Nutritional Supplements and Skeletal Health.

PURPOSE OF REVIEW: Nutrition influences skeletal health throughout the lifespan, from the impact of maternal intakes during development, through the development of peak bone mass, to the rate of bone loss during aging. However, there are limited data available on the effects of nutritional supplements on bone density, let alone fracture risk. This review will assess the current literature, focusing on human studies, and emphasizing nutrients where bone density or fracture data are available. RECENT FINDINGS: Calcium and vitamin D supplements, in combination, reduce fracture risk, particularly in populations with low intakes. Extensive recent analyses have supported the safety of these interventions at recommended intakes. There is growing evidence that specific isoflavones may improve bone density although fracture data are lacking. Multiple other nutrient supplements may benefit skeletal health, but data are limited. The effect size of nutrient interventions are relatively small, requiring large sample sizes for trials with bone outcomes, may be difficult to blind, and the impact of supplementation may depend on baseline intake. However, nutrition is the only intervention that can be implemented life long and on a population wide basis. Further investigation is needed into the potential benefits of nutritional supplements to determine in which settings supplements may add benefit in addition to dietary intakes.

A Randomized Controlled Trial of Exercise to Prevent Bone Loss in Premenopausal Women with Breast Cancer.

Background/Introduction/Objective: Premenopausal women treated for breast cancer are at high risk for bone loss. This trial examined the effects of a 1-year combined aerobic and resistance exercise program on bone mineral density (BMD) in women treated for premenopausal breast cancer. MATERIALS AND METHODS: Premenopausal women (n = 206) age ≤ 55 years at cancer diagnosis who were within two years of receiving adjuvant chemotherapy were randomized to a 12-month exercise program or a control group. BMD was measured by dual-energy X-ray absorptiometry at baseline and after 1 year; blood was drawn for skeletal markers. Change from baseline to end of study was compared within and between treatment groups using paired and unpaired t-tests. RESULTS: Lumbar spine BMD declined in both treatment groups with no significant difference between treatment groups (-0.008 ± 0.003 g/cm2 exercise vs. -0.014 ± 0.003 g/cm2 control, p = 0.24). However, among the women who did not lose lean mass during the study (n = 100, 54 control, 46 exercise), the exercise intervention prevented lumbar spine bone loss (0.001 ± 0.005 g/cm2 treatment group vs. -0.014 ± 0.005 g/cm2 control group, p = 0.03). Bone turnover markers decreased significantly in both groups with no differences between groups. CONCLUSIONS: Among women who maintained lean mass, our exercise intervention prevented bone loss; however, our intervention did not prevent bone loss among women who lost muscle mass. Additional investigation into exercise regimens that can prevent both bone and muscle loss may help prevent long-term consequences of premenopausal breast cancer treatment.

FSH Levels Predict Bone Loss in Premenopausal Women Treated for Breast Cancer More Than One Year After Treatment.

CONTEXT: Biomarkers to predict bone loss in premenopausal women after breast cancer treatment have not been examined. OBJECTIVE: To determine whether baseline FSH predicts subsequent bone loss. DESIGN: Secondary data analysis of the Exercise for Bone Health: Young Breast Cancer Survivors study, in which women were randomized to a 12-month exercise program or monthly health newsletter. SETTING: Community dwelling women. PARTICIPANTS: A total of 206 women age less than or equal to 55 years at breast cancer diagnosis who had received adjuvant chemotherapy and were at least 1 year after diagnosis. INTERVENTION: Serum collected at baseline (an average of 302 ± 148 d after completing chemotherapy) was analyzed for FSH. MAIN OUTCOME MEASURE: Change in bone mineral density. RESULTS: In linear regression models, baseline FSH levels predicted bone loss over the ensuing 12 months at the lumbar spine and femoral neck including after adjustment for age, ethnicity, treatment group (exercise vs control), baseline bone density, and high-sensitivity C-reactive protein (P < .001). In multiply adjusted models, the 12-month rate of change in bone density was +0.007% in the lowest tertile of FSH (FSH = 9 ± 7 IU/L, mean ± SD), -0.96% in the middle tertile (mean FSH = 41 ± 11 IU/L), and -2.2% in the highest tertile (mean FSH = 86 ± 19 IU/L), P for trend <.001. CONCLUSIONS: Among premenopausal women with breast cancer treated with chemotherapy, baseline FSH levels are strongly associated with subsequent bone loss. Further studies are needed to establish the optimal timing of FSH measurement in relation to breast cancer treatment and to investigate potential strategies to prevent bone loss.

