Table 3.

Practices affecting bone health among adolescents and young adults.

Studies	Primary Objective	Populations	Location	Age	Study Design	Findings
Actively engaged in osteoprotective behaviours
Chen et al. (2012) [37]	To examine demographic characteristics, knowledge, and attitudes of adolescents on osteoprotective practices in Taichung City, Taiwan	329 (120 male and 209 female) randomly selected high schools and colleges students	Taichung City, Taiwan	Adolescents (senior high school students) and young adults (undergraduates)	Cross-sectional study using Osteoporosis Lifestyle Scale (OLS) questionnaires	Adolescent females had higher osteoprotective behaviour scores than young adult females in milk drinking (3.28 ± 1.00 vs. 2.96 ± 1.02), supplement taking (2.05 ± 0.96 vs. 1.76 ± 0.95), and sun exposure (3.64 ± 1.06 vs. 3.20 ± 1.03). Adolescent males scored higher in avoiding harmful behaviours such as smoking, alcohol, coffee, soft drinks consumption than did young adult males (18.65 ± 2.31 vs. 17.13 ± 3.32)
Not actively engaged in osteoprotective behaviours
Al-Raddadi et al. (2018) [18]	To estimate the prevalence of behaviours affecting bone health and vitamin D status and to identify factors associated with vitamin D deficiency among Saudi adolescent females	421 female adolescents	Secondary schools in Jeddah City, Saudi Arabia	Mean age 17.2 ± 1.2 years	Cross-sectional study using self-design questionnaire	Almost half of the participants (46.1%) reported very low consumption of dairy products 62.9% of the participants reported drinking canned soft drinks 1–4 cans/week Only 12.4% of the participants were taking calcium and vitamin D supplements. 49.4% of them reported avoidance of sun exposure Almost half (43.7%) of the participants did not perform any exercise, and only 13.9% performed the recommended exercise per week
Al-Zu’bi, Almuhtaseb & Amayreyh (2010) [32]	To assess the knowledge in a group of teenage girls about risk factors and lifestyle affecting osteoporosis	320 girls attending the 8–10th grade	School from east and west of Amman, the capital city in Jordan, Arab	13–17 years (mean age 14.4 ± 0.9 years)	Self-design questionnaire to assess lifestyle of students	62.8% of the students reported eating dairy products frequently Around 68% of them do not participate in any regular exercise. 43.4% of them avoid exposure to the sun.
Barzanji, Alamri and Mohamed (2013) [15]	To assess the awareness of adults in Riyadh about osteoporosis and its associated factors as well as compare knowledge, attitude and practice levels of men and women	505 participants from eight malls	Riyadh city, Saudi Arabia	Mean age 33.78 ± 10.46 years	Cross-sectional study using pre-coded Arabic questionnaire	Only 10% of females have adequate physical exercise in comparison to 23% of males 22% of females had no exposure to sun, in comparison to 3% of males
Bilal et al. (2017) [44]	To assess knowledge, attitudes and practices about osteoporosis among female medical school entrants in Karachi	400 female medical school entrants of DOW University of Health Sciences (DUHS) and Jinnah Sindh Medical University (JSMU)	Karachi, Pakistan	Mean age 19.4 ± 1.2 years	Cross-sectional study using self-design questionnaire	The RDA for calcium was equal to or greater than 700 mg per day which was met by only 29.0% of the participants despite of the high motivation towards consuming a calcium rich diet Exercise levels were insufficient in terms of both, duration and the recommended type of exercise. Only 12.0% of the participants engaged in exercises based on the recommended guidelines. Only 5.5% subjects were involved in definitive behaviours to improve bone health
Ediriweera de Silva et al. (2014) [20]	To determine the knowledge, beliefs and practices regarding osteoporosis among young females entering medical schools in Sri Lanka	186 female medical school entrants	Faculties of Medicine, Universities of Colombo and Kelaniya, Sri Lanka	Mean age 20.7 ± 2.1 years	Cross-sectional study using modified validated food frequency questionnaire and questions regarding positive and negative behaviours towards osteoporosis	Only 35 (18.8%) of the participants achieved the Recommended Daily Allowance for calcium. Only 23 (13.6%) of the participants engaged in the recommended exercises in type and duration
Park et al. (2015) [30]	To examine dietary intakes and patterns, health behaviours in relation to obesity and bone mineral density (BMD)	160 females nursing students	College in Seoul, Republic of Korea	Mean age 20.6 ± 1.48	Cross-sectional study examines dietary habits (3- day food dairy collection) and health behaviours	90% (n = 144) of them reported as alcohol and coffee consumers 76% (n = 122) students had low milk drinking 63.1% of the students admitted that they were not engaged in regular exercise
Sidor, Glabska & Wlodarek (2016) [40]	To analyze the osteoporosis risk, based on diet assessment in young Polish women	75 young Polish women	Warsaw, Poland	20–30 years (mean age 24.1 ± 3.4)	Three-day dietary record was used	Only 25% had an adequate intake of calcium and, while supplementation was considered, 10% had an adequate intake of vitamin D.
Effect of lifestyle on vitamin D status
Al-daghri et al. (2015) [19]	To investigate vitamin D status and its association with consumption frequencies of various dairy products in Saudi population	820 adolescents and 565 young adults	Different primary health care centers within Riyadh, Saudi Arabia	Adolescents: 327 boys (mean age 14.9 ±1.6 years) and 493 girls (mean age 14.8 ± 1.6) Young Adults: 249 men (mean age 27.9 ± 0.8) and 316 women (32.2 ± 0.6)	A qualitative food frequency questionnaire was used	Adolescents: 80% of boys and 90% of girls had deficient/insufficient levels of vitamin D Young adults: 64% of men and 50% of women had deficient/insufficient levels of vitamin D Frequency of overall dairy product consumption was significant only in women (p < 0.05) and this association was lost after adjusting for age and BMI Frequency of fresh milk consumption affected vitamin D levels in the overall population and more specifically in children and female gender (p ≤ 0.001)
Tonneson et al. (2016) [41]	To investigate the association between lifestyle and vitamin D status in a sample of untreated young adults	738 young adults (361 male and 339 female)	Educational institutions in the Copenhagen area, Denmark	Women: mean age 22 ± 2.2 years Men: mean age 21.6 ± 2.3 years	Cross-sectional study assessing exercise and smoking habits, alcohol intake and dietary habits	The relative risk (RR) for vitamin D deficiency was highest for men 2.09 (1.52, 2.87); obese subjects 2.00 (1.27, 3.15); smokers 1.33 (1.02, 1.73); subjects who exercised 0–½ h a week 1.88 (1.21, 2.94); and subjects who consumed fast food once a week 1.59 (1.05, 2.43)