition is the only intervention that can be implemented life long and on a population wide basis. Further investigation is needed into the potential benefits of nutritional supplements to determine in which settings supplements may add benefit in addition to dietary intakes.

Partial Replacement of Animal Proteins with Plant Proteins for 12 Weeks Accelerates Bone Turnover Among Healthy Adults: A Randomized Clinical Trial

BACKGROUND

Plant-based diets may reduce the risk of chronic diseases, but can also lead to low calcium and vitamin D intakes, posing a risk for bone health.

OBJECTIVES

We investigated whether partial replacement of animal proteins with plant-based proteins using a whole-diet approach affects bone and mineral metabolism in healthy adults in 3 groups fed diets differing in protein composition.

METHODS

This 12-week clinical trial was comprised of 107 women and 29 men (20-69 years old; BMI mean ± SD, 24.8 ± 3.9) randomly assigned to consume 1 of 3 diets designed to provide 17 energy percent (E%) protein: "animal" (70% animal protein, 30% plant protein of total protein intake), "50/50" (50% animal, 50% plant), and "plant" (30% animal, 70% plant) diets. We examined differences in bone formation [serum intact procollagen type I amino-terminal propeptide (S-iPINP)], bone resorption [serum collagen type 1 cross-linked C-terminal telopeptide (S-CTX)], mineral metabolism markers (primary outcomes), and nutrient intakes (secondary outcomes) by ANOVA/ANCOVA.

RESULTS

S-CTX was significantly higher in the plant group (mean ± SEM, 0.44 ± 0.02 ng/mL) than in the other groups (P values < 0.001 for both), and differed also between the animal (mean ± SEM, 0.29 ± 0.02 ng/mL) and 50/50 groups (mean ± SEM, 0.34 ± 0.02 ng/mL; P = 0.018). S-iPINP was significantly higher in the plant group (mean ± SEM, 63.9 ± 1.91 ng/mL) than in the animal group (mean ± SEM, 55.0 ± 1.82 ng/mL; P = 0.006). In a subgroup without a history of vitamin D supplement use, plasma parathyroid hormone was significantly higher in the plant than in the animal group (P = 0.018). Vitamin D and calcium intakes were below recommended levels in the plant group (mean ± SEM, 6.2 ± 3.7 μg/d and 733 ± 164 mg/d, respectively).

CONCLUSIONS

Partial replacement of animal proteins with plant-based proteins for 12 weeks increased the markers of bone resorption and formation among healthy adults, indicating a possible risk for bone health. This is probably caused by lower vitamin D and calcium intakes from diets containing more plant-based proteins, but it is unclear whether differences in protein intake or quality play a major role. This trial was registered at clinicaltrials.gov as NCT03206827.

Joint position statement on management of patient with osteoporosis during COVID-19 contingency from the AMMOM, CONAMEGER, FELAEN, FEMECOG, FEMECOT, and ICAAFYD

Infection by SARS-Cov-2 (COVID-19) has affected practically all the world. This joint position statement of Latin American Medical Societies provides an updated guide for the prevention, diagnosis, and treatment of osteoporotic patients in the face of possible clinical scenarios posed by the COVID-19 health crisis.

BACKGROUND

Infection by SARS-Cov-2 (COVID-19) has affected practically all the world. Characterized by high contagiousness, significative morbidity, and mortality in a segment of those infected, it has overwhelmed health services and forced to redirect resources to the emergency while impacting the attention of acute non-COVID-19 and many chronic conditions.

OBJECTIVE

The objective of this study is to provide an updated guide for the prevention, diagnosis, and treatment of osteoporotic patients in the face of possible clinical scenarios posed by the COVID-19 health crisis.

METHODS

A task force, of bone specialists with a wide range of disciplines in the field of osteoporosis and fragility fracture, was convened with the representation of several professional associations, namely, the Mexican Association of Bone and Mineral Metabolism (AMMOM), the National College of Geriatric Medicine (CONAMEGER), the Latin American Federation of Endocrinology (FELAEN), the Mexican Federation of Colleges of Obstetrics and Gynecology (FEMECOG), the Mexican Federation of Colleges of Orthopedics and Traumatology (FEMECOT), and the Institute of Applied Sciences for Physical Activity and Sports of the University of Guadalajara (ICAAFYD). Clinical evidence was collated, and an evidence report was rapidly generated and disseminated. After finding the gaps in the available evidence, a consensus opinion of experts was made. The resulting draft was reviewed and modified accordingly, in 4 rounds, by the participants.

