Redefining vitamin D insufficiency

Vitamin D deficiency and secondary hyperparathyroidism are common complications in patients with peripheral arterial disease

OBJECTIVE

To investigate via the vitamin D status whether patients with peripheral arterial disease (PAD) tend to develop vitamin D deficiency that in turn influences their clinical symptoms.

DESIGN

Cross-sectional.

SETTING

University hospital.

PATIENTS AND PARTICIPANTS

Three hundred twenty-seven patients were evaluated; subjects with secondary causes of bone disease or bone active medication were excluded. One hundred sixty-one patients with either PAD stage II (n = 84) or stage IV (n = 77) were enrolled and compared to 45 age- and sex-matched healthy controls.

MEASUREMENTS AND MAIN RESULTS

All patients underwent determinations of serum chemistry, 25-hydroxyvitamin D (vitamin D3) intact parathyroid hormone (iPTH), alkaline phosphatase (ALP), and osteocalcin and were further stratified according to an individual restriction score into 3 groups: mildly, moderately, or severely restricted in daily life due to the underlying disease. Patients with PAD IV showed significantly lower vitamin D3 (P =.0001), and calcium (P =.0001) values and significantly higher iPTH (P =.0001), osteocalcin (P =.0001) and ALP (P =.02) levels as compared to patients with PAD II. Patients considering themselves as severely restricted due to the underlying disease showed lower vitamin D3 and higher iPTH levels than those who described only a moderate (vitamin D3: P <.001; iPTH: P <.01) or mild (vitamin D3: P <.001; iPTH: P <.001) restriction in daily life.

CONCLUSION

Patients with PAD IV, especially those who feel severely restricted due to the disease, are at high risk of developing vitamin D deficiency, secondary hyperparathyroidism, and ultimately osteomalacia due to immobilization and subsequent lack of exposure to sunlight, all of which in turn lead to further deterioration. Monitoring of vitamin D metabolism and vitamin D replacement therapy could be a simple, inexpensive approach to mitigating clinical symptoms and improving quality of life in patients with advanced PAD.

Vitamin D receptor (VDR) mRNA and VDR protein levels in relation to vitamin D status, insulin secretory capacity, and VDR genotype in Bangladeshi Asians

Associations have been reported between vitamin D receptor (VDR) gene polymorphisms, type 1 diabetes, insulin secretion, and the insulin resistance syndrome. As VDR polymorphisms have no known functional significance, these findings may implicate a variant of the VDR gene or a locus in linkage disequilibrium with the VDR. We have examined VDR mRNA and VDR protein levels in relation to VDR polymorphisms (41 Bangladeshi subjects) and analyzed insulin secretory capacity (143 Bangladeshi subjects), allowing for other known determinants. Peripheral blood mononuclear cells (PBMCs) from subjects who had been genotyped for BsmI, ApaI, TaqI, and FokI VDR restriction fragment length polymorphisms were used for both total VDR mRNA quantitation (using TaqMan) and measurement of VDR protein levels (using a specific micro-immunoassay). Stepwise multiple regression analyses were used (to P < 0.05) to analyze the data. For the insulin secretion index, the best-fit model (n = 143, P < 0.0001) gave age (P = 0.002), TaqI (P < 0.0001), and BMI (P = 0.001) as independent determinants; with the inclusion of VDR mRNA and VDR protein levels, VDR mRNA was the sole independent determinant (n = 41, P = 0.024). However, the best-fit model for VDR mRNA (P = 0.004) gave FokI (P = 0.044) and TaqI (P = 0.04) genotypes and insulin secretory capacity (P = 0.042) as independent determinants. For VDR protein levels, the best-fit model (P = 0.006) gave TaqI genotype (P = 0.005) and circulating 1,25-dihydroxyvitamin-D levels (P = 0.03) as independent determinants. In conclusion, these studies confirm an association between VDR polymorphisms and insulin secretory capacity and demonstrate the VDR genotype to be a significant determinant of VDR mRNA and VDR protein levels in PBMCs, providing functional support to previously described genetic associations with the VDR gene. Furthermore, VDR expression has been shown to be a determinant of insulin secretory capacity.

Hypovitaminosis D prevalence and determinants among African American and white women of reproductive age: third National Health and Nutrition Examination Survey, 1988-1994

BACKGROUND

Recent reports of rickets among African American children drew attention to the vitamin D status of these infants and their mothers. African American women are at higher risk of vitamin D deficiency than are white women, but few studies have examined determinants of hypovitaminosis D in this population.

OBJECTIVE

We examined the prevalence and determinants of hypovitaminosis D among African American and white women of reproductive age.

DESIGN

We examined 1546 African American women and 1426 white women aged 15-49 y who were not pregnant and who participated in the third National Health and Nutrition Examination Survey (1988-1994). Hypovitaminosis D was defined as a serum 25-hydroxyvitamin D concentration < or =37.5 nmol/L. Multiple logistic regression was used to examine the independent association of dietary, demographic, and behavioral determinants of hypovitaminosis D.

RESULTS

The prevalence of hypovitaminosis D was 42.4 +/- 3.1% ( +/- SE) among African Americans and 4.2 +/- 0.7% among whites. Among African Americans, hypovitaminosis D was independently associated with consumption of milk or breakfast cereal <3 times/wk, no use of vitamin D supplements, season, urban residence, low body mass index, and no use of oral contraceptives. Even among 243 African Americans who consumed the adequate intake of vitamin D from supplements (200 IU/d), 28.2 +/- 2.7% had hypovitaminosis D.

CONCLUSIONS

The high prevalence of hypovitaminosis D among African American women warrants further examination of vitamin D recommendations for these women. The determinants of hypovitaminosis D among women should be considered when these women are advised on dietary intake and supplement use.

