As the population ages, osteoporosis (OP) and fractures have become increasingly prominent and have become major public health challenges. According to statistics, the prevalence of osteoporosis in the elderly population over 65 years old in China has exceeded 30%, which is a alarming figure.
Among the many nutrients that support bone health, in addition to calcium and vitamin D, dietary protein also plays a pivotal role. Recent studies have shown that total dietary protein, as well as animal proteins, especially white meat protein, can effectively reduce bone loss in the femoral neck and trochanter, providing strong support for bone health. This finding provides us with new ideas and methods for the prevention and treatment of osteoporosis.
Background:
Nutritional factors play an important role in the prevention of OP, and the contribution of dietary protein to bone health is particularly significant. This is because collagen and non-collagen make up nearly half of the bone volume and are important building blocks for the building blocks of bone, and the cross-linking of collagen molecules within the bone requires translational modifications of amino acids, such as hydroxylation of lysine and proline. Studies estimate that about 2-4% of changes in bone mineral density in adults are directly affected by protein intake. In recent years, more and more attention has been paid to dietary protein intake as an important means to maintain bone health in adults, in order to strengthen bone structure and reduce the risk of OP by adjusting dietary habits.
Observational studies and randomized controlled trials have confirmed that increasing protein intake can help improve bone health. However, these studies have focused primarily on Western populations, and their findings may not be fully applicable to other populations due to differences in genetics, dietary habits, and lifestyles. More critically, longitudinal studies on the effects of different dietary protein types (e.g., animal protein vs. vegetable protein, red meat protein vs. white meat protein) and amino acid profiles on bone mass are still scarce.
In order to fill this research gap, this study explored the relationship between total dietary protein, different protein sources, amino acid profiles and changes in bone mineral density during the 3-year follow-up period based on the middle-aged and elderly population in China. This study not only helps us to understand the complex relationship between protein and bone health more comprehensively, but also provides an important scientific basis for formulating dietary nutrition recommendations for the Chinese population in the future.
Research Methods:
Analysis was based on a prospective cohort study, the Guangzhou Nutrition and Health Study (GNHS, https://clinicaltrials.gov, no. NCT03179657). A total of 3169 participants were included at baseline, of whom 2496 and 2179 attended the first and second follow-up, respectively. The analysis of this study was conducted on the basis of these two follow-up visits, excluding 192 participants who did not meet the requirements.
1. Questionnaires and body measurements
Information on socioeconomic and demographic data, lifestyle factors, family and medical history, and supplement use was collected through questionnaires. Body measurements include weight, height, and a body mass index (BMI, in kg/m2) is calculated.
2. Dietary assessment
Habitual food intake in the previous year was assessed using a 79-item food frequency questionnaire (FFQ) at the first follow-up. Calculate the total intake of energy, protein, amino acids, and other nutrients in a meal. Estimate the dietary intake of amino acids.
3. Bone mineral density (BMD) measurement
During the two follow-up periods, bone mineral density (mg/cm2) was measured at multiple bone locations, including total body (WB), lumbar spine (LS, L1–L4), total hip (TH), femoral neck (FN), and trochanter.
Findings:
The study ended up with 1987 participants, who completed a dietary survey at the first follow-up visit and BMD measurements at the first and second follow-up visits (see figure below). The mean interval between follow-up visits was 2.37 years.
The mean age of the participants was 60.3±4.9 (y) and the mean BMI was 23.5±3.2 (kg/m2). Total dietary protein accounted for 17.5% ± 5.8% of total energy, of which animal food accounted for 49.1%. The average daily protein intake (g/kg/d) was 1.13±0.24 for total protein, 0.57±0.21 for animal protein, 0.57±0.15 for plant protein, 0.22±0.13 for red meat protein, and 0.21±0.13 for white meat. The highest quartile had higher energy expenditure on physical activity and higher dietary calcium intake compared to the lowest quartile of total protein intake. BMD changes were lower in the general, total hip, and femoral neck categories at the second follow-up compared to the first follow-up, while changes in bone mineral density were increased in the L1 category of the spine.
At 3 years of follow-up, the relationship between various dietary protein intakes and annualized BMD changes was tested by multivariate linear regression. After controlling for potential confounders, a significant positive correlation between dietary intake of total protein (P<0.001), animal protein (P<0.05) and white meat protein (P< 0.01) was observed with changes in femoral neck and rotor bone mineral density. No significant correlation was observed in other bone sites.
After fully adjusting for covariates, the participants in the highest quartile of total protein had significantly lower bone loss compared to the lowest quartile, with a change rate of 9.48% (p=0.012) in the femoral neck (Ptrend=0.003) and 46.67% (p=0.049) in the rotor (Ptrend=0.018). At the femoral neck, only marginal benefit was observed for animal protein intake, and bone loss was reduced by 3.18% (p=0.057) at the highest quartile compared with the lowest quartile (Ptrend=0.084).
No significant correlation was observed between plant protein intake and changes in bone mineral density. After adjusting for potential confounders, white meat protein intake resulted in a 7.16% reduction in femoral neck bone loss (p=0.030) and a 31.21% (p=0.022) reduction in rotor bone loss (both Ptrend<0.05).
Multiple linear regression analysis showed that except for lysine and histidine, other dietary amino acids were positively correlated with BMD changes in femoral neck or trochanter, with regression coefficients ranging from 0.12 to 3.82 (p<0.05).
summary
This longitudinal study of middle-aged and older adults in China revealed an important finding: the higher the intake of total protein and animal protein, especially white meat protein, the more slight the bone loss. It is worth noting that this is the first study to report the positive effect of white meat protein on bone loss in Chinese people. In view of this finding, we recommend that increasing the intake of animal protein, mainly white meat, in the dietary regimen of the Chinese elderly has significant clinical and public health implications for preventing aging-related bone loss and reducing healthcare costs.