Geographical differences in vitamin D status, with particular reference to European countries

Vitamin D is produced endogenously when the skin is exposed to sunlight and can be obtained exogenously from a few natural food sources, from food fortification and from supplements. Generally, vitamin D intake is low < or = 2-3 microg/d in Europe. Casual exposure to sunlight is thought to provide most of the vitamin D requirement of the human population. However, skin synthesis of vitamin D may not compensate for the low nutritional intake in Europe, even in countries with high supplies from food fortification and supplements. For assessment of vitamin D nutritional status the concentration of 25-hydroxyvitamin D (25(OH)D) in serum is considered to be an accurate integrative measure reflecting an individual's dietary intake and cutaneous production. A substantial percentage of the elderly and adolescents in Europe have a low concentration of 25(OH)D; in the elderly this percentage ranges from approximately 10 in the Nordic countries to approximately 40 in France. Low vitamin D status seems to be aggravated by disease and immobility, and by a low frequency of supplement use.     

Vitamin D: An overview of vitamin D status and intake in Europe

In recent years, there have been reports suggesting a high prevalence of low vitamin D intakes and vitamin D deficiency or inadequate vitamin D status in Europe. Coupled with growing concern about the health risks associated with low vitamin D status, this has resulted in increased interest in the topic of vitamin D from healthcare professionals, the media and the public. Adequate vitamin D status has a key role in skeletal health. Prevention of the well‐described vitamin D deficiency disorders of rickets and osteomalacia are clearly important, but there may also be an implication of low vitamin D status in bone loss, muscle weakness and falls and fragility fractures in older people, and these are highly significant public health issues in terms of morbidity, quality of life and costs to health services in Europe. Although there is no agreement on optimal plasma levels of vitamin D, it is apparent that blood 25‐hydroxyvitamin D [25(OH)D] levels are often below recommended ranges for the general population and are particularly low in some subgroups of the population, such as those in institutions or who are housebound and non‐Western immigrants. Reported estimates of vitamin D status within different European countries show large variation. However, comparison of studies across Europe is limited by their use of different methodologies. The prevalence of vitamin D deficiency [often defined as plasma 25(OH)D <25 nmol/l] may be more common in populations with a higher proportion of at‐risk groups, and/or that have low consumption of foods rich in vitamin D (naturally rich or fortified) and low use of vitamin D supplements. The definition of an adequate or optimal vitamin D status is key in determining recommendations for a vitamin D intake that will enable satisfactory status to be maintained all year round, including the winter months. In most European countries, there seems to be a shortfall in achieving current vitamin D recommendations. An exception is Finland, where dietary survey data indicate that recent national policies that include fortification and supplementation, coupled with a high habitual intake of oil‐rich fish, have resulted in an increase in vitamin D intakes, but this may not be a suitable strategy for all European populations. The ongoing standardisation of measurements in vitamin D research will facilitate a stronger evidence base on which policies can be determined. These policies may include promotion of dietary recommendations, food fortification, vitamin D supplementation and judicious sun exposure, but should take into account national, cultural and dietary habits. For European nations with supplementation policies, it is important that relevant parties ensure satisfactory uptake of these particularly in the most vulnerable groups of the population.     

Vitamin D fortification as public health policy: significant improvement in vitamin D status in young Finnish men

BACKGROUND: Vitamin D insufficiency is common in northern countries during wintertime. In Finland, after the recommendation by the Ministry of Social Affairs and Health, vitamin D has been added to liquid milk products and margarines from February 2003. OBJECTIVE: We determined the effects of national policy on vitamin D fortification on vitamin D status among young Finnish men. DESIGN: A comparison before and after intervention with study population of 196 young Finnish men (18-28 years) was carried out. Serum 25-hydroxyvitamin D3 (25-OHD3) concentrations were determined with the OCTEIA enzymeimmunoassay by IDS (Immunodiagnostic Systems Limited, Bolden, UK) in January 2003 (n = 96) and in January 2004 (n = 100), nearly 1 year after national vitamin D fortification had started. RESULTS: The mean serum 25-OHD3 concentrations during the wintertime increased by 50% after implementation of the vitamin D fortification of dairy products. Correspondingly, the prevalence of vitamin D insufficiency (serum 25-OHD3 < 40 nmol/l) was decreased by 50% from 78% in January 2003 to 35% in January 2004. CONCLUSIONS: Our results demonstrate that national vitamin D fortification substantially improved the vitamin D status of young Finnish men. Still, a third remained vitamin D insufficient.     