RESULTS

The task force approved the initial guidance statements, with moderate and high consensus. These were combined, resulting in the final guidance statements on the (1) evaluation of fracture risk; (2) stratification of risk priorities; (3) indications of bone density scans and lab tests; (4) initiation and continuation of pharmacologic therapy; (5) interruptions of therapy; (6) treatment of patients with incident fracture; (7) physical therapy and fall prevention; and (8) nutritional interventions.

CONCLUSION

These guidance statements are provided to promote optimal care to patients at risk for osteoporosis and fracture, during the current COVID-19 pandemic. However, given the low level of available evidence and the rapidly evolving literature, this guidance is presented as a "living document" and future updates are anticipated.

Relationship Between Serum Amino Acid Levels and Bone Mineral Density: A Mendelian Randomization Study

BACKGROUND

This study aimed to explore the association between serum amino acids (AAs) levels and bone mineral density (BMD).

METHODS

We performed a two-sample Mendelian randomization (MR) analysis to analyze the associations between the levels of eight AAs and BMD values by using summary-level genome-wide association study (GWAS) data. We applied the MR Steiger filtering method and MR Pleiotropy RESidual Sum and Outlier (MR-PRESSO) global test to check for and remove single nucleotide polymorphisms (SNPs) that were horizontally pleiotropic. The associations were estimated with the inverse variance weighted (IVW), MR-Egger, weighted median and MR Robust Adjusted Profile Score (MR.RAPS) methods.

RESULTS

Our study found that genetically increased isoleucine (Ile) [IVW: effect = 0.1601, 95% confidence interval (CI) = 0.0604 ~ 0.2597, p = 0.0016] and valine (Val) levels (IVW: effect = 0.0953, 95% CI = 0.0251 ~ 0.1655, p = 0.0078) were positively associated with total body BMD (TB-BMD). The results also revealed that genetically increased tyrosine (Tyr) levels were negatively associated with TB-BMD (IVW: effect = -0.1091, 95% CI = -0.1863 ~ -0.0320, p = 0.0055).

CONCLUSIONS

In this study, associations between serum AA levels and BMD were established. These findings underscore the important role that serum AAs play in the development of osteoporosis and provide evidence that osteoporosis can be prevented and treated by the intake of certain AAs.

Protein intake and osteosarcopenic adiposity in Korean adults aged 50 years and older

Intake of plant-based protein and recommended protein intake are associated with a lower risk of osteosarcopenic adiposity (co-occurrence of osteopenia/osteoporosis, sarcopenia, and adiposity) in elderly Korean men.

INTRODUCTION

Osteosarcopenic adiposity (OSA) syndrome is defined as the concurrent presence of osteopenia/osteoporosis, sarcopenia, and adiposity and leads to negative functional and metabolic outcomes in late adulthood. This study aimed to investigate the association between OSA and protein intake in adults aged 50 or older.

METHODS

A population-based, cross-sectional survey was conducted using the Korea National Health and Nutrition Examination Survey 2008-2009 data and included 645 men and 706 women aged 50 or older. Subjects were classified into normal and OSA groups. Protein intake was analyzed using the 24-h recall method.

RESULTS

There was no significant difference in the intake of total protein and animal-based protein between normal and OSA groups. However, in males, the intake of plant-based protein (p = 0.0031) was significantly lower in the OSA group than that in the normal group. Further, the protein intake in the OSA group was 0.96 g/kg/day, which was significantly lower than that in the normal group (1.06 g/kg/day; p = 0.0203). After adjusting for confounding factors, men over 65 years old who consumed less than the recommended nutrient intake (RNI) of 0.91 g/kg/day had 5.82 times higher risk of OSA compared with subjects consuming protein equal to or greater than the RNI amount (95% CI 1.81-18.66).

