Body Mass Index, Lean Mass, and Body Fat Percentage as Mediators of the Relationship between Milk Consumption and Bone Health in Young Adults

The Relationship between Skeletal Muscle Mass and Bone Mass at Different Sites in Older Adults

INTRODUCTION

It has been well recognized that sarcopenia is closely related with osteoporosis, while the relationship between bone mass at different sites and muscle mass remains largely unexplored. This study aims to explore the relationship between bone mass at different sites and skeletal muscle mass in older adults.

METHODS

A total of 228 patients over 65 years old were enrolled in this study, and then 180 valid participants with accessible dual-energy X-ray absorptiometry (DXA) scanning data and absence of malignant tumors, mobility disorders, serious liver and kidney disease, and cardiac insufficiency were selected (138 male and 42 female). These individuals were further divided into control group and low skeletal muscle mass index (SMI) group. DXA scanning was used to access skeletal muscle mass and bone mass. SMI or body mass index was defined as appendicular muscle mass or weight divided by squared height, respectively. Low SMI <7.0 kg/m2 in male or <5.4 kg/m2 in female was defined as low SMI; while the bone density score at or below 2.5 standard deviations (T-score) below normal peak bone values, was regarded as osteoporosis.

RESULTS

The average age of enrolled patients was 82.72 years; the ratios of osteoporosis, low SMI, and low SMI with osteoporosis were 48.8%, 23.3%, and 15.0%, respectively. Compared with the control group, the prevalence of osteoporosis was higher, and the total bone mass and bone mass at various sites including limbs, spine, and pelvis, were all lower in low SMI group. Correlation analysis showed that SMI was positively related with total bone mass and bone mass at various sites. Covariance analysis showed that only total bone mass and appendicular bone mass decreased with decreasing SMI. After multiple adjustment, osteoporosis was positively related with the prevalence of low SMI, as evidenced by logistic regression analysis (odds ratio = 1.33, 95% confidential interval: 1.04-3.24, p = 0.045). Furthermore, compared with the highest quartile of appendicular bone mass, the lowest quartile was related with the increasing prevalence of low SMI (odds ratio = 7.29, 95% confidential interval: 1.21-67.45, p = 0.042).

CONCLUSION

Compared with the other sites, the bone mass reduction at limbs of older adults was positively associated with skeletal muscle loss. It may be more beneficial to increase bone mass at the limbs for improved sarcopenia prevention and therapy. Further investigations are needed to explore the effects of other confounders (e.g., energy, calcium and vitamin D intake, and physical activity) on the osteoporosis and sarcopenia in older adults.

Yak (Bos grunniens) milk improves bone mass and microarchitecture in mice with osteoporosis

The effect of milk on bone health is controversial. In this study, the effects of yak milk in mice with retinoic acid-induced osteoporosis (OP) were evaluated. Yak milk was provided to OP mice as a nutrition supplement for 6 wk. The results showed that yak milk significantly reduced bone turnover markers (tartrate acid phosphatase and alkaline phosphatase). The yak milk treatment was also associated with remarkably increased bone mineral density, bone volume, trabecular thickness, and trabecular number, as well as improved biomechanical properties (maximum load and stress) of the tibia. Furthermore, yak milk mitigated the deterioration of the network and thickness of trabecular bone in treated OP mice compared with the OP model group. The results indicated that yak milk could improve bone mass and microarchitecture through the inhibition of bone resorption in OP mice.

Relevance of body mass index and bioelectrical impedance analysis vs. deuterium dilution technique to assess excess of fat among young adults

Our study aimed to assess the nutritional status by using body composition among young Tunisian adults through three measurement methods: body mass index (BMI), bioelectrical impedance analysis (BIA) and deuterium oxide dilution technique (²H₂O) and to determine the accuracy of BMI and BIA in order to evaluate the overweight and obesity among young adults in Tunisia. Our study involved 144 young adults. Anthropometric parameters were measured. The fat mass percentage (%FM) was determined by ²H₂O and BIA techniques. The analysis of deuterium enrichment was performed using a Fourier transform infrared spectrophotometer (FTIR). According to BMI, 26.4% of subjects were overweight and 5.5% were obese. The mean of %FM estimated by BIA was significantly higher than that determined by ²H₂O (29.7 ± 7.7 vs. 26.3 ± 10.6, p < .0001). Consequently, the prevalence of overweight and obesity assessed by BIA was significantly higher than by ²H₂O (51.4% vs. 34%, p < .0001). Using BMI, the prevalence of overweight and obesity was similar to that estimated by ²H₂O (31.9% vs. 34%, p = 0.544). Compared to ²H₂O, BIA overestimates the prevalence of overweight and obesity in young adults. On the other hand, the BMI showed an interesting correlation with the %FM determined by ²H₂O.

Milk and Dairy Products: Good or Bad for Human Bone? Practical Dietary Recommendations for the Prevention and Management of Osteoporosis

Osteoporosis affects women twice as often as men. Additionally, it is estimated that 0.3 million and 1.7 million people have hip fractures in the USA and Europe, respectively. Having a proper peak bone mass and keeping it as long as possible is especially important for osteoporosis prevention. One of the most important calcium sources is milk and dairy products. Breast milk is the best infant food, but milk should not be avoided later in life to prevent losing bone mass. On the other hand, more and more people limit their milk consumption and consume other dairy or non-dairy products. For example, they are usually replaced with plant beverages, which should be consumed carefully in several age groups. Additionally, an important element of milk and dairy products, as well as plant beverages, are probiotics and prebiotics, which may modulate bone turnover. Dietary recommendations focused on milk, and dairy products are an important element for the prevention of osteoporosis.

The "Fat but Fit" Paradigm and Bone Health in Young Adults: A Cluster Analysis

The fat but fit paradox has suggested that obese individuals with good fitness levels have lower cardiometabolic risk compared to individuals with normal weight but lower fitness levels. This paradigm has not been explored in the context of bone health. The aim of this study was to test whether categories of fat but fit paradigm assessed by body fat percentage and handgrip strength holds up in young adults and to analyze the relationship between fat but fit categories and bone outcomes. Cluster cross-sectional analyses of data from 499 young adults aged 18 to 30 from Toledo and Cuenca, Spain were conducted. Body fat percentage, handgrip strength, bone mineral content (BMC), bone mineral density (BMD), and dietary nutrients such as, proteins, magnesium, calcium, phosphorus, potassium, and vitamin D were assessed. Cluster analysis of body fat percentage and handgrip z scores resulted in a classification of four clusters that could be interpreted according to Fat Unfit (FU), Unfat Unfit (UU), Fat Fit (FF) and Unfat Fit (UF) categories. ANCOVA models showed that young adults in clusters with higher handgrip strength levels (FF, UF) and with higher key bone nutrients levels (UF) had significantly higher total BMC values than their peers in the UU and FU cluster categories, after controlling for sex, age and height. This study provides two novel conclusions in relation to the fat but fit paradigm: first, it confirms the construct of the four clusters of body fat percentage and handgrip strength, and second, it reinforces the predictive validity of the fat but fit paradigm categories, indicating the positive effect, although it may not just be a causal relationship, of muscular strength and key bone nutrients on counteracting the negative effect of obesity on bone health.