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Vitamin D intake and status in Irish postmenopausal women

Abstract

Objective:

The objective of this study was to assess vitamin D status during late-summer and late-winter/early-spring in postmenopausal Irish women, and whether it was influenced by vitamin D-containing supplement use.

Design:

A longitudinal observational study.

Setting:

Cork City, Ireland (51° north).

Subjects:

A total of 59 apparently healthy, free-living, postmenopausal women aged between 51 and 69 y were sampled during February/March 2002. Of these, 48 and 47 returned during August/September 2002 and February/March 2003, respectively. None of the women were suffering from any medical condition likely to affect vitamin D status. Fasting serums were collected and analysed for 25-hydroxyvitamin D (25 (OH) D) and parathyroid hormone (PTH) by enzyme immunoassays.

Results:

Mean daily intake of vitamin D was 3.2 μg from food sources alone and 5.8 μg when vitamin D-containing supplements were included (P<0.01). Serum 25 (OH) D was significantly lower (P<0.001) during February/March 2002 than both August/September 2002 and February/March 2003. Serum 25 (OH) D was also significantly higher (P≤0.05) in women who were vitamin D-containing supplement users than nonusers during all three sampling points. Between 17 and 36% of women had inadequate vitamin D status (defined as serum 25 (OH) D <40 nmol/l) during late-winter, but only 4% had inadequate vitamin D status during late-summer. Serum 25 (OH) D was inversely related to serum PTH (r=−0.33; P=0.028).

Conclusion:

Suboptimal vitamin D status is common in postmenopausal Irish women during winter. Vitamin D supplementation is associated with improved vitamin D status, even during summertime.

Sponsorship:

Irish Government under the National Development Plan 2000–2006.

Introduction

Vitamin D is the major regulator of calcium metabolism and hence is an important determinant of bone health (Chapuy & Meunier, 1997; Van Leeuwen et al, 2001). Prolonged and severe vitamin D deficiency leads to rickets in children and osteomalacia in adults (Compston, 1998), whereas less severe vitamin D deficiency causes secondary hyperparathyroidism, increases bone turnover and bone loss mainly from cortical sites such as the femoral neck (Parfitt et al, 1982; Lips et al, 1982, 1987; Ooms et al, 1995; Chapuy et al, 1997). There is also growing evidence for the contribution of vitamin D insufficiency (ie, serum 25-hydroxyvitamin D (25 (OH) D) levels below 50 nmol/l) to the development of various chronic diseases (eg, some inflammatory and autoimmune diseases, some forms of cancer, hypertension, cardiovascular diseases and diabetes mellitus), which are frequent in Western societies (for review, see Zittermann, 2003; Holick, 2004).

In humans, vitamin D is obtained primarily through cutaneous biosynthesis in the presence of UVB sunlight and but also from the diet (Parfitt et al, 1982). Consequently, season is a major determinant of vitamin D status (Stamp & Round, 1974). Vitamin D status is highest in northern European populations around late-summer (August/september) and lowest around late-winter/early-spring (February/March) (McKenna, 1992; Lips et al, 2001). In northern Europe (latitude 40–60°N), including Ireland (latitude 51–55°N), sunlight is too weak during the winter months (ie, October/November to February/March) to stimulate cutaneous vitamin D synthesis (Webb et al, 1988; Food and Agriculture Organization/World Health Organization, 1998). This creates an increased reliance on dietary sources during these winter months to help maintain adequate vitamin D status. However, the usual dietary vitamin D intake in Europe is not sufficient to maintain adequate vitamin D status especially during wintertime (Van Der Wielen et al, 1995; see review by Ovesen et al, 2003).

