Myocardial infarction is inversely associated with plasma 25-hydroxyvitamin D3 levels: a community-based study

Serum levels of vitamin D and haemostatic factors in healthy subjects: the Tromsø study

BACKGROUND

Receptors for vitamin D have been found in various tissues, including the vascular endothelium. The role of vitamin D in the haemostatic process is uncertain, but in vitro studies may indicate a pro-fibrinolytic effect.

METHODS

Two hundred and six subjects (105 males) were included in the study. The relations between indices of calcium metabolism and haemostatic factors [tissue plasminogen activator antigen (tPA Ag), plasminogen activator inhibitor 1 (PAI-1), prothrombin fragment 1+2, activated factor VII and total factor VII coagulant activity] and high-sensitivity C-reactive protein (HS-CRP) were examined.

RESULTS

There were significant and negative correlations between serum 25(OH) vitamin D and PAI-1 and tPA Ag, and between serum 1,25(OH)2 vitamin D and tPA Ag and HS-CRP. In a multiple linear regression model with age, gender, body mass index and smoking status as covariables, only the relation between 25(OH) vitamin D and tPA Ag was significant. There were no significant relations between any of the haemostatic factors tested and serum parathyroid hormone.

CONCLUSION

It appears that the serum level of vitamin D is related to fibrinolytic activity and to the integrity of the vascular endothelium, but the clinical importance of this observation remains to be determined.

Serum 25-hydroxyvitamin D3 concentrations and carotid artery intima-media thickness among type 2 diabetic patients

OBJECTIVE

To estimate the prevalence of hypovitaminosis D among type 2 diabetic adults and to assess the relationship between hypovitaminosis D and intimal medial thickening (IMT) of the common carotid artery, a marker of preclinical atherosclerosis.

DESIGN, PATIENTS AND MEASUREMENTS

We compared winter serum 25-hydroxyvitamin D3 [25(OH)D] concentrations in 390 consecutive type 2 diabetic patients and 390 nondiabetic controls who were comparable for age and sex. Common carotid IMT was measured with ultrasonography only in diabetic patients by a single trained operator blinded to subjects' details.

RESULTS

The prevalence of hypovitaminosis D (i.e. 25(OH)D <or= 37.5 nmol/l) was higher in diabetic patients (34.0 vs 16.4%, P < 0.001) than in controls. Among diabetic patients, those with hypovitaminosis D (n = 130) had a marked increase in common carotid IMT (1.10 +/- 0.15 vs 0.87 +/- 0.14 mm, P < 0.001) when compared with their vitamin d-sufficient counterparts (n = 260). These patients also had significantly higher haemoglobin A1c, fibrinogen and C-reactive protein (hs-CRP) concentrations. In multivariate regression analysis, low 25(OH)D concentrations independently predicted carotid IMT (P < 0.001) in people with type 2 diabetes after adjustment for classical risk factors, diabetes duration, HbA1c, calcium, renal function tests, inflammatory markers, use of medications, and presence of the metabolic syndrome (as defined by the Adult Treatment Panel III criteria).

CONCLUSIONS

Hypovitaminosis D is highly prevalent in type 2 diabetic adults and is strongly and independently associated with increased carotid IMT. Further investigation into whether vitamin D may play a role in the prevention of atherosclerosis appears to be warranted.

Low serum concentrations of 25-hydroxyvitamin D in older persons and the risk of nursing home admission

BACKGROUND

The prevalence of vitamin D deficiency in nursing home patients is high.

OBJECTIVE

We aimed to ascertain whether lower serum 25-hydroxyvitamin D [25(OH)D] concentrations increase the risk of future nursing home admission and early death.

DESIGN

We included 1260 independent, community-dwelling persons aged > or =65 y who were participating in the Longitudinal Aging Study Amsterdam (1995-1996). Study outcomes were time to nursing home admission during 6 y of follow-up and time to death until 1 April 2003.

RESULTS

Vitamin D deficiency [25(OH)D < 25 nmol/L] and insufficiency [25(OH)D = 25-49.9 nmol/L] were present in 127 (10.1%) and 462 (36.7%) subjects, respectively. During follow-up, 138 subjects (11.0%) were admitted to nursing homes, and 380 subjects (30.2%) died. The risk of nursing home admission for participants with 25(OH)D deficiency was 53 cases per 1000 person-years higher than that for those with high 25(OH)D (> or =75 nmol/L) concentrations (58 compared with 5 cases). After adjustment for potential confounders, the hazard ratio (95% CI) of nursing home admission was 3.48 (1.39, 8.75) for vitamin D-deficient, 2.77 (1.17, 6.55) for vitamin D-insufficient, and 1.92 (0.79, 4.66) for vitamin D-borderline persons as compared with persons with high 25(OH)D (P for trend = 0.002). The results remained after additional adjustment for frailty indicators. Lower 25(OH)D was associated with higher mortality risk, but this association was not significant after adjustment for frailty indicators.

CONCLUSION

Lower serum 25(OH)D concentrations in older persons are associated with a greater risk of future nursing home admission and may be associated with mortality.

Associations between serum 25-hydroxyvitamin D3 concentrations and liver histology in patients with non-alcoholic fatty liver disease

BACKGROUND AND AIM

To explore associations between serum 25-hydroxyvitamin D(3) [25(OH)D] concentrations and liver histology in patients with non-alcoholic fatty liver disease (NAFLD).

METHODS AND RESULTS

We studied 60 consecutive patients with biopsy-proven NAFLD, and 60 healthy controls of comparable age, sex and body mass index (BMI). NAFLD patients had a marked decrease in winter serum 25(OH)D concentrations (51.0+/-22 vs. 74.5+/-15 nmol/L, P<0.001) compared with controls. Metabolic syndrome (MetS; as defined by the Adult Treatment Panel III criteria) and its individual components occurred more frequently among NAFLD patients. The marked differences in 25(OH)D concentrations observed between the groups were little affected by adjustment for age, sex, BMI, creatinine, calcium, homeostasis model assessment (HOMA)-insulin resistance, and the presence of the MetS. Interestingly, among NAFLD patients, decreased 25(OH)D concentrations were closely associated with the histological severity of hepatic steatosis, necroinflammation and fibrosis (P<0.001 for all) independent of age, sex, BMI, creatinine, calcium, HOMA-insulin resistance, and presence of the MetS.

CONCLUSIONS

Compared with controls, NAFLD patients have a marked decrease in serum 25(OH)D concentrations, which is closely associated with histopathological features of NAFLD. Further investigation into whether vitamin D(3) may play a role in the development and progression of NAFLD appears to be warranted.

Vitamin D and African Americans

Vitamin D insufficiency is more prevalent among African Americans (blacks) than other Americans and, in North America, most young, healthy blacks do not achieve optimal 25-hydroxyvitamin D [25(OH)D] concentrations at any time of year. This is primarily due to the fact that pigmentation reduces vitamin D production in the skin. Also, from about puberty and onward, median vitamin D intakes of American blacks are below recommended intakes in every age group, with or without the inclusion of vitamin D from supplements. Despite their low 25(OH)D levels, blacks have lower rates of osteoporotic fractures. This may result in part from bone-protective adaptations that include an intestinal resistance to the actions of 1,25(OH)2D and a skeletal resistance to the actions of parathyroid hormone (PTH). However, these mechanisms may not fully mitigate the harmful skeletal effects of low 25(OH)D and elevated PTH in blacks, at least among older individuals. Furthermore, it is becoming increasingly apparent that vitamin D protects against other chronic conditions, including cardiovascular disease, diabetes, and some cancers, all of which are as prevalent or more prevalent among blacks than whites. Clinicians and educators should be encouraged to promote improved vitamin D status among blacks (and others) because of the low risk and low cost of vitamin D supplementation and its potentially broad health benefits.