CONCLUSION

In conclusion, a protein intake of RNI or more is associated with a lower risk of OSA in Korean elderly men.

Vegetarian and vegan diets and risks of total and site-specific fractures: results from the prospective EPIC-Oxford study

BACKGROUND

There is limited prospective evidence on possible differences in fracture risks between vegetarians, vegans, and non-vegetarians. We aimed to study this in a prospective cohort with a large proportion of non-meat eaters.

METHODS

In EPIC-Oxford, dietary information was collected at baseline (1993-2001) and at follow-up (≈ 2010). Participants were categorised into four diet groups at both time points (with 29,380 meat eaters, 8037 fish eaters, 15,499 vegetarians, and 1982 vegans at baseline in analyses of total fractures). Outcomes were identified through linkage to hospital records or death certificates until mid-2016. Using multivariable Cox regression, we estimated the risks of total (n = 3941) and site-specific fractures (arm, n = 566; wrist, n = 889; hip, n = 945; leg, n = 366; ankle, n = 520; other main sites, i.e. clavicle, rib, and vertebra, n = 467) by diet group over an average of 17.6 years of follow-up.

RESULTS

Compared with meat eaters and after adjustment for socio-economic factors, lifestyle confounders, and body mass index (BMI), the risks of hip fracture were higher in fish eaters (hazard ratio 1.26; 95% CI 1.02-1.54), vegetarians (1.25; 1.04-1.50), and vegans (2.31; 1.66-3.22), equivalent to rate differences of 2.9 (0.6-5.7), 2.9 (0.9-5.2), and 14.9 (7.9-24.5) more cases for every 1000 people over 10 years, respectively. The vegans also had higher risks of total (1.43; 1.20-1.70), leg (2.05; 1.23-3.41), and other main site fractures (1.59; 1.02-2.50) than meat eaters. Overall, the significant associations appeared to be stronger without adjustment for BMI and were slightly attenuated but remained significant with additional adjustment for dietary calcium and/or total protein. No significant differences were observed in risks of wrist or ankle fractures by diet group with or without BMI adjustment, nor for arm fractures after BMI adjustment.

CONCLUSIONS

Non-meat eaters, especially vegans, had higher risks of either total or some site-specific fractures, particularly hip fractures. This is the first prospective study of diet group with both total and multiple specific fracture sites in vegetarians and vegans, and the findings suggest that bone health in vegans requires further research.

Dietary protein and bone health: towards a synthesised view

The present paper reviews published literature on the relationship between dietary protein and bone health. It will include arguments both for and against the anabolic and catabolic effects of dietary protein on bone health. Adequate protein intake provides the amino acids used in building and maintaining bone tissue, as well as stimulating the action of insulin-like growth factor 1, which in turn promotes bone growth and increases calcium absorption. However, the metabolism of dietary sulphur amino acids, mainly from animal protein, can lead to increased physiological acidity, which may be detrimental for bone health in the long term. Similarly, cereal foods contain dietary phytate, which in turn contains phosphate. It is known that phosphate consumption can also lead to increased physiological acidity. Therefore, cereal products may produce as much acid as do animal proteins that contain sulphur amino acids. The overall effect of dietary protein on physiological acidity, and its consequent impact on bone health, is extremely complex and somewhat controversial. The consensus is now moving towards a synthesised approach. Particularly, how anabolic and catabolic mechanisms interact; as well as how the context of the whole diet and the type of protein consumed is important.

Milk Consumption for the Prevention of Fragility Fractures

Results indicating that a high milk intake is associated with both higher and lower risks of fragility fractures, or that indicate no association, can all be presented in the same meta-analysis, depending on how it is performed. In this narrative review, we discuss the available studies examining milk intake in relation to fragility fractures, highlight potential problems with meta-analyses of such studies, and discuss potential mechanisms and biases underlying the different results. We conclude that studies examining milk and dairy intakes in relation to fragility fracture risk need to study the different milk products separately. Meta-analyses should consider the doses in the individual studies. Additional studies in populations with a large range of intake of fermented milk are warranted.

