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Biomedical subjects

Jean L F Woo

Publications and source records attributed to Jean L F Woo.

9 recordsLinked to original sources
PubMed2007

Calcium absorption in postmenopausal Chinese women: a randomized crossover intervention study.

The Ca intake and food sources of Chinese postmenopausal women are quite different from those of their Western counterparts. But, little information on Ca metabolism is available in Chinese populations. We determined true fractional calcium absorption (TFCA), true Ca absorption(= TFCA x Ca intake, Va), urinary Ca excretion (Vu,) and the difference between Va and Vu, (Va-u), in response to three dietary Ca intake levels. Twenty-one healthy postmenopausal Chinese women aged 49-64 years were recruited for this randomized crossover trial from a general community, Guangzhou, China. Subjects were randomly assigned to receive 0, 500 and 1000 mg Ca/d for 5 weeks separated by 2-week washout periods. TFCA using Ca stable isotopes, total urinary Ca excretion and Ca intake were determined after 4 weeks of adaptation. Mean values for total Ca intake (Vi) of the three phases were 391 (SD 197), 880 (SD 130) and 1382 (SD 160) mg/d. On usual diet, TFCA, Vu, Va, and Va-u were 0.57 (SD 0.12), 175 (SD 59) mg/d, 216 (SD 98) mg/d and 41 (SD 99) mg/d, respectively. With the supplementations of 500 and 1000 mg Ca/d, TFCAsignificantly decreased to 0.52 (SD 0.12) and 0.43 (SD 0.13) (P<0.001); whereas urinary Ca (P=0.003), Va and Va-u increased significantly (P< 0.001). Using a mixed-effects nonlinear regression model, it was estimated that Va-u was approaching a plateau when mean Ca intake reached 1300 mg/d. In conclusion, the present findings suggest postmenopausal Chinese women have high Ca absorption efficiency and a mean Ca intake of about 1300 mg/d is required to maximize the Va-u.

Biomarkers↗
PubMed2006

Greater fruit and vegetable intake is associated with increased bone mass among postmenopausal Chinese women.

Although studies in Caucasian populations have reported the beneficial effects of intakes of fruit and vegetables on bone mass, limited data are available in the Asian populations. We examined the association of the intake of fruits and vegetables with bone mineral density (BMD) in a population-based cross-sectional study of 670 postmenopausal Chinese women aged 48-63 years. Habitual dietary intakes were assessed using a food frequency questionnaire. BMD at the whole body, lumbar spine and left hip were measured with dual-energy X-ray absorptiometry. Univariate regression analyses showed that the total intake of fruits and vegetables was significantly associated with greater BMD at the whole body, lumbar spine (L1-L4), total hip, trochanter and intertrochanter. An independently positive association between fruit and vegetable intake and BMD at the whole body (P = 0.005), lumbar spine (P < 0.001) and total hip (P = 0.024) remained even after adjusting for age, years since menopause, body weight and height, dietary energy, protein and Ca, and physical activities. A daily increase of 100 g fruit and vegetable intake was associated with 0.0062 (95 % CI 0.0019, 0.0105) g/cm2, 0.0098 (95 % CI 0.0041, 0.0155) g/cm2 and 0.0060 (95 % CI 0.0011, 0.0109) g/cm2 increases in BMD at the whole body, lumbar spine and total hip, respectively. In conclusion, greater fruit and vegetable intake is independently associated with better BMD among postmenopausal Chinese women.

Absorptiometry, Photon↗
PubMed2005

Educational level and osteoporosis risk in postmenopausal Chinese women.

Many studies have shown that better education is favorable for lowering the risks for a number of chronic diseases, but little information is available on the relation with bone health. The authors examined the association of educational level, classified as levels I-IV, with bone mineral density (BMD) and with the prevalence of osteoporosis among 685 population-based, postmenopausal, Chinese women aged 48-63 years during 1999-2001. They observed a significant dose-response positive relation between educational level and BMDs at the total-body (p = 0.011), lumbar spine, and hip sites (p < 0.001) after adjusting for age, years since menopause, and body weight. Mean BMDs of educational level IV women were higher by 4.2-11.9% at the various sites compared with level I women (analysis of covariance, p < 0.05). Similarly, the authors also observed a significant inverse dose-response relation between educational level and prevalence of osteoporosis. Women of educational level I were 3.5-8.6 times more likely to be osteoporotic compared with those of level IV at the various sites. The proportion of BMD or osteoporosis variations accounted for by educational level was attenuated by about 40% after further controlling for potentially explanatory covariates. In conclusion, a higher level of education is independently associated with better BMDs and lower prevalence of osteoporosis among postmenopausal Chinese women.

Absorptiometry, Photon↗
PubMed2004

High habitual calcium intake attenuates bone loss in early postmenopausal Chinese women: an 18-month follow-up study.