Relation between serum phosphate level and cardiovascular event rate in people with coronary disease

BACKGROUND

Higher levels of serum phosphate are associated with adverse cardiovascular outcomes, especially in the setting of overt hyperphosphatemia. Given the biological importance of phosphorus, it is plausible that higher levels of serum phosphate within the normal range may also be associated with adverse outcomes.

METHODS AND RESULTS

We performed a post hoc analysis of data from the Cholesterol And Recurrent Events (CARE) study. Baseline serum phosphate levels were measured in 4127 fasting participants who were randomized to receive pravastatin 40 mg daily or placebo and followed up for a median of 59.7 months. We used Cox proportional-hazards models to examine the association between serum phosphate and adverse clinical outcomes after adjustment for potential confounders. During nearly 60 months of follow-up, 375 participants died. A significant association was noted between baseline serum phosphate level and the age-, race-, and sex-adjusted risk of all-cause death (hazard ratio per 1 mg/dL, 1.27; 95% confidence interval, 1.02 to 1.58). After categorization based on baseline phosphate level (<2.5, 2.5 to 3.4, 3.5 to 3.9, and > or =4 mg/dL) and further adjustment, a graded independent relation between phosphate and death was observed (P for trend=0.03). For instance, participants with serum phosphate > or =3.5 mg/dL had an adjusted hazard ratio for death of 1.27 (95% confidence interval, 1.02 to 1.59) compared with those with serum phosphate of <3.5 mg/dL. Higher levels of serum phosphate were also associated with increased risk of new heart failure, myocardial infarction, and the composite of coronary death or nonfatal myocardial infarction, but not the risk of stroke.

CONCLUSIONS

We found a graded independent relation between higher levels of serum phosphate and the risk of death and cardiovascular events in people with prior myocardial infarction, most of whom had serum phosphate levels within the normal range. Given the ready availability and low cost of serum phosphate assays, this finding may prove clinically useful.

Relationship between serum 25-hydroxyvitamin d and pulmonary function in the third national health and nutrition examination survey

CONTEXT

Age, gender, height, ethnicity, and smoking are important determinants of lung function but do not explain all of the variation between individuals. Low concentrations of vitamin D have been associated with a number of diseases, including osteoporosis, hypertension, and type I diabetes. It is possible that serum concentrations of vitamin D might also influence pulmonary function.

OBJECTIVES

To determine the relationship between serum concentrations of 25-hydroxy vitamin D and pulmonary function.

DESIGN, SETTING AND PARTICIPANTS

The analysis was conducted using data from the Third National Health and Nutrition Examination Survey, which was a cross-sectional survey of the US civilian population that was conducted from 1988 to 1994. The analyses were restricted to 14,091 people who > or = 20 years of age, were interviewed at mobile examination centers, and had undergone spirometry, and in whom serum 25-hydroxy vitamin D levels had been measured.

RESULTS

After adjustment for age, gender, height, body mass index, ethnicity, and smoking history, the mean FEV1 was 126 mL (SE, 22 mL), and the mean FVC was 172 mL (SE, 26 mL) greater for the highest quintile of serum 25-hydroxy vitamin D level (> or = 85.7 nmol/L) compared with the lowest quintile (< or = 40.4 nmol/L; p < 0.0001). With further adjustment for physical activity, the intake of vitamin D supplements, milk intake, and the level of serum antioxidants, the mean difference between the highest and lowest quintiles of 25-hydroxy vitamin D was 106 mL (SE, 24 mL) for FEV1, and 142 mL (SE, 29 mL) for FVC (p < 0.0001).

CONCLUSIONS

There is a strong relationship between serum concentrations of 25-hydroxy vitamin D, FEV1, and FVC. Further studies are necessary to determine whether supplementation with vitamin D is of any benefit in patients with respiratory disease.

The role of vitamin D in cancer prevention

Vitamin D status differs by latitude and race, with residents of the northeastern United States and individuals with more skin pigmentation being at increased risk of deficiency. A PubMed database search yielded 63 observational studies of vitamin D status in relation to cancer risk, including 30 of colon, 13 of breast, 26 of prostate, and 7 of ovarian cancer, and several that assessed the association of vitamin D receptor genotype with cancer risk. The majority of studies found a protective relationship between sufficient vitamin D status and lower risk of cancer. The evidence suggests that efforts to improve vitamin D status, for example by vitamin D supplementation, could reduce cancer incidence and mortality at low cost, with few or no adverse effects.

Vitamin D endocrine system and the genetic susceptibility to diabetes, obesity and vascular disease. A review of evidence

The Vitamin D endocrine system regulates multiple aspects of calcium metabolism and cellular differentiation and replication in the immune system, endocrine pancreas, liver, skeletal muscles and adipocytes. It plays an important role in glucose homeostasis, notably, in the mechanism of insulin release. Actions of vitamin D are mediated by the binding of 1, 25-(OH)2D3 to a specific cytosolic/nuclear vitamin D receptor (VDR), a member of the steroid/thyroid hormone receptor superfamily. Several frequent polymorphisms are found in the VDR gene and were reported to be associated with a variety of physiological and pathological phenotypes in many populations. In this paper, we will review the evidences suggesting associations of allelic variations in the VDR gene and phenotypes related to body weight, glucose homeostasis, diabetes and its vascular complications.

Hypovitaminosis D is associated with reductions in serum apolipoprotein A-I but not with fasting lipids in British Bangladeshis

BACKGROUND

Although hypovitaminosis D has been suggested to increase the risk of heart disease, its relation to components of the fasting lipid profile has not been clarified for specific ethnic groups.

OBJECTIVE

The objective was to determine the relation of circulating 25-hydroxyvitamin D [25(OH)D] concentrations to fasting lipid concentrations in South Asian subjects at risk of hypovitaminosis D.

DESIGN

The present study was conducted in 170 British Bangladeshi adults, 69 men and 101 women, from east London who were free of known diabetes or chronic disorders. Vitamin D repletion was assessed by measuring fasting serum 25(OH)D concentrations. Fasting lipid profiles were measured as part of a study of the risk factors for type 2 diabetes and ischemic heart disease, which included hypovitaminosis D.

RESULTS

A univariate analysis showed that total cholesterol, LDL cholesterol, and both apolipoprotein (apo) A-I and apo B concentrations correlated directly with serum 25(OH)D concentrations. However, a multiple regression analysis, which included all the documented risk factors for diabetes and ischemic heart disease, showed that the 25(OH)D concentration (vitamin D status) was an independent predictor of increasing apo A-I concentrations (standardized coefficient beta = 0.3; P < 0.001) but not of fasting lipid concentrations.

CONCLUSIONS

In this study of British South Asians, the data showed a positive relation of fasting apo A-I concentrations to serum 25(OH)D concentrations, independent of glycemia and other dietary, anthropometric, and lifestyle risk factors for type 2 diabetes and ischemic heart disease after multiple regression analyses. Subjects with hypovitaminosis D are likely to have an increased risk of ischemic heart disease independent of their increased risk of type 2 diabetes.