There are very few natural sources of vitamin D that are commonly consumed in Ireland. A recent analysis of the North/South Ireland Food Consumption Survey for vitamin intakes (Hill et al, 2004) estimated that the mean daily intake of vitamin D was 4.2 μg in adult men and women (aged 18–64 y) from all sources, including nutritional supplements. These intake data show that a considerable proportion of Irish adults have very low dietary intakes of vitamin D and are largely dependent on sunlight to maintain adequate vitamin D status. A very high prevalence (50–100%) of severe vitamin D deficiency (serum 25 (OH) D levels <25 nmol/l) has been reported in older studies of elderly (generally >65 y) hospitalised and community-dwelling Irish subjects during wintertime (McKenna et al, 1981, 1985; Meade et al, 1986; Freaney et al, 1993). Moreover, Freaney et al (1993) found that 32% of a group of free-living ambulatory elderly Irish subjects had severe vitamin D deficiency during summertime. There is much current debate about the serum 25 (OH) D cutoff levels defining vitamin D adequacy/sufficiency (Zittermann, 2003; Lips, 2004), with some suggesting that levels as high as 80–100 nmol/l are required (Zittermann, 2003; Holick, 2004), which would mean that much greater proportions of elderly Irish subjects may have suboptimal vitamin D status.

While several studies have indicated that elderly among various populations are at particular risk of suboptimal status (Lips, 2001), less is known about vitamin D status in younger postmenopausal women, a subgroup of the population also at increased risk of osteopenia and osteoporosis. A range of recommended vitamin D intakes (0–10 μg/day) has been set for Irish adults aged up to 65 y, which allows for a variety of sun exposure during summer, while 10 μg/day is recommended for Irish adults aged 65 y and older (Food Safety Authority of Ireland, 1999). About 88% of 51- to 64-y-old Irish adult women fail to reach intakes of 10 μg/day (Hill et al, 2004). The significance of these low intakes for vitamin D status in this age group is unknown, especially during wintertime.

Therefore, the objective of the present study was to assess vitamin D status during late-summer and late-winter/early-spring in postmenopausal Irish women (aged 51–69 y), and to estimate vitamin D intake in this group of women. In addition, the impact of using vitamin D-containing supplements on vitamin D status was also assessed.

Subjects and methods

Subjects

A convenience sample of 63 apparently healthy, free-living adult women (mean age 59.8 (range 51.0–68.7 y)) were recruited by leaflet or direct contact from the Cork region. None of the subjects were suffering from any condition likely to affect vitamin D status. Women were excluded if they were taking medicines likely to affect vitamin D status or calcium metabolism (such as active vitamin D metabolites, parathyroid hormone (PTH), anticonvulsants, steroid hormones). Four of the women were taking very high levels of supplemental vitamin D (56–63 μg/day), which is nonreflective of levels in vitamin D-containing supplements used by women aged 50 y and older in the general Irish population (Kiely et al, 2001), as well as being higher than the tolerable upper intake level (50 μg/day; Institute of Medicine, 1997). Therefore, these women were excluded from further analysis. The mean (s.d.; range) height, weight and body mass index (BMI) of the women were 1.61 (0.06; 1.46–1.73) m, 70.6 (12.1; 51.6–104.0) kg and 27.4 (5.0; 18.9–40.1) kg/m2, respectively.

Ethical considerations

Before participation in this study, all subjects signed an informed consent document approved by the Clinical Research Ethics Committee of the Cork Teaching Hospitals.