Vitamin D insufficiency among free-living healthy young adults

Long-term vitamin D insufficiency can cause secondary hyperparathyroidism and osteomalacia (1). In addition, there is increasing evidence that vitamin D may protect against common cancers, such as cancer of the colon (–4), prostate (5), and breast (6). Young adults aged 17 to 35 years drink inadequate amounts of milk (7) and are concerned about exposure to the sun because of the fear of developing skin cancer (8,9), which increases the risk of vitamin D insufficiency (10). We sought to examine the prevalence of vitamin D insufficiency in a group of free-living healthy young adults, consisting of mostly health care professionals, in Boston, Massachusetts.

Serum 25-hydroxyvitamin D status of adolescents and adults in two seasonal subpopulations from NHANES III

Subclinical vitamin D deficiency may be common in certain subgroups in the U.S., but to date vitamin D data from other groups in the population have not been available. We used serum 25-hydroxyvitamin D (25-OHD) data from 18,875 individuals examined in the Third National Health and Nutrition Examination Survey (NHANES III 1988-1994) to assess the vitamin D status of selected groups of the noninstitutionalized U.S. adolescent and adult population. Serum 25-OHD levels were measured by a radioimmunoassay kit (DiaSorin, Inc., Stillwater, MN; normal range 22.5-94 nmol/L). Because physical exams are performed in mobile vans in NHANES, data could not be collected in northern latitudes during the winter; instead data were collected in northern latitudes during summer and in southern latitudes in winter. To address this season-latitude aspect of the NHANES design, we stratified the sample into two seasonal subpopulations (winter/lower latitude and summer/higher latitude) before examining vitamin D status. Less than 1% of the winter/lower latitude subpopulation had vitamin D deficiency (25-OHD <17.5 nmol/L). However, the prevalence of vitamin D insufficiency in this group ranged from 1%-5% with 25-OHD <25 nmol/L to 25%-57% with 25-OHD <62.5 nmol/L, even though the median latitude for this subsample (32 degrees N) was considerably lower than the latitude at which vitamin D is not synthesized during winter months (approximately 42 degrees N). With the exception of elderly women, prevalence rates of vitamin D insufficiency were lower in the summer/higher latitude subpopulation (<1%-3% with 25-OHD <25 nmol/L to 21%-49% with 25-OHD <62.5 nmol/L). Mean 25-OHD levels were highest in non-Hispanic whites, intermediate in Mexican Americans, and lowest in non-Hispanic blacks. Our findings suggest that vitamin D deficiency is unlikely in the two seasonal subpopulations of noninstitutionalized adolescents and adults that can be validly assessed in NHANES III. However, vitamin D insufficiency is more common in these two seasonal subpopulations. Of particular interest is that insufficiency occurred fairly frequently in younger individuals, especially in the winter/lower latitude subsample. Our findings support continued monitoring of this vitamin in the U.S. population.

The effect of conventional vitamin D(2) supplementation on serum 25(OH)D concentration is weak among peripubertal Finnish girls: a 3-y prospective study

OBJECTIVES

To study the effect of vitamin D supplementation and the impact of summer season on serum 25-hydroxyvitamin D (S-25(OH)D) in Finnish 9-15-y-old girls.

DESIGN

Three-year follow-up study with vitamin D(2) supplementation using D(2) 10 microg daily from October to January for the first and from October to February for the second winter as well as 20 microg daily from October to March for the third winter.

SETTING

Paavo Nurmi Centre, University of Turku, Turku, Finland.

SUBJECTS

A total of 171 female volunteers aged 9-15 y.

METHODS

Vitamin D and calcium intakes were estimated by a semi-quantitative food frequency questionnaire (FFQ). S-25(OH)D was measured by radioimmunoassay.

RESULTS

The median daily dietary intakes of vitamin D and calcium were 3.8 microg (interquartile range (IQR) 2.7-5.0) and 1451 mg (IQR 1196-1812), respectively, over 3 y. The prevalence of severe hypovitaminosis D (S-25(OH)D<20 nmol/l) was 14% and of moderate hypovitaminosis D (20 nmol/l < or = S-25(OH)D < or = 37.5 nmol/l) 75% at baseline in winter. None of the participants had severe hypovitaminosis D in summer. The effect of 10 microg of D(2) daily was insufficient to raise S-25(OH)D from baseline. The daily supplementation of 20 microg of D(2) increased S-25(OH)D significantly in wintertime compared with the non-supplement users (to 45.5 vs 31.8 nmol/l; P<0.001). None of the subjects with vitamin D(2) supplementation approximately 20 microg daily had severe hypovitaminosis D; however, 38% of those participants had moderate hypovitaminosis D at 36 months. Sun exposure in summer raised mean S-25(OH)D to 62.0 nmol/l. Both the daily supplementation of approximately 20 microg of D(2) and summer sunlight exposure had more effect on those who had severe hypovitaminosis than those who had a normal vitamin D status (increase of 24.2 vs 0.9 nmol/l (P<0.001), and 38.8 vs 18.2 nmol/l (P<0.001), respectively).

CONCLUSION

Vitamin D supplementation daily with 20 microg is needed to prevent hypovitaminosis D in peripubertal Finnish girls in winter. Sunlight exposure in summer is more effective than approximately 20 microg of D(2) supplementation daily in winter to raise S-25(OH)D. Both the daily supplementation with 20 microg of D(2) and summertime sunlight exposure had more effect on those who had severe hypovitaminosis D than those who had a normal vitamin D status.