Vitamin D intake: a global perspective of current status

Global high prevalence of vitamin D insufficiency and re-emergence of rickets and the growing scientific evidence linking low circulating 25-hydroxyvitamin D to increased risk of osteoporosis, diabetes, cancer, and autoimmune disorders have stimulated recommendations to increase sunlight (UVB) exposure as a source of vitamin D. However, concern over increased risk of melanoma with unprotected UVB exposure has led to the alternative recommendation that sufficient vitamin D should be supplied through dietary sources alone. Here, we examine the adequacy of vitamin D intake worldwide and evaluate the ability of current fortification policies and supplement use practices among various countries to meet this recommendation. It is evident from our review that vitamin D intake is often too low to sustain healthy circulating levels of 25-hydroxyvitamin D in countries without mandatory staple food fortification, such as with milk and margarine. Even in countries that do fortify, vitamin D intakes are low in some groups due to their unique dietary patterns, such as low milk consumption, vegetarian diet, limited use of dietary supplements, or loss of traditional high fish intakes. Our global review indicates that dietary supplement use may contribute 6-47% of the average vitamin D intake in some countries. Recent studies demonstrate safety and efficacy of community-based vitamin D supplementation trials and food staple fortification introduced in countries without fortification policies. Reliance on the world food supply as an alternative to UVB exposure will necessitate greater availability of fortified food staples, dietary supplement use, and/or change in dietary patterns to consume more fish.     

Impact of national fortification of fluid milks and margarines with vitamin D on dietary intake and serum 25-hydroxyvitamin D concentration in 4-year-old children

OBJECTIVE: To assess the impact of national fortification of fluid milks and margarines with vitamin D on dietary intake and on serum 25-hydroxyvitamin D concentration in Finnish 4-year-old children. DESIGN, SUBJECTS AND METHODS: Two cohorts of children were studied during wintertime, one before (n=82) in 2001-2002 and the other after (n=36) the initiation of fortification in 2003-2004. Dietary intake was estimated by 4-day food records and serum 25-hydroxyvitamin D concentration was analyzed by radioimmunoassay. RESULTS: The mean intake of vitamin D was higher the after initiation of fortification (mean (95% confidence interval (CI)); 4.5 (3.8-5.1) microg) than before it (2.1 (95% CI 1.8-2.3) microg; P<0.001), although there were no differences in consumption of the main food sources of vitamin D between the two cohorts. The difference between the cohorts was also evident when the intake of vitamin D was adjusted for energy intake (0.78 (95% CI 0.70-0.90) and 0.37 (95% CI 0.32-0.42) microg/MJ after and before fortification, respectively, P<0.001). After fortification, the mean intake approached that recommended, but was achieved by only 30.6% of the children. Equally, the serum 25-hydroxyvitamin D concentration was higher after fortification (64.9 (95% CI 59.7-70.1) nmol/l) compared to prior it (54.7 (95% CI 51.0-58.4) nmol/l; P=0.002). CONCLUSIONS: The results indicate that the national fortification of fluid milks and margarines with vitamin D safely improved the vitamin D status of children. This approach, in view of the novel health effects beyond bone metabolism, encourages fortification of new food sources with vitamin D or use of vitamin D supplements particularly during wintertime.     

A systematic review of vitamin D status in southern European countries

Purpose

Despite an acknowledged dearth of data on serum 25-hydroxyvitamin D (25(OH)D) concentrations from Southern European countries, inter-country comparison is hampered by inconsistent data reporting. The purpose of the current study was to conduct a systematic literature review of available data on serum 25(OH)D concentrations and estimate vitamin D status in Southern European and Eastern Mediterranean countries, both at a population level and within key population subgroups, stratified by age, sex, season and country.

Methods

A systematic review of the literature was conducted to identify and retrieve scientific articles reporting data on serum 25(OH)D concentration and/or vitamin D status following standard procedures.

