Lipid buildup predicts weaker bones once it exceeds a critical threshold

Lipid buildup predicts weaker bones once it exceeds a critical threshold

A study of US adults finds that excess central fat, measured by LAP, is associated with lower spine bone density only after reaching a certain tipping point, suggesting a new early warning sign of osteoporosis.

In a recent study in the journal Scientific Reports, researchers evaluated the relationship between a new indicator of lipid accumulation, “lipid accumulation products (LAP),” and bone mineral density (BMD). The study dataset included 3,883 (mean age = 39.33 years; 45.48% women) NHANES participants with analyzes including subgroup, interaction, and threshold analyzes adjusted for covariates.

The study results showed a nonlinear negative relationship between LAP and lumbar BMD, with the negative association only observed above a certain lap threshold (LN-RAP ≈ 2.85); No significant association was found below this value. Interaction analysis showed no effect of subgroups, suggesting that the observed pattern held across demographic and health characteristics. These results suggest the clinical utility of LAP as a bioindicator and predictor of osteoporosis, providing valuable insights that may lead to earlier intervention strategies in the treatment of these chronic diseases.

background

Osteoporosis is a bone disease characterized by severe weakening of the bones (reduced bone mass) and significantly increases the likelihood of a fracture, especially in adults over 50 years of age. The chronic disease is a growing public health problem, with an estimated 158 million adults (>50 years) living with the disease. Alarmingly, predictive models suggest this number will only double by 2040, highlighting the need for prevention, early detection and intervention against this societal burden.

Previous research has found a link between osteoporosis and obesity, with the latter significantly exacerbating the risk of the former. Interestingly, validated studies have shown that body mass index (BMI) and waist circumference (WC) - the most common metrics of obesity - are not sufficient predictors of osteoporosis due to the latter's nuanced relationship with adipose tissue and lean tissue.

Lipid accumulation products (LAP) is a relatively novel lipid accumulation assessment system that combines serum triglyceride (TG) levels with WC to calculate an estimate of central adiposity. The measure has been at the center of recent scientific debate and research because of growing evidence that it may be able to predict the risks of several health conditions, including diabetes and other metabolic syndromes, insulin resistance, non-alcoholic fatty liver disease and even osteoarthritis. Unfortunately, the connection between LAP and osteoporosis (bone mineral density [BMD]) has never been officially established.

About the study

The present study aims to address this knowledge gap and inform future research on osteoporosis interventions by assessing the relationship between LAP and BMD in a nationally representative United States (US) cohort. The study hopes to facilitate improved detection, early detection and improved prevention of future osteoporosis incidence.

Study data were obtained from participants in the National Health and Nutrition Examination Survey (NHANES) program conducted by the US National Center for Health Statistics (NCHS). Data from four NHANES survey periods (2011–2018) were enrolled, which included demographic, medical examination, dietary records, and questionnaire data. Participants younger than 20 years and those with missing BMD, LAP, or covariate data were excluded from subsequent analyses.

The exposure variable (LAP) was calculated using the following formula: men – WC (cm) –65 × TG (mmol/L), women – WC (CM) –58 × TG (MMOL/L). Data for these calculations were obtained from serum sample triglyceride measurements. The outcome variable (lumbar BMD) was measured using a fan beam densitometer conforming to the International Society for Clinical Bone Densitometry (ISCD) guidelines.

Covariates included age, race, gender, BMI, education, poverty income ratio (PIR), laboratory blood assays, smoking and alcohol status, and chronic disease status. Statistical analyzes were performed using linear regression models, weighted chi-square tests, multivariate linear regression models, threshold effect analysis, and interaction analysis.

Study results

Of the 39,156 NHANES records initially enrolled in the study, 16,539 and 18,374 were excluded based on age and missing data, leaving a final dataset of 3,883 participants (mean age = 39.33 years; 45.48% female). Regression models showed a negative association between LAP and lumbar BMD, which was confirmed by threshold analyzes that identified a threshold for LAP (LN-LAP ≈ 2.85).

Importantly, the negative association between LAP and BMD was only observed when LAP values ​​were above this threshold. No significant association was found at this point. Surprisingly, subgroup and interaction analyzes did not highlight the significant effects of covariates on study results. This indicates that the negative association above the threshold is consistent across different demographic and health groups. Notably, associations between LAP and BMD were observed to be nonlinear. Taken together, these results suggest the untapped potential of using RAP in the early detection of osteoporosis and routine monitoring of overall bone health.

The study authors note that while the analysis used a large, nationally representative data set and adjusted for many potential confounding factors, it is cross-sectional in nature and therefore cannot establish causality. Furthermore, the analysis was limited to lumbar spine BMD because the relevant data for femoral BMD were not available in the NHANES cycles used. Further studies are needed to clarify the biological mechanisms linking lap and bone density and to verify these results in prospective studies.

Conclusions

The present study uses a large, nationally representative US dataset to establish and describe the relationship between LAP and BMD. Study results indicate a nonlinear negative correlation between variables, with only one significant association above a defined LAP threshold, supporting the clinical and research use of LAP in future osteoporosis interventions.

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