Intestinal Calcium Absorption Decreases Dramatically After Gastric Bypass Surgery Despite Optimization of Vitamin D Status.

Roux-en-Y gastric bypass (RYGB) surgery has negative effects on bone, mediated in part by effects on nutrient absorption. Not only can RYGB result in vitamin D malabsorption, but the bypassed duodenum and proximal jejunum are also the predominant sites of active, transcellular, 1,25(OH)2 D-mediated calcium (Ca) uptake. However, Ca absorption occurs throughout the intestine, and those who undergo RYGB might maintain sufficient Ca absorption, particularly if vitamin D status and Ca intake are robust. We determined the effects of RYGB on intestinal fractional Ca absorption (FCA) while maintaining ample 25OHD levels (goal ≥30 ng/mL) and Ca intake (1200 mg daily) in a prospective cohort of 33 obese adults (BMI 44.7 ± 7.4 kg/m(2)). FCA was measured preoperatively and 6 months postoperatively with a dual stable isotope method. Other measures included calciotropic hormones, bone turnover markers, and BMD by DXA and QCT. Mean 6-month weight loss was 32.5 ± 8.4 kg (25.8% ± 5.2% of preoperative weight). FCA decreased from 32.7% ± 14.0% preoperatively to 6.9% ± 3.8% postoperatively (p < 0.0001), despite median (interquartile range) 25OHD levels of 41.0 (33.1 to 48.5) and 36.5 (28.8 to 40.4) ng/mL, respectively. Consistent with the FCA decline, 24-hour urinary Ca decreased, PTH increased, and 1,25(OH)2 D increased (p ≤ 0.02). Bone turnover markers increased markedly, areal BMD decreased at the proximal femur, and volumetric BMD decreased at the spine (p < 0.001). Those with lower postoperative FCA had greater increases in serum CTx (ρ = -0.43, p = 0.01). Declines in FCA and BMD were not correlated over the 6 months. In conclusion, FCA decreased dramatically after RYGB, even with most 25OHD levels ≥30 ng/mL and with recommended Ca intake. RYGB patients may need high Ca intake to prevent perturbations in Ca homeostasis, although the approach to Ca supplementation needs further study. Decline in FCA could contribute to the decline in BMD after RYGB, and strategies to avoid long-term skeletal consequences should be investigated.

Potassium citrate supplementation results in sustained improvement in calcium balance in older men and women.

The dietary acid load created by the typical Western diet may adversely impact the skeleton by disrupting calcium metabolism. Whether neutralizing dietary acid with alkaline potassium salts results in sustained improvements in calcium balance remains controversial. In this randomized, double-blind, placebo-controlled study, 52 men and women (mean age 65.2 ± 6.2 years) were randomly assigned to potassium citrate 60 mmol/d, 90 mmol/d, or placebo daily with measurements of bone turnover markers, net acid excretion, and calcium metabolism, including intestinal fractional calcium absorption and calcium balance, obtained at baseline and at 6 months. At 6 months, net acid excretion was significantly lower in both treatment groups compared to placebo and it was negative, meaning subjects' dietary acid was completely neutralized (-11.3 mmol/d on 60 mmol/d; -29.5 mmol/d on 90 mmol/d, p < 0.001 compared to placebo). At 6 months, 24-hour urine calcium was significantly reduced in persons taking potassium citrate 60 mmol/d (-46 ± 15.9 mg/d) and 90 mmol/d (-59 ± 31.6 mg/d) compared with placebo (p < 0.01). Fractional calcium absorption was not changed by potassium citrate supplementation. Net calcium balance was significantly improved in participants taking potassium citrate 90 mmol/d compared to placebo (142 ± 80 mg/d on 90 mmol/d versus -80 ± 54 mg/d on placebo; p = 0.02). Calcium balance was also improved on potassium citrate 60 mmol/d, but this did not reach statistical significance (p = 0.18). Serum C-telopeptide decreased significantly in both potassium citrate groups compared to placebo (-34.6 ± 39.1 ng/L on 90 mmol/d, p = 0.05; -71.6 ± 40.7 ng/L on 60 mmol/d, p = 0.02) whereas bone-specific alkaline phosphatase did not change. Intact parathyroid hormone was significantly decreased in the 90 mmol/d group (p = 0.01). Readily available, safe, and easily administered in an oral form, potassium citrate has the potential to improve skeletal health. Longer-term trials with definitive outcomes such as bone density and fracture are needed.

