Calcium, dairy foods, and risk of incident and fatal prostate cancer: the NIH-AARP Diet and Health Study

Calcium and dairy foods in relation to prostate cancer were examined in the National Institutes of Health (NIH)-AARP (formerly known as the American Association of Retired Persons) Diet and Health Study (1995/1996-2001). Diet was assessed with a food frequency questionnaire at baseline. Multivariate relative risks and 95% confidence intervals were estimated by Cox regression. During up to 6 years of follow-up (n = 293,888), the authors identified 10,180 total prostate cancer cases (8,754 nonadvanced, 1,426 advanced, and 178 fatal cases). Total and supplemental calcium were unrelated to total and nonadvanced prostate cancer. However, a statistically nonsignificant positive association with total calcium was observed for advanced (> or = 2,000 vs. 500-<750 mg/day: relative risk (RR) = 1.25, 95% confidence interval (CI): 0.91, 1.71; p(trend) = 0.06) and fatal (> or = 1,000 vs. 500-<750 mg/day: RR = 1.39, 95% CI: 0.92, 2.09; p(trend) = 0.10) prostate cancer. Skim milk, but not other dairy foods, was associated with increased risk of advanced prostate cancer (> or = 2 vs. zero servings/day: RR = 1.23, 95% CI: 0.99, 1.54; p(trend) = 0.01). In contrast, calcium from nondairy foods was associated with lower risk of nonadvanced prostate cancer (> or = 600 vs. < 250 mg/day: RR = 0.82, 95% CI: 0.68, 0.99; p(trend) = 0.04). Although the authors cannot definitively rule out a weak association for aggressive prostate cancer, their findings do not provide strong support for the hypothesis that calcium and dairy foods increase prostate cancer risk.     

Effects of 3 diets with various calcium contents on 24-h energy expenditure, fat oxidation, and adipose tissue message RNA expression of lipid metabolism-related proteins

BACKGROUND: Evidence from molecular and animal research and epidemiologic investigations indicates that calcium intake may be inversely related to body weight, possibly through alterations in 1,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)] metabolism. OBJECTIVE: We tested whether energy and substrate metabolism and adipose tissue enzyme messenger RNA (mRNA) expression can be altered by dietary calcium intake in healthy, nonobese, human volunteers consuming an isocaloric diet. DESIGN: Twelve healthy men [age: 28 +/- 2 y; body mass index (BMI; in kg/m(2)): 25.2 +/- 06] received 3 isocaloric diets [high calcium (1259 +/- 9 mg/d), high dairy (high/high); high calcium (1259 +/- 9 mg/d), low dairy (high/low); and low calcium (349 +/- 8 mg/d), low dairy (low/low)] in a randomized crossover design. At the end of the 7-d dietary periods, 24-h energy expenditure and substrate metabolism were measured, and fat biopsy specimens were obtained to determine mRNA expression in genes involved in the lipolytic and lipogenic pathways. RESULTS: The 24-h energy expenditure was 11.8 +/- 0.3, 11.6 +/- 0.3, and 11.7 +/- 0.3 MJ/24 h in the high/high, high/low, and low/low conditions, respectively. Fat oxidation in these conditions was 108 +/- 7, 105 +/- 9, and 100 +/- 6 g/24 h. These differences were not statistically significant. mRNA concentrations of UCP2, FAS, GPDH2, HSL, and PPARG did not differ significantly. Serum 1,25(OH)(2)D(3) concentrations changed from 175 +/- 16 to 138 +/- 15, 181 +/- 23 to 159 +/- 19, and 164 +/- 13 to 198 +/- 19 pmol/L in the high/high, high/low, and low/low conditions, respectively, and was significantly different between the high/high and low/low conditions (P < 0.05). CONCLUSION: Altering the dietary calcium content for 7 d does not influence substrate metabolism, energy metabolism, or gene expression in proteins related to fat metabolism, despite significant changes in 1,25(OH)(2)D(3) concentrations.     

