Caffeine intake increases the rate of bone loss in elderly women and interacts with vitamin D receptor genotypes.

BACKGROUND: The role of caffeine as a risk factor for bone loss is controversial. OBJECTIVE: Our goals were 1) to compare in both a cross-sectional study and a 3-y longitudinal study the bone mineral density (BMD) of postmenopausal women consuming high or low amounts of caffeine and 2) to study the interaction between caffeine intake, vitamin D receptor (VDR) polymorphism, and BMD in the longitudinal study. DESIGN: The results are derived from cross-sectional measurements of BMD in 489 elderly women (aged 65-77 y) and from longitudinal measurements made in 96 of these women who were treated with a placebo for 3 y. Changes in BMD were adjusted for confounding factors and were compared between groups with either low (< or =300 mg/d) or high (>300 mg/d) caffeine intakes and between the VDR genotype subgroups of the low- and high-caffeine groups. RESULTS: Women with high caffeine intakes had significantly higher rates of bone loss at the spine than did those with low intakes (-1.90 +/- 0.97% compared with 1.19 +/- 1.08%; P = 0.038). When the data were analyzed according to VDR genotype and caffeine intake, women with the tt genotype had significantly (P = 0.054) higher rates of bone loss at the spine (-8.14 +/- 2.62%) than did women with the TT genotype (-0.34 +/- 1.42%) when their caffeine intake was >300 mg/d. CONCLUSIONS: Intakes of caffeine in amounts >300 mg/d ( approximately 514 g, or 18 oz, brewed coffee) accelerate bone loss at the spine in elderly postmenopausal women. Furthermore, women with the tt genetic variant of VDR appear to be at a greater risk for this deleterious effect of caffeine on bone.     

Risk factors for fractures of the distal forearm and proximal humerus. The Study of Osteoporotic Fractures Research Group.

The Study of Osteoporotic Fractures is a prospective cohort study begun in 1986 that includes 9,704 women aged 65 years and older from Maryland, Minnesota, Oregon, and Pennsylvania. A total of 171 women suffered fractures of the distal forearm, and 79 women had fractures of the proximal humerus during the first 2.2 years of follow-up. Most fractures at both sites occurred as a result of a fall. Low bone mineral density was a strong predictor of these fractures; comparing those in the lowest quintile of bone mineral density in the distal radius with those in the highest quintile, the rate ratio was 4.1 for fractures of the distal forearm and 7.5 for fractures of the proximal humerus. Other factors associated with an increased rate of distal forearm fracture independently of low bone mineral density included poor visual acuity, number of falls in the year before baseline, and frequent walking. Factors that appeared to be independently associated with an increased rate of fracture of the proximal humerus included a recent decline in health status, insulin-dependent diabetes mellitus, infrequent walking, and several indicators of neuromuscular weakness such as inability to stand with feet in a tandem position for more than a few seconds. These data support the hypothesis that distal forearm fractures often occur as a result of a fall in women with low bone mineral density who are relatively healthy and active and have good neuromuscular function, while fractures of the proximal humerus tend to occur as a result of a fall in women with low bone mineral density who are less healthy and less active than average and who have poor neuromuscular function.     

Effect of high vegetable protein diets on urinary calcium loss in middle-aged men and women

OBJECTIVE: To determine the effect of high-protein diets, which have recently been promoted for their health benefits, on urinary calcium losses and bone turnover in older subjects. DESIGN: Randomized controlled cross-over study. SETTING: Teaching hospital and university. SUBJECTS: Twenty hyperlipidemic men and postmenopausal women (age 56+/-2 y) completed the study. INTERVENTION: One-month test and control phases during which subjects consumed equi-energy metabolic diets high in calcium (1578 and 1593 mg/day, respectively). On the test diet 11% of total dietary energy from starch in the control bread was replaced by protein (wheat gluten), resulting in 27% of energy from protein on the test diet vs 16% on the control diet. MAIN OUTCOME MEASURE: Urinary calcium excretion. RESULTS: Compared with the control diet, at week 4, the test diet increased mean (+/-s.e.m.) 24 h urinary output of calcium (139+/-15 vs 227+/-21 mg, P=0.004). The treatment difference in urinary calcium loss correlated with the serum anion gap as a marker of metabolic acid production (r=0.57, P=0.011). Serum calcium levels were marginally lower 2.41+/-0.02 vs 2.38+/-0.02 mmol/l (P=0.075), but there was no significant treatment difference in calcium balance, possibly related to the high background calcium intake on both diets. CONCLUSION: In the presence of high dietary calcium intakes the vegetable protein gluten does not appear to have a negative effect on calcium balance despite increased urinary calcium loss.     