Results

Data were extracted from 107 studies, stratified by sex and age group, representing 630,093 individuals. More than one-third of the studies reported mean 25(OH)D concentrations below 50 nmol/L and ~?10% reported mean serum 25(OH)D concentrations below 25 nmol/L. Overall, females, neonates/ infants and adolescents had the higher prevalence of poor vitamin D status. As expected, there was considerable variability between studies. Specifically, mean 25(OH)D ranged from 6.0 (in Italian centenarians) to 158 nmol/L (in elderly Turkish men); the prevalence of serum 25(OH)D?<?50 nmol/L ranged from 6.8 to 97.9% (in Italian neonates).

Conclusions

Contrary to expectations, there was a high prevalence of low vitamin D status in the Southern Europe and the Eastern Mediterranean regions, despite abundant sunshine. These data further emphasize the need for strategies, such as fortification of foods with vitamin D and/or vitamin D supplementation, which will be tailored to the needs of specific population groups with higher risk of insufficiency or deficiency, to efficiently tackle the pandemic of hypovitaminosis D in Europe.

     

25-hydroxyvitamin D3 affects vitamin D status similar to vitamin D3 in pigs--but the meat produced has a lower content of vitamin D

In food databases, the specific contents of vitamin D3 and 25-hydroxyvitamin D3 in food have been implemented in the last 10 years. No consensus has yet been established on the relative activity between the components. Therefore, the objective of the present study was to assess the relative activity of 25-hydroxyvitamin D3 compared to vitamin D3. The design was a parallel study in pigs (n 24), which from an age of 12 weeks until slaughter 11 weeks later were fed approximately 55 microg vitamin D/d, as vitamin D3, in a mixture of vitamin D3 and 25-hydroxyvitamin D3, or 25-hydroxyvitamin D3. The end-points measured were plasma 25-hydroxyvitamin D3, and in the liver and loin the content of vitamin D3 and 25-hydroxyvitamin D3. Vitamin D3 and 25-hydroxyvitamin D3 in the feed did not affect 25-hydroxyvitamin D3 in the plasma, liver or loin differently, while a significant effect was shown on vitamin D3 in the liver and loin (P < 0.001). 25-Hydroxyvitamin D3 in the plasma, liver and loin significantly correlates with the sum of vitamin D3 and 25-hydroxyvitamin D3 in the feed (P < 0.05). Therefore, 25-hydroxyvitamin D3 should be regarded as having the same activity as vitamin D3 in food databases. Sole use of 25-hydroxyvitamin D3 as a vitamin D source in pig feed will produce liver and meat with a negligible content of vitamin D3, while an increased content of vitamin D3 in the feed will produce liver and meat with increased content of both vitamin D3 and 25-hydroxyvitamin D3.     

Prospective study on food fortification with vitamin D among adolescent females in Finland: minor effects

Vitamin D insufficiency is common particularly during winter time. After the recommendation by the Ministry of Social Affairs and Health, Finnish fluid milks and margarines have been fortified with vitamin D since February 2003. The aims of the present study were to examine the impact of vitamin D fortification of food supplies on serum 25-hydroxyvitamin D (S-25(OH)D) concentrations and on daily dietary vitamin D intake among adolescent females. One hundred and forty-two girls of Caucasian ethnicity aged 12-18 years completed semi-quantitative FFQ from which the dietary vitamin D and Ca intakes were calculated. S-25(OH)D was measured by radioimmunoassay. The study was performed from February-March 2000 to February-March 2004, one year after the initiation of fortification. The mean dietary intake of vitamin D was < 7.5 microg in 91.5 % of the adolescent girls in 2000 and 83.8 % in 2004. The midwinter mean S-25(OH)D concentration did not change significantly during the follow-up period (48.3 v. 48.1 nmol/l, NS). The proportion of participants who had S-25(OH)D concentration < 50 nmol/l was 60.6 % in 2000 and 65.5 % in 2004. Only 7.0 % of the participants had an adequate S-25(OH)D ( >or= 75 nmol/l) level in 2000 or 4 years later. The vitamin D fortification of fluid milks and margarines was inadequate to prevent vitamin D insufficiency. There are numerous adolescent girls and women who are not reached by the current fortification policy. Therefore new innovative and feasible ways of improving vitamin D nutrition are urged.     