Calcium intake and vitamin D metabolism and action, in healthy conditions and in prostate cancer

An association between Ca intake and the risk of prostate cancer has been reported in some but not all epidemiological studies. Assuming that a pathophysiological relationship would underlie this association, a favoured hypothesis proposes that relatively high Ca consumption could promote prostate cancer by reducing the production of 1,25-dihydroxyvitamin D (1,25(OH)2D; calcitriol), the hormonal form of vitamin D. The present review analyses the plausibility of this hypothesis by considering the quantitative relationships linking Ca intake to 1,25(OH)2D production and action in healthy conditions and in prostate cancer. Changes in the plasma level of 1,25(OH)2D in response to Ca intake are of very small magnitude as compared with the variations required to influence the proliferation and differentiation of prostate cancer cells. In most studies, 1,25(OH)2D plasma level was not found to be reduced in patients with prostate cancer. The possibility that the level of 1,25(OH)2D in prostate cells is decreased with a high-Ca diet has not been documented. Furthermore, a recent randomised placebo-controlled trial did not indicate that Ca supplementation increases the relative risk of prostate cancer in men. In conclusion, the existence of a pathophysiological link between relatively high Ca intake and consequent low production and circulation level of 1,25(OH)2D that might promote the development of prostate cancer in men remains so far an hypothesis, the plausibility of which is not supported by the analysis of available clinical data.     

Determination of the optimal number of dairy servings to ensure a low prevalence of inadequate calcium intake in Americans

BACKGROUND: Many Americans are not getting the recommended amounts of calcium in their diet. Since dairy foods provide most of the calcium in the diet, the number of recommended servings of dairy products may need to be revised. OBJECTIVE: 1. To determine the calcium intake of various age groups that met or exceeded the intake of dairy products recommended by the Food Guide Pyramid (FGP). 2. To determine the optimal level of dairy consumption that ensures a low prevalence of inadequate calcium (Ca) intake by Americans. METHODS: Using data from the Continuing Survey of Food Intake by Individuals, 1994-96, 1998, (CSFII) and the National Health and Nutrition Examination Survey, 1999-2000 (NHANES) we determined the calcium intake in individuals who met the recommended daily dairy servings as well as the minimum number of dairy servings required for the mean Ca intake of various age groups to exceed their respective Adequate Intakes (AI). RESULTS: Objective 1: Meeting or exceeding the FGP dairy recommendation led to calcium intakes that met recommended levels. However, very few individuals in all age groups met or exceeded the number of dairy servings recommended by FGP. Objective 2: Results indicated that in children 2-8 yrs, 2 dairy servings/d were required for the mean Ca intake (835 +/- 72 and 822 +/- 68 mg/d, in CSFII and NHANES IV, respectively) to exceed the AI. In children 9-18 yrs, 4 dairy servings/d) were required for the mean Ca intake of the group (1540 +/- 93 and 1518 +/- 86 mg/d) to exceed the AI. Similar data were observed in adults 19+ yrs, e.g., in adults 51+ yrs, 3 dairy servings/d were required for the mean Ca intake of the group (1241 +/- 53 and 1217 +/- 53 mg/d) to exceed the AI. CONCLUSION: Groups that met or exceeded the FGP dairy recommendations were more likely to have a mean calcium intake above the AI but had an average intake of about one serving higher than current recommendations. In individuals 9 yrs and older, 3-4 servings of dairy products are needed to meet or exceed the Ca AI and to ensure a low prevalence of inadequate Ca intake.     

