Characteristics of the study participants
Among 19,429 participants in NHANES 2018-2020. We excluded 8,209 males and females younger than 40 years old. Individuals with missing or invalid data on the alpha-carotene, beta-carotene, beta-cryptoxanthin, lycopene, and lutein+zeaxanthin (n = 3161) and data on the prior fracture (n=2568). Finally, 5491 participants were included in the analysis (Figure 1).
After 1:4 propensity score matching, 1140 subjects with prior fracture cases and 4351 subjects without prior fracture were included in our study from NHANES 2018-2020 (Figure 1). All baseline characteristics were well-balanced between the two groups. There were no significant differences between the groups for all baseline characteristics including age, sex, and bone mass index (BMI).
Of the total included subjects, 2609 subjects were men, accounting for 47.51% of the total enrolled population, and 2881 subjects were women, accounting for 52.49%. The average age of the subjects was 55.62 years old. Over 75% of the study population has lay in the range of overweight with an average body mass index (BMI) greater than 25 kg/m2. Only 21.60% of the study population weight within the normal range. 44.64% of the study population suffered from hypertension. In the survey population, the majority of the population were never smokers, which accounts for 82.30%, only 17.70% were reported as smokers in this cross-sectional data. Out of the total population in this study, 84.87% were alcohol users and 15.13% were non-users. The study population was mostly non-Hispanic white (2177 people) followed by non-Hispanic black (1317 people), accounting for 39.65% and 23.98% of the total study subjects respectively. The demographic characteristics of the research participants are shown in (Table 1).
Table 1 Demographic characteristics of the research population of NHANES.
Characteristics
|
n (%)
|
Age a
|
|
55.62 ± 14.84
|
Gender
|
Male
|
2609 (47.51)
|
|
Female
|
2882 (52.49)
|
BMI (kg/m2)
|
< 18.5
|
57 (1.04)
|
|
18.5~24.9
|
1180 (21.60)
|
|
25.0~29.9
|
1749 (32.02)
|
|
≥30.0
|
2476 (45.33)
|
History of hypertension
|
Yes
|
2451 (44.64)
|
|
No
|
1062 (55.36)
|
Smoking status
|
Ever smoker
|
972 (17.70)
|
|
Non-smoker
|
4519 (82.30)
|
Alcohol use
|
Yes
|
4660 (84.87)
|
|
No
|
831 (15.13)
|
Race
|
Mexican American
|
691 (12.58)
|
|
Other Hispanic
|
481 (8.76)
|
|
Non-Hispanic white
|
2177 (39.65)
|
|
Non-Hispanic black
|
1317 (23.98)
|
|
Others
|
825 (15.02)
|
Age a: measure in mean (± standard deviation); Categorical variables are described by percent (%); BMI: Body mass index
Table 2 lists the daily calcium, vitamin D intake, and physical activity of the study subjects. The average intake of calcium in the study subject is 0.89mg/day/kcal, which is lower than the recommended dietary allowance (reference value) level as per Unites States guidelines. The median daily intake of vitamin D was 4.00 mg/day/kcal, which is within the reference value of 1~4. The median duration of physical activity performed was 1.67 hours/day. It is within the clinical normal reference value range.
Table 2 Dietary calcium, vitamin D intake, and physical activity per day of the participants
Variable
|
Mean ± SD
|
Reference value
|
Calcium (mg/day/kcal)
|
|
0.89 ± 0.47
|
1.00~1.200
|
Vitamin D (mg/day/kcal)
|
|
4.00 (2.00, 7.25)
|
1.00~4.00
|
Physical activity (hour/day)
|
|
1.67 (0.77, 1.57)
|
1.2~1.95
|
Abbreviations: SD Standard deviation, a Median (Q1, Q3)
Carotenoid intakes among the study subject
In this study, Lycopene was the highest average dietary intake among individual carotenoids, which accounts for a median of 2.170 mg/day/kcal. The median dietary intakes of α-carotene, β-carotene, β-cryptoxanthin, and Lutein+zeaxanthin was 0.085, 1.210, 0.041, and 0.885 mg/day/kcal respectively (Table 3).