SPONSORSHIP

Supported by the Yrjö Jahnsson Foundation and the Medical Research Foundation of the Turku University Central Hospital.

Pharmacotherapy of osteoporosis in postmenopausal women: focus on safety

The therapy of osteoporosis has made enormous strides in the last decade. There is now a range of interventions, each with its pros and cons. Calcium and vitamin D supplementation remain the foundation and have few safety issues. Bisphosphonates are widely used, though gastrointestinal tolerance is a problem with some oral preparations. Intravenous administration may circumvent this, although this introduces the smaller problem of acute phase reactions. The side effect profile of hormone replacement therapy (HRT) is still being delineated after 40 years of use, with substantial new information expected in the next few years. This will clarify its place in the medical management of the menopause. Raloxifene appears to have a superior safety profile to HRT, though its efficacy on bone may be less. While none of these options is suitable for everyone, the range of available therapies does mean that most patients can find an intervention that is effective and acceptable.

Vitamin D deficiency, muscle function, and falls in elderly people

An inadequate serum vitamin D status is commonly seen in elderly people as the result of various risk factors interacting in this population. Apart from the well-known effects on bone metabolism, this condition is also associated with muscle weakness, predominantly of the proximal muscle groups. Muscle weakness below a certain threshold affects functional ability and mobility, which puts an elderly person at increased risk of falling and fractures. Therefore, we wanted to determine the rationale behind vitamin D supplementation in elderly people to preserve and possibly improve muscle strength and subsequently functional ability. From experimental studies it was found that vitamin D metabolites directly influence muscle cell maturation and functioning through a vitamin D receptor. Vitamin D supplementation in vitamin D-deficient, elderly people improved muscle strength, walking distance, and functional ability and resulted in a reduction in falls and non-vertebral fractures. In healthy elderly people, muscle strength declined with age and was not prevented by vitamin D supplementation. In contrast,severe comorbidity might affect muscle strength in such a way that restoration of a good vitamin D status has a limited effect on functional ability. Additional research is needed to further clarify to what extent vitamin D supplementation can preserve muscle strength and prevent falls and fractures in elderly people.

Hypovitaminosis D and hyperparathyroidism in physically inactive elderly Japanese living in nursing homes: relationship with age, sunlight exposure and activities of daily living

BACKGROUND AND AIMS

The purposes of this study were to investigate the prevalences of hypovitaminosis D and hyperparathyroidism in physically inactive elderly people living in Japanese nursing homes and determine any correlations with demographic, environmental and/or life-style factors.

METHODS

We targeted 220 elderly people living in nursing homes for the physically disabled in Japan. Of these, 133 (women, 113; men, 20) subjects who agreed and met our inclusion criteria were studied. The average age of the subjects was 84.6 years (SD 8.2). Serum 25-hydroxyvitamin D3 (25[OH]D3), intact parathyroid hormone (intact PTH), creatinine, and albumin concentrations were measured in each subject. Total hours of sunshine during the previous 5 weeks, activities of daily living (ADL) levels, and dietary vitamin D intake were also measured. ADL levels were evaluated using the Physical Self-Maintenance Scale (5-point scale). The examinations were performed between October and December, 1999.

RESULTS

The average concentrations of serum 25(OH)D3 and intact PTH were 29.9 nmol/L (SD 13.1) and 5.04 pmol/L (SD 2.27), respectively. The prevalences of hypovitaminosis D (25[OH]D3<30 nmol/L) and hyperparathyroidism (intact PTH>6.90 pmol/L) were 77/133 (57.9%) and 21/133 (15.8%), respectively. Serum 25(OH)D3 concentrations were positively associated with hours of sunshine (R2=0.371, p<0.001) and serum albumin concentrations (R2=0.086, p<0.001), but not with age (p=0.075) or total ADL score (p=0.527). A negative association between serum intact PTH and 25(OH)D3 levels was found in subjects who were 80 years or older (p<0.001) but not in subjects under the age of 80 years.

CONCLUSIONS

Hypovitaminosis D and hyperparathyroidism are commonly seen in elderly Japanese with low ADL levels. Hypovitaminosis D seems to adversely affect PTH levels, especially in the very elderly.

[Prevalence of hypovitaminosis D in elderly institutionalized residents: influence of a substitutive treatment]

BACKGROUND

Osteoporosis in the elderly is a common and severe disease, vitamin D deficiency being an important causative factor. Hypovitaminosis D is frequent in old people, particularly those living in nursing homes.

SUBJECTS AND METHOD

We performed a cross-sectional study of 100 randomly recruited elderly institutionalized subjects. The prevalence of hypovitaminosis D and its possible repercussion on the phosphocalcium metabolism were assessed. The degree of sun exposure and the existence of co-morbidity were also recorded. Individuals with hypovitaminosis D were included in a longitudinal study (6 months' duration) aimed at assess the efficacy of treatment with calcium and two different therapeutic regimens with calcidiol (16,000 IU/week or 16,000 IU every 3 weeks).

RESULTS

87% of individuals had hypovitaminosis D; 21.8% of them had secondary hyperparathyroidism. The study population had a low degree of sun exposure and a high level of co-morbidity. The two doses of calcidiol led to a normalization of 25-OHD3 levels, increased calciuria and compensated secondary hyperparathyroidism, yet higher 25-OHD3 levels were achieved with the weekly therapeutic scheme.

CONCLUSIONS

Hypovitaminosis D prevalence appears to be very high In the elderly institutionalized population. Calcium and calcidiol supplementation normalized 25-OHD3, improved calcium absorption and compensated secondary hyperparathyroidism. Calcium and vitamin D supplementation should be employed routinely in the elderly institutionalized population.

