Bone mineral density, nutrient intake, and physical activity among young women from Uganda

Abstract

Few studies have characterized bone mineral density (BMD) among health young African women. In our study of 496 Ugandan women age ≤25 years, we found that women had healthy BMD that were lower on average than the standard reference ranges. Reference ranges available for BMD measurements need greater precision.

Purpose: Data describing bone mineral density (BMD), nutrient intake, and body composition among healthy, young women in sub-Saharan Africa are limited. Using baseline data from a cohort of young, healthy Ugandan women, we summarize bone health and associated risk factors for reduced bone mass.

Methods: Using baseline data from Ugandan women ages 16-25 years who enrolled in an ongoing cohort study of bone health with concurrent use of injectable contraception and oral HIV pre-exposure prophylaxis, we describe the distribution of BMD, nutrient intake, physical activity, and body composition. The association of low BMD (1 or more standard deviations below the age, sex, and race-matched reference range from the USA) and calcium intake, vitamin D intake, physical activity, and body composition was estimated using multivariable logistic regression.

Results: In 496 healthy, Ugandan women with median age of 20 years (interquartile range [IQR] 19-21) and median fat:lean mass ratio of 0.55 (IQR 0.46-0.64), median lumbar spine and total hip BMD was 0.9g/cm² (IQR 0.9-1.0) each. For lumbar spine, Z-score distributions were lower overall than the reference population and 9.3% and 36.3% of women had Z-score >2 and >1 standard deviations below the reference range, respectively. For total hip, Z-scores were similar to the reference population and 1.0% and 12.3% of women had Z-score >2 and >1 standard deviations below the reference range, respectively. In the week prior to enrollment, 41.1% of women consumed >7 servings of calcium, 56.5% had >7 servings of vitamin D, and 98.6% reported ≥2.5 h of physical activity. Having greater body fat was associated with greater frequency of low lumbar spine BMD (p<0.01 for fat:lean mass ratio, total body fat percentage, waist circumference, and BMI).

Conclusion: Young Ugandan women exhibited healthy levels of BMD that were lower than the reference range population.

Keywords: Bone mineral density; Calcium; Physical activity; Uganda; Women.

Figure 1.

Dietary intake, servings per week, among young, healthy women in Uganda

Figure 2.

Distribution of bone mineral density in spine (A and C) and hip (B and D), shown in g/cm2 (A and B) and z-scores (C and D) and percentages with low and very low density (E and F) among young, healthy women in Uganda. In C-D, the blue line is the normal curve fit to our data and the orange line is the standard normal curve.