Dietary calcium and serum 25-hydroxyvitamin D status in relation to BMD among U.S. adults

Vitamin D insufficiency

Vitamin D deficiency, which classically manifests as bone disease (either rickets or osteomalacia), is characterized by impaired bone mineralization. More recently, the term vitamin D insufficiency has been used to describe low levels of serum 25-hydroxyvitamin D that may be associated with other disease outcomes. Reliance on a single cutoff value to define vitamin D deficiency or insufficiency is problematic because of the wide individual variability of the functional effects of vitamin D and interaction with calcium intakes. In adults, vitamin D supplementation reduces the risk of fractures and falls. The evidence for other purported beneficial effects of vitamin D is primarily based on observational studies. We selected studies with the strongest level of evidence for clinical decision making related to vitamin D and health outcomes from our personal libraries of the vitamin D literature and from a search of the PubMed database using the term vitamin D in combination with the following terms related to the potential nonskeletal benefits of vitamin D: mortality, cardiovascular, diabetes mellitus, cancer, multiple sclerosis, allergy, asthma, infection, depression, psychiatric, and pain. Conclusive demonstration of these benefits awaits the outcome of controlled clinical trials.

Effect of calcium and vitamin D supplementation on bone mineral density in women aged 65-71 years: a 3-year randomized population-based trial (OSTPRE-FPS)

SUMMARY

The Osteoporosis Risk Factor and Prevention-Fracture Prevention Study (OSTPRE-FPS) was a randomized population-based open trial (n = 593). The supplementation group (n = 287) received daily cholecalciferol 800 IU + calcium 1,000 mg for 3 years while the control group (n = 306) received neither supplementation nor placebo. Daily vitamin D and calcium supplementation have a positive effect on the skeleton in ambulatory postmenopausal women.

INTRODUCTION

vitamin D deficiency is common in the elderly, and vitamin D levels are associated with low bone mineral density (BMD). The working hypothesis was that vitamin D and calcium supplementation could prevent bone loss in ambulatory postmenopausal women.

METHODS

the OSTPRE-FPS was a randomized population-based open trial with a 3-year follow-up in 3,432 women (aged 66 to 71 years). A randomly selected subsample of 593 subjects underwent BMD measurements. The supplementation group (n = 287) received daily cholecalciferol 800 IU + calcium 1,000 mg for 3 years while the control group (n = 306) received neither supplementation nor placebo.

RESULTS

in the intention-to-treat analysis, total body BMD (n = 362) increased significantly more in the intervention group than in the control group (0.84% vs. 0.19%, p = 0.011). The BMD change differences at the lumbar spine (p = 0.372), femoral neck (p = 0.188), trochanter (p = 0.085), and total proximal femur (p = 0.070) were statistically nonsignificant. Analyses in compliant women (≥ 80% of use) resulted in stronger and statistically significant effects at the total body and femoral regions.

CONCLUSION

daily vitamin D and calcium supplementation have a positive effect on the skeleton in ambulatory postmenopausal women with adequate nutritional calcium intake.

Skeletal manifestations of systemic autoimmune diseases

PURPOSE OF REVIEW

There is an increased risk of osteoporotic fractures and osteonecrosis often at a young age among patients with certain systemic autoimmune diseases. The loss of bone mineral density and bone integrity seen with these diseases often cannot be explained by traditional risk factors alone. In this review, we focus on rheumatoid arthritis and systemic lupus erythematosus, two systemic autoimmune diseases in which skeletal manifestations have been well described.

RECENT FINDINGS

There is recent evidence that autoimmunity and its associated inflammation and vitamin D deficiency play key roles in the pathogenesis of adverse skeletal effects.

SUMMARY

Understanding these processes carries implications for the prevention and treatment of osteoporosis and osteonecrosis among patients with autoimmune diseases.

Benefit-risk assessment of vitamin D supplementation

Current intake recommendations of 200 to 600 IU vitamin D per day may be insufficient for important disease outcomes reduced by vitamin D.

INTRODUCTION

This study assessed the benefit of higher-dose and higher achieved 25-hydroxyvitamin D levels [25(OH)D] versus any associated risk.