This study assessed the association of habitual dietary calcium intake and bone loss in early postmenopausal women. Four hundred fifty-four healthy postmenopausal Chinese women were enrolled for this 18-month cohort study. The subjects were 48-62 yr of age and within 12 yr of natural menopause. Dietary intake was assessed by the food frequency method, and bone mass was measured using dual energy x-ray absorptiometry at baseline and 9 and 18 months. The association between mean habitual dietary intake over the follow-up period and the rate of bone loss was examined. During the 18-month follow-up, the total loss rates of BMD at the whole body, lumber spine, femoral neck, and total hip were 1.28, 0.60, 1.54, and 0.56% (all P < 0.01). Subjects were stratified into four quartiles according to calcium intake during the period of follow-up. Quartiles I-IV had median intakes of 341, 505, 682, and 934 mg Ca/d. Subjects in quartile IV had significantly less BMD loss at the whole body and less BMD/bone mineral content loss at Ward's triangle, even after adjustments for confounding factors (by analysis of covariance). Multiple linear regression analyses showed significant positive associations between calcium intake and BMD change at the whole body (P = 0.006) and Ward's triangle (P = 0.021). Calcium intake was significantly associated with bone mineral content change at the trochanter (P = 0.025) and Ward's triangle (P < 0.001). No significant effect of calcium intake at the spine was found. In conclusion, habitual dietary calcium intake had a beneficial effect on bone loss at the whole body and some regions of the hip. Our findings suggest that an intake exceeding 900 mg calcium/d was helpful in the prevention of cortical bone loss among early postmenopausal Chinese women.

Bone Density↗
PubMed2003

Soy isoflavones have a favorable effect on bone loss in Chinese postmenopausal women with lower bone mass: a double-blind, randomized, controlled trial.

Animal studies have shown that soy isoflavones have an effect in preventing estrogen-related bone loss, but few data are available in humans, especially in the Asian populations. This double-blind, placebo-controlled, randomized trial examines the effects of soy isoflavones on bone loss in postmenopausal Chinese women, aged 48-62 yr. Two hundred and three eligible subjects were randomly assigned to three treatment groups with daily doses of placebo (1 g starch; n = 67), mid-dose (0.5 g starch, 0.5 g soy extracts, and approximately 40 mg isoflavones; n = 68), and high dose (1.0 g soy extracts and approximately 80 mg isoflavones; n = 68). All were given 12.5 mmol (500 mg) calcium and 125 IU vitamin D(3). Bone mineral density (BMD) and bone mineral content (BMC) of the whole body, spine, and hip were measured using dual energy x-ray absorptiometry at baseline and 1 yr post treatment. Both univariate and multivariate analyses showed that women in the high dose group had mild, but statistically significantly, higher favorable change rate in BMC at the total hip and trochanter (P < 0.05) compared with the placebo and mid-dose groups, even after further adjustments for the potential confounding factors. Further stratified analyses revealed that the positive effects of soy isoflavone supplementation were observed only among women with lower initial baseline BMC (median or less). In conclusion, soy isoflavones have a mild, but significant, independent effect on the maintenance of hip BMC in postmenopausal women with low initial bone mass.

Asian People↗
PubMedDate not supplied

Beneficial effect of soy isoflavones on bone mineral content was modified by years since menopause, body weight, and calcium intake: a double-blind, randomized, controlled trial.

OBJECTIVE: Many studies have shown that soy isoflavones have an effect in preventing estrogen-related bone loss, but no data reported whether such an effect could be influenced by other important factors affecting bone loss. This study examines whether the associations between isoflavone supplementation and rates of change in bone mineral content (BMC) could be modified by years since menopause (YSM), body weight (BW), and dietary calcium intake in postmenopausal Chinese women aged 48 to 62 years. DESIGN: A group of 203 eligible women were randomly assigned to three treatment groups: placebo (daily dose of 0 mg isoflavones + 500 mg calcium, n = 67), mid-dose (40 mg isoflavones + 500 mg calcium, n = 68); and high-dose (80 mg isoflavones + 500 mg calcium, n = 68). Bone mineral density (BMD) and BMC at the whole body, spine, and hip were measured by dual-energy x-ray absorptiometry at baseline and posttreatment after 1 year. YSM, BW, and dietary calcium intake stratified analyses were performed to evaluate whether the associations between isoflavones supplementation and BMC change rates were varied with these factors. RESULTS: Both univariate and multivariate analyses observed significant favorable effect of isoflavone supplementation on rates of change in BMC at the total hip and trochanter among later postmenopausal women (> 4 y), in women with lower BW (< or =median, 55.5 kg), or among women with lower level of calcium intake (< or =median, 1095 mg/d). CONCLUSIONS: The independent effect of soy on the maintenance of hip BMC is more marked in women in later menopause or those with lower BW or calcium intake.

Absorptiometry, Photon↗
PubMedDate not supplied

Homocysteine, endothelial dysfunction, and coronary artery disease: emerging strategy for secondary prevention.

Atherosclerosis is an important medical problem of the 21st century, but traditional risk factors could only account for 50% of the problem. Hyperhomocysteinemia is emerging as an independent atherosclerosis risk factor, associated with folate deficiency, renal failure, and relative deficiency of MTHFR (C677T polymorphism) or other enzymes depending on gender, age, and smoking status. Hyperhomocysteinemia has been reported to occur in 11-22% of western people, in 3-5% of normal asymptomatic Chinese subjects aged 18-70 years in Hong Kong, Macau, Sydney, and San Francisco, 23-36% of Chinese in Hong Kong with premature coronary artery disease, and 29% of a nonselective series of coronary subjects in Hong Kong. Evidence is accumulating that documents its associations with atherosclerosis disease in both case-control observations and prospective cohort studies, in vitro experiments, and in vivo experimental models in both animals and human subjects, as well as the successful improvement by homocysteine-lowering of endothelial function as surrogate atherosclerosis endpoints in asymptomatic human and coronary patients (secondary prevention). A number of large scale homocysteine-lowering trials are currently underway for stroke and heart attacks prevention. Collectively these trials will include more than 65,000 patients at high-risk for cardiovascular and stroke events, and should provide a reliable evidence-base for prevention.

Adolescent↗