A reduced ratio of dietary carbohydrate to protein improves body composition and blood lipid profiles during weight loss in adult women

Claims about the merits or risks of carbohydrate (CHO) vs. protein for weight loss diets are extensive, yet the ideal ratio of dietary carbohydrate to protein for adult health and weight management remains unknown. This study examined the efficacy of two weight loss diets with modified CHO/protein ratios to change body composition and blood lipids in adult women. Women (n = 24; 45 to 56 y old) with body mass indices >26 kg/m(2) were assigned to either a CHO Group consuming a diet with a CHO/protein ratio of 3.5 (68 g protein/d) or a Protein Group with a ratio of 1.4 (125 g protein/d). Diets were isoenergetic, providing 7100 kJ/d, and similar amounts of fat ( approximately 50 g/d). After consuming the diets for 10 wk, the CHO Group lost 6.96 +/- 1.36 kg body weight and the Protein Group lost 7.53 +/- 1.44 kg. Weight loss in the Protein Group was partitioned to a significantly higher loss of fat/lean (6.3 +/- 1.2 g/g) compared with the CHO Group (3.8 +/- 0.9). Both groups had significant reductions in serum cholesterol ( approximately 10%), whereas the Protein Group also had significant reductions in triacylglycerols (TAG) (21%) and the ratio of TAG/HDL cholesterol (23%). Women in the CHO Group had higher insulin responses to meals and postprandial hypoglycemia, whereas women in the Protein Group reported greater satiety. This study demonstrates that increasing the proportion of protein to carbohydrate in the diet of adult women has positive effects on body composition, blood lipids, glucose homeostasis and satiety during weight loss.     

A model for time to fracture with a shock stream superimposed on progressive degradation: the Study of Osteoporotic Fractures

Osteoporotic hip fractures in the elderly are associated with a high mortality in the first year following fracture and a high incidence of disability among survivors. We study first and second fractures of elderly women using data from the Study of Osteoporotic Fractures. We present a new conceptual framework, stochastic model, and statistical methodology for time to fracture. Our approach gives additional insights into the patterns for first and second fractures and the concomitant risk factors. Our modeling perspective involves a novel time‐to‐event methodology called threshold regression, which is based on the plausible idea that many events occur when an underlying process describing the health or condition of a person or system encounters a critical boundary or threshold for the first time. In the parlance of stochastic processes, this time to event is a first hitting time of the threshold. The underlying process in our model is a composite of a chronic degradation process for skeletal health combined with a random stream of shocks from external traumas, which taken together trigger fracture events. Copyright © 2014 John Wiley & Sons, Ltd.     

Low dietary potassium intakes and high dietary estimates of net endogenous acid production are associated with low bone mineral density in premenopausal women and increased markers of bone resorption in postmenopausal women