Milk and lactose intakes and ovarian cancer risk in the Swedish Mammography Cohort

BACKGROUND: High intakes of dairy products and of the milk sugar lactose have been hypothesized to increase ovarian cancer risk, but prospective data are scarce. OBJECTIVE: We examined the association between intakes of dairy products and lactose and the risk of total epithelial ovarian cancer and its subtypes. DESIGN: This was a prospective population-based cohort study of 61 084 women aged 38-76 y who were enrolled in the Swedish Mammography Cohort. Diet was assessed in 1987-1990 with the use of a self-administered food-frequency questionnaire. During an average follow-up of 13.5 y, 266 women were diagnosed with invasive epithelial ovarian cancer; 125 of those women had serous ovarian cancer. RESULTS: After adjustment for potential confounders, women who consumed >/=4 servings of total dairy products/d had a risk of serous ovarian cancer (rate ratio: 2.0; 95% CI: 1.1, 3.7; P for trend = 0.06) twice that of women who consumed <2 servings/d. No significant association was found for other subtypes of ovarian cancer. Milk was the dairy product with the strongest positive association with serous ovarian cancer (rate ratio comparing consuming >/=2 glasses milk/d with consuming milk never or seldom: 2.0; 95% CI: 1.1, 3.7; P for trend = 0.04). We observed a positive association between lactose intake and serous ovarian cancer risk (P for trend = 0.006). CONCLUSIONS: Our data indicate that high intakes of lactose and dairy products, particularly milk, are associated with an increased risk of serous ovarian cancer but not of other subtypes of ovarian cancer. Future studies should consider ovarian cancer subtypes separately.     

The impact of calcium and dairy product consumption on weight loss

OBJECTIVE: Recent evidence suggests that diets high in calcium and dairy products are associated with lower body weight, particularly lower body fat levels. The purpose of this study was to compare weight and body fat loss on a calorie-restricted, low-dairy (CR) vs. high-dairy (CR+D) diet. RESEARCH METHODS AND PROCEDURES: Fifty-four subjects (BMI 30 +/- 2.5 kg/m2, 45 +/- 6.6 years, 4 men) were randomly assigned to calorie-restricted (-500 kcal/d) low-dairy calcium (n = 29; approximately 1 serving dairy/d, 500 mg/d calcium) or high-dairy calcium (n = 25; 3 to 4 servings dairy/d, 1200 to 1400 mg/d calcium) diets for 12 months. Main outcome measures included change in weight (kilograms) and body fat (percentage). RESULTS: There were no significant differences between groups at baseline. At 12 months, weight and body fat loss were not significantly different. Subjects in the CR vs. CR+D conditions lost 9.6 +/- 6.5 vs. 10.8 +/- 5.9 kg (p = 0.56) and 9.0 +/- 3.8 vs. 10.1 +/- 3.6 kg body fat (p = 0.37). DISCUSSION: These findings suggest that a high-dairy calcium diet does not substantially improve weight loss beyond what can be achieved in a behavioral intervention.     

Dairy, calcium, and vitamin D intakes and prostate cancer risk in the National Health and Nutrition Examination Epidemiologic Follow-up Study cohort

BACKGROUND: Dairy intake may increase prostate cancer risk, but whether this is due to calcium's suppression of circulating vitamin D remains unclear. Findings on calcium and vitamin D intake and prostate cancer are inconsistent. OBJECTIVE: We examined the association of dairy, calcium, and vitamin D intake with prostate cancer. DESIGN: In a prospective study of 3612 men followed from 1982-1984 to 1992 for the first National Health and Nutrition Examination Epidemiologic Follow-up Study, 131 prostate cancer cases were identified. Dietary intake was estimated from questionnaires completed in 1982-1984. Relative risk (RR) and 95% CIs were estimated by using Cox proportional hazards models adjusted for age, race, and other covariates. RESULTS: Compared with men in the lowest tertile for dairy food intake, men in the highest tertile had a relative risk (RR) of 2.2 (95% CI: 1.2, 3.9; trend P = 0.05). Low-fat milk was associated with increased risk (RR = 1.5; 95% CI: 1.1, 2.2; third compared with first tertile; trend P = 0.02), but whole milk was not (RR = 0.8; 95% CI: 0.5, 1.3; third compared with first tertile; trend P = 0.35). Dietary calcium was also strongly associated with increased risk (RR = 2.2; 95% CI: 1.4, 3.5; third compared with first tertile; trend P = 0.001). After adjustment for calcium intake, neither vitamin D nor phosphorus was clearly associated with risk. CONCLUSIONS: Dairy consumption may increase prostate cancer risk through a calcium-related pathway. Calcium and low-fat milk have been promoted to reduce risk of osteoporosis and colon cancer. Therefore, the mechanisms by which dairy and calcium might increase prostate cancer risk should be clarified and confirmed.     