Design

This study was a longitudinal observational study of seasonal differences in vitamin D status in 51- to 69-y-old women. Each participant was invited to provide a fasting blood sample at the University on three separate occasions: February/March 2002, August/September 2002 and again in February/March 2003. After an overnight fast, a blood sample (20 ml) was taken between 0830 and 1030 hours on each of the three occasions. Anthropometric measurements (weight and height) were taken. Habitual food intake was assessed by a 14-day diet history, which consisted of a one-to-one interview detailing usual food and drink intakes in a typical 14-day period. Food intakes were quantified using a photographic food atlas of food portion sizes (Ministry of Agriculture, Fisheries and Food, 1997). The dietary history was administered to one-third of participants at each of the three visits so that the full sample had been assessed by the end of the third visit. We have previously shown that dietary vitamin D intake within Irish adults does not differ between summer- and wintertime (Hill et al, 2004). A general health and lifestyle questionnaire was administered to each participant during each visit, which provided information on medical history, use of hormone replacement therapy, visits to hospital, fracture history and smoking history. The questionnaire also detailed sun holidays and the use of sunbeds, medicines and nutritional supplements, including calcium-containing supplements. Of the 59 women who participated at the first sampling point (February/March 2002), 48 and 47 returned for the second (August/September 2002) and third sampling point (February/March 2003), respectively. Data on daily sunshine duration (in hours) in Cork city during the sampling periods were obtained from the Irish Meteorological Service (http://www.met.ie).

Collection and preparation of samples

Blood was collected by venepuncture into a vacutainer tube with no additive and processed to serum, which was immediately stored at −80°C until required for analysis.

Experimental techniques

Serum intact parathyroid hormone. Serum intact parathyroid hormone (iPTH) levels were measured in serum using an ELISA (OCTEIA® Intact parathyroid hormone, Immuno Diagnostic Systems Ltd, Boldon, UK). The intra- and interassay CV was 3.4 and 3.8%, respectively. Based on the manufacturer's information, the suggested normal range for PTH is 0.8–3.9 pmol/l, while values between 4.1 and 29.0 pmol/l are suggestive of primary hyperparathyroidism.

Serum 25-hydroxyvitamin D. Serum 25-hydroxyvitamin D (25 (OH) D) levels were measured in serum samples using a recently developed ELISA (OCTEIA® 25-Hydroxy Vitamin D, Immuno Diagnostic Systems Ltd, Boldon, UK). The intra- and interassay CV was 5.9 and 6.6%, respectively. The quality and accuracy of the serum 25 (OH) D analysis in this laboratory was assured on an ongoing basis by participation in the Vitamin D External Quality Assessment Scheme (DEQAS, Charing Cross Hospital, London, UK). There is no international consensus on cutoff levels for vitamin D deficiency and vitamin D insufficiency (McKenna & Freaney, 1998). Therefore, for illustrative and comparative purposes in the present study, three suggested sets of serum 25 (OH) D cutoff values for defining vitamin D status were used. These include the definitions of vitamin D status suggested by Heaney and Weaver (2003) (<80 nmol/l, insufficient; >80 nmol/l, sufficient), Vieth (1999) (>40 nmol/l, adequate; 25–40 nmol/l, marginally deficient; <25 nmol/l; severely deficient) and Lips (2001) (>50 nmol/l, replete; 25–50 nmol/l, mildly deficient; 12.5–25 nmol/l, moderately deficient; <12.5 nmol/l, severely deficient).

Serum calcium levels. Calcium was analysed in duplicate in serum samples by atomic absorption spectrophotometry (Spectr AA-600, Varian Australia Ltd, Victoria, Australia) after appropriate dilution with LaCl3 solution (5 g/l; BDH Ltd, Poole, Dorset, UK). A range of calcium standards was used to obtain a calcium calibration curve. The intra- and interassay CV for calcium was 2.8 and 7.8%, respectively. The accuracy of mineral analysis was assured in each analytical run by appropriate recovery of mineral in a reference serum sample (Seronorm Trace Elements™: Serum, Nycomed, Olso, Norway).

Statistical analysis

Data are presented as means and standard deviations. Data for all variables (except vitamin D intakes) were normally distributed and allowed for parametric tests of significance. Seasonal differences in serum 25 (OH) D and PTH concentrations were analysed using repeated measures analysis of variance (ANOVA) (n=44 present at all three sampling points). Where significant (P<0.05) differences were found, Fisher's least significant difference test was used to perform post hoc comparison of all pairs of means (Snedecor & Cochran, 1967). Differences in serum 25 (OH) D and PTH levels between vitamin D supplement users and nonusers, within a season, were evaluated using unpaired Student's t-tests. The difference in vitamin D intake from food sources only compared to all sources (food and supplements) was evaluated using a Wilcoxon's test. The difference in calcium intake from food sources only compared to all sources (food and supplements) was evaluated using a paired Student's t-test. A linear regression model was used to investigate the association between serum 25 (OH) D and PTH (levels averaged over the three sampling points; n=44).