METHODS AND RESULTS

Based on double-blind randomized control trials (RCTs), eight for falls (n = 2426) and 12 for non-vertebral fractures (n = 42,279), there was a significant dose-response relationship between higher-dose and higher achieved 25(OH)D and greater fall and fracture prevention. Optimal benefits were observed at the highest dose tested to date for 700 to 1000 IU vitamin D per day or mean 25(OH)D between 75 and 110 nmol/l (30-44 ng/ml). Prospective cohort data on cardiovascular health and colorectal cancer prevention suggested increased benefits with the highest categories of 25(OH)D evaluated (median between 75 and 110 nmol/l). In 25 RCTs, mean serum calcium levels were not related to oral vitamin D up to 100,000 IU per day or achieved 25(OH)D up to 643 nmol/l. Mean levels of 75 to 110 nmol/l were reached in most RCTs with 1,800 to 4,000 IU vitamin D per day without risk.

CONCLUSION

Our analysis suggests that mean serum 25(OH)D levels of about 75 to 110 nmol/l provide optimal benefits for all investigated endpoints without increasing health risks. These levels can be best obtained with oral doses in the range of 1,800 to 4,000 IU vitamin D per day; further work is needed, including subject and environment factors, to better define the doses that will achieve optimal blood levels in the large majority of the population.

The relative influence of calcium intake and vitamin D status on serum parathyroid hormone and bone turnover biomarkers in a double-blind, placebo-controlled parallel group, longitudinal factorial design

BACKGROUND

Adequate calcium and vitamin D are needed to maintain calcium balance.

OBJECTIVE

Our objective was to examine the influence of calcium intake and vitamin D exposure separately and their interaction on biomarkers of calcium sufficiency.

DESIGN

Healthy men and women, age 20-80 yr, were randomly allocated to four groups: 1) double placebo, 2) calcium (1200 mg daily) plus placebo, 3) vitamin D(3) (100 microg) plus placebo, and 4) vitamin D(3) and calcium. Fasting serum and urine as well as serum and urine 2 h after a calcium load (600 mg of calcium carbonate) were obtained at baseline and 3 months.

RESULTS

Ninety-nine participants were randomized; 78 completed the study. Baseline demographics, protein intake and laboratory studies did not differ among the four groups. Study medication compliance was 90%. Fasting bone turnover markers declined after 3 months only in the two groups given calcium supplements and increased in the vitamin D(3) plus placebo calcium group. The calcium load resulted in a decrease in PTH and in bone turnover markers that did not differ among groups. Urinary calcium excretion increased in the combined group. Mean serum 25-hydroxyvitamin D increased from a baseline of 67 (18 sd) nmol/liter to 111 (30 sd) nmol/liter after vitamin D supplementation.

CONCLUSION

Increased habitual calcium intake lowered markers of bone turnover. Acute ingestion of a calcium load lowered PTH and bone turnover markers. Additional intake of 100 microg/d vitamin D(3) did not lower PTH or markers of bone turnover.

Vitamin D and fracture prevention

This article discusses the amount of vitamin D supplementation needed and the desirable 25-hydroxyvitamin D level to be achieved for optimal fracture prevention.

High prevalence of severe vitamin D deficiency in combined antiretroviral therapy-naive and successfully treated Swiss HIV patients

OBJECTIVES

To evaluate the prevalence of 25-hydroxyvitamin D [25(OH)D] deficiency in HIV-positive patients, a population at risk for osteoporosis.

DESIGN

Retrospective assessment of vitamin D levels by season and initiation of combined antiretroviral therapy (cART).

METHODS

25(OH)D was measured in 211 HIV-positive patients: samples were taken before initiation of cART from February to April or from August to October as well as 12 (same season) and 18 months (alternate season) after starting cART. 1,25-Dihydroxyvitamin D [1,25(OH)2D] was measured in a subset of 74 patients. Multivariable analyses included season, sex, age, ethnicity, BMI, intravenous drug use (IDU), renal function, time since HIV diagnosis, previous AIDS, CD4 cell count and cART, in particular nonnucleoside reverse transcriptase inhibitor (NNRTI) and tenofovir (TDF) use.

RESULTS

At baseline, median 25(OH)D levels were 37 (interquartile range 20-49) nmol/l in spring and 57 (39-74) nmol/l in the fall; 25(OH)D deficiency less than 30 nmol/l was more prevalent in spring (42%) than in fall (14%), but remained unchanged regardless of cART exposure. In multivariable analysis, 25(OH)D levels were higher in white patients and those with a longer time since HIV diagnosis and lower in springtime measurements and in those with active IDU and NNRTI use. 1-Hydroxylation rates were significantly higher in patients with low 25(OH)D. Hepatitis C seropositivity, previous AIDS and higher CD4 cell counts correlated with lower 1,25(OH)2D levels, whereas BMI and TDF use were associated with higher levels. In TDF-treated patients, higher 1,25(OH)2D correlated with increases in serum alkaline phosphatase.