Higher prevalence of vitamin D deficiency is associated with immigrant background among children and adolescents in Germany

In recent years, a high prevalence of vitamin D deficiency among children and adolescents has been reported in countries with moderate climates. Those with an immigrant background living under these conditions are at especially high risk. To date, representative data in Germany is lacking. We analyzed 25-hydroxyvitamin D [25(OH)D] concentrations of 10,015 children and adolescents, aged 1-17 y, who participated in the German National Health Interview and Examination Survey for Children and Adolescents. The proportion of immigrants was 25.4%, corresponding well to their percentage of the population. Among 3- to 17-y-old participants, 29% of immigrant boys and 31% of immigrant girls had 25(OH)D concentrations <25 nmol/L (severe to moderate vitamin D deficiency) compared with 18% of nonimmigrant boys and 17% of nonimmigrant girls. Furthermore, 92% of immigrant boys and 94% of immigrant girls had 25(OH)D concentrations <75 nmol/L (levels above 75 nmol/L are defined as optimal regarding various health outcomes) compared with 87% of nonimmigrants. Boys with a Turkish or Arab-Islamic background had an increased risk of having 25(OH)D concentrations <25 nmol/L compared with nonimmigrants (odds ratio [OR] 2.3; [95% CI] 1.4-3.8 and OR 7.6; [95% CI] 3.0-19.1). The same was true for girls with a Turkish (OR 5.2; [95% CI] 2.9-9.6), Arab-Islamic (OR 5.9; [95% CI] 2.5-14.0), Asian (OR 6.7; [95% CI] 2.2-19.8), or African (OR 7.8; [95% CI] 1.5-40.8) background. Supplementation of vitamin D beyond infancy, especially in high-risk groups, or fortification of food should be considered.     

The ODIN project: Development of food‐based approaches for prevention of vitamin D deficiency throughout life

Vitamin D deficiency has significant implications for human health throughout life and impacts on healthy growth and development and successful ageing. Persistent knowledge gaps are barriers to developing and implementing a safe and effective public health strategy to prevent vitamin D deficiency and maintain nutritional adequacy throughout the year. The European Commission‐funded ODIN project (Food‐based solutions for optimal vitamin D nutrition and health through the life cycle) will provide the evidence base to prevent vitamin D deficiency and improve nutrition and public health through food. ODIN will deliver the first internationally comparable dataset of vitamin D status and report the prevalence of vitamin D deficiency across Europe for the first time. In a series of dose‐response randomised controlled trials, ODIN will estimate dietary requirements for vitamin D in pregnant women, children, adolescents and adults of South Asian and East African origin resident in Northern European countries. Using clinically validated, disease‐specific cohorts with standardised 25(OH)D data, ODIN will investigate associations between vitamin D status and perinatal outcomes, atopic disease and bone growth in children, and cardiovascular and mortality risk in older adults. We will publish estimates of the distribution of vitamin D intake and serum 25(OH)D concentration resulting from changes in vitamin D in the food supply, accounting for latitude, sun exposure and diet. Utilising advanced food production systems and targeted animal and human feeding studies, ODIN will propose safe, novel and effective food‐based strategies to eradicate vitamin D deficiency that are inclusive, sustainable and affordable.     

Effects of vitamin D fortified milk on vitamin D status in Mongolian school age children

Mongolians are at high risk for vitamin D deficiency because of their residence at northern latitude, reduced exposure to UV-B rays during the winter months, and a low availability of vitamin-D fortified foods. We performed a pilot study in May 2005 to estimate the prevalence of hypovitaminosis D in Mongolian school age children and to determine the feasibility of conducting a longer and larger trial with fortified milk and vitamin D supplements. In a group of 46 Mongolian children (22 girls and 24 boys) aged 9-11 years, 76% (35) had levels of 25-hydroxyvitamin D (25(OH)D) below 50 nmol/L (20 ng/mL) and 32% had levels below 37 nmol/L (15 ng/mL). After a month of consuming 710 ml of vitamin D-fortified (total 300 IU or 7.5 microg) milk daily, only 3 of the children were below 50 nmol/L (20 ng/mL) and none below 37 nmol/L (15 ng/mL). These results reveal prevalent and serious 25(OH)D deficiency among Mongolian prepubertal school age children that appears to be ameliorated by a month of consuming approximately 7.5 microg of vitamin D3 in fortified milk.     