Calcium and dairy food intakes are inversely associated with colorectal cancer risk in the Cohort of Swedish Men

BACKGROUND: Recent epidemiologic studies have generally reported a modest inverse association between calcium intake and the risk of colorectal cancer. However, findings pertaining to specific subsites in the colorectum have been conflicting. OBJECTIVE: Our objective was to prospectively examine the relations between intakes of calcium and dairy foods and the risk of colorectal cancer, overall and by anatomic subsite, in men from the Cohort of Swedish Men. DESIGN: In 1997, 45 306 men aged 45-79 y and without a history of cancer completed a food-frequency questionnaire. The men were followed through 31 December 2004. RESULTS: During a mean follow-up of 6.7 y, we ascertained 449 incident cases of colorectal cancer. After adjustment for age and other known or potential risk factors, the multivariate rate ratio (RR) of colorectal cancer for men in the highest quartile of total calcium intake compared with those in the lowest quartile was 0.68 (95% CI: 0.51, 0.91; P for trend = 0.01). A high consumption of dairy foods was also associated with a lower risk of colorectal cancer. The multivariate RR of colorectal cancer for > or = 7 servings/d of total dairy foods compared with <2 servings/d was 0.46 (0.30, 0.71; P for trend = 0.01). For cancer subsites, the corresponding RRs were 0.37 (0.16, 0.88) for proximal colon, 0.43 (0.20, 0.93) for distal colon, and 0.48 (0.23, 0.99) for rectum. CONCLUSION: Our findings provide support for inverse associations between intakes of calcium and dairy foods and the risk of colorectal cancer.     

Dairy products, calcium and phosphorus intake, and the risk of prostate cancer: results of the French prospective SU.VI.MAX (Supplémentation en Vitamines et Minéraux Antioxydants) study

Although dairy products have been found to be associated with an elevated risk of prostate cancer, studies investigating the potential effect of Ca are limited, and findings are inconsistent. The objective of the present study was to test the relationship between the risk of prostate cancer and consumption of dairy products and Ca. The analysis included 2776 men from the French SU.VI.MAX (Supplementation en Vitamines et Minéraux Antioxydants) prospective study, among whom sixty-nine developed prostate cancer during the follow-up period (median: 7.7 years). Food consumption was assessed at inclusion from repeated 24 h records and nutrient intake was calculated using a food composition table. A higher risk of prostate cancer was observed among subjects with higher dairy product (relative risk (RR; 95 % CI), 4th quartile v. 1st: 1.35 (1.02, 1.78), P = 0.04) and Ca intake (RR (95 % CI), 4th quartile v. 1st: 2.43 (1.05, 5.62), P = 0.04). Nevertheless, we identified a harmful effect of yoghurt consumption upon the risk of prostate cancer (RR (95 % CI), increment 125 g/d: 1.61 (1.07, 2.43), P = 0.02) independently of the Ca content. Our data support the hypothesis that dairy products have a harmful effect with respect to the risk of prostate cancer, largely related to Ca content. The higher risk of prostate cancer with linear increasing yoghurt consumption seems to be independent of Ca and may be related to some other component.     