VITAMIN D IN HEALTH AND DISEASE: Beyond Minerals and Parathyroid Hormone: Role of Active Vitamin D in End-Stage Renal Disease

Secondary hyperparathyroidism is a common complication of end-stage renal disease (ESRD) that is often treated with activated forms of intravenous vitamin D. The natural course and treatment of secondary hyperparathyroidism in hemodialysis patients is punctuated by episodes of hypercalcemia, hyperphosphatemia, and increased calcium-phosphate product, which in previous studies were linked to increased mortality. Historically these episodes have been attributed to vitamin D, leading some authorities to favor decreased vitamin D use. However, the studies that examined the impact of mineral levels and parathyroid hormone (PTH) on survival did not consistently account for vitamin D therapy itself on hemodialysis patient survival. The current review examines in detail two recent large-scale studies of hemodialysis patients: one that demonstrated a survival advantage of paricalcitol over calcitriol and a second that demonstrated a significant survival advantage of any intravenous vitamin D formulation versus none. In both studies, the effects were independent of mineral and PTH levels, suggesting "nontraditional" actions of vitamin D contributed to the observed survival advantage. Several of these nontraditional actions are reviewed with an emphasis on those that might impact hemodialysis outcomes.

Dietary and serum vitamins and minerals as predictors of myocardial infarction and stroke in elderly subjects

BACKGROUND AND AIM

According to a widespread hypothesis, antioxidative vitamins and trace elements may protect the body against atherosclerotic diseases, especially in the elderly. We assessed dietary and serum vitamins and minerals for prediction of acute myocardial infarction (AMI) and stroke in elderly subjects.

METHODS AND RESULTS

In a population-based health survey with special emphasis on the diet, subjects aged 65-99 years were followed up for up to 10 years. The study population consisted of 361 men and 394 women. Information on individual food consumption was elicited by means of dietary history interviews. Serum vitamins and mineral elements were analysed utilizing commonly applied biochemical methods. Prediction analyses were based on 130 cases accumulated in the AMI group, 70 subjects in the stroke group, and corresponding control subjects. The cases were determined on the basis of revised information from the National Register of Cases of Death, and from the National Hospital Discharge Register. Low intake of vitamin D (p = 0.011) and low serum levels of 1,25-dihydroxy-vitamin D (p = 0.0053) were significantly predictive of stroke when adjusted for age, gender, smoking and functional capacity. On the other hand, high dietary intakes of two flavonoids, luteolin (p = 0.0096) and kaempferol (p = 0.002) were associated with lowered risk of AMI. Furthermore, low serum levels of iron predicted both AMI (p = 0.013) and stroke (p = 0.019). The results remained essentially unchanged when adjusted for additional major risk factors of atherosclerosis.

CONCLUSIONS

From the items in the dietary interview, low intakes of vitamin D and certain flavonoids emerged as the sole predictors of AMI and stroke. In biochemical analyses, on the other hand, these disorders were predicted only by low levels of 1,25-dihydroxy-vitamin D and iron in the serum.

Vitamin D and the elderly

This review summarizes current knowledge on vitamin D status in the elderly with special attention to definition and prevalence of vitamin D insufficiency and deficiency, relationships between vitamin D status and various diseases common in the elderly, and the effects of intervention with vitamin D or vitamin D and calcium. Individual vitamin D status is usually estimated by measuring plasma 25-hydroxyvitamin D (25OHD) levels. However, reference values from normal populations are not applicable for the definition of vitamin D insufficiency or deficiency. Instead vitamin D insufficiency is defined as the lowest threshold value for plasma 25OHD (around 50 nmol/l) that prevents secondary hyperparathyroidism, increased bone turnover, bone mineral loss, or seasonal variations in plasma PTH. Vitamin D deficiency is defined as values below 25 nmol/l. Using these definitions vitamin D deficiency is common among community-dwelling elderly in the developed countries at higher latitudes and very common among institutionalized elderly, geriatric patients and patients with hip fractures. Vitamin D deficiency is an established risk factor for osteoporosis, falls and fractures. Clinical trials have demonstrated that 800 IU (20 microg) per day of vitamin D in combination with 1200 mg calcium effectively reduces the risk of falls and fractures in institutionalized patients. Furthermore, 400 IU (10 microg) per day in combination with 1000 mg calcium or 100 000 IU orally every fourth month without calcium reduces fracture risk in individuals over 65 years of age living at home. Yearly injections of vitamin D seem to have no effect on fracture risk probably because of reduced bioavailability. Simulation studies suggest that fortification of food cannot provide sufficient vitamin D to the elderly without exceeding present conventional safety levels for children. A combination of fortification and individual supplementation is proposed. It is argued that all official programmes should be evaluated scientifically. Epidemiological studies suggest that vitamin D insufficiency is related to a number of other disorders frequently observed among the elderly, such as breast, prostate and colon cancers, type 2 diabetes, and cardiovascular disorders including hypertension. However, apart from hypertension, causality has not been established through randomized intervention studies. It seems that 800 IU (20 microg) vitamin D per day in combination with calcium reduces systolic blood pressure in elderly women.

Activated injectable vitamin D and hemodialysis survival: a historical cohort study

Patients with ESRD commonly experience secondary hyperparathyroidism, a condition primarily managed with activated injectable vitamin D. The biologic effects of vitamin D, however, are widespread, and it is possible that activated injectable vitamin D alters survival in ESRD. This hypothesis was tested in a historical cohort study of incident hemodialysis patients who lived throughout the United States between January 1996 and December 1999. The primary outcome was 2-yr survival among those who survived for at least 90 d after initiation of chronic hemodialysis. During this period, 51,037 chronic hemodialysis patients survived for at least 90 d from the initiation of hemodialysis, and in the ensuing 2 yr, 37,173 received activated injectable vitamin D and 13,864 did not. At 2 yr, mortality rates were 13.8/100 person-years in the group that received injectable vitamin D compared with 28.6/100 person-years in the group that did not (P < 0.001). Cox proportional hazards analyses adjusting for several potential confounders and examining injectable vitamin D therapy as a time-dependent exposure suggested that compared with patients who did not receive injectable vitamin D, the 2-yr survival advantage associated with the group that did receive injectable vitamin D was 20% (hazard ratio, 0.80; 95% confidence interval, 0.76 to 0.83). The incidence of cardiovascular-related mortality was 7.6/100 person-years in the injectable vitamin D group, compared with 14.6/100 person-years in the non-vitamin D group (P < 0.001). The benefit of injectable vitamin D was evident in 48 of 49 strata examined, including those with low serum levels of intact parathyroid hormone and elevated levels of serum calcium and phosphorus, situations in which injectable vitamin D is often withheld. Repeating the entire analysis using marginal structural models to adjust for time-dependent confounding by indication yielded a survival advantage of 26% (hazard ratio, 0.74; 95% confidence interval, 0.71 to 0.79) associated with the injectable vitamin D group. In this historical cohort study, chronic hemodialysis patients in the group that received injectable vitamin D had a significant survival advantage over patients who did not. Randomized clinical trials would permit definitive conclusions.