BACKGROUND: The Western diet may be a risk factor for osteoporosis. Excess acid generated from high protein intakes increases calcium excretion and bone resorption. Fruit and vegetable intake could balance this excess acidity by providing alkaline salts of potassium. Algorithms based on dietary intakes of key nutrients can be used to approximate net endogenous acid production (NEAP) and to explore the association between dietary acidity and bone health. OBJECTIVE: We investigated the relation between dietary potassium and protein, NEAP (with an algorithm including the ratio of protein to potassium intake), and potential renal acid load (with an algorithm including dietary protein, phosphorous, potassium, magnesium, and calcium) and markers of bone health. DESIGN: Measurements of bone mineral density (BMD) (n = 3226) and urinary bone resorption markers (n = 2929) at the lumbar spine and femoral neck were performed in perimenopausal and early postmenopausal women aged 54.9 +/- 2.2 y (x +/- SD) in 1997-1999. BMD (g/cm(2)), free pyridinoline (fPYD), and free deoxypyridinoline (fDPD) were expressed relative to creatinine. Dietary intake was assessed with a food-frequency questionnaire. RESULTS: Comparison of the highest with the lowest quartile of potassium intake or the lowest with the highest NEAP showed a 6-8% increase in fPYD/creatinine and fDPD/creatinine. A difference of 8% in BMD was observed between the highest and lowest quartiles of potassium intake in the premenopausal group (n = 337). CONCLUSIONS: Dietary potassium, an indicator of NEAP and fruit and vegetable intake, may exert a modest influence on markers of bone health, which over a lifetime may contribute to a decreased risk of osteoporosis.     

A diet high in meat protein and potential renal acid load increases fractional calcium absorption and urinary calcium excretion without affecting markers of bone resorption or formation in postmenopausal women

Our objective in this study was to determine the effects of a high-protein and high-potential renal acid load (PRAL) diet on calcium (Ca) absorption and retention and markers of bone metabolism. In a randomized crossover design, 16 postmenopausal women consumed 2 diets: 1 with low protein and low PRAL (LPLP; total protein: 61 g/d; PRAL: -48 mEq/d) and 1 with high protein and high PRAL (HPHP; total protein: 118 g/d; PRAL: 33 mEq/d) for 7 wk each separated by a 1-wk break. Ca absorption was measured by whole body scintillation counting of radio-labeled (47)Ca. Compared with the LPLP diet, the HPHP diet increased participants' serum IGF-I concentrations (P < 0.0001), decreased serum intact PTH concentrations (P < 0.001), and increased fractional (47)Ca absorption (mean ± pooled SD: 22.3 vs. 26.5 ± 5.4%; P < 0.05) and urinary Ca excretion (156 vs. 203 ± 63 mg/d; P = 0.005). The net difference between the amount of Ca absorbed and excreted in urine did not differ between 2 diet periods (55 vs. 28 ± 51 mg/d). The dietary treatments did not affect other markers of bone metabolism. In summary, a diet high in protein and PRAL increases the fractional absorption of dietary Ca, which partially compensates for increased urinary Ca, in postmenopausal women. The increased IGF-I and decreased PTH concentrations in serum, with no change in biomarkers of bone resorption or formation, indicate a high-protein diet has no adverse effects on bone health.     

Biohumoral parameters and bone mineral content in the identification of high risk subjects for postmenopausal osteoporosis.

BACKGROUND: The aim of this study was to evaluate the possibility of identifying women with a high risk of postmenopausal osteoporosis by using computerised bone mineral analysis (CBMA) associated with markers of bone turnover in order to provide a valid and reliable screening test. METHODS: A total of 925 patients were evaluated, 252 of whom had already undergone a preliminary densitometric test six months earlier and were diagnosed as fast bone losers. 225 of them (89%) also showed altered bone turnover markers. CBMA was negative in the remaining 673 patients but 13 patients showed altered bone turnover markers and three of the latter then showed a positive CBMA 18 months later. The 673 patients who, after six months of study, were not fast bone losers were monitored over time. RESULTS: It emerges from these results that fast bone losers are characterised by higher levels of hydroxyprolinuria and calcium, lower levels of oestrone and estradiol, and reduced body weight compared to healthy subjects. CONCLUSIONS: This simplified method enabled 79% of the fast bone losers to be identified, whereas densitometry identified 87.5% of the high-risk subjects. The main advantage of our simplified method compared to the measurement of bone mineral content is that it identifies the majority of fast bone losers in the initial postmenopausal period, before a substantial reduction in BMC has taken place.     