Results

Dietary intake of vitamin D and calcium

Mean (s.d.) daily intake of vitamin D and calcium from food sources alone (excluding supplements) was 3.2 (2.0) μg and 922 (395) mg, respectively, in 51- to 69-y-old women. The mean daily intakes of vitamin D (P<0.01) and calcium (P=0.01) were significantly higher when vitamin D- and calcium-containing supplements were accounted for (mean (s.d.), vitamin D 5.8 (5.6) μg, calcium 993 (442) mg).

Seasonal variation in serum 25 (OH) D and impact on serum PTH

Mean serum 25 (OH) D concentrations in 51- to 69-y-old women (n=44) differed (P<0.01) over the three time points (February/March 2002, August/September 2002 and February/March 2003). Serum 25 (OH) D concentrations during February/March 2002 were significantly lower (P<0.001) than August/September 2002 and February/March 2003 (Table 1). However, there was no significant difference in serum 25 (OH) D concentrations between August/September 2002 and February/March 2003 (Table 1). Local sunshine data for the entire month of March 2003 showed that there were 132 h of sunshine recorded, well above that recorded during March 2002 (92 h) and similar to that in August 2002 (133 h). While 18% of women took a sun-holiday in the 3 months prior to February/March 2003, only 9% of women took a sun-holiday in the 3 months prior to February/March 2002.

Table 1 Serum 25 (OH) D and PTH levels in 51- to 69-y-old Irish women (n=44) by season

Stratifying women into those with BMI above and below 30 showed that serum 25 (OH) D concentrations were significantly lower (P=0.039) in those with BMI greater than 30 during August/September 2002, but not during the winter sampling points (data not shown).

Mean serum PTH concentrations were significantly (P<0.001) lower during August/September 2002 than February/March 2002 and February/March 2003 (Table 1). Mean serum PTH concentrations were significantly (P<0.001) higher during February/March 2003 than February/March 2002 (Table 1). However, during February/March 2003, four women had serum PTH values outside the normal range (>4.1 pmol/l), but had normal serum calcium levels, suggestive of secondary hyperparathyroidism. Serum 25 (OH) D levels in these women were low to normal (25.7, 26.7, 49.9 and 53.5 nmol/l) during this sampling point. When these women were excluded from the analysis, there was no significant (P>0.05) difference between February/March 2002 and February/March 2003 (data not shown).

Impact of vitamin D supplement use on serum vitamin D and PTH levels

About 46, 25 and 40% of women took a vitamin D-containing supplement during the three respective sampling points. The vitamin D content of the supplements ranged from 2.5 to 20 μg, and the mean content of vitamin D was similar (6.2, 7.7 and 7.0 μg; P=0.290) for the three respective sampling points. Stratification of women into vitamin D-containing supplement ‘users’ and ‘nonusers’ revealed that mean serum 25 (OH) D levels were significantly higher (P≤0.05) in users than nonusers at all three sampling points (Figure 1). There was no effect of vitamin D-containing supplement use on serum PTH concentrations in any of the three sampling points (data not shown).

Figure 1
figure1

Serum 25 (OH) D level in 51- to 69-y-old Irish women (n=59) stratified by vitamin D supplement use and by season.