Vitamin D, Shedding Light on the Development of Disease in Peripheral Arteries

Vitamin D is generally associated with calcium metabolism, especially in the context of uptake in the intestine and the formation and maintenance of bone. However, vitamin D influences a wide range of metabolic systems through both genomic and nongenomic pathways that have an impact on the properties of peripheral arteries. The genomic effects have wide importance for angiogenesis, elastogenesis, and immunomodulation; the nongenomic effects have mainly been observed in the presence of hypertension. Although some vitamin D is essential for cardiovascular health, excess may have detrimental effects, particularly on elastogenesis and inflammation of the arterial wall. Vitamin D is likely to have a role in the paradoxical association between arterial calcification and osteoporosis. This review explores the relationship between vitamin D and a range of physiological and pathological processes relevant to peripheral arteries.

Effect of oral vitamin D2 yearly bolus on hip fracture risk in elderly women: a community primary prevention study

BACKGROUND AND AIMS

Vitamin D deficiency is a well-known risk for hip fracture, and vitamin D insufficiency is so frequent in the elderly that population-wide preventive intervention would be useful. The objective of the study was to evaluate the efficacy of vitamin D bolus on hip fracture incidence in elderly women.

METHODS

All women aged > 65 years registered at Health District 20 of the Regione Veneto, Italy, were eligible for this quasi-experimental, prospective community intervention study. A vial containing 400,000 IU vitamin D2 (Ostelin 800, Teofarma, Italy) was offered for oral administration to all women in the winters of 2000-2001 and 2001-2002. The only exclusion criteria for treatment were age and gender, and the control group included women who did not participate in the Health District initiative. Analysis of hip fracture incidence was carried out for 4 years, from 1999 to 2002. Patients with incident hip fracture were identified as soon as they were admitted to one of the 3 hospitals of the health district and interviewed regarding their participation in the vitamin D preventive intervention program. In 120 of the women (age range 68-90 years), serum concentrations of 25-OH vitamin D were measured from October to June, both before and 1 and 4 months after vitamin D administration.

RESULTS

23,325 and 24,747 women received the vitamin D bolus during winters 2000-2001 and 2001-2002 respectively, i.e. 45-47% of eligible women. The proportion of women who accepted the bolus declined with advancing age, from 50-55% in women aged 60-70 years to 22-26% in those aged > 90 years. The two-year intervention on the community decreased the incidence of fracture by 10% (p = 0.050) in comparison with the previous two years. The age-adjusted risk reduction (RR) of hip fracture during 2001 and 2002 in women who had received vitamin D, with respect to women who had not, decreased by 17% (p = 0.056) and 25% (p = 0.005) respectively. The RR was considerably greater and statistically significant over both 2001 and 2002 in the cohort aged > 75 years. 25-OH vitamin D concentrations, in the subset of women in whom it was measured, rose significantly (p < 0.0001) by 9 ng/ml over 4 months after administration.

CONCLUSION

Despite several obvious limitations due to its nature, this study sufficiently documents that yearly vitamin D bolus supplements, given as primary prevention to elderly Caucasian women, may decrease the incidence of hip fracture. For its probable safety and excellent feasibility and cost-effectiveness, this primary intervention has a great potential for generalisability.

Vitamin D: importance in the prevention of cancers, type 1 diabetes, heart disease, and osteoporosis

The purpose of this review is to put into perspective the many health benefits of vitamin D and the role of vitamin D deficiency in increasing the risk of many common and serious diseases, including some common cancers, type 1 diabetes, cardiovascular disease, and osteoporosis. Numerous epidemiologic studies suggest that exposure to sunlight, which enhances the production of vitamin D(3) in the skin, is important in preventing many chronic diseases. Because very few foods naturally contain vitamin D, sunlight supplies most of our vitamin D requirement. 25-Hydroxyvitamin D [25(OH)D] is the metabolite that should be measured in the blood to determine vitamin D status. Vitamin D deficiency is prevalent in infants who are solely breastfed and who do not receive vitamin D supplementation and in adults of all ages who have increased skin pigmentation or who always wear sun protection or limit their outdoor activities. Vitamin D deficiency is often misdiagnosed as fibromyalgia. A new dietary source of vitamin D is orange juice fortified with vitamin D. Studies in both human and animal models add strength to the hypothesis that the unrecognized epidemic of vitamin D deficiency worldwide is a contributing factor of many chronic debilitating diseases. Greater awareness of the insidious consequences of vitamin D deficiency is needed. Annual measurement of serum 25(OH)D is a reasonable approach to monitoring for vitamin D deficiency. The recommended adequate intakes for vitamin D are inadequate, and, in the absence of exposure to sunlight, a minimum of 1000 IU vitamin D/d is required to maintain a healthy concentration of 25(OH)D in the blood.

Vitamin D in preventive medicine: are we ignoring the evidence?

Vitamin D is metabolised by a hepatic 25-hydroxylase into 25-hydroxyvitamin D (25(OH)D) and by a renal 1alpha-hydroxylase into the vitamin D hormone calcitriol. Calcitriol receptors are present in more than thirty different tissues. Apart from the kidney, several tissues also possess the enzyme 1alpha-hydroxylase, which is able to use circulating 25(OH)D as a substrate. Serum levels of 25(OH)D are the best indicator to assess vitamin D deficiency, insufficiency, hypovitaminosis, adequacy, and toxicity. European children and young adults often have circulating 25(OH)D levels in the insufficiency range during wintertime. Elderly subjects have mean 25(OH)D levels in the insufficiency range throughout the year. In institutionalized subjects 25(OH)D levels are often in the deficiency range. There is now general agreement that a low vitamin D status is involved in the pathogenesis of osteoporosis. Moreover, vitamin D insufficiency can lead to a disturbed muscle function. Epidemiological data also indicate a low vitamin D status in tuberculosis, rheumatoid arthritis, multiple sclerosis, inflammatory bowel diseases, hypertension, and specific types of cancer. Some intervention trials have demonstrated that supplementation with vitamin D or its metabolites is able: (i) to reduce blood pressure in hypertensive patients; (ii) to improve blood glucose levels in diabetics; (iii) to improve symptoms of rheumatoid arthritis and multiple sclerosis. The oral dose necessary to achieve adequate serum 25(OH)D levels is probably much higher than the current recommendations of 5-15 microg/d.

Effect of four monthly oral vitamin D3 (cholecalciferol) supplementation on fractures and mortality in men and women living in the community: randomised double blind controlled trial

OBJECTIVE

To determine the effect of four monthly vitamin D supplementation on the rate of fractures in men and women aged 65 years and over living in the community.

DESIGN

Randomised double blind controlled trial of 100 000 IU oral vitamin D3 (cholecalciferol) supplementation or matching placebo every four months over five years.

SETTING AND PARTICIPANTS

2686 people (2037 men and 649 women) aged 65-85 years living in the general community, recruited from the British doctors register and a general practice register in Suffolk.

MAIN OUTCOME MEASURES

Fracture incidence and total mortality by cause.

RESULTS

After five years 268 men and women had incident fractures, of whom 147 had fractures in common osteoporotic sites (hip, wrist or forearm, or vertebrae). Relative risks in the vitamin D group compared with the placebo group were 0.78 (95% confidence interval 0.61 to 0.99, P=0.04) for any first fracture and 0.67 (0.48 to 0.93, P=0.02) for first hip, wrist or forearm, or vertebral fracture. 471 participants died. The relative risk for total mortality in the vitamin D group compared with the placebo group was 0.88 (0.74 to 1.06, P=0.18). Findings were consistent in men and women and in doctors and the general practice population.