Effects of dietary protein on the composition of weight loss in post-menopaus al women

Objectives: To determine whether a hypocaloric diet higher in protein can prevent the loss of lean mass that is commonly associated with weight loss.Design: An intervention study comparing a hypocaloric diet moderately high in protein to one lower in protein.Setting: Study measurements were taken at the Wake Forest University General Clinical Research Center (GCRC) and Geriatric Research Center (GRC).Participants: Twenty-four post-menopausal, obese women (mean age = 58 ± 6.6 yrs; mean BMI = 33.0 ± 3.6 kg/m²).Intervention: Two 20-week hypocaloric diets (both reduced by 2800 kcal/wk) were compared: one maintaining dietary protein intake at 30% of total energy intake (1.2–1.5 g/kg/d; HI PROT), and the other maintaining dietary protein intake at 15% of total energy (0.5–0.7 g/kg/d; LO PROT). The GCRC metabolic kitchen provided lunch and dinner meals which the women picked up 3 days per week and ate outside of the clinic.Measurements: Body composition, including total body mass, total lean mass, total fat mass, and appendicular lean mass, assessed by dual energy x-ray absorptiometry, was measured before and after the diet interventions.Results: The HI PROT group lost 8.4 ± 4.5 kg and the LO PROT group lost 11.4 ± 3.8 kg of body weight (p = 0.11). The mean percentage of total mass lost as lean mass was 17.3% ± 27.8% and 37.5% ± 14.6%, respectively (p = 0.03).Conclusion: Maintaining adequate protein intake may reduce lean mass losses associated with voluntary weight loss in older women.     

Protein intake: effects on bone mineral density and the rate of bone loss in elderly women

BACKGROUND: The role of dietary protein in bone metabolism is controversial. OBJECTIVE: We investigated the associations of dietary protein intake with baseline bone mineral density (BMD) and the rate of bone loss over 3 y in postmenopausal elderly women. DESIGN: Women aged 65-77 y (n = 489) were enrolled in an osteoporosis intervention trial. We studied the associations of protein intake as a percentage of energy with baseline BMD and the rate of bone loss in 96 women in the placebo group (n = 96). We also examined the effect of the interaction of dietary calcium intake with protein intake on BMD. RESULTS: In the cross-sectional study, a higher intake of protein was associated with higher BMD. BMD was significantly higher (P < 0.05) in the spine (7%), midradius (6%), and total body (5%) in subjects in the highest quartile of protein intake than in those in the lower 2 quartiles. This positive association was seen in women with calcium intakes > 408 mg/d. There was no significant effect of protein intake on hip BMD. In the longitudinal study of the placebo group, there was no association between protein intake and the rate of bone loss. CONCLUSIONS: The highest quartile of protein intake (: 72 g/d) was associated with higher BMD in elderly women at baseline only when the calcium intake exceeded 408 mg/d. In the longitudinal study, no association was seen between protein intake and the rate of bone loss, perhaps because the sample size was too small or the follow-up period of 3 y was not long enough to detect changes.     

Urinary isoflavonoid excretion is inversely associated with the ratio of protein to dietary fibre intake in young women

OBJECTIVE: To examine the prevalence of excretion of urinary isoflavonoids in women and determine any relationships with accustomed macronutrient intake. DESIGN: Volunteers in one of two 4-month studies. Study 1 was a randomised crossover study whereby subjects consumed a placebo or isoflavone supplement for 2 months and crossed over. Study 2 was a parallel design in which subjects consumed a placebo for 1 month and an isoflavone supplement for 3 months. SETTING: All subjects were free-living, healthy volunteers. SUBJECTS: A total of 25 (study 1, n=14; study 2, n=11) premenopausal women were recruited through advertisements. INTERVENTIONS: Volunteers were supplemented for 2 months (study 1) or 3 months (study 2) with purified isoflavones (86 mg/day) derived from red clover. Urinary isoflavonoids were measured during the placebo and the second month of isoflavone treatment. Macronutrient intakes were determined from weighed food records. RESULTS: During isoflavone supplementation, the concentration of urinary total isoflavonoids increased by 15-fold (P<0.0001), with 5.4-fold variation between individuals. Multiple linear regression analysis showed that 24% of this variation could be explained by an interaction between dietary fibre and protein (P=0.047), with a highly significant inverse association between total isoflavonoid concentration and the protein to fibre ratio (r=-0.51, P=0.009). CONCLUSIONS: Supplementation with purified isoflavones results in an increase in urinary isoflavonoid excretion and part of the individual variation in response is associated with an interaction between intakes of protein and dietary fibre. Whether manipulation of these macronutrients could enhance efficacy of isoflavone supplements remains to be determined.     