Prevalence of vitamin D deficiency

The percentages of women classified as vitamin D adequate/sufficient or deficient/insufficient according to a number of suggested serum 25 (OH) D cutoff levels are shown in Table 2. Depending on the cutoff values applied, 15–64, 37–96, and 32–83% of women had adequate/sufficient vitamin D levels during February/March 2002, August/September 2002 and February/March 2003, respectively. Stratification of women by vitamin D-containing supplement use showed that compared to nonusers, a higher proportion of supplement users had adequate/sufficient vitamin D levels during all three sampling points, irrespective of which cutoff values were used (Table 2).

Table 2 The percentages of women classified as vitamin D adequate/sufficient or deficient/insufficient according to a number of suggested 25 (OH) D cutoff levels

Relationship between serum 25 (OH) D and serum PTH

Using a linear regression model, there was a significant inverse correlation between serum 25 (OH) D levels and serum PTH levels (r=−0.33;. P=0.028).

Discussion

In the present study, the mean daily vitamin D intake of Irish postmenopausal women (51–69 y old) was 5.8 μg from all sources (ie, food and nutritional supplements) and 3.2 μg from food sources only. These intake estimates are in line with those recently reported for a nationally representative sample of Irish adult women (50- to 64-y-old) (5.1 μg from food and supplements and 3.4 μg from food sources only) (Hill et al, 2004).

The problem with establishing appropriate Dietary Reference Values (DRVs) for vitamin D has been a long-standing one. Determining the amount of vitamin D provided by sunlight is difficult. For this reason, an RDA of 0–10 μg/day has been set for adults aged up to 65 y and 10 μg/day for adults 65 y and older (Food Safety Authority of Ireland, 1999). In the US, it is recommended that 51-y-olds and older consume at least 10 μg vitamin D daily (Institute of Medicine, 1997) to help counteract the slower rate of skin production with age, and thus to maintain adequate serum levels of 25 (OH) D for bone health. Similarly, the Food and Agriculture Organization/World Health Organization expert group on human vitamin and mineral requirements recommends 10 μg/day for adults 50 y and older (Food and Agriculture Organization/World Health Organization, 1998). The mean daily intake of vitamin D in the current sample of 51- to 69-y-old Irish women (5.8 μg/day) is below this recommendation, and furthermore, 84% of the group of women failed to reach the recommendation of 10 μg/day. These low values are consistent with vitamin D intake data from other European countries (McKenna, 1992; Van Der Wielen et al, 1995; Rasmussen et al, 2000; see reviews by Lips, 2001; Henderson et al, 2003; Ovesen et al, 2003).

Of particular interest in the current study was the much lower prevalence of vitamin D inadequacy/insufficiency in supplement users compared with nonusers, especially during late-winter/early-spring (a time at which vitamin D status is at its lowest). These findings suggest that the use of vitamin D-containing supplements was to some degree protective of vitamin D status. However, the level of protection offered by vitamin D-containing supplements depends on the serum 25 (OH) D cutoff values of vitamin D adequacy/sufficiency applied. For example, in the present study, the vitamin D content of the supplements used by the women ranged from 2.5 to 20 μg, with a mean content of 7.5 μg. At this supplemental level, 81–100 and 56–95% of women had adequate vitamin D status (defined as serum 25 (OH) D>40 nmol/l (Vieth, 1999) and >50 nmol/l (Lips, 2001), respectively) during wintertime. However, if a serum 25 (OH) D cutoff level of >80 nmol/l (Heaney & Weaver, 2003) is applied, then a much lower proportion of the postmenopausal women had sufficient vitamin D status during wintertime, suggesting that higher supplemental levels of vitamin D may be required. It is noteworthy that Dawson-Hughes et al (1997a) reported that at least 20 μg/day is required to prevent osteoporosis. In the present study, only 2% of the women had an intake of 20 μg/day, and none of the woman were able to achieve a dietary intake ≥20 μg/day without using supplements.