Age-related hyperkyphosis: its causes, consequences, and management.

SYNOPSIS: Age-related hyperkyphosis is an exaggerated anterior curvature in the thoracic spine that occurs commonly with advanced age. This condition is associated with low bone mass, vertebral compression fractures, and degenerative disc disease, and contributes to difficulty performing activities of daily living and decline in physical performance. While there are effective treatments, currently there are no public health approaches to prevent hyperkyphosis among older adults. Our objective is to review the prevalence and natural history of hyperkyphosis, associated health implications, measurement tools, and treatments to prevent this debilitating condition. LEVEL OF EVIDENCE: Diagnosis/prognosis/therapy, level 5.J Orthop Sports Phys Ther 2010;40(6):352-360, Epub 15 April 2010. doi:10.2519/jospt.2010.3099.

NIH consensus development conference statement: Lactose intolerance and health.

OBJECTIVE: To provide health care providers, patients, and the general public with a responsible assessment of currently available data on lactose intolerance and health. PARTICIPANTS: A non-DHHS, nonadvocate 14-member panel representing the fields of internal medicine, pediatrics, pediatric and adult endocrinology, gastroenterology, hepatology, neonatology and perinatology, geriatrics, racial/ethnic disparities, radiology, maternal and fetal nutrition, vitamin and mineral metabolism, nutritional sciences, bone health, preventive medicine, biopsychology, biostatistics, statistical genetics, epidemiology, and a public representative. In addition, 22 experts from pertinent fields presented data to the panel and conference audience. EVIDENCE: Presentations by experts and a systematic review of the literature prepared by the University of Minnesota Evidence-based Practice Center, through the Agency for Healthcare Research and Quality. Scientific evidence was given precedence over anecdotal experience. CONFERENCE PROCESS: The panel drafted its statement based on scientific evidence presented in open forum and on published scientific literature. The draft statement was presented on the final day of the conference and circulated to the audience for comment. The panel released a revised statement later that day at http://consensus.nih.gov. This statement is an independent report of the panel and is not a policy statement of the NIH or the Federal Government. CONCLUSIONS: • Lactose intolerance is a real and important clinical syndrome, but its true prevalence is not known. • The majority of people with lactose malabsorption do not have clinical lactose intolerance. Many individuals who think they are lactose intolerant are not lactose malabsorbers. • Many individuals with real or perceived lactose intolerance avoid dairy and ingest inadequate amounts of calcium and vitamin D, which may predispose them to decreased bone accrual, osteoporosis, and other adverse health outcomes. In most cases, individuals do not need to eliminate dairy consumption completely. • Evidence-based dietary approaches with and without dairy foods and supplementation strategies are needed to ensure appropriate consumption of calcium and other nutrients in lactose-intolerant individuals. • Educational programs and behavioral approaches for individuals and their healthcare providers should be developed and validated to improve the nutrition and symptoms of individuals with lactose intolerance and dairy avoidance.

Elevations in serum and urinary calcium with parathyroid hormone (1-84) with and without alendronate for osteoporosis.