Dairy intakes affect bone density in the elderly

BACKGROUND: Race and sex differences in the effect of diet on bone mineral density (BMD) at the hip in the elderly are unknown. OBJECTIVES: This study related cross-sectional nutrient and dairy product consumption to hip BMD in white and black men and women aged >60 y and evaluated the influence of nutrient and dairy product consumption on changes in BMD in a white cohort participating in a calcium, vitamin D, or placebo trial. DESIGN: The Health Habits and History Questionnaire was used in 289 white women and 116 white men who participated in the trial and in 265 black women and 75 black men to predict total hip and femoral neck BMD or changes in BMD. RESULTS: Blacks had higher calcium intakes than did whites (700 and 654 mg/d, respectively; P = 0.0094), and men had higher calcium intakes than did women (735 and 655 mg/d, respectively; P = 0.0007). For men, the correlation between total hip BMD and dairy calcium intake after adjustment for age, race, and weight was 0.23 (P < 0.005); this relation was not significant in women (r = 0.02, P = 0.12). Similar results were found for femoral neck BMD. In the longitudinal study, calcium supplementation reduced bone loss from the total hip and femoral neck in those who consumed <1.5 servings of dairy products/d and were <72 y old. CONCLUSIONS: Cross-sectional results indicated that higher dairy product consumption is associated with greater hip BMD in men, but not in women. Calcium supplementation protected both men and women from bone loss in the longitudinal study of whites.     

Cultured milk, yogurt, and dairy intake in relation to bladder cancer risk in a prospective study of Swedish women and men

BACKGROUND: Findings from epidemiologic studies of the effect of dairy foods (mainly milk) on the risk of bladder cancer have been inconsistent. OBJECTIVE: We aimed to examine the association between the intake of cultured milk and other dairy foods and the incidence of bladder cancer in a prospective, population-based cohort. DESIGN: We prospectively followed 82,002 Swedish women and men who were cancer-free and who completed a 96-item food-frequency questionnaire in 1997. Incident cases of bladder cancer were identified in the Swedish cancer registries. RESULTS: During a mean follow-up of 9.4 y, 485 participants (76 women and 409 men) were diagnosed with bladder cancer. Total dairy intake was not significantly associated with risk of bladder cancer [> or =7.0 servings/d compared with < 3.5 servings/d: multivariate rate ratio (RR) = 0.87; 95% CI: 0.66, 1.15; P for trend = 0.33]. However, a statistically significant inverse association was observed for the intake of cultured milk (sour milk and yogurt). The multivariate RRs for the highest category of cultured milk intake (> or =2 servings/d) compared with the lowest category (0 serving/d) were 0.62 (95% CI: 0.46, 0.85; P for trend = 0.006) in women and men combined, 0.55 (95% CI: 0.25, 1.22; P for trend = 0.06) in women, and 0.64 (95% CI: 0.46, 0.89; P for trend = 0.03) in men. The intake of milk or cheese was not associated with bladder cancer risk. CONCLUSION: These findings suggest that a high intake of cultured milk may lower the risk of developing bladder cancer.     

Protein and legume intake and prostate cancer mortality in Puerto Rican men

Prostate cancer is the number 1 cancer killer among Puerto Rican (PR) men. Plant foods have been inversely associated with prostate cancer. Legumes play a significant role in the PR diet; consumption of legumes in PR (14 lb/capita) was double that of the United States (7 lb/capita). We examined dietary protein consumption (from baseline 24-h dietary recalls) and prostate cancer mortality in the PR Heart Health Program, a cohort study of 9,824 men aged 35-79 years at baseline (1964) with follow-up until 2005. Total protein intake in the cohort was 85 g/day, and sources of protein were 30% vegetable, 30% dairy, 31% animal, and 8% seafood protein. Legume intake was 2.3 servings/day (1/4 cup each). Legume intake was not associated with prostate cancer mortality [comparing highest quartile to lowest quartile-odds ratio (OR) 1.40 [95% confidence interval (CI) 0.91-2.18], P trend 0.17]-nor were total protein, animal, seafood, dairy, or vegetable protein intakes. Consuming 1-2 servings of fruit was inversely associated (OR 0.50, 95% CI 0.32-0.77), whereas consuming more than 2 servings of fruit was not associated with prostate cancer mortality. Thus, we find no association between legumes or protein intake and prostate cancer mortality in this longitudinal cohort study of PR men.     