CONCLUSION

Four monthly supplementation with 100 000 IU oral vitamin D may prevent fractures without adverse effects in men and women living in the general community.

Serum 25-hydroxyvitamin D3 levels are elevated in South Indian patients with ischemic heart disease

Several lines of evidence point to a possible relationship between vitamin D and cardiovascular disease. Animal experiments and observational studies in humans suggest vitamin D to be arteriotoxic and an association of high intake of vitamin D with increased incidence of ischemic heart disease (IHD). The major source of vitamin D in adults is vitamin D synthesized in the skin through exposure to the sun. In tropical environment there is a possibility of high level of solar exposure and enhanced serum levels of vitamin D in the population. We explored the relation between serum level of 25-hydroxyvitamin D3 and IHD in a case-control study involving 143 patients with either angiographic evidence of coronary artery disease or patients with acute myocardial infarction and 70 controls, all men in the age group of 45-65 years. Fasting blood samples were collected, serum separated and serum levels of 25-hydroxyvitamin D3 was measured by protein binding radioligand assay. Serum levels of cholesterol, triglyceride, calcium, magnesium and inorganic phosphate were also determined. Prevalences of diabetes, hypertension and smoking history were noted. Statistical comparisons of variables between cases and controls were done using chi2-tests. Multivariate logistic regression analysis was done to examine the association of IHD with serum levels of 25-hydroxyvitamin D3 controlling for selected variables. Serum levels of 25-hydroxyvitamin D3, calcium, inorganic phosphate, total cholesterol, low density lipoprotein and triglycerides were elevated in a higher proportion of patients, compared to controls. Serum levels of 25-OH-D3 above 222.5 nmol/l (89 ng/ml) was observed in 59.4% of cases compared to 22.1% in controls (p < 0.001; unadjusted odds ratio (OR): 5.17; 95% confidence interval (CI): 2.62-10.21). When controlled for age and selected variables using the multivariate logistic regression, the adjusted OR relating elevated serum 25-hydroxyvitamin D3 levels (> or = 222.5 nmol/l, > or = 89 ng/ml) and IHD is 3.18 (95% CI: 1.31-7.73). Given the evidences for the arteriotoxicity of vitamin D, further investigations are warranted to probe whether the elevated serum levels of 25-hydroxyvitamin D3 observed in patients with IHD in a tropical environment has any pathogenic significance.

Effects of a short-term vitamin D(3) and calcium supplementation on blood pressure and parathyroid hormone levels in elderly women

Calcium supplementation is effective in reducing blood pressure in various states of hypertension, including pregnancy-induced hypertension and preeclampsia. In addition, calcitropic hormones are associated with blood pressure. The hypothesis is that short-term therapy with calcium and vitamin D(3) may improve blood pressure as well as secondary hyperparathyroidism more effectively than calcium monotherapy. The effects of 8 weeks of supplementation with vitamin D(3) (cholecalciferol) and calcium on blood pressure and biochemical measures of bone metabolism were studied. The sample consisted of 148 women (mean +/- SD age, 74 +/- 1 yr) with a 25-hydroxycholecalciferol (25OHD(3)) level below 50 nmol/L. They received either 1200 mg calcium plus 800 IU vitamin D(3) or 1200 mg calcium/day. We measured intact PTH, 25OHD(3), 1,25-dihydroxyvitamin D(3), blood pressure, and heart rate before and after treatment. Compared with calcium, supplementation with vitamin D(3) and calcium resulted in an increase in serum 25OHD(3) of 72% (P < 0.01), a decrease in serum PTH of 17% (P = 0.04), a decrease in systolic blood pressure (SBP) of 9.3% (P = 0.02), and a decrease in heart rate of 5.4% (P = 0.02). Sixty subjects (81%) in the vitamin D(3) and calcium group compared with 35 (47%) subjects in the calcium group showed a decrease in SBP of 5 mm Hg or more (P = 0.04). No statistically significant difference was observed in the diastolic blood pressures of the calcium-treated and calcium- plus vitamin D(3)-treated groups (P = 0.10). Pearson coefficients of correlation between the change in PTH and the change in SBP were 0.49 (P < 0.01) for the vitamin D(3) plus calcium group and 0.23 (P < 0.01) for the calcium group. A short-term supplementation with vitamin D(3) and calcium is more effective in reducing SBP than calcium alone. Inadequate vitamin D(3) and calcium intake could play a contributory role in the pathogenesis and progression of hypertension and cardiovascular disease in elderly women.

Vitamin D deficiency and disorders of vitamin D metabolism

The disorders of vitamin D metabolism are inherited metabolic abnormalities involving mutations of the vitamin D receptor or enzymes involved in the metabolism of vitamin D to its biologically active form 1,25-dihydroxyvitamin D. Although these mutations are rare, studies in affected patients and animal models have helped to identify critical actions of vitamin D and the mechanism by which it exerts its effects. Vitamin D deficiency, however, is an increasingly recognized problem among the elderly and in the general population. Screening for vitamin D deficiency only in those patients with known risk factors will result in a large proportion of unrecognized affected patients.

Putative susceptibility markers of coronary artery disease: association between VDR genotype, smoking, and aromatic DNA adduct levels in human right atrial tissue

Cancer and cardiovascular diseases share risk factors such as smoking, and the onset of both diseases have been suggested to have a common mechanistic basis. The binding of carcinogens to DNA (carcinogen-DNA adducts), genetic polymorphisms in carcinogen-detoxifying enzymes glutathione S-transferases (GSTs), and genetic polymorphisms in the vitamin D receptor (VDR) are among the candidates for modifiers of cancer risk. We determined whether these biomarkers could be related to individual characteristics of patients suffering from cardiovascular diseases. For that purpose, DNA from the right atrial appendage of 41 patients who underwent open heart surgery was analyzed for smoking-related DNA adducts and polymorphisms in GSTM1, GSTT1, and VDR genes. Statistical analysis was used to identify any patient's characteristics associated with these molecular markers. Our results showed that heart tissue of cigarette smokers contained a variety of aromatic DNA adducts in significantly elevated levels compared to ex-smokers (P<0.01) or nonsmokers (P<0.001). A linear relationship was observed between DNA adduct levels and daily cigarette smoking (rs=0.73; P=0.0003). Since cardiac myocytes are terminally differentiated cells that have lost their ability to divide and seemingly have limited DNA repair capacities, their levels might accumulate with time and thereby affect heart cell function or viability. Substantial interindividual differences between DNA adduct levels were observed, and persons with severe coronary artery disease (CAD), as assessed by coronary angiography, had higher DNA adduct levels than persons with no or mild CAD (P=0.04). As polymorphisms in GST genes have been shown to modulate DNA adduct levels and risk for lung cancer in smokers, we explored for the first time whether the GST polymorphisms could also explain deviating heart DNA adduct levels and CAD risk. However, no relation could be found between these covariants. In contrast, a VDR genotype, which has been associated with decreased serum levels of the active hormonal form of vitamin D and increased risk for certain cancers, seemed to be related to severity of CAD (P=0.025). Our findings support the hypothesis that smoking-related DNA damage may be involved in the onset of cardiovascular diseases and suggest that VDR genotype may be a useful susceptibility marker of CAD.