Prevalence of fracture risk estimated by quantitative ultrasound of the calcaneus in a population of postmenopausal women

A strong aging tendency is currently being observed in the world population, leading to an increase n the prevalence of such diseases as osteoporosis and fractures. This study aimed to determine the prevalence of fracture risk, estimated by quantitative ultrasound of the calcaneus in a population of postmenopausal women residing in the Ilha de Paquetá neighborhood of Rio de Janeiro, Brazil. We conducted anthropometric measurements and quantitative ultrasound of the calcaneus using Sonost 2000 in 385 postmenopausal women. Some 59.22% of the sample showed a T-score < -1, while 16.88% had T-score < -2.5. The test parameters varied with increasing age, with a statistically significant difference (p < 0.05) between fracture risk groups according to age, time since menopause, weight, BMI, and body fat. There was a correlation between sound velocity and BMI (r = 0.155; p = 0.002). We concluded that some 60% of the female study population showed some degree of fracture risk. The women at highest risk (T-score < -2.5) were older, with more time since menopause, and had higher weight and BMI as compared to the other groups.     

Effects of rapid or slow weight loss on body composition and metabolic risk factors in obese postmenopausal women. A pilot study

To compare the effect of rapid or slow weight loss (WL) on body composition and metabolic risk factors following a caloric restriction. Ten obese, postmenopausal women were matched for total body WL. Dependent variables were: body composition, lipid profile and blood pressure. Both groups decreased obesity measures (all P≤0.05) while lean body mass decreased in the rapid WL group (P≤0.05). Significant improvements in fasting triglyceride level and diastolic blood pressure were observed only in the slow WL group. A slower WL seems to be more beneficial to improve body composition as well as metabolic risk factors in postmenopausal women.     

Soy protein isolate increases urinary estrogens and the ratio of 2:16alpha-hydroxyestrone in men at high risk of prostate cancer

Specific estrogen metabolites may initiate and promote hormone-related cancers. In epidemiological studies, significantly lower excretion of urinary estradiol (E2) and lower ratio of urinary 2-hydroxy estrogens to 16alpha-hydroxyestrone (2:16 OH-E1) have been reported in prostate cancer cases compared to controls. Although soy supplementation has been shown to increase the ratio 2:16 OH-E1 in women, no studies to our knowledge have investigated the effects of soy supplementation on estrogen metabolism in men. The objective of this randomized controlled trial was to determine the effects of soy protein isolate consumption on estrogen metabolism in men at high risk for developing advanced prostate cancer. Fifty-eight men supplemented their habitual diets with 1 of 3 protein isolates: 1) isoflavone-rich soy protein isolate (SPI+) (107 mg isoflavones/d); 2) alcohol-washed soy protein isolate (SPI-) (<6 mg isoflavones/d); or 3) milk protein isolate (MPI), each providing 40 g protein/d. At 0, 3, and 6 mo of supplementation, the urinary estrogen metabolite profile was measured by GC-MS. Both soy groups had higher E2 excretion than the MPI group at 3 and 6 mo. After 6 mo of supplementation, the SPI+ group had a significantly higher urinary 2:16 OH-E1 ratio than the MPI group. Increased urinary E2 excretion and 2:16 OH-E1 ratio in men consuming soy protein isolate are consistent with studies in postmenopausal women and suggest that soy consumption may be beneficial in men at high risk of progressing to advanced prostate cancer as a result of effects on endogenous estrogen metabolism.     

Efficacy and acceptability of transdermal estradiol in the treatment of postmenopausal bone loss.

