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Urbanisation and the associated nutrition transition have been linked with the recent rise in osteoporotic fragility fracture incidence in many countries. Predictions indicate that hip fracture incidence will increase 6-fold in Africa and Asia by 2050, partially attributed to demographic transition and population ageing. Differences in areal bone mineral density (aBMD) between rural and urban locations indicate that urban regions of high-income countries (HIC) have lower aBMD and a higher incidence of hip fracture. The few studies conducted in low and middle-income countries (LMIC) provide inconsistent results; in contrast to HIC, most have found higher aBMD in urban populations. To investigate the impact of migrating to an urban environment, detailed studies of bone phenotype and factors affecting bone health have been conducted in two groups of pre-menopausal Gambian women: urban migrant (n=58) and rural (n=81). Both groups spent their formative years in the same rural setting of Kiang West, urban women were known to have migrated to coastal districts, concentrated in Brikama and Kanifing, when aged ≥16 years. Bone phenotype (bone mineral content (BMC); bone area (BA); aBMD, and size-adjusted BMC (adjusted for height, weight and BA) of the whole-body, lumbar spine and hip) was measured by dual energy x-ray absorptiometry (DXA), with further characterisation by peripheral quantitative computed tomography (pQCT). Data were also collected on anthropometry, body composition, food and nutrient intakes, physical activity, socio-demographic characteristics, vitamin D status, and 24hr urinary mineral outputs (Na, K, P, and Ca). Mean age and height of rural and urban migrant groups were not significantly different (p > 0.05). Urban migrant women were significantly heavier (p < 0.01). Significant differences in BMC and aBMD were found between groups at all skeletal sites, with urban women having higher BMC and aBMD; BA was not significantly different. The greatest difference in BMC was found at the lumbar spine (8.5% ± SE 3.0, p < 0.01), a meaningful difference, equivalent to 0.76 of rural SD. T- Scores were also calculated using a young adult (white, female) reference population, mean T- scores were -1.03 and -0.22, for rural and urban groups respectively. After adjusting for size, differences in whole-body and hip BMC were mostly attenuated (p > 0.05), but difference in spine BMC remained significant (6.2% ± SE 2.1, p < 0.01). These results indicate that rural-to-urban migration is associated with higher BMC; BA and height were similar, and difference in body weight could not fully account for higher BMC at the lumbar spine. Calcium intakes were low in both groups, urban migrant 294mg/d (IQR: 235 to 385) and rural 305mg/d (IQR: 222 to 420). Urban women had significantly lower intakes of potassium, magnesium and dietary fibre (p < 0.01), related to lower consumption of fruit, green leafy vegetables and groundnuts. 25-hydroxy vitamin D status was good in both groups, urban migrant 64.0 ± 14.2nmol/L and rural 68.3 ± 15.7nmol/L (M ± SD, p > 0.05). Implications for bone health of the nutrition and demographic transition, principally future fracture risk and other non-communicable diseases require further research in LMICs. ORIGINAL CONTRIBUTION TO KNOWLEDGE To my knowledge, this is the first study investigating the impact of rural-to-urban migration on bone health to be conducted in sub Saharan Africa. It is the first study of bone health and determinants of bone health in an urban population in The Gambia.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The aim of this study was to assess and compare the bone mineral density (BMD): total and regional (legs, spine, pelvis and arms) of athletes from four sports: volleyball (VA), soccer (SA), swimming (SA) and cycling (CA) and a control group (CG). The sample was selected conveniently, was composed by 51 subjects: 10 SA (21,28 ± 4,43 years, 74,75 ± 6,63 kg and 1,78 ± 0,06 m), 11 VA (20,10 ± 1,34 years, 81,27 ± 8,89 kg and 1,86 ± 0,07 m), 10 SA (22,2 ± 3,92 years, 73,61 ± 16,55 kg; 1,76 ± 0,08 m), 10 CA (29,06 ± 1,45 years, 71,00 ± 11,31 kg, 1,71 ± 0,08 m) and 10 subjects who formed the CG (24,59 ± 2,75 years, 72,85 ± 10,52 kg, 1,73 ± 0,05 m). The BMD, total and regional levels were measured and compared using ANOVA and post hoc LSD beyond the ANCOVA to lessen the effects of intervening variables, with the level of p <0,05. Mean value for BMD total of SA was 1,31 ± 0,09, BMD of the legs of that group was 1,55 ± 0,09, BMD of the arms had mean score of 0,92 ± 0,10, BMD of the spine and BMD of the pelvis was 1,21 ± 0,13 and 1,47 ± 0,12, for VA, the results of BMD total, BMD leg, BMD of the arms, spine and pelvis were respectively 1,35 ± 0,08, 1,58 ± 0,11, 1,00 ± 0,07, 1,25 ± 0,14, 1,45 ± 0,21 for SA the average results for the BMD total BMD of the legs, BMD arms, BMD of the spine and pelvis, were respectively 1,21 ± 0,05, 1,32 ± 0,11, 0,93 ± 0,07, 1,12 ± 0,13 and 1,25 ± 0,11, for CA the BMD total, legs, arms, spine and pelvis were respectively 1,26 ± 0,15, 1,43 ± 0,22, 1,11 ± 