Vitamin A antagonizes calcium response to vitamin D in man

For unknown reasons, the highest incidence of osteoporosis is found in northern Europe. In these populations, the sunlight exposure is limited and the vitamin A intake is high. The interaction between vitamin A and D has been the subject of several in vitro and animal studies. We have studied the acute effects of vitamin A and D on calcium homeostasis in 9 healthy human subjects. We compared the effect of (i) 15 mg of retinyl palmitate, (ii) 2 microg of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], (iii) 15 mg of retinyl palmitate plus 2 microg of 1,25(OH)2D3, and (iv) placebo in a double-blind crossover study. The subjects took vitamin preparations at 10:00 p.m. and the following day blood samples were collected five times from 8:00 a.m. to 4:00 p.m. Serum levels of 1,25(OH)2D3 and retinyl esters increased (1.7-fold and 8.3-fold, respectively; p < 0.01). As expected, serum calcium (S-calcium) increased (2.3%; p < 0.01) and S-parathyroid hormone (PTH) decreased (-32%; p < 0.05) after 1,25(OH)2D3 intake. In contrast, retinyl palmitate intake resulted in a significant decrease in S-calcium when taken alone (-1.0%; p < 0.05) and diminished the calcium response to 1,25(OH)2D3 after the combined intake (1.4%; p < 0.01). S-PTH was unaffected by retinyl palmitate. No significant changes in serum levels of the degradation product of C-telopeptide of type I collagen (CrossLaps), or U-calcium/creatinine levels were found. In conclusion, an intake of vitamin A corresponding to about one serving of liver antagonizes the rapid intestinal calcium response to physiological levels of vitamin D in man.

Vitamin D deficiency and secondary hyperparathyroidism in the elderly: consequences for bone loss and fractures and therapeutic implications

Vitamin D deficiency is common in the elderly, especially in the housebound and in geriatric patients. The establishment of strict diagnostic criteria is hampered by differences in assay methods for 25-hydroxyvitamin D. The synthesis of vitamin D3 in the skin under influence of UV light decreases with aging due to insufficient sunlight exposure, and a decreased functional capacity of the skin. The diet contains a minor part of the vitamin D requirement. Vitamin D deficiency in the elderly is less common in the United States than elsewhere due to the fortification of milk and use of supplements. Deficiency in vitamin D causes secondary hyperparathyroidism, high bone turnover, bone loss, mineralization defects, and hip and other fractures. Less certain consequences include myopathy and falls. A diet low in calcium may cause an increased turnover of vitamin D metabolites and thereby aggravate vitamin D deficiency. Prevention is feasible by UV light exposure, food fortification, and supplements. Vitamin D3 supplementation causes a decrease of the serum PTH concentration, a decrease of bone turnover, and an increase of bone mineral density. Vitamin D3 and calcium may decrease the incidence of hip and other peripheral fractures in nursing home residents. Vitamin D3 is recommended in housebound elderly, and it may be cost-effective in hip fracture prevention in selected risk groups.

Vitamin D status and its adequacy in healthy Danish perimenopausal women: relationships to dietary intake, sun exposure and serum parathyroid hormone

We conducted this study to assess the prevalence of vitamin D insufficiency in a population of normal perimenopausal women, to examine the influence of sun exposure and vitamin D intake on the concentration of 25-hydroxyvitamin D (25OHD) and to examine the association between parathyroid hormone (PTH) and 25OHD. A total of 2016 healthy women aged 45-58, who had recently undergone a natural menopause, were enrolled over a 2.5-year period in the Danish Osteoporosis Prevention Study. A marked seasonal fluctuation of 25OHD was seen, with an abrupt rise in June and high values until October. The fluctuation could be related to number of hours of sunshine per month with a two months time lag. Dietary vitamin D intake, vitamin supplementation, sunlight exposure, and use of sun-bed were all significantly related to 25OHD concentrations. Sun exposure seemed to contribute the most. The overall prevalence of vitamin D deficiency (defined as serum ) was 7 %. However, in the subgroup avoiding direct sunshine and abstaining from vitamin D supplementation 32.8 % were vitamin D deficient in the winter-spring period. Although mean PTH was increased in the group with low serum 25OHD, PTH was not a sensitive marker of hypovitaminosis D in the individual, as only 16 % of those with vitamin D deficiency had PTH levels above normal range. Thus, we have shown, that healthy middle-aged Danish women are prone to vitamin D insufficiency in the winter-spring period, if they avoid sun exposure in the summer period and abstain from vitamin D supplementation.

Relation between vitamin D insufficiency, bone density, and bone metabolism in healthy postmenopausal women

Although only few postmenopausal women exhibit biochemical signs of hypovitaminosis D, vitamin D insufficiency has been shown to have adverse effects on bone metabolism and could be an important risk factor for osteoporosis and fracture. We determined serum levels of 25-hydroxyvitamin D [25(OH)D], intact parathyroid hormone (iPTH), bone turnover markers, dietary calcium intake, and bone mineral density (BMD; measured by dual X-ray absorptiometry) in 161 consecutive ambulatory women, healthy except for osteoporosis, referred to a bone metabolic unit. The prevalence of vitamin D insufficiency [25(OH)D < or = 15 ng/ml] was 39.1%. 25(OH)D was lower in the osteoporotic subjects (15.7 +/- 5.3 ng/ml vs. 21.8 +/- 9.7 ng/ml; p < 0.001). After controlling for all other variables, lumbar spine (LS) BMD was found to be significantly associated with 25(OH)D, body mass index (BMI), and years after menopause (YSM) (R2 = 0.253; p < 0.001). For femoral neck (FN), significant independent predictors of BMD were YSM, BMI, iPTH, and 25(OH)D (R2 = 0.368; p < 0.001). The probability of meeting osteoporosis densitometric criteria was higher in the vitamin D insufficiency group (odds ratio [OR], 4.17, 1.83-9.48) after adjusting by YSM, BMI, iPTH, and dietary calcium intake. Our study shows that vitamin D insufficiency in an otherwise healthy postmenopausal population is a common risk factor for osteoporosis associated with increased bone remodeling and low bone mass.