In order to assess the effects and acceptability of transdermal estradiol on the prevention of the loss of bone mass, the Authors administered transdermal estradiol (ETTS 50 mcgr/day) for 3 weeks and, cyclically, medroxyprogesterone 10/mg/day from day 10 to day 21 of each cycle for 12 months, to 20 operated patients for bilateral ovariectomy. Primary markers of the bone turnover (hydroxyproline urinary, osteocalcin, PTH) were estimated before therapy and after 3, 6, 9, 12 months. The BMD was evaluated before therapy and after 6 and 12 months. Our study clearly shows that the transdermal administration of estradiol prevents the postmenopausal bone loss, also in postmenopausal women at higher risk of developing osteoporosis as those evaluated in our study.     

Isoflavone-rich soy protein isolate attenuates bone loss in the lumbar spine of perimenopausal women

BACKGROUND: No published studies have directly examined the effect of soy protein with isoflavones on bone or bone turnover in perimenopausal women. OBJECTIVE: Our objective was to determine the effects of 24 wk of consumption of soy protein isolate with isoflavones (80.4 mg/d) in attenuating bone loss during the menopausal transition. DESIGN: Perimenopausal subjects were randomly assigned, double blind, to treatment: isoflavone-rich soy (SPI+; n = 24), isoflavone-poor soy (SPI-; n = 24), or whey (control; n = 21) protein. At baseline and posttreatment, lumbar spine bone mineral density (BMD) and bone mineral content (BMC) were measured by using dual-energy X-ray absorptiometry. At baseline, midtreatment, and posttreatment, urinary N:-telopeptides and serum bone-specific alkaline phosphatase (BAP) were measured. RESULTS: The percentage change in lumbar spine BMD and BMC, respectively, did not differ from zero in the SPI+ or SPI- groups, but loss occurred in the control group (-1.28%, P: = 0.0041; -1.73%, P: = 0.0037). By regression analysis, SPI+ treatment had a positive effect on change in BMD (5.6%; P: = 0.023) and BMC (10.1%; P: = 0.0032). Baseline BMD and BMC (P: < or = 0.0001) negatively affected the percentage change in their respective models; baseline body weight (P: = 0.0036) and bone-free lean weight (P: = 0.016) contributed positively to percentage change in BMD and BMC, respectively. Serum BAP posttreatment was negatively related to percentage change in BMD (P: = 0.0016) and BMC (P: = 0.019). Contrast coding using analyses of covariance with BMD or BMC as the outcome showed that isoflavones, not soy protein, exerted the effect. CONCLUSION: Soy isoflavones attenuated bone loss from the lumbar spine in perimenopausal women.     

A comparison of nutrition knowledge and attitudes, dietary practices, and bone densities of postmenopausal women, female college athletes, and nonathletic college women.

This study evaluated the nutrition knowledge and attitudes, dietary practices, and bone densities of four groups of women: 18 postmenopausal women, 14 college-aged dancers, 13 members of a college track team, and 14 nonathletic college women. Subjects completed a personal information questionnaire, a 24-hour food recall, a food frequency questionnaire, a nutrition knowledge test, and an attitude survey; measurements of the subjects' spinal bone density were also taken. The mean (+/- 0.5 standard error [SEM]) nutrition knowledge score of the dancers (22.5) was significantly lower than the mean scores of the postmenopausal women (28.5), the nonathletes (29.7), and the track team members (26.5). Dancers also reported eating fewer mean (+/- 4.0 SEM) servings of high-calcium foods per month (43) than did postmenopausal women (77), nonathletes (66), or track team members (73). Track team members had a significantly higher mean (+/- 0.2 SEM) anorexia/bulimia score (3.7) than did postmenopausal women (2.5), nonathletes (2.1), or dancers (2.2). There were no significant differences in bone mineral density among the four groups. The number of servings of high-calcium foods eaten was significantly correlated with nutrition knowledge scores (r = .38) and attitude scores (R = .32), but nutrition knowledge and attitude scores were not significantly correlated with each other. The track team members exercised significantly more than women in all other groups--mean (+/- 40 SEM) minutes exercise time was 700 minutes/week for track team members, 79 minutes/week for postmenopausal women, 92 minutes/week for nonathletes, and 500 minutes/week for dancers--and also experienced the most amenorrhea.