Public health strategies to overcome barriers to optimal vitamin D status in populations with special needs

In North America, there is increasing public health awareness of the importance of adequate vitamin D intake to the maintenance of optimal vitamin D status and overall health. Experts now define this as circulating levels of 25-hydroxyvitamin D of 75-80 nmol/L. This serum level and high levels of dietary intake have been associated with significantly reduced risk of chronic diseases, such as osteoporosis, cardiovascular disease, diabetes, and some cancers. All of these diseases are more prevalent in the elderly of all races, and some are more prevalent and of greater severity among blacks than whites. Our objective is to review recent actions to increase public awareness of the health importance of maintaining optimal circulating 25(OH)D and potential strategies to increase vitamin D intake. Clinicians and educators are encouraged to promote improved vitamin D intake and status, particularly among the elderly and blacks. This will largely depend on combined efforts to judiciously fortify our food supply and to develop individual supplementation protocols for supplements or controlled use of UV light exposure to maintain optimal serum 25(OH)D, especially in high-risk groups. Growing evidence supports a low risk of toxicity with vitamin D use in fortification or supplementation, despite its past reputation of potential toxicity in excess. The cost to fortify food or supplements with vitamin D is relatively inexpensive compared with developing drugs used to treat or prevent chronic diseases; moreover, there is significant potential for broad health benefits in the reduced risk and prevention of multiple chronic diseases.     

Study to evaluate two dosage regimens of vitamin D through an academic year in middle school girls: a randomized trial

Vitamin D is an essential hormone for growth and development of bones in children. There is a lot of evidence for deficiency of this vitamin in Middle East females. This study conduct to find a way to combat deficiency in girls during rapid growth phase of puberty in academic year. One hundred and two Middle School girls who had not consumed any vitamins supplement have been participated in this randomized clinical trial. They allocated randomly in two case groups who received 50,000 or 100,000 IU vitamin D3 in October and three months later in January or in control group who received vitamin E. At the end of winter blood samples for 25-hydroxyvitamin D were checked. The mean of 25-hydroxyvitamin D were 5.5±1.5 ng/ml, 15.2±6 ng/ml, 23.0±6.8 ng/ml in control, 50,000 and 100,000 IU vitamin D groups respectively (P<0.05). Neither dosage of vitamin D could raise 25-hydroxyvitamin D above 20 ng/ml in all cases. However, none of the students in 100,000 IU of vitamin D3 had severe deficiency in winter. Headache, dizziness, and weakness were the most common complain after vitamin D consumption, but no difference between groups detected (P>0.05). Urine calcium/creatinin ratio was equal in case and control groups (P>0.05). 100,000 IU of vitamin D3 every three months (equal to 800 IU/day) can raise 25-hydroxyvitamin D above 12 ng/ml in all cases but for area with high prevalence of sever deficiency, dosage more than 100,000 IU every three months or shorter interval recommended to achieve optimal level.     

Prevalence and predictors of vitamin D inadequacy amongst Lebanese osteoporotic women

In Middle-Eastern countries, more particularly in Lebanon, the incidence of vitamin D deficiency has been found to be surprisingly high in schoolchildren and young individuals. However, the prevalence and risk factors for vitamin D inadequacy amongst Lebanese osteoporotic women seeking medical health care has never been studied. We analysed vitamin D-inadequacy risk factors among the 251 Lebanese postmenopausal osteoporotic women (from both Muslim and Christian communities) who participated in a vitamin D international epidemiological study. Vitamin D inadequacy prevalence (25-hydroxyvitamin D (25(OH)D) , 30 ng/ml) was 84.9%. 25(OH)D was negatively correlated with BMI (r 20.41; P<0.001) and positively correlated with educational level (r 0.37; P<0.001) and self-reported general health (r 0.17; P<0.01). No significant correlation was found with age and no seasonal variation was observed. There was no significant correlation between 25(OH)D and sun exposure index or vitamin D-rich food consumption. However, 25(OH)D strongly correlated with vitamin D supplement intake (r 0.48; P<0.0001). Muslim community participants had lower 25(OH)D levels compared with their Christian counterparts (P<0.001). They also had higher BMI, lower educational level and vitamin D supplement consumption and followed more frequently a dress code covering the arms (P<0.0001 for all variables). In a multivariate model, in Muslims, inadequate vitamin D supplements and a dress code covering the arms are the independent predictors of 25(OH)D inadequacy (P<0.001 for both variables). However, in Christians, the predictors are inadequate vitamin D supplements, high BMI and low educational level (P<0.001; P=002 and P=0.02 respectively). There is an urgent need to increase vitamin D supplement use in Middle-Eastern osteoporotic women, more particularly in those from the Muslim community.     