Plasma 25-hydroxyvitamin D concentrations are inversely associated with blood pressure of Dahl salt-sensitive rats

Dietary salt is a contributing factor to the development of hypertension in individuals who are salt-sensitive. The vitamin D endocrine system has been reported to modulate vascular structure and function. Since elderly hypertensive females with low plasma renin activity, typical of salt-sensitivity, had significantly lower 25-hydroxyvitamin D concentrations compared with normotensive elderly and young females, we have used Dahl salt-sensitive and salt-resistant rats fed high (80 g/kg diet) and low (3 g/kg diet) salt diets as models to examine the relationship between salt-sensitivity and 25-hydroxyvitamin D, the precursor of the hormonal form of vitamin D, 1,25-dihydroxyvitamin D. Plasma 25-hydroxyvitamin D concentrations of salt-resistant rats were unaffected by a high salt diet, but plasma 25-hydroxyvitamin D concentrations of salt-sensitive rats were significantly reduced within three weeks to lower than 25%. There was a negative association between plasma 25-hydroxyvitamin D concentrations of salt-sensitive rats and the number of days that the rats were fed a high salt diet (r = -0.98, P < 0.02) and a positive association between blood pressure and the number of days that the rats were fed a high salt diet (r = 0.97, P < 0.05). An inverse relationship was found between plasma 25-hydroxyvitamin D concentrations and blood pressure (r = -0.99, P < 0.01). Spontaneously hypertensive rats did not have low plasma 25-hydroxyvitamin D concentrations, suggesting that reduction of plasma 25-hydroxyvitamin D concentration might be specific to salt-induced hypertension.

Seasonal distribution of acute myocardial infarction in the second National Registry of Myocardial Infarction

OBJECTIVES

This observational study sought to determine whether cases of acute myocardial infarction (AMI) reported to the second National Registry of Myocardial Infarction (NRMI-2) varied by season.

BACKGROUND

The existence of circadian variation in the onset of AMI is well established. Examination of this periodicity has led to new insights into pathophysiologic triggers of atherosclerotic plaque rupture. Although a seasonal pattern for mortality from AMI has been previously noted, it remains unclear whether the occurrence of AMI also displays a seasonal rhythmicity. Documentation of such a pattern may foster investigation of new pathophysiologic determinants of plaque rupture and intracoronary thrombosis.

METHODS

We analyzed the number of cases of AMI reported to NRMI-2 by season during the period July 1, 1994 to July 31, 1996. Data were normalized so that seasonal occurrence of AMI was reported according to a standard 90-day length.

RESULTS

A total of 259,891 cases of AMI were analyzed during the study period. Approximately 53% more cases were reported in winter than during the summer. The same seasonal pattern (decreasing occurrence of reported cases from winter to fall to spring to summer) was seen in men and women, in different age groups and in 9 of 10 geographic areas. In-hospital case fatality rates for AMI also followed a seasonal pattern, with a peak of 9% in winter.

CONCLUSION

The present results suggest that there is a seasonal pattern in the occurrence of AMIs reported to NRMI-2 that is characterized by a marked peak of cases in the winter months and a nadir in the summer months. This pattern was seen in all subgroups analyzed as well as in different geographic areas. These findings suggest that the chronobiology of seasonal variation in AMI may be affected by variables independent of climate.

Inadequate vitamin D status: does it contribute to the disorders comprising syndrome 'X'?

Environmental factors are important in the aetiology of glucose intolerance, type II diabetes and IHD. The lack of vitamin D, which is necessary for adequate insulin secretion, relates demographically to increased risk of myocardial infarction. These disorders are connected, degenerative vascular disease increasing with glucose intolerance and diabetes and, with its risk factors, comprising syndrome 'X'. Evidence is presented suggesting that vitamin D deficiency may be an avoidable risk factor for syndrome 'X', adding another preventative measure to current recommendations which are aimed at reducing the worldwide epidemic of these disorders. Experimentally, vitamin D deficiency progressively reduces insulin secretion; glucose intolerance follows and becomes irreversible. Relationships between vitamin D status, glucose tolerance and 30 min insulin secretion during oral glucose tolerance tests are reported in British Asians; insulin secretion, but not glycaemia, improving with short-term supplementation. Studies showing reduction in blood pressure and in risk of heart attack and diabetes with exercise (usually outdoor), rarely consider the role of vitamin D status. Glycaemia and insulin secretion in elderly European men, however, relate to vitamin D status, independent of season or physical activity. Prolonged supplementation can improve glycaemia. Hypertension improves with vitamin D treatment with or without initial deficiency. Vitamin D status and climate are reviewed as risk factors for myocardial infarction; the risk reducing with altitude despite increasing cold. Glycaemia and fibrinogenaemia improve with insulin secretion increases in summer. Variation in vitamin D requirements could arise from genetic differences in vitamin D processing since bone density can vary with vitamin D-receptor genotype. Vitamin D receptors are present in islet beta cells and we report insulin secretion in healthy Asians differing profoundly with the Apa I genotype, being independent of vitamin D status. Those at risk of vitamin D deficiency include the elderly, those living indoors or having a covered-up style of dress, especially dark-skinned immigrants, and pregnant women, and these are groups recognized as being at increased risk of diabetes.

The French paradox unmasked: the role of folate

The French paradox relates to the paradoxical association of a diet high in saturated fat and cholesterol with low coronary heart disease mortality and is contrary to the 'lipid hypothesis'. France and other regions with low heart disease mortality have a high consumption of fruit and vegetables. Epidemiologic studies show fruit and vegetable consumption is inversely related to coronary heart disease mortality, but recent intervention studies do not support the theory that protection is due to antioxidant vitamins. Fruit and vegetables, however, are rich sources of folate. Folate lowers plasma homocysteine levels. Even mild to moderate elevation in plasma homocysteine level is a strong risk factor for arteriosclerosis of the coronary, cerebral, and peripheral arteries. This should explain not only the French paradox but also why known risk factors may explain as little as 25% of the risk for coronary heart disease.

Bone mass, vitamin D deficiency, and hyperparathyroidism in congestive heart failure

PURPOSE

In contrast to renal and hepatic failure, congestive heart failure (CHF) has not been associated with a defined metabolic bone disorder. However, low bone mass has been reported in patients with CHF who receive a cardiac transplant. Both the pathophysiology and therapy of CHF may influence bone and mineral homeostasis and evidence that calciotropic hormones may affect cardiovascular function is accumulating. Therefore, we evaluated patients with severe CHF to determine the prevalence of osteoporosis and to characterize relationships between mineral homeostasis, bone turnover, bone mass, and severity of CHF.

PATIENTS AND METHODS

One hundred one patients (79 men and 22 women, aged 25 to 70 years) with severe CHF (New York Heart Association functional class III or IV) referred for consideration for cardiac transplantation were evaluated with measurements of serum 25-hydroxyvitamin D (25-OHD), 1,25 dihydroxyvitamin D [1,25(OH)2D], intact parathyroid hormone (PTH), markers of bone turnover (serum osteocalcin, urinary hydroxyproline, and pyridinium crosslinks); bone mineral density (BMD) by dual energy x-ray absorptiometry was measured in 91 patients. Left ventricular ejection fraction (LVEF) and resting cardiac output (CO) were determined in 88 and maximal treadmill exercise testing and peak oxygen consumption were performed in 45 patients.