Calcium, vitamin D, and dairy product intake and prostate cancer risk: the Multiethnic Cohort Study

High intakes of calcium and dairy products have been suggested to be related to prostate cancer risk. Such associations were examined in the Multiethnic Cohort Study (1993-2002) among 82,483 men who completed a detailed quantitative food frequency questionnaire. During a mean follow-up of 8 years, 4,404 total cases of prostate cancer were identified. In Cox proportional hazards models, no association was found between calcium and vitamin D intake and total, advanced, or high-grade prostate cancer risk, whether for total intake, intake from foods, or intake from supplements, among all male participants or among nonusers of supplemental calcium. No association of calcium or vitamin D intake was seen across racial/ethnic groups. In analyses of food groups, dairy product and total milk consumption were not associated with prostate cancer risk. However, low-/nonfat milk was related to an increased risk and whole milk to a decreased risk of total prostate cancer; after stratification, these effects were limited to localized or low-grade tumors. Although the findings from this study do not support an association between the intakes of calcium and vitamin D and prostate cancer risk, they do suggest that an association with milk consumption may vary by fat content, particularly for early forms of this cancer.     

Calcium,vitamin D,milk consumption,and hip fractures: a prospective study among postmenopausal women

BACKGROUND: Short trials of calcium supplementation show that it reduces loss of bone density in postmenopausal women; longer observational studies do not generally find a lower risk of hip fracture with higher-calcium diets. Fewer studies have focused on vitamin D in preventing postmenopausal osteoporosis or fractures. OBJECTIVE: We assessed relations between postmenopausal hip fracture risk and calcium, vitamin D, and milk consumption. DESIGN: In an 18-y prospective analysis in 72 337 postmenopausal women, dietary intake and nutritional supplement use were assessed at baseline in 1980 and updated several times during follow-up. We identified 603 incident hip fractures resulting from low or moderate trauma. Relative risks (RRs) from proportional hazards models were controlled for other dietary and nondietary factors. RESULTS: Women consuming > or = 12.5 microg vitamin D/d from food plus supplements had a 37% lower risk of hip fracture (RR = 0.63; 95% CI: 0.42, 0.94) than did women consuming < 3.5 microg/d. Total calcium intake was not associated with hip fracture risk (RR = 0.96; 95% CI: 0.68, 1.34 for > or = 1200 compared with < 600 mg/d). Milk consumption was also not associated with a lower risk of hip fracture (P for trend = 0.21). CONCLUSIONS: An adequate vitamin D intake is associated with a lower risk of osteoporotic hip fractures in postmenopausal women. Neither milk nor a high-calcium diet appears to reduce risk. Because women commonly consume less than the recommended intake of vitamin D, supplement use or dark fish consumption may be prudent.     

Calcium and cholecalciferol: effects of small supplements in normal men

The effect of small calcium and vitamin D supplements on mineral metabolism in normal persons is unclear. To investigate the biochemical response to these medications, we administered 1000 mg Ca and 25 micrograms cholecalciferol per day or a placebo to 92 normal men for 1 y. The Ca and cholecalciferol were tolerated well. 25-Hydroxycholecalciferol [25-(OH)D] and 24,25-dihydroxycholecalciferol [24,25-(OH)2D] levels rose in treated subjects; there was no definite change in 1,25-(OH)2D concentrations. The average difference in 25-(OH)D levels between treated and untreated subjects was 30 nmol/L at 1 y. Fasting serum Ca, alkaline phosphatase, creatinine, and parathyroid hormone levels and the fasting urinary excretion of Ca, phosphorus and cAMP, were not affected. However, 24-h urinary Ca excretion was higher in the supplemented group (3.5 +/- 1.9 vs 4.7 +/- 1.7 mmol/d, p = 0.006). Serum P concentrations were slightly higher in the supplemented group at 1 y. In normal men small calcium and cholecalciferol supplements are safe, provide adequate vitamin D nutrition and apparently increase net gastrointestinal Ca absorption.     