The prevention of vitamin D deficiency in the elderly

Vitamin D deficiency is common in the house-bound and institutionalised elderly population of Britain. A study of patients over 65 years discharged with a diagnosis of osteomalacia from Greater Glasgow Health Board hospitals between 1970 and 1981 inclusive showed a low incidence in the 65 to 74 years age group but a steeply rising incidence in older age groups. The majority (83%) of patients were female. The fortification of margarine, butter and milk with concentrations of vitamin D acceptable to the general population does not produce significant elevations in serum 25-hydroxyvitamin D (25-OHD) levels in vitamin D-deficient elderly patients. Low intensity background ultraviolet radiation (UVR) and intermittent high intensity UVR produce significant elevations in serum 25-OHD levels in elderly patients but both methods have disadvantages which limit their widespread use. Vitamin D supplements equivalent to 10 micrograms daily produce significant elevations in serum 25-OHD levels in vitamin D-deficient elderly patients. A vitamin D supplement policy for the housebound and institutionalised elderly population of Britain is required.     

Vitamin D and bone health in early life

Prolonged vitamin D deficiency resulting in rickets is seen mainly during rapid growth. A distinct age distribution has been observed in the Copenhagen area where all registered hospital cases of rickets were either infants and toddlers or adolescents from immigrant families. Growth retardation was only present in the infant and toddler group. A state of deficiency occurs months before rickets is obvious on physical examination. Growth failure, lethargy and irritability may be early signs of vitamin D deficiency. Mothers with low vitamin D status give birth to children with low vitamin D status and increased risk of rickets. Reports showing increasing rates of rickets due to insufficient sunlight exposure and inadequate vitamin D intake are cause for serious concern. Many countries (including the USA from 2003) recommend vitamin D supplementation during infancy to avoid rickets resulting from the low vitamin D content of human milk. Without fortification only certain foods such as fatty fish contain more than low amounts of vitamin D, and many children will depend entirely on sun exposure to obtain sufficient vitamin D. The skin has a high capacity to synthesize vitamin D, but if sun exposure is low vitamin D production is insufficient, especially in dark-skinned infants. The use of serum 25-hydroxyvitamin D to evaluate vitamin D status before development of rickets would be helpful; however, there is no agreement on cut-off levels for deficiency and insufficiency. Furthermore, it is not known how marginal vitamin D insufficiency affects children's bones in the long term.     

Wintertime vitamin D insufficiency is common in young Canadian women, and their vitamin D intake does not prevent it.

OBJECTIVE: We asked whether women self-reporting the recommended consumption of vitamin D from milk and multivitamins would be less likely to have low wintertime 25-hydroxyvitamin D (25(OH)D) levels. METHODS: This cross-sectional study enlisted at least 42 young women each month (age 18-35 y, 796 women total) through one year. We measured serum 25(OH)D and administered a lifestyle and diet questionnaire. RESULTS: Over the whole year, prevalence of low 25(OH)D (<40 nmol/l) was higher in non-white, non-black subjects (25.6% of 82 women) than in the white women (14.8% of 702 white women, P<0.05). Of the 435 women tested during the winter half of the year (November-April), prevalence of low 25(OH)D was not affected by vitamin D intake: low 25(OH)D occurred in 21% of the 146 consuming no vitamin D, in 26% of the 140 reporting some vitamin D intake, up to 5 microg/day (median, 2.5 microg/day), and in 20% of the 149 women reporting vitamin D consumption over 5 microg/day (median, 10 microg/day). INTERPRETATION: The self-reported vitamin D intake from milk and/or multivitamins does not relate to prevention of low vitamin D nutritional status of young women in winter. Recommended vitamin D intakes are too small to prevent insufficiency. Vitamin D nutrition can only be assessed by measuring serum 25(OH)D concentration.     

Relationship between vitamin D deficiency, bone remodelling and iron status in iron-deficient young women consuming an iron-fortified food

Background

Iron and vitamin D deficiencies are two of the most widespread nutritional disorders in the world. Our aim was to know whether the consumption of an iron-fortified fruit juice modifies bone remodelling and the possible influence of baseline vitamin D status on the recovery of iron status in a group of iron-deficient women.