RESULTS

Osteoporosis (T score < or = -2.5) was present in 7% at the lumbar spine, 6% at the total hip, and 19% at the femoral neck. Osteopenia (T scores between -1.0 and -2.5) was present in 43% at the lumbar spine, 47% at the total hip, and 42% at the femoral neck. Women were more severely affected (P = 0.007). Frankly low serum 25-OHD (< or = 9 pg/mL) and 1,25(OH)2D (< or = 15 pg/mL) levels were found in 17% and 26% of the patients, respectively, and elevated serum PTH (> or = 65 pg/mL) in 30%. Both low serum 1,25(OH)2D and increased serum PTH were associated with prerenal azotemia. Low serum vitamin D metabolites were associated with biochemical evidence of increased bone turnover, but BMD did not differ by vitamin D or PTH status. Patients with more severe CHF had significantly lower vitamin D metabolites and higher bone turnover, whereas elevated PTH was associated with better LVEF (21 +/- 1 versus 18 +/- 1%; P = 0.05) and correlated positively with resting CO (R = 0.220; P = 0.04).

CONCLUSIONS

Osteopenia or osteoporosis were observed in approximately half of these patients with severe CHF. Abnormal calciotropic hormone concentrations, also common, were associated with evidence of increased bone resorption but were not related to BMD in this cross-sectional study. Abnormal concentrations of calciotropic hormones were related to the severity of cardiovascular compromise. Because both low BMD and low serum concentrations of 25-OHD in patients with CHF are associated with higher rates of bone loss and fracture after cardiac transplantation, patients should be evaluated for and receive appropriate therapy for these disorders.

Bone mineral density and blood flow to the lower extremities: the study of osteoporotic fractures

This study tests the hypothesis that reduced blood flow to the lower extremities may affect bone remodeling, resulting in a decrease in bone mineral density (BMD). BMD was measured in the axial and appendicular skeleton of 1292 elderly women (mean age, 71 years) enrolled in the Study of Osteoporotic Fractures. The ratio of the posterior tibial and brachial systolic blood pressures, the ankle/arm index, was used as a measure of blood flow to the legs. In the cross-sectional analysis, this index was positively correlated with BMD at the radius, calcaneus, and hip, but not at the spine. A decrease in the index of 2 standard deviations (SD) (as might occur in patients with moderate arterial disease) was associated with a decrease of 3.7% (95% CI, 1.7%, 5.8%) in hip BMD. The effect size at the hip decreased from 3.7 to 1.8% (and was not statistically significant) when adjustment was made for smoking and/or body mass index (BMI). In the prospective analysis, the rate of bone loss at the hip and calcaneus was greater (p < 0.05) among women whose annual decrease in ankle/arm index was more than 1 SD greater than the mean decrease. This increase was independent of estrogen use, smoking, BMI, pattern of fat distribution, history of diabetes, exercise, and ability to walk. The results from this prospective community-based study provide the first evidence that among relatively healthy older women decreased vascular flow in the lower extremities may be associated with an increased rate of bone loss at the hip and calcaneus.

Fat-soluble vitamin levels in familial hypercholesterolemia

OBJECTIVE

To examine serum levels of retinol, 25-hydroxyvitamin D, and alpha-tocopherol and their potential determinants in familial hypercholesterolemia (FH).

SUBJECTS

Study 1: 151 boys and girls with FH aged 7 to 16 years who were following a lipid-reduced diet but not taking lipid-lowering drugs. Study 2: 87 boys and girls with FH, of whom 24 were taking bile acid-binding resins in addition to the diet, and 30 age- and sex-matched control subjects.

DESIGN

Cross-sectional survey.

SETTING

Lipid referral clinic.

RESULTS

None of the subjects had suboptimal retinol or 25-hydroxyvitamin D levels. Only one girl had a low alpha-tocopherol level and alpha-tocopherol/lipid ratio. In multiple regression analysis, pubertal onset and gender were associated with retinol and 25-hydroxyvitamin D levels. The triglyceride level was positively related to level of retinol, and body mass index was inversely related to 25-hydroxyvitamin D level. Vitamin supplementation was positively related to 25-hydroxyvitamin D level and the alpha-tocopherol/lipid ratio. This ratio was lower in subjects whose total cholesterol level was above the median (8.0 mmol/L (310 mg/dl)) than in subjects whose cholesterol level was below the median (p = 0.01). In study 2, the alpha-tocopherol/lipid ratio in control subjects (median, 5.1 mumol/mmol) was higher than in subjects with FH who were not taking resins (median, 3.3 mumol/mmol; p < 0.05) but similar to the ratio in treated subjects (median, 5.4 mumol/mmol).

CONCLUSIONS

Pubertal onset, gender, lipid levels, vitamin supplementation, and body mass index are significant predictors of fat-soluble vitamin levels in children with FH. Though children following a lipid-lowering diet have normal serum levels of fat-soluble vitamins, the alpha-tocopherol level does not appear to increase proportionately to the increase in cholesterol level. Treatment with resins may restore a normal alpha-tocopherol/lipid ratio.

The role of vitamin D3 in the aetiology of abdominal aortic aneurysms

Abdominal aortic aneurysms (AAAs) have traditionally been attributed to atherosclerosis, although there is increasing epidemiological, biochemical and genetic evidence that aneurysmal arterial disease is different from occlusive atherosclerosis. One of the most consistent biochemical findings in the aneurysmal aorta is a significant reduction in elastin protein; the cause, for this remains unclear. There is in vitro evidence that vitamin D3 (1,25 dihydrocholecalciferol) inhibits the production of elastin by smooth muscle cells. On the basis of this observation and the possibility that some subjects may be exposed to excess vitamin D3, the hypothesis that vitamin D3 may be a previously unrecognized aetiological factor in the pathogenesis of AAA is developed.

Serum 25-hydroxyvitamin D3 is related to physical activity and ethnicity but not obesity in a multicultural workforce

BACKGROUND

Recent research suggests that body vitamin D levels are decreased in coronary heart disease and diabetes, but it is unclear which cardiovascular risk factors are related to vitamin D status.

AIMS

To examine the relation between vitamin D status and major cardiovascular risk factors.

METHODS

Serum 25-hydroxyvitamin D3, a marker of recent sun exposure and vitamin D status, was measured in 390 New Zealand residents (95 Pacific Islanders, 74 Maori and 221 others mostly of European descent), who were part of a larger cross-sectional survey of a workforce (n = 5677) aged 40-64 years.

RESULTS

Serum 25-hydroxyvitamin D3 levels were significantly lower in Pacific Islanders (mean (SE) = 56 (3) nmol/L; p = 0.0001) and Maoris (68 (3) nmol/L; p = 0.036) compared with Europeans (75 (2) nmol/L) after adjusting for age, sex and time of year. Also adjusting for ethnic group, 25-hydroxyvitamin D3 was higher in people doing vigorous (aerobic) leisure physical activities (71 (2) nmol/L; p = 0.0066) and moderate (non-aerobic) activities (68 (3) nmol/L; p = 0.12) compared with those who were inactive (63 (2) nmol/L). However, 25-hydroxyvitamin D3 was unrelated to body mass index, serum lipids, blood pressure or cigarette smoking.

CONCLUSIONS

People with increased skin pigmentation, such as Polynesians, and people who are inactive, have decreased body levels of vitamin D; this might partly explain their increased risk of cardiovascular disease.