A Call to Action: Now Is the Time to Screen Elderly and Treat Osteosarcopenia, a Position Paper of the Italian College of Academic Nutritionists MED/49 (ICAN-49)

Aging is a risk factor for the development of multiple chronic diseases, including cardiovascular disease, cancer and dementia. Life expectancy has increased in certain countries but this phenomenon is associated with a reduction of years of healthy life. Aging is associated with a number of physical and functional changes, especially sarcopenia. Sarcopenia is a clinical condition associated with a decrease in skeletal muscle and muscle strength, however, sarcopenia is a reversible condition. On the basis of the current scientific literature, sarcopenia could more appropriately capture an individual's vulnerability to negative health-related outcomes since it represents an early form of the chronic diseases. Recognition of this clinical condition can improve the management of older individuals in many different clinical settings. Despite the limitations of the indirect methods used to study body composition, the Italian College of the Academic Nutritionists ME/49 recommends that health authorities and health professionals around the world should make a greater effort to diagnose sarcopenia earlier and to manage it more effectively. In line with the development of cancer screening, the use of two diagnostic tools for sarcopenia (BIA and DXA) should be implemented.

Systematic review and meta-analysis of the association between dairy consumption and the risk of hip fracture: critical interpretation of the currently available evidence

In the present meta-analysis, reductions in the risk of hip fracture with milk consumption were only observed among American adults, but not among Scandinavian adults, possibly because milk products are more commonly fortified with vitamin D in the former population than in Scandinavian countries. The reduction in the risk of hip fracture was also observed with yogurt consumption, which is often associated with healthy lifestyles and dietary patterns that contribute to improved bone health.

INTRODUCTION

Although dairy products contain bone-beneficial nutrients, the association between dairy consumption and the risk of hip fracture remains equivocal. Fueling this uncertainty, the elevated risk of hip fracture in association with milk consumption was observed in a cohort of Swedish women. A systematic review and meta-analysis of prospective cohort studies was performed to critically evaluate the association, or lack thereof, between dairy consumption (milk, yogurt, and cheese) and the risk of hip fracture.

METHODS

A random effects model was used to generate the summary relative risks (RRs) with their 95% confidence intervals (CIs) for the associations of interest.

RESULTS

In the meta-analysis of the highest versus lowest category of consumption, higher consumption of yogurt (RR 0.78, 95% CI 0.68, 0.90), but not milk (RR 0.86, 95% CI 0.73, 1.02) or cheese (RR 0.85, 95% CI 0.66, 1.08), was associated with a lower risk of hip fracture. For milk, the reduced risk of fracture with higher milk consumption was observed in the USA (RR 0.75, 95% CI 0.65, 0.87), but not in Scandinavian countries (RR 1.00, 95% CI 0.85, 1.17). These findings were further supported by the fact that American studies (RR 0.93, 95% CI 0.88, 0.98; per 1 glass/day), but not Scandinavian studies (RR 1.01, 95% CI 0.95, 1.07; per 1 glass/day), demonstrated a linear association between milk consumption and the risk of hip fracture.

CONCLUSIONS

The cumulative evidence from prospective cohort studies reassuringly suggests that the risk of hip fracture may not be elevated among people who consume milk, yogurt, and cheese, and that a greater consumption of milk or yogurt may even be associated with a lower risk of hip fracture depending on the factors that may differ across the population of interest.

Effects of dairy products on bone mineral density in healthy postmenopausal women: a systematic review and meta-analysis of randomized controlled trials

PURPOSE

To investigate the effects of dairy products on bone mineral density (BMD) in healthy postmenopausal women.

METHODS

The EMBASE, Cochrane Library, Medline, and Web of Science databases were systematically searched for relevant studies. The pooled standardized mean difference (SMD) with its 95% confidence interval (CI) was used as the effect size. Subgroup analysis and Begg's test were conducted.