Diabetes prevalence is associated with serum 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D in US middle-aged Caucasian men and women: a cross-sectional analysis within the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial

Hypovitaminosis D may be associated with diabetes, hypertension and CHD. However, because studies examining the associations of all three chronic conditions with circulating 25-hydroxyvitamin D (25(OH)D) and 1,25-dihydroxyvitamin D (1,25(OH)(2)D) are limited, we examined these associations in the US Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial (n 2465). Caucasian PLCO participants selected as controls in previous nested case-control studies of 25(OH)D and 1,25(OH)(2)D were included in this analysis. Diabetes, CHD and hypertension prevalence, risk factors for these conditions and intake of vitamin D and Ca were collected from a baseline questionnaire. Results indicated that serum levels of 25(OH)D were low (< 50 nmol/l) in 29 % and very low (< 37 nmol/l) in 11 % of subjects. The prevalence of diabetes, hypertension and CHD was 7, 30 and 10 %, respectively. After adjustment for confounding by sex, geographical location, educational level, smoking history, BMI, physical activity, total dietary energy and vitamin D and Ca intake, only diabetes was significantly associated with lower 25(OH)D and 1,25(OH)(2)D levels. Caucasians who had 25(OH)D ≥ 80 nmol/l were half as likely to have diabetes (OR 0·5 (95 % CI 0·3, 0·9)) compared with those who had 25(OH)D < 37 nmol/l. Those in the highest quartile of 1,25(OH)(2)D (≥ 103 pmol/l) were less than half as likely to have diabetes (OR 0·3 (95 % CI 0·1, 0·7)) than those in the lowest quartile (< 72 pmol/l). In conclusion, the independent associations of 25(OH)D and 1,25(OH)(2)D with diabetes prevalence in a large population are new findings, and thus warrant confirmation in larger, prospective studies.     

Dairy Products,Dietary Calcium and Vitamin D Intake as Risk Factors for Prostate Cancer: A Meta-Analysis of 26,769 Cases From 45 Observational Studies

In this study, we examined the available evidence and sources of heterogeneity for studies of dairy products, calcium, and vitamin D intake and the risk of prostate cancer. We pooled data from 45 observational studies using a general variance-based, meta-analytic method employing CIs. Summary relative risks (RRs) were calculated for specific dairy products such as milk and dairy micronutrients. Sensitivity analyses were performed to test the robustness of these summary measures of effect. Cohort studies showed no evidence of an association between dairy [RR = 1.06; 95% confidence interval (CI) = 0.92–1.22] or milk intake (RR = 1.06; 95% CI = 0.91–1.23) and risk of prostate cancer. This was supported by pooled results of case-control analyses (RR = 1.14; 95% CI = 1.00–1.29), although studies using milk as the exposure of interest were heterogeneous and could not be combined. Calcium data from cohort studies were heterogeneous. Case-control analyses using calcium as the exposure of interest demonstrated no association with increased risk of prostate cancer (RR = 1.04; 95% CI = 0.90–1.15). Dietary intake of vitamin D also was not related to prostate cancer risk (RR = 1.16; 95% CI = 0.98–1.38). The data from observational studies do not support an association between dairy product use and an increased risk of prostate cancer.     