In the elderly women, there was a seasonal variation in serum 25 (OH) D levels among both supplement users and nonusers, suggesting that supplement use during summertime still, on average, conferred a benefit to vitamin D status. The seasonal variation in serum 25 (OH) D levels observed in postmenopausal women in the present study has been reported in other studies of more elderly Irish subjects (McKenna et al, 1985; Freaney et al, 1993), as well as in various other European populations (see reviews by Lips, 2001; Ovesen et al, 2003; Zittermann, 2003). The high levels of serum 25 (OH) D during second winter sampling point compared to the first may have related to the higher number of total hours of daily sunshine in the former compared to the latter, as well as the greater number of women taking a sun-holiday in the 3 month prior to blood sampling. It is also possible that by the third visit women may have been more aware of possible vitamin D deficiency during winter and took steps to improve their status, such as taking a sun-holiday or consciously obtaining more sunlight exposure.

The secretion of PTH has also been suggested as a biochemical marker for vitamin D deficiency (Chapuy et al, 1997; McKenna & Freaney, 1998). In the present study, a significant inverse correlation between serum 25 (OH) D and serum PTH was observed in the postmenopausal women, which is in line with the findings of some (Chapuy et al, 1997; Dawson-Hughes et al, 1997b) but not other studies (Chapuy et al, 1987; Rapuri et al, 2002). Serum PTH concentration also exhibited a seasonal variation (from February/March 2002 to August/September 2002) in postmenopausal women in the present study. Serum PTH levels were significantly higher during February/March 2003 than February/March 2002, even though serum 25 (OH) D levels were significantly higher during the former. However, when four women with secondary hyperparathyroidism during February/March 2003 were excluded, there was no significant difference in serum PTH levels between the two winter sampling periods. The underlying reason for the secondary hyperparathyroidism in these women is unclear; their serum 25 (OH) D levels were low to normal. However, in addition to being influenced by serum 25 (OH) D levels, serum PTH is also affected by dietary calcium (Karkkainen et al, 1997) and phosphate (Miyamoto et al, 2000) intake and kidney function (Freaney et al, 1993) among other factors.

Conclusion

The findings of the present study show that inadequate vitamin D status (serum 25 (OH) D levels below 40 or 50 nmol/l) is quite common in postmenopausal Irish women aged 51–69 y. These findings extend existing data, which show a high prevalence of vitamin D deficiency in elderly (generally >65 y) Irish subjects (McKenna et al, 1981, 1985; Meade et al, 1986; Freaney et al, 1993). While bone status measurements were not assessed in the present study, there is considerable evidence to suggest that vitamin D deficiency and inadequacy (defined as serum 25 (OH) D levels below 25 and 40 nmol/l, respectively) may be detrimental to bone health in adults (for reviews, see Institute of Medicine, 1997; Food and Agriculture Organization/World Health Organization, 1998; Lips, 2001). Therefore, the impact of this inadequate vitamin D status on bone health in postmenopausal women needs to be investigated. Vitamin D supplementation was associated with a considerably lower prevalence of inadequacy/insufficiency of vitamin D in postmenopausal Irish women in the present study. Vitamin D supplementation was also associated with improved vitamin D status in the postmenopausal women during summertime, suggesting that summer sunlight exposure was not sufficient to optimise vitamin D status.

References

  1. Chapuy MC & Meunier PJ (1997): Vitamin D insufficiency in adults and the elderly. In Vitamin D, eds, D Feldman, F Glorieux & JW Pike, pp 679–693. San Diego, CA: Academic press.

    Google Scholar 

  2. Chapuy MC, Chapuy P & Meunier PJ (1987): Calcium and vitamin D supplements: effects on calcium metabolism in elderly people. Am. J. Clin. Nutr. 46, 324–328.

    CAS  Article  Google Scholar 

  3. Chapuy MC, Preziosi P, Maamer M, Arnaud S, Galan P, Hercberg S & Meunier PJ (1997): Prevalence of vitamin D insufficiency in an adult normal population. Osteoporos. Int. 7, 439–443.