Methods

Iron biomarkers, 25-hydroxyvitamin D levels and dietary intake were measured in 123 iron-deficient menstruating women. A subgroup (n = 41) participated in a randomised double-blind placebo-controlled study of 16-weeks during winter. They consumed a placebo fruit juice (P) or iron-fortified fruit juice (F). Dietary intake, 25-hydroxyvitamin D, parathormone (PTH), bone alkaline phosphatase (ALP), aminoterminal telopeptide of collagen I (NTX) and iron biomarkers were determined.

Results

Ninety-two per cent of the iron-deficient women were vitamin D deficient or insufficient. Transferrin saturation and 25-hydroxyvitamin D were positively correlated. Iron status improved in F, 25-hydroxyvitamin D decreased in F and P, and PTH, ALP and NTX levels were within the normal range and did not vary. Women with 25-hydroxyvitamin D ≥ 50 nmol/L compared with 25-hydroxyvitamin D < 50 nmol/L showed a higher increase in transferrin saturation (a marker of iron supply to tissues) during iron recovery.

Conclusion

The prevalence of vitamin D deficiency or insufficiency is very high in iron-deficient women. The recovery of iron status by consuming an iron-fortified food does not affect 25-hydroxyvitamin D levels; however, the increase in iron supply to tissues is lower if the women also present vitamin D deficiency. Although bone health does not seem to be affected in this group of women, correction of iron and vitamin D deficiencies should be promoted in young women to improve present and future health.     

Low wintertime vitamin D levels in a sample of healthy young adults of diverse ancestry living in the Toronto area: associations with vitamin D intake and skin pigmentation

Background  

Vitamin D plays a critical role in bone metabolism and many cellular and immunological processes. Recent research indicates that concentrations of serum 25-hydroxyvitamin D [25(OH)D], the main indicator of vitamin D status, should be in excess of 75 nmol/L. Low levels of 25(OH)D have been associated with several chronic and infectious diseases. Previous studies have reported that many otherwise healthy adults of European ancestry living in Canada have low vitamin D concentrations during the wintertime. However, those of non-European ancestry are at a higher risk of having low vitamin D levels. The main goal of this study was to examine the vitamin D status and vitamin D intake of young Canadian adults of diverse ancestry during the winter months.     

Teenage girls and elderly women living in northern Europe have low winter vitamin D status

OBJECTIVE: To determine the vitamin D status (serum 25-hydroxyvitamin D; S-25OHD) in adolescent girls and elderly community-dwelling women living in four countries of northern Europe and to explain differences in S-25OHD concentrations between and within the countries. DESIGN: A cross-sectional observational study conducted in a standardised way during February-March. S-25OHD was analysed by high-performance liquid chromatography. Vitamin D and calcium intake was calculated using a standardised food composition database. SETTING: Denmark, Finland, Ireland, and Poland. SUBJECTS: A total of 199 girls (mean (s.d.) age 12.6 (0.5) y) and 221 women (mean (s.d.) age 71.8 (1.4) y). RESULTS: The median (inter quartiles) concentration of S-25OHD was 29.4 (20.3, 38.3) nmol/l for the girls and 40.7 (28.0, 54.2) nmol/l for the women. S-25OHD below 25 nmol/l was found in 37% of the girls and 17% of the women, and S-25OHD below 50 nmol/l was found in 92% of the girls and 37% of the women. Positive significant determinants for S-25OHD in girls were use of vitamin D supplements, and in women sun habits, dietary vitamin D intake, use of vitamin D and calcium supplements. Body mass index and smoking were negative determinants in women. For women predictors could explain the differences between countries (P(country) = 0.09, R(2) = 0.39), but for girls the difference remained significant even after including predictors (P(country) = 0.03, R(2) = 0.15). CONCLUSION: Vitamin D status is low in northern Europe during winter. More than one-third of the adolescent girls have vitamin D status below 25 nmol/l and almost all are below 50 nmol/l. Two-thirds of the elderly community-dwelling women have vitamin D status below 50 nmol/l. Use of vitamin D supplements is a significant positive determinant for S-25OHD for both girls and women (P = 0.001). SPONSORSHIP: The European Fifth Framework Programme (Contract No. QLK1-CT-2000-00623).