Dairy products, dietary calcium and vitamin D intake as risk factors for prostate cancer: a meta-analysis of 26,769 cases from 45 observational studies

In this study, we examined the available evidence and sources of heterogeneity for studies of dairy products, calcium, and vitamin D intake and the risk of prostate cancer. We pooled data from 45 observational studies using a general variance-based, meta-analytic method employing CIs. Summary relative risks (RRs) were calculated for specific dairy products such as milk and dairy micronutrients. Sensitivity analyses were performed to test the robustness of these summary measures of effect. Cohort studies showed no evidence of an association between dairy [RR = 1.06; 95% confidence interval (CI) = 0.92-1.22] or milk intake (RR = 1.06; 95% CI = 0.91-1.23) and risk of prostate cancer. This was supported by pooled results of case-control analyses (RR = 1.14; 95% CI = 1.00-1.29), although studies using milk as the exposure of interest were heterogeneous and could not be combined. Calcium data from cohort studies were heterogeneous. Case-control analyses using calcium as the exposure of interest demonstrated no association with increased risk of prostate cancer (RR = 1.04; 95% CI = 0.90-1.15). Dietary intake of vitamin D also was not related to prostate cancer risk (RR = 1.16; 95% CI = 0.98-1.38). The data from observational studies do not support an association between dairy product use and an increased risk of prostate cancer.     

Vitamin D and intervention trials in prostate cancer: from theory to therapy

Studies of vitamin D and prostate cancer have advanced rapidly from the hypothesis that vitamin D deficiency increases the risk of prostate cancer to intervention trials of vitamin D administration in clinical cancer. The hormonal form of vitamin D, 1,25(OH)(2)D, exerts prodifferentiating, antiproliferative, anti-invasive, and antimetastatic effects on prostate cells. Moreover, normal prostate cells synthesize 1,25(OH)(2)D from serum levels of the prohormone, 25-hydroxyvitamin D. The autocrine synthesis of 1,25(OH)(2)D by prostatic cells provides a biochemical mechanism whereby vitamin D may prevent prostate cancer. Many prostate cancer cells have lost the ability to synthesize 1,25(OH)(2)D but still possess 1,25(OH)(2)D receptors. This suggests that whereas vitamin D (e.g., cholecalciferol) might prevent prostate cancer, existing prostate tumors likely would require treatment with 1,25(OH)(2)D and/or its analogs. The major obstacle to the use of 1,25(OH)(2)D in patients therapeutically is the risk of hypercalcemia. Several maneuvers to reduce this risk, including pulse dosing and the use of less calcemic 1,25(OH)(2)D analogs, have been explored in Phase I-III clinical trials. Once merely a promise, vitamin D-based therapies for prostate cancer may soon be medical practice.     

Bone mineral content in girls perinatally infected with HIV

BACKGROUND: Early diagnostic efforts and advances in multidrug therapy have considerably prolonged the survival time of children infected perinatally with HIV. Despite these advances, few studies have addressed calcium status and bone growth in HIV-infected children. OBJECTIVE: Our objective was to examine the effect of HIV infection on calcium status and bone growth in children. DESIGN: We measured calcitropic hormones, urinary calcium excretion, bone mineral content, and body composition in 19 young girls aged 9.2 +/- 2.6 y (range: 5.9-15.2 y) who were infected perinatally with HIV. RESULTS: Serum concentrations of 1,25-dihydroxyvitamin D [1,25(OH)(2)D] and parathyroid hormone concentrations were elevated above normal ranges in 25% and 12% of these girls, respectively. Urinary calcium excretion normalized for creatinine excretion was also elevated (Ca/Cr >0.18) in 17% of these children despite suboptimal calcium intakes (679 +/- 437 mg/d). Total-body bone mineral content, measured with the use of dual-energy X-ray absorptiometry, averaged 845.1 +/- 279.0 g and was on average 2.7 z scores below age- and race-matched values reported in non-HIV-infected healthy girls. Significant positive correlations were found between an indirect marker of bone resorption in urine (N:-telopeptide) and 1,25(OH)2D (P < 0.02, r2 = 0.586, n = 9), and between serum N-telopeptide and total alkaline phosphatase (P < 0.001, r2 = 0.541, n = 17), suggesting that calcium insufficiency may be increasing bone resorption in this group. CONCLUSIONS: Young girls with HIV infection had low bone mass and evidence of calcium insufficiency. Nutritional counseling of children with HIV infection should emphasize adequate calcium intakes because of the importance of this age period in bone mineral acquisition.