Vitamin D nutrition and bone disease in adults

The consequences of vitamin D deficiency upon the skeleton are well known and management in the absence of renal failure is relatively straightforward. Vitamin D, either by mouth or parenterally will correct the deficiency and heal the osteomalacia. The mechanisms underlying the causation of vitamin D deficiency are now better understood and indicate the importance of underlying calcium malabsorption and secondary hyperparathyroidism leading to 1,25(OH)2D-induced catabolism of 25(OH)D and possibly also of vitamin D itself. In such situations, e.g., gastrointestinal and pancreaticobiliary disease, calcium supplementation in addition to vitamin D is indicated. The reasons behind nutritional vitamin D deficiency and the possible role of meat in protecting from osteomalacia await further elucidation, but from epidemiological studies, calcium deficiency, per se, is not implicated in the etiopathogenesis. The concept of vitamin D insufficiency is poorly understood, and difficult to define since a single value or close range of serum 25(OH)D values is unlikely to predict the needs of all subjects. Oral calcium intake and renal function are also likely to be relevant to the level of 25(OH)D which is found to be sufficient or insufficient for any given individual to maintain a normal serum calcium level without secondary hyperparathyroidism. There is increasing evidence that vitamin D insufficiency, by leading to sustained hyperparathyroidism, is prejudicial to the skeleton, particularly cortical bone. Since it is without symptoms until fractures occur, it should be actively sought in those clinical situations now recognized as contributing to risk. It can only be identified by the periodic measurement of serum 25(OH)D and the calcitropic hormones PTH and 1,25(OH)2D. In addition, BMD should be measured in a predominantly cortical site such as the proximal forearm, as well as the more conventional sites of spine and hip. The implications of these recommendations are an increase in the use of assays for PTH and vitamin D metabolites in the groups of subjects discussed in this review. Patients with chronic malabsorption states might reasonably be expected to have measurements performed twice-yearly. When vitamin D insufficiency is found, treatment with either vitamin D, calcium or both will be necessary, depending on the etiology of the insufficiency state in the inividual. In some malabsorptive states, calcium malabsorption is the cause of hyperparathyroidism and oral calcium alone can be used to reverse excess PTH activity in those with an adequate state of vitamin D nutrition. However, even in those vitamin D replete individuals, vitamin D catabolism will be enhanced and a small additional oral dose of vitamin D can do no harm. Regular monitoring of PTH and vitamin D metabolites will remain a necessity to ensure continued efficacy of treatment. Current recommendations for dietary supplements of vitamin D are clearly inadequate [61]. There is compelling evidence for supplements of 800 IU per day in the elderly and other high risk populations. Such a dose is safe and without side effects. The available evidence suggests that this should be combined with calcium supplements of 1200 mg/day [19] and that the current UK recommendations for a daily calcium intake of 700 mg contrast with those from the USA at 1,200 mg for people over 50 years old. Physicians need to be aware of both the small but important problem of vitamin D depletion and osteomalacia with its sometimes ambiguous presentation, and the more common but covert vitamin D (and calcium) insufficiency with its widespread and varied clinical associations.

Osteoporosis in men

Although less common than in women, osteoporosis in men is a prevalent worldwide problem with important socioeconomic implications. Our understanding of this condition in men is growing, but there remains a great deal more to be determined. Definitions for osteoporosis in men are needed. Cost-effective guidelines on who should be investigated and treated, and how, are clearly necessary. The role of bone mineral densitometry in diagnosis and treatment decisions needs to be clarified. The efficacy of drug therapies for osteoporosis in men requires greater attention. Currently, a large multicenter study is underway in the United States and should provide much needed insight into the epidemiology of osteoporosis in men.

Vitamin D deficiency among older women with and without disability

BACKGROUND

Vitamin D deficiency is associated with bone loss and bone fractures, and the identification of vulnerable populations is important to clinical practice and public health.

OBJECTIVE

The objectives of this study were to determine the prevalence of vitamin D deficiency and to examine associated risk factors for vitamin D deficiency in older women.

DESIGN

We measured serum concentrations of 25-hydroxyvitamin D [25(OH)D], 1,25-dihydroxyvitamin D [1, 25(OH)(2)D], intact parathyroid hormone (PTH), osteocalcin, and ionized calcium in women aged >/=65 y who were participating in the Women's Health and Aging Study I, an observational study of women representing the approximately one-third most disabled women living in the community, and women aged 70-80 y who were participating in the Women's Health and Aging Study II, an observational study of women among the two-thirds least disabled women living in the community in Baltimore.

RESULTS

The women were classified into 4 domains of physical disability. Among 371 women with 0 or 1 domain of disability and 682 women with >/=2 domains of disability, 6.2% and 12.6%, respectively, had vitamin D deficiency [serum concentrations of 25(OH)D < 25 nmol/L]. In univariate analyses, risk factors for vitamin D deficiency included increasing age, black race, low educational level, high body mass index, high triceps skinfold thickness, increasing level of disability, winter season, and elevated creatinine concentration. In multivariate models, black race had a strong association with vitamin D deficiency when other risk factors were adjusted for.

CONCLUSIONS

Vitamin D deficiency, a preventable disorder, is a common and important public health problem for older disabled women living in the community; black women are at higher risk than are white women.