0,38, 1,13 ± 0,11 and 1,27 ± 0,19 for control group, the average performance of the same BMD were respectively 1,29 ± 0,09, 1,47 ± 0,14, 1,00 ± 0,10, 1,17 ± 0,13 and 1,30 ± 0,17.The BMD of the legs of VA and SA was greater than that of SA, the VA also showed superiority of this BMD than the CA. This same BMD in SA was lower than the CG. Thus, it can be concluded that VA and SA can present, at least with respect to the BMD of the lower limbs, the greater osteogenic response and possible protection against bone loss in old age, while athletes in sports with less participation of gravitational force or impact, particularly swimmers may not experience significant stress to promote osteogenic responses. / O objetivo desse estudo foi verificar e comparar a Densidade Mineral Óssea (DMO): total e regional (pernas, coluna, pelve e braços) de atletas de quatro modalidades esportivas: voleibol (AV), futebol de campo (AF), natação (AN) e ciclismo (AC) e, um grupo controle (GC). A amostra deste estudo foi selecionada convenientemente, foi composta por 51 sujeitos: 10 AF, (21,28±4,43 anos, 74,75±6,63 Kg e 1,78±0,06 m), 11 AV (20,10±1,34 anos, 81,27±8,89 Kg e 1,86±0,07 m), 10 AN (22,2±3,92 anos; 73,61±16,55 Kg; 1,76±0,08 m), 10 AC (29,06±1,45 anos; 71,00±11,31 Kg; 1,71±0,08 m) e 10 sujeitos que formaram o GC (24,59±2,75 anos; 72,85±10,52 Kg; 1,73±0,05 m). As DMO, total e regional, foram medidas e a comparação de cada uma, entre os grupos, foi feita utilizando a ANOVA e teste post hoc LSD além da ANCOVA para diminuir os efeitos das variáveis intervenientes, com o nível de significância de p< 0,05. O valor médio para a DMO total dos AF foi de 1,31±0,09, a DMO das pernas desse mesmo grupo foi de 1,55±0,09, a DMO dos braços apresentou resultado médio de 0,92±0,10, a DMO da coluna 1,21±0,13 e a DMO da pelve 1,47±0,12; para os AV, os resultados da DMO total, DMO das pernas, DMO dos braços, da coluna e da pelve foram, respectivamente 1,35±0,08, 1,58±0,11, 1,00±0,07, 1,25±0,14, 1,45±0,21; para os AN os resultados médios para as DMO total, DMO das pernas, DMO dos braços, DMO da coluna e da pelve, foram respectivamente 1,21±0,05, 1,32±0,11, 0,93±0,07, 1,12±0,13 e 1,25±0,11; para os AC as DMO total, das pernas, dos braços da coluna e da pelve foram, respectivamente 1,26±0,15, 1,43±0,22, 1,11±0,38, 1,13±0,11 e 1,27±0,19; para o GC os resultados médios das mesmas DMO foram, respectivamente 1,29±0,09, 1,47±0,14, 1,00±0,10, 1,17±0,13 e 1,30±0,17. A DMO das pernas dos AV e dos AF foi superior que a dos AN, os AV ainda apresentaram superioridade dessa mesma DMO que a dos AC. Essa mesma DMO nos AN foi menor que a do GC. Dessa forma, pode-se concluir que AV e AF podem apresentar, ao menos no que diz respeito à DMO dos membros inferiores, maior resposta osteogênica e possível proteção contra as perdas ósseas em idades avançadas, enquanto que atletas de modalidades esportivas com menor participação da força gravitacional ou impacto, particularmente atletas de natação podem não experimentar estresses significativos para promoção de respostas osteogênicas. Palavras-chave: osteogênese, saúde óssea, resposta osteogênica, exercício físico

<p>Obesity is a major health concern. Strategies to reduce obesity including weight loss by energy restriction have disease risk reduction benefits, however, energy restriction alone often leads to the loss of muscle mass. Muscle is a very important tissues in the body particularly from a metabolic standpoint, thus, efforts to maintain it by promoting weight loss with the greatest ratio of fat:lean mass loss should be implemented. Also, bone health may be negatively affected by weight loss if hypoenergetic diets are suboptimal in calcium. Hence, the objective of this thesis was to determine how hypoenergetic diets varying in protein (amount and type) with exercise impacted the composition of weight lost and bone health in premenopausal, overweight and obese women. Ninety women were randomized to three groups (n=30/group): HiDairyPro, DairyPro and Control, differing in the quantity of total protein consumed (30%, 15% or 15% of energy, respectively) and the amount from dairy foods (high, moderate or low, respectively). Body composition was measured by DXA and fourier-transform near infrared spectroscopy (FT-NIR) at 0, 8 and 16 weeks, and visceral adipose tissue by MRI (<em>n</em>=39) at 0 and 16 weeks. Blood and urine samples were taken at 0 and 16 weeks. All groups lost similar body weight, but HiDairyPro lost significantly more total and visceral fat, and gained significantly more lean mass than Control (Chapter 2). HiDairyPro significantly improved bone health and vitamin D status compared to Control (Chapter 3). DXA and FT-NIR measured fat mass correlated and agreed well with each other (Chapter 4). Therefore, diet- and exercise-induced weight loss with higher protein and dairy promoted more favourable body composition changes and improved bone health versus diets with lower protein and no dairy. These data have strong implications for the design of weight loss programs to combat obesity.</p> / Doctor of Philosophy (PhD)

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