    CAS  Article  Google Scholar 

  4. Compston JE (1998): Vitamin D deficiency: time for action. BMJ 317, 1466–1467.

    CAS  Article  Google Scholar 

  5. Dawson-Hughes B, Harris SS, Krall EA & Dallal GE (1997a): Effect of calcium and vitamin D supplementation on bone density in men and women 65 years of age and older. N. Engl. J. Med. 337, 670–676.

    CAS  Article  Google Scholar 

  6. Dawson-Hughes B, Harris SS & Dallal GE (1997b): Plasma calcidiol, season, and serum parathyroid hormone concentrations in healthy elderly men and women. Am. J. Clin. Nutr. 65, 67–71.

    CAS  Article  Google Scholar 

  7. Food and Agriculture Organization/World Health Organization (1998): Human vitamin and mineral requirements: a report of the joint Food and Agriculture Organization/World Health Organization expert consultation, Bangkok, Thailand. Food and Nutrition Division, Rome http://ftp.fao.org/es/esn/nutrition.

  8. Food Safety Authority of Ireland (1999): Recommended Dietary Allowances for Ireland. Dublin: Government Publications Sales Office.

  9. Freaney R, McBrinn Y & McKenna MJ (1993): Secondary hyperparathyroidism in elderly people: combined effect of renal insufficiency and vitamin D deficiency. Am. J. Clin. Nutr. 58, 187–191.

    CAS  Article  Google Scholar 

  10. Heaney RP & Weaver CM (2003): Calcium and vitamin D. Endocrinol. Metab. Clin. N. Am. 32, 181–194.

    CAS  Article  Google Scholar 

  11. Henderson L, Irving K, Gregory J, Bates CJ, Prentice A, Perks J, Swan G & Farron M (2003): The National Diet and Nutrition Survey: adults aged 19 to 64 years—vitamin and mineral intake and urinary analytes. http://www.foodstandards.gov.uk/multimedia/pdfs/ndnsv3.pdf.

  12. Hill TR, O’Brien MM, Kiely M, Flynn A & Cashman KD (2004): Vitamin D intakes in 18–64 year-old Irish adults. Eur. J. Clin. Nutr. 58, 1509–1517.

    CAS  Article  Google Scholar 

  13. Holick MF (2004): Vitamin D: importance in the prevention of cancers, type 1 diabetes, heart disease and osteoporosis. Am. J. Clin. Nutr. 79, 362–371.

    CAS  Article  Google Scholar 

  14. Institute of Medicine (1997): Dietary Reference Intakes. For Calcium, Phosphorus, Magnesium, Vitamin D and Fluoride. Washington, DC: Food and Nutrition Board, National Academy Press.

  15. Karkkainen MU, Wiersma JW & Lamberg-Allardt CJ (1997): Postprandial parathyroid response to four calcium-rich foodstuffs. Am. J. Clin. Nutr. 65, 1726–1730.

    CAS  Article  Google Scholar 

  16. Kiely M, Flynn A, Harrington KE, Robson PJ, O’Connor N, Hannon EM, O’Brien MM, Bell S & Strain JJ (2001): The efficacy and safety of nutritional supplement use in a representative sample of adults in the North/South Ireland Food Consumption Survey. Public Health Nutr. 4, 1089–1097.

    CAS  PubMed  Google Scholar 

  17. Lips P (2001): Vitamin D deficiency and secondary hyperparathyroidism in the elderly: consequences for bone loss and fractures and therapeutic implications. Endocr. Rev. 22, 477–501.

    CAS  Article  Google Scholar 

  18. Lips P (2004): Which circulating level of 25-hydroxyvitamin D is appropriate? J. Steroid Biochem. Mol. Biol. 89–90, 611–614.

    Article  Google Scholar 

  19. Lips P, Netelenbos JC, Jongen MJM, van Ginkel FC, Althuis AL, van Schaik CL, van der Vijgh WJF, Vermeiden JPW & van der Meer C (1982): Histomorphometric profile and vitamin D status in patients with femoral neck fracture. Metab. Bone Dis. Relat. Res. 4, 85–93.