RESULTS

Six studies with a total of 618 participants were included in the meta-analysis. Milk was the main dairy product used in the trials. There was a significant association between dairy product consumption and BMD of the lumbar spine (SMD 0.21, 95% CI 0.05-0.37, P = 0.009), femoral neck (SMD 0.36, 95% CI 0.19-0.53, P < 0.001), total hip (SMD 0.37, 95% CI 0.20-0.55, P < 0.001), and total body (SMD 0.58, 95% CI 0.39-0.77, P < 0.001). Subgroup analysis suggested that there was a positive effect of dairy product consumption on the BMD of the total hip starting from 12 months and the femoral neck starting from 18 months. There was also a positive association with the BMD in the four sites in people living in low-calcium intake countries.

CONCLUSION

This meta-analysis provides evidence that dairy products can increase BMD in healthy postmenopausal women. Dairy product consumption should be considered an effective public health measure to prevent osteoporosis in postmenopausal women.

Dietary protein intake and bone health

Considerable attention has recently focused on dietary protein's role in the mature skeleton. The aim was to conduct a systematic review evaluating the effects of dietary protein intake alone on bone health measures in adults (Bone Mineral Density (BMD) and bone biomarkers. Searches across 3 databases were conducted through February 2019 including randomized controlled trials (RCT's) and prospective cohort studies examining the effects of ''high versus low'' protein intake. Studies in various populations are currently limited, varying doses and dietary compositions were used or prescribed, respectively, and there was medium risk of bias among the RCTs and the cohort studies examined. Moderate evidence suggested that higher protein intake may have protective effect on lumbar spine (LS) bone mineral density (BMD) compared with lower protein intake but no effect on total hip (TH), femoral neck (FN), or total body BMD or bone biomarkers. Current evidence shows no adv erse effects of higher protein intakes. Although there were positive trends on BMD at most bone cites, only the LS showed moderate evidence to support benefits of higher protein intake. Studies were heterogeneous. High-quality, long-term studies are needed to clarify dietary protein's role in bone health.

Osteosarcopenia: A case of geroscience

Many older persons lose their mobility and independence due to multiple diseases occurring simultaneously. Geroscience is aimed at developing innovative approaches to better identify relationships among the biological processes of aging. Osteoporosis and sarcopenia are two of the most prevalent chronic diseases in older people, with both conditions sharing overlapping risk factors and pathogenesis. When occurring together, these diseases form a geriatric syndrome termed "osteosarcopenia," which increases the risk of frailty, hospitalizations, and death. Findings from basic and clinical sciences aiming to understand osteosarcopenia have provided evidence of this syndrome as a case of geroscience. Genetic, endocrine, and mechanical stimuli, in addition to fat infiltration, sedentarism, and nutritional deficiencies, affect muscle and bone homeostasis to characterize this syndrome. However, research is in its infancy regarding accurate diagnostic markers and effective treatments with dual effects on muscle and bone. To date, resistance exercise remains the most promising strategy to increase muscle and bone mass, while sufficient quantities of protein, vitamin D, calcium, and creatine may preserve these tissues with aging. More recent findings, from rodent models, suggest treating ectopic fat in muscle and bone marrow as a possible avenue to curb osteosarcopenia, although this needs testing in human clinical trials.

Dietary Protein and Muscle Mass: Translating Science to Application and Health Benefit

Adequate consumption of dietary protein is critical for the maintenance of optimal health during normal growth and aging. The current Recommended Dietary Allowance (RDA) for protein is defined as the minimum amount required to prevent lean body mass loss, but is often misrepresented and misinterpreted as a recommended optimal intake. Over the past two decades, the potential muscle-related benefits achieved by consuming higher-protein diets have become increasingly clear. Despite greater awareness of how higher-protein diets might be advantageous for muscle mass, actual dietary patterns, particularly as they pertain to protein, have remained relatively unchanged in American adults. This lack of change may, in part, result from confusion over the purported detrimental effects of higher-protein diets. This manuscript will highlight common perceptions and benefits of dietary protein on muscle mass, address misperceptions related to higher-protein diets, and comment on the translation of academic advances to real-life application and health benefit. Given the vast research evidence supporting the positive effects of dietary protein intake on optimal health, we encourage critical evaluation of current protein intake recommendations and responsible representation and application of the RDA as a minimum protein requirement rather than one determined to optimally meet the needs of the population.