Table 3 A dietary carotenoid intake with bone mineral density and fracture risk of the study population.
Dietary intakes
|
Median (Q1, Q3)
|
α-carotene (mg/day/kcal)
|
0.085 (0.025, 0.426)
|
β-carotene (mg/day/kcal)
|
1.210 (0.463, 2.985)
|
β-cryptoxanthin (mg/day/kcal)
|
0.041 (0.015, 0.100)
|
Lycopene (mg/day/kcal)
|
2.170 (0.554, 6.121)
|
Lutein+zeaxanthin (mg/day/kcal)
|
0.885 (0.505, 1.651)
|
Median (Q1, Q3): Median (Quartile 1, Quartile 3)
Dietary carotenoids and fracture risk
In the multivariate logistic regression model, we included variables such as smoking status, alcohol use, and race. In this analysis; only alcohol use was statistically significant (p<0.001). For a non-alcohol user, the odds ratio of fracture risk was 0.658 (95%CI: 0.401 to 0.942) compared with the alcohol users. Compared to Mexican Americans, the non-Hispanic white race was associated with the reduction of fracture risk, but not statistically significant.
The relationship between dietary individual carotenoid intake and the risk of fracture was determined using a multiple logistic regression model. The results of this analysis show that dietary beta-carotene and lycopene significantly reduce the risk of fracture. The risk of fracture was decreased by 6.2% (OR: 0.938; 95%CI: 0.699 to 0.989) and 1.4% (OR 0.986; 95%CI: 0.975 to 0.997) for dietary intake of beta-carotene and lycopene respectively. Moreover, dietary intakes of alpha-carotene, beta-cryptoxanthin, and lutein+zeaxanthin were involved in protecting the risk of fracture in our multivariate logistic regression analysis but were not statistically significant (Table 4).
Table 4 Multivariate logistic regression analysis of osteoporotic fracture risk and related factors
Variable
|
|
β
|
S.E.
|
Z
|
P
|
OR
|
95% CI for OR
|
Age
|
|
|
0.048
|
0.003
|
17.043
|
0.531
|
1.049
|
1.044 to 1.056
|
Prior history of hypertension
|
|
Yes
|
|
|
|
|
1
|
|
|
No
|
-0.146
|
0.075
|
-1.947
|
0.052
|
0.864
|
0.746 to 1.001
|
Alcohol use
|
|
Yes
|
|
|
|
|
1
|
|
|
|
No
|
-0.541
|
0.108
|
-5.016
|
<0.001
|
0.658
|
0.401 to 0.942
|
Race
|
|
Mexican American
|
|
|
|
|
1
|
|
|
|
Other Hispanic
|
0.172
|
0.165
|
1.038
|
0.229
|
1.187
|
0.857 to 1.642
|
|
|
Non-Hispanic white
|
0.492
|
0.123
|
3.996
|
<0.001
|
1.635
|
1.289 to 2.089
|
|
|
Non-Hispanic black
|
-0.029
|
0.135
|
0.216
|
0.829
|
1.029
|
0.791 to 1.347
|
|
|
Others
|
-0.175
|
0.158
|
-1.11
|
0.266
|
0.839
|
0.615 to 1.144
|
|
|
Alpha-carotene
|
-0.001
|
0.047
|
-0.012
|
0.990
|
0.999
|
0.907 to 1.094
|
Carotenoid
|
|
Beta-carotene
|
0.001
|
0.016
|
0.059
|
0.953
|
0.938
|
0.699 to 0.989
|
|
|
Beta-cryptoxanthin
|
-0.076
|
0.163
|
-0.466
|
0.641
|
0.927
|
0.649 to 1.238
|
|
|
Lycopene
|
-0.014
|
0.006
|
-2.409
|
0.016
|
0.986
|
0.975 to 0.997
|
|
|
Lutein+zeaxanthin
|
-0.017
|
0.016
|
-1.122
|
0.262
|
0.983
|
0.952 to 1.012
|