Vitamin D: a natural inhibitor of multiple sclerosis

Inheriting genetic risk factors for multiple sclerosis (MS) is not sufficient to cause this demyelinating disease of the central nervous system; exposure to environmental risk factors is also required. MS may be preventable if these unidentified environmental factors can be avoided. MS prevalence increases with decreasing solar radiation, suggesting that sunlight may be protective in MS. Since the vitamin D endocrine system is exquisitely responsive to sunlight, and MS prevalence is highest where environmental supplies of vitamin D are lowest, we have proposed that the hormone, 1, 25-dihydroxycholecalciferol (1,25-(OH)2D3), may protect genetically-susceptible individuals from developing MS. Evidence consistent with this hypothesis comes not only from geographic studies, but also genetic and biological studies. Over-representation of the vitamin D receptor gene b allele was found in Japanese MS patients, suggesting it may confer MS susceptibility. Fish oil is an excellent vitamin D source, and diets rich in fish may lower MS prevalence or severity. Vitamin D deficiency afflicts most MS patients, as demonstrated by their low bone mass and high fracture rates. However, the clearest evidence that vitamin D may be a natural inhibitor of MS comes from experiments with experimental autoimmune encephalomyelitis (EAE), a model of MS. Treatment of mice with 1,25-(OH)2D3 completely inhibited EAE induction and progression. The hormone stimulated the synthesis of two anti-encephalitogenic cytokines, interleukin 4 and transforming growth factor beta-1, and influenced inflammatory cell trafficking or apoptosis. If vitamin D is a natural inhibitor of MS, providing supplemental vitamin D to individuals who are at risk for MS would be advisable.

Vitamin D insufficiency and hyperparathyroidism in a low income, multiracial, elderly population

This report examines the wintertime vitamin D and PTH status of 308 participants in the Boston Low Income Elderly Osteoporosis Study of noninstitutionalized low income elderly men and women (age, 64-100 yr) living in subsidized housing in Boston, MA. Twenty-one percent of the 136 black subjects and 11% of the 110 whites had very low plasma 25-hydroxyvitamin D (25OHD) concentrations (<25 nmol/L), and 73% of the blacks and 35% of the whites had 25OHD concentrations less than 50 nmol/L. The mean 25OHD levels of the smaller Hispanic and Asian subsets were generally similar to those of the white subjects. In addition to race, significant predictors of 25OHD included vitamin D intake (positive association) and smoking (inverse association), but not sex or age. Low 25OHD concentrations were associated with increased PTH and reduced serum calcium. The PTH level in the black subjects was substantially higher than that in the white subjects, and this difference was only partially explained by the racial difference in 25OHD. Elderly individuals who live in northern areas, particularly African-Americans, should be strongly encouraged to increase their vitamin D intake, especially in winter.

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.

Vitamin D status: effects on parathyroid hormone and 1, 25-dihydroxyvitamin D in postmenopausal women

BACKGROUND

Low serum 25-hydroxyvitamin D ¿25(OH)D concentrations are commonly found in the elderly and are associated with hip fracture. Treatment with vitamin D and calcium can reduce the risk of fracture. The relation between the rise in parathyroid hormone (PTH) with age and the decrease in 25(OH)D is not clear. Neither is there any consensus on the serum concentration of 25(OH)D required for bone health.

OBJECTIVE

Our objective was to study the relations between serum PTH, serum vitamin D metabolites, and other calcium-related variables in postmenopausal women.

DESIGN

This was a cross-sectional study of 496 postmenopausal women without vertebral fractures attending our menopausal osteoporosis clinics.

RESULTS

PTH was significantly positively related to age and serum 1, 25-dihydroxyvitamin D ¿1,25(OH)(2)D and inversely related to 25(OH)D and plasma ionized calcium. There was a step-like increase in PTH as serum 25(OH)D fell below 40 nmol/L. In women with 25(OH)D concentrations >40 nmol/L, 1,25(OH)(2)D was positively related to 25(OH)D; in women with 25(OH)D concentrations </=40 nmol/L, the relation was the inverse. In women with 25(OH)D concentrations </=40 nmol/L, 1,25(OH)(2)D was most closely related to PTH; in women with 25(OH)D concentrations >40 nmol/L, 1,25(OH)(2)D was most closely (inversely) related to plasma creatinine. Therefore, with serum 25(OH)D concentrations increasingly <40 nmol/L, serum 1,25(OH)(2)D becomes critically dependent on rising concentrations of PTH.

CONCLUSION

The data suggest that aging women should maintain 25(OH)D concentrations >40 nmol/L (which is the lower limit of our normal range for healthy young subjects) for optimal bone health.

Serum 25-hydroxyvitamin D concentrations and related dietary factors in peri- and postmenopausal Japanese women

BACKGROUND

Few studies of vitamin D nutrition in Asian populations have been conducted.

OBJECTIVE

The objective was to assess 25-hydroxyvitamin D [25(OH)D] concentrations in healthy elderly Japanese women during the winter and to determine whether 25(OH)D concentrations are associated with lifestyle.

DESIGN

We investigated 151 women aged 66.5 +/- 6.7 y (f1.gif" BORDER="0"> +/- SD) living in a rural community in February 1999. Serum 25(OH)D and intact parathyroid hormone were measured by using HPLC and an immunoradiometric assay, respectively. Information on lifestyle factors, including sunshine exposure and the consumption of vitamin D-rich foods, was also obtained through an interview.