CONTEXT: The effect of PTH therapy on serum and urinary calcium levels and the risk of hypercalcemia or hypercalciuria has not been formally evaluated. OBJECTIVE: The objective was to examine changes in serum and urinary calcium associated with PTH(1-84) therapy in the PaTH trial and the extent to which a defined algorithm resolved the elevated values. DESIGN, SETTING, PARTICIPANTS, AND INTERVENTION: A total of 178 postmenopausal women were randomized to PTH(1-84) either alone or in combination with alendronate during the first year of the PaTH study. MAIN OUTCOME MEASURE(S): The main outcome measures were fasting serum calcium at baseline and 1, 3, and 12 months and 24-h urinary calcium at baseline and 3 months. RESULTS: In 14% of participants, serum calcium more than 10.5 mg/dl (>2.6 mmol/liter) developed. Following the defined algorithm, 58% of elevated measurements were normal on repeat testing; 38% required discontinuation of calcium and vitamin D supplementation, and one necessitated a decrease in PTH injection frequency to normalize serum calcium. One participant developed transient hypercalcemia between study visits and required hospitalization; the episode resolved with iv hydration and PTH discontinuation. Baseline characteristics associated with the development of hypercalcemia were serum calcium [relative hazards = 1.9 per 0.5 mg/dl (0.12 mmol/liter); 95% confidence interval = 1.1-3.2] and serum 1,25-dihydroxyvitamin D [relative hazard = 1.9 per 10 pg/ml (26 pmol/liter); 95% confidence interval = 1.2-3.1]. Fifteen women (8%) developed hypercalciuria [urinary calcium > 400 mg (100 mmol)/24 h or calcium/creatinine ratio > 0.4]; 80% of cases resolved after discontinuing calcium and vitamin D, 13% without intervention, and one after PTH injection frequency was decreased. Higher baseline urinary calcium excretion was associated with development of hypercalciuria [relative hazard = 1.5 per 50 mg/d (12.5 mmol/d); 95% confidence interval = 1.2-4.0]. Proportions of patients with elevated serum and urinary calcium were similar on single and combination therapy. CONCLUSIONS: The frequency of episodic hypercalcemia or hypercalciuria in the PaTH trial was 21%. Episodes were generally mild, and nearly all cases resolved spontaneously or with discontinuation of calcium and vitamin D. The algorithms used to address hypercalcemia and hypercalciuria in the PaTH trial proved effective in safely resolving clinical episodes of increased urinary or serum calcium and might therefore be helpful to clinicians caring for patients on PTH.

Vitamin D insufficiency does not affect bone mineral density response to raloxifene.

CONTEXT: Vitamin D insufficiency and osteoporosis are common and often coexist in postmenopausal women. OBJECTIVE: The objective of this study was to test whether the presence of vitamin D insufficiency at the initiation of raloxifene therapy affected the subsequent response of bone mineral density (BMD). DESIGN, SETTING, AND PARTICIPANTS: We studied 7522 postmenopausal participants of the Multiple Outcomes of Raloxifene Evaluation, a placebo-controlled trial of the effects of raloxifene on BMD and fracture. INTERVENTION: After enrollment, all participants began daily supplements of 500 mg calcium and 400-600 IU cholecalciferol; 1 month later, women were randomly assigned to placebo or raloxifene. MAIN OUTCOME MEASURE: Serum levels of vitamin D [25-hydroxy vitamin D (25OHD)] were measured at enrollment, randomization, and 6 months later. We categorized participants' vitamin D status (deficient, insufficient, or sufficient) based on their randomization 25OHD level. We estimated the effects of treatment on BMD within these subgroups using linear regression models. RESULTS: At enrollment, 3.2% of participants were vitamin D deficient, and 51.8% were insufficient; after 7 months of cholecalciferol supplementation, 0.2% of all participants remained D deficient, and 23.6% remained insufficient. The effects of raloxifene on hip and spine BMD did not vary by vitamin D status at randomization (P = 0.08 and P = 0.7, respectively). CONCLUSION: We conclude that vitamin D status at initiation of raloxifene therapy does not affect the subsequent BMD response when coadministered with cholecalciferol and calcium. After 7 months of cholecalciferol therapy, very few women continued to have 25OHD levels in the deficient range; however, 25OHD levels remained suboptimal in nearly one fourth of the cohort. Additional research is needed to determine whether these observations can be generalized to other antiresorptive agents.