Beard calcium concentration as a marker for coronary heart disease as affected by supplementation with micronutrients including selenium

Hair calcium concentration is biologically regulated and inversely correlated to the concentration in the aorta. Populations generally divide into high and low hair calcium groups which differ significantly from each other. It has been found that about 90% of people who suffer an acute myocardial infarction belong to the low hair calcium group. It follows that raising a person's calcium status from the low to the high group should decrease their risk of coronary heart disease. A trial was set up with four groups of 12 people, randomly allocated to one of the following treatments: placebo; vitamin D; antioxidants; and antioxidants plus vitamin D. Beard samples were collected for two months prior to four months of supplementation and for two months afterwards. Blood samples were collected at the end of the supplementation period. All treatments significantly lowered plasma calcium concentrations but did not significantly affect beard calcium concentrations due, primarily, to some large individual fluctuations. Within the limitations of the experiment the combined treatment was the most effective as it was the only one to raise beard calcium levels for the duration of the supplementation period. A higher rate of vitamin D supplementation [i.e., > 50% recommended daily allowance (RDA)] might have established clear differences but larger group sizes would also have been helpful. Of the unsupplemented subjects 80% had plasma selenium concentrations of < 90 micrograms l-1 in contrast to only 10% of supplemented ones.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum 25-hydroxyvitamin D3 levels decreased in impaired glucose tolerance and diabetes mellitus

A cross-sectional survey was carried out in a New Zealand Polynesian and Caucasian workforce of 5677 staff aged 40-64 years to determine whether serum concentrations of 25-hydroxyvitamin D3 are altered in people with newly diagnosed diabetes mellitus and impaired glucose tolerance (IGT). Serum 25-hydroxyvitamin D3 concentration was significantly lower in newly detected cases with diabetes and IGT (n = 238) compared with controls individually matched by sex, age (+/- 2 years), ethnicity, and date of interview (mean (S.D.): 69 (31) vs. 76 (34) nmol/l; P = 0.0016). Among controls, serum concentrations were significantly lower in Maori (mean (S.E.) = 65 (5) nmol/l; P = 0.0013) and Pacific Islanders (59 (4) nmol/l; P = 0.0001) compared with Europeans (82 (3) nmol/l), after adjusting for age, sex, and time of year. We conclude that diabetes and IGT are associated with low serum concentrations of 25-hydroxyvitamin D3 and that low concentrations of this hormone in New Zealand Polynesians may partly explain their increased prevalence of diabetes/IGT compared with Europeans.

Artificial ultraviolet whole-body radiation does not modify serum lipoprotein, plasma fibrinogen, plasminogen or antithrombin III concentrations in post-myocardial infarction patients

The relationship of ischaemic heart disease (IHD) to seasonal and latitude variation has prompted speculation that exposure to the ultraviolet component of solar radiation may reduce IHD risk. This hypothesis was partially tested by exposing 14 post-myocardial infarction patients to a 6 week course of artificial whole-body ultraviolet radiation (UVR). Serum lipoprotein and plasma coagulation factor concentrations were measured before and after the course of UVR. Results were compared with similar measurements from a placebo-controlled group of 13 post-myocardial patients. Despite a more than two-fold rise in mean serum 25-OHD, serum lipoprotein and plasma fibrinogen, antithrombin III and plasminogen concentrations did not change significantly in the UVR group. Significant but minor change in prothrombin time and thrombin time in the placebo group appear unlikely to be of biological significance. Seasonal and latitude variation in these IHD risk factors appear unrelated to corresponding variation in solar UVR exposure.

The quality of epidemiological data in coronary heart disease and atherosclerosis

There are inherent difficulties in the use of indirect observations in the epidemiology of a chronic ubiquitous disease such as atherosclerosis. Such difficulties do not condone basic errors in epidemiological methodology, the use of low quality data, a lack of precision in measurements, invalid extrapolations and inappropriate use of terminology and coronary heart disease as a surrogate or synonym of coronary atherosclerosis and bias in the interpretation of data. These errors reveal a lack of rigorous and scientific standards in the epidemiology of coronary heart disease. Analysis cannot launder such data. Independent scientists must evaluate the data in respect of precision, logic and truth.

Association between low bone density and stroke in elderly women. The study of osteoporotic fractures

BACKGROUND AND PURPOSE

To determine whether women with low bone mineral density are at increased risk of stroke, the present study was conducted.

METHODS

We studied 4024 ambulatory women aged 65 years or older participating in the prospective Study of Osteoporotic Fractures. Bone mineral density was measured at baseline using single photon absorptiometry; strokes were ascertained using a computerized Medicare data base and death certificates.

RESULTS

During a mean of 1.98 years of follow-up, 83 women suffered first strokes (five fatal). Osteopenia was associated with an increased stroke risk: Each SD decrease in bone mineral density at the calcaneus (0.09 g/cm2) was associated with a 1.31-fold increase in stroke (95% confidence interval, 1.03-1.65), adjusted for age, follow-up time, and several potential confounders, including diabetes, systolic blood pressure, use of alcohol, cigarettes or postmenopausal estrogens, cognitive ability, grip strength, and functional ability. The observed relation between bone density and stroke was strongest for intracerebral hemorrhages and occlusions.

CONCLUSIONS

Most likely, low bone density does not cause stroke; some other process probably results in both osteopenia and cerebrovascular disease.

Environmental factors and the etiology of melanoma

In this piece, we have argued that, despite educational programs designed to prevent melanoma, the mortality and incidence rates for the disease have soared steadily. Even on the conventional interpretation of the data, just more than half of the presented cases of melanoma can be explained solely as 'sun-caused.' The conventional interpretation has little to offer by way of explaining the remainder of these cases, some of which, as we discussed earlier, involve melanomas on parts of the body not exposed to the sun. We have argued that the dominant interpretation in which increasing exposures to sunlight account for the increasing incidence of melanomas is a misleading oversimplification. To resolve the melanoma enigma in preventive health terms, it is imperative to acknowledge and to explore the implications of the important associations between the rise in the incidence of melanomas and environmental factors such as our increasing exposure to artificial light, electromagnetic radiation, and photo-sensitizing chemicals added to many processed foods and a range of medicinal drugs. Our argument has been that these environmental factors contribute to the problem either by altering body chemistry to make it more susceptible to the admittedly harmful effects associated with irregular and excessive exposure to the sun, and/or acting directly, as in the case of electromagnetic radiation, as promoters of melanoma.

Plasma 25-hydroxyvitamin D3 and its relation to physical activity and other heart disease risk factors in the general population

The relation between plasma levels of 25-hydroxyvitamin D3, the main metabolite of sun-induced vitamin D, and major coronary heart disease risk factors was examined in 295 men, aged 35 to 64 years, who were randomly sampled from the general population. Men who did regular vigorous leisure-time activity had a mean plasma 25-hydroxyvitamin D3 level that was 4.8 nmol/L (95% confidence limits: 0.1, 9.5) higher than that in inactive men, with the increase greatest in the winter months. Plasma 25-hydroxyvitamin D3 was positively associated with weekly hours of sun exposure (r = 0.27, P < 0.01), and showed a weak inverse association with age (r = -0.12, P < 0.05) and diastolic blood pressure (r = -0.15, P < 0.05), although this latter finding was no longer significant when allowance was made for the effects of age and season on vitamin D levels. In contrast, plasma 25-hydroxyvitamin D3 had no relation with either serum total or high-density-lipoprotein cholesterol levels, body mass index, or cigarette smoking. We hypothesize that vigorous leisure-time activity may protect against coronary heart disease, in part, by increasing body levels of vitamin D.