RESULTS

The mean (+/-SD) 25(OH)D concentration was 59.9 +/- 17.0 nmol/L. Vitamin D insufficiencies (<30 nmol/L) were found in 4.6% of the women, a value lower than that found in white populations. No correlation was found between age and 25(OH)D concentrations (r = 0.004, P = 0.957). The 25(OH)D concentration of subjects who consumed fish frequently (>/=4 times/wk) was 10.1 nmol/L higher (P < 0.001) than that of subjects with a moderate consumption of fish (1-3 times/wk). Additionally, those who did not consume eggs had significantly lower 25(OH)D concentrations than did those who consumed eggs >/=1 time/wk (P < 0.05).

CONCLUSIONS

: The nutritional status of vitamin D in Japanese populations seems to be better than that in most Western populations. Frequent fish consumption is believed to help maintain adequate concentrations of serum 25(OH)D in elderly Japanese women during the winter.

[High prevalence of vitamin D deficiency in postmenopausal women at a rheumatology office in Madrid. Evaluation of 2 vitamin D prescription regimens]

BACKGROUND

Vitamin D deficiency has been frequently observed in the elderly population in Europe. However few information is available about the vitamin D status in postmenopausal women in the Mediterranean countries. The aim of this study was to evaluate the vitamin D status assessed by serum 25(OH)D3 (calcidiol) in postmenopausal women who attended a Rheumatology practice in Madrid area, and to evaluate calcidiol serum levels through one year after two forms of vitamin D administration.

PATIENTS AND METHODS

Calcidiol serum levels were measured in 171 postmenopausal women (111 with osteoporosis and 60 without osteoporosis). 82 women with calcidiol serum levels < 10 ng/ml were distributed in two groups: Group I received 800 U/day of vitamin D3 associated with calcium (1 g/day) and group II, one dose of 80,000 U vitamin D orally as calcidiol and latter a daily dose of 800 U vitamin D3 plus 1 g calcium. Calcidiol serum levels were measured by RIA in both groups at basal condition and after three, six and twelve months under treatment.

RESULTS

Three cut-offs were considered: 10, 15 and 20 ng/ml of calcidiol. Percentages of postmenopausal women with vitamin D deficiency for such cut-offs were: 35.3%, 64.1% and 87.1%, respectively. After three months of treatment, women from group II showed calcidiol serum levels higher than group I. At six and twelve months calcidiol serum levels were similar in both groups.

CONCLUSIONS

A high prevalence of vitamin D deficiency was observed in a group of postmenopausal women who attended a rheumatology practice in Madrid area. Both forms of vitamin D administration seem not sufficient to maintain the adequate calcidiol serum levels in postmenopausal deficient women. A dose of 80,000 U of calcidiol twice a year should be considered.

Calcium and vitamin D. Their potential roles in colon and breast cancer prevention

The geographic distribution of colon cancer is similar to the historical geographic distribution of rickets. The highest death rates from colon cancer occur in areas that had high prevalence rates of rickets--regions with winter ultraviolet radiation deficiency, generally due to a combination of high or moderately high latitude, high-sulfur content air pollution (acid haze), higher than average stratospheric ozone thickness, and persistently thick winter cloud cover. The geographic distribution of colon cancer mortality rates reveals significantly low death rates at low latitudes in the United States and significantly high rates in the industrialized Northeast. The Northeast has a combination of latitude, climate, and air pollution that prevents any synthesis of vitamin D during a five-month vitamin D winter. Breast cancer death rates in white women also rise with distance from the equator and are highest in areas with long vitamin D winters. Colon cancer incidence rates also have been shown to be inversely proportional to intake of calcium. These findings, which are consistent with laboratory results, indicate that most cases of colon cancer may be prevented with regular intake of calcium in the range of 1,800 mg per day, in a dietary context that includes 800 IU per day (20 micrograms) of vitamin D3. (In women, an intake of approximately 1,000 mg of calcium per 1,000 kcal of energy with 800 IU of vitamin D would be sufficient.) In observational studies, the source of approximately 90% of the calcium intake was vitamin D-fortified milk. Vitamin D may also be obtained from fatty fish. In addition to reduction of incidence and mortality rates from colon cancer, epidemiological data suggest that intake of 800 IU/day of vitamin D may be associated with enhanced survival rates among breast cancer cases.

Effect of vitamin D nutrition on parathyroid adenoma weight: pathogenetic and clinical implications

In primary hyperparathyroidism, adenoma size is a major determinant of disease severity and manner of presentation, but the reason for the large variation in size (>100-fold) is unknown. One factor could be the level of vitamin D nutrition, because in India, where vitamin D deficiency is endemic, adenomas are larger and the disease more severe than in the U.S. Accordingly, we determined the relationship between vitamin D nutrition, as measured by serum levels of 25-hydroxyvitamin D (25OHD), and parathyroid gland weight, expressed on a logarithmic scale, in 148 U.S. patients with primary hyperparathyroidism. A significant inverse relationship was found between log gland weight as dependent variable and serum 25OHD as independent variable (r = -0.365; P < 0.0001). The only other influence on gland weight was a weak inverse correlation with age. Log gland weight as an independent variable was significantly related to adjusted calcium, PTH, and alkaline phosphatase (AP) as dependent variables. In 51 patients with serum 25OHD levels less than 15 ng/mL, gland weight, PTH, AP, and adjusted calcium were each significantly higher than in 97 patients with 25OHD levels of 15 ng/mL or more, but 1,25-dihydroxyvitamin D levels were similarly increased in both groups. In the former group the response of adjusted calcium to PTH was blunted, and the response of AP was enhanced, based on significant differences in regression slopes (P = 0.0004 and 0.0022, respectively). Suboptimal vitamin D nutrition stimulates parathyroid adenoma growth by a mechanism unrelated to hypocalcemia or 1,25-dihydroxyvitamin D deficiency and reduces the calcemic response to PTH, so that a higher PTH level and more parathyroid cells are needed to raise the patient's serum calcium to the level corresponding to the increased set-point that is characteristic of the disease. Improved vitamin D nutrition in the population is partly, perhaps largely, responsible for the historical changes in disease severity and manner of presentation that have occurred over the last 50 yr.