CONCLUSION

Based on the high rate of vitamin D deficiency in HIV-positive patients, systematic screening with consideration of seasonality is warranted. The impact of NNRTIs on 25(OH)D and TDF on 1,25(OH)2D needs further attention.

The effect of a fortified milk drink on vitamin D status and bone turnover in post-menopausal women from South East Asia

Calcium and vitamin D are essential for bone growth; milk is an appropriate vehicle to be fortified with calcium, vitamin D and other minerals. The purpose of the current study was to compare the effect of supplementing with a high calcium milk drink with added vitamin D, magnesium and zinc (HCM) versus a placebo drink on serum parathyroid hormone (PTH) and vitamin D status as well as markers of bone formation/resorption in postmenopausal women living in South East Asia (Jakarta, Indonesia and Manila, the Philippines) over a period of 4 months. Calcium intake at baseline was 237 mg (median; 176-316, interquartile range) for Indonesia and 353 mg (median; 222-480, interquartile range) for the Filipino women per day. Fortified milk supplementation reduced the percentage of women that were insufficient in 25 (OH) vitamin D(3) (<50 nmol/L) from 70% to 22% in the Indonesian women and 20% to 0% in the Filipino women. Fortified milk supplementation significantly reduced parathyroid hormone levels (PTH) by week 2 (22% and 11%), C-telopeptide of type I collagen (CTX) by week 2 (34% and 27%), osteocalcin (OC) by week 8 (18% and 25%) and procollagen type I N-propeptide (PINP) by week 8 (15% and 21%), in women from Indonesia and the Philippines, respectively. Thus, the HCM intervention was able to significantly improve vitamin D status, lower PTH levels and reduce bone turnover in two groups of South East Asian women.

Vitamin D status during pregnancy and aspects of offspring health

Low maternal vitamin D levels during pregnancy have been linked to various health outcomes in the offspring, ranging from periconceptional effects to diseases of adult onset. Maternal and infant cord 25(OH)D levels are highly correlated. Here, we review the available evidence for these adverse health effects. Most of the evidence has arisen from observational epidemiological studies, but randomized controlled trials are now underway. The evidence to date supports that women should be monitored and treated for vitamin D deficiency during pregnancy but optimal and upper limit serum 25(OH)D levels during pregnancy are not known.

Update in vitamin D

The past decade, particularly the last 18 months, witnessed a vigorous increase in interest in vitamin D from both the lay and biomedical worlds. Much of the growing interest in vitamin D is powered by new data being extracted from the National Health and Nutrition Examination Survey (NHANES). The newest statistics demonstrate that more than 90% of the pigmented populace of the United States (Blacks, Hispanics, and Asians) now suffer from vitamin D insufficiency (25-hydroxyvitamin D <30 ng/ml), with nearly three fourths of the white population in this country also being vitamin D insufficient. This represents a near doubling of the prevalence of vitamin D insufficiency seen just 10 yr ago in the same population. This review attempts to provide some explanation for: 1) the rapid decline in vitamin D status in the United States; 2) the adverse impact of vitamin D insufficiency on skeletal, infectious/inflammatory, and metabolic health in humans; and 3) the therapeutic rationale and reliable means for vigorous supplementation of our diets with vitamin D.

Menopause care for obese and diabetic women

Women with obesity or/and diabetes form an increasing part of the peri- and post-menopausal women cared for by general practicioners and gynaecologists. Menopausal obese/diabetic women have a different hormonal milieu than lean women, with increased exposure to androgens and oestrogens. In spite of this, obese women experience more menopause-related symptoms, particularly vasomotor symptoms and urinary incontinence. Obese and diabetic women also have a higher risk of breast and endometrial cancer, dementia, coronary heart disease (CHD) and venous and arterial thromboembolism. Bone mineral density loss is variable yet diabetic women show a uniformly higher rate of fractures, partly through a greater likelihood of falls. Although oestrogen-progestagen-type hormone therapy (HT) -improves glycaemic control and the lipoprotein profile in diabetic women, HT should be used very cautiously in obese and diabetic postmenopausal women because of accrued risks of thrombosis and CHD. Instead, the primary goal is to stimulate physical activity which improves general fitness and body weight control during the menopause transition, and which reduces the risk of breast cancer and osteoporosis. Also, vitamin D sufficiency should be ensured together with a healthy calcium intake, but anti-osteoporosis drugs which strongly suppress bone remodelling should be used with caution.