Parathyroid hormone may be a cancer promoter - an explanation for the decrease in cancer risk associated with ultraviolet light, calcium, and vitamin D

Epidemiological studies reporting an inverse association between sunlight exposure and risk for cancers of the breast, colon, and prostate, have not yet been explained. Since ultraviolet (UV) light promotes dermal vitamin D generation, studies suggesting that dietary calcium and vitamin D may likewise have cancer-preventive activity are potentially of relevance. UV light, calcium, and vitamin D have the common property of suppressing parathyroid hormone (PTH) production; these considerations raise the possibility that PTH may have promotional activity for certain cancers. PTH might function indirectly in this regard, by increasing hepatic production of the progression growth factor IGF-I, a likely cancer promoter. A more direct role is suggested by recent evidence that many cancers express receptors for PTH/PTH-related protein; these receptors mediate co-mitogenic and/or pro-invasive signals in some cancers. High risk for previous or concurrent neoplasms has been reported in patients with parathyroid adenomas. In light of the increase in cancer risk associated with hypertension, it is notable that PTH levels are typically increased in salt-sensitive hypertensives. Prospective case-control studies examining serum PTH in relation to subsequent cancer risk appear warranted.

Commonly recommended daily intake of vitamin D is not sufficient if sunlight exposure is limited

OBJECTIVES

Sunlight exposure of the skin is known to be the most important source of vitamin D. The aims of this study were: (i) to estimate vitamin D status amongst sunlight-deprived individuals (veiled Arab women, veiled ethnic Danish Moslem women and Danish controls); and (ii) through food intake analysis to estimate the oral intake of vitamin D necessary to keep a normal vitamin D status in sunlight-deprived individuals.

DESIGN

Cross-sectional study amongst randomly selected Moslem women of Arab origin living in Denmark. Age-matched Danish women were included as controls. To control for racial differences, a group of veiled ethnic Danish Moslem women (all Caucasians) was included.

SETTING

Primary Health Care Centre, City Vest and Department of Endocrinology and Metabolism C, University Hospital of Aarhus, Aarhus Amtssygehus, Aarhus, Denmark.

SUBJECTS

Sixty-nine Arab women (60 veiled, nine non-veiled) and 44 age-matched Danish controls were randomly selected amongst patients contacting the primary health care centre for reasons other than vitamin D deficiency. Ten ethnic Danish Moslem women were included through a direct contact with their community.

MAIN OUTCOME MEASURES

Serum levels of 25-hydroxyvitamin D were used as estimates of vitamin D status. Intact parathyroid hormone (PTH) was used to control for secondary hyperparathyroidism. Alkaline phosphatase and bone-specific alkaline phosphatase were used as markers for osteomalacic bone involvement. Oral intake of vitamin D and calcium were estimated through a historical food intake interview performed by a trained clinical dietician.

RESULTS

Veiled Arab women displayed extremely low values of 25-hydroxyvitamin D: 7.1 +/- 1.1 nmol L-1, compared with 17.5 +/- 2. 3 (P < 0.002) in ethnic Danish Moslems and 47.1 +/- 4.6 (P < 10-17) in Danish controls. PTH was increased amongst veiled Arab women: 15. 6 +/- 1.8 pmol L-1, compared with 5.7 +/- 1.4 in ethnic Danish Moslems and 2.7 +/- 0.3 (P < 10-6) in Danish controls. The vitamin D intake (including food supplementation) was very low amongst Arab women: 1.04 microg day-1, compared with 13.53 amongst ethnic Danish Moslems and 7.49 amongst Danish controls (P < 0.0005).

CONCLUSIONS

Severe vitamin D deficiency is prevalent amongst sunlight-deprived individuals living in Denmark. In veiled Arab women, vitamin D deficiency is the result of a combination of limitations in sunlight exposure and a low oral intake of vitamin D. The oral intake of vitamin D amongst veiled ethnic Danish Moslems was, however, very high, at 13.53 microgram (approximately 600 IU), but they were still vitamin D-deficient. Our results suggest that the daily oral intake of vitamin D in sunlight-deprived individuals should exceed 600 IU; most probably it should be 1000 IU day-1 to secure a normal level of 25-hydroxyvitamin D. This finding is in contrast with the commonly used RDA (recommended daily allowance) for adults in Europe: 200 IU day-1.

Perspective on assessment of vitamin D nutrition

Although routine fortification of milk and a few other dairy products has been successful in preventing rickets in children, its impact on preventing vitamin D depletion in adults is less than satisfactory. The prevalence of vitamin D depletion in the elderly is on the rise again and appears to be more common than is currently appreciated. Several groups of individuals are at risk of developing vitamin D depletion, and a significant minority of otherwise healthy individuals is vitamin D insufficient. Unrecognized vitamin D depletion leads to secondary hyperparathyroidism, accelerates cortical bone loss, and increases the risk of hip fractures. With the availability of techniques to assess vitamin D nutrition, it is probably cost effective to routinely measure 25-hydroxyvitamin D levels in individuals at the greatest risk and in patients with various metabolic bone diseases to prevent vitamin D depletion. Early recognition and prompt treatment of vitamin D depletion improves functional well being of the individual, reduces morbidity related to bone loss and fractures, and is associated with a highly favorable cost/benefit ratio.