    CAS  Article  Google Scholar 

  20. Lips P, van Ginkel FC, Jongen MJ, Rubertus F, van der Vijgh WJ & Netelenbos JC (1987): Determinants of vitamin D status in patients with hip fracture and in elderly control subjects. Am. J. Clin. Nutr. 46, 1005–1010.

    CAS  Article  Google Scholar 

  21. Lips P, Duong T, Oleksik A, Black D, Cummings S, Cox D & Nickelsen T (2001): A global study of vitamin D status and parathyroid function in postmenopausal women with osteoporosis: baseline data from the multiple outcomes of raloxifene evaluation clinical trial. J. Clin. Endocrinol. Metab. 3, 1212–1221.

    Article  Google Scholar 

  22. McKenna MJ (1992): Differences in vitamin D status between countries in young adults and the elderly. Am. J. Clin. Nutr. 93, 69–77.

    CAS  Google Scholar 

  23. McKenna MJ & Freaney R (1998): Secondary hyperparathyroidism in the elderly: means to defining hypovitaminosis D. Osteoporos. Int. 8, S3–S6.

    CAS  Article  Google Scholar 

  24. McKenna MJ, Freaney R, Keating D & Muldowney FP (1981): The prevalence and management of vitamin D deficiency in an acute geriatric unit. Ir. Med. J. 74, 336–338.

    CAS  PubMed  Google Scholar 

  25. McKenna MJ, Freaney R, Meade A & Muldowney FP (1985): Hypovitaminosis D and elevated serum alkaline phosphatase in elderly Irish people. Am. J. Clin. Nutr. 41, 101–109.

    CAS  Article  Google Scholar 

  26. Meade A, Moloney M & O’Keeffe D (1986): Prevalence of vitamin D deficiency in the elderly in two rural areas in Ireland. Ir. Med. J. 79, 359.

    CAS  PubMed  Google Scholar 

  27. Ministry of Agriculture, Fisheries and Food (MAFF) (1997): Food Portion Sizes. London: The Stationary Office.

  28. Miyamoto K, Ito M, Segawa H & Kuwahata M (2000): Secondary hyperparathyroidism and phosphate sensing in parathyroid glands. J. Med. Invest. 47, 118–122.

    CAS  PubMed  Google Scholar 

  29. Ooms ME, Lips P, Roos JC, van der Vijgh WJ, Popp-Snijders C, Bezemer PD & Bouter LM (1995): Vitamin D status and sex hormone binding globulin: determinants of bone turnover and bone mineral density in elderly women. J. Bone Miner. Res. 10, 1177–1184.

    CAS  Article  Google Scholar 

  30. Ovesen L, Andersen R & Jakobsen J (2003): Geographical differences in vitamin D status, with particular reference to European countries. Proc. Nutr. Soc. 62, 813–821.

    CAS  Article  Google Scholar 

  31. Parfitt AM, Gallagher JC, Heaney RP, Johnston CC, Neer R & Whedon GD (1982): Vitamin D and bone health in the elderly. Am. J. Clin. Nutr. 36, 1014–1031.

    CAS  Article  Google Scholar 

  32. Rapuri PB, Kinyamu HK, Gallagher JC & Haynatzka V (2002): Seasonal changes in calciotropic hormones, bone markers, and bone mineral density in elderly women. J. Clin. Endocrinol. Metab. 87, 2024–2032.

    CAS  Article  Google Scholar 

  33. Rasmussen LB, Hansen GL, Hansen E, Koch B, Mosekilde L, Mølgaard C, Sørensen OH & Ovesen L (2000): Vitamin D: should the supply in the Danish population be increased? Int. J. Food Sci. Nutr. 51, 209–215.

    CAS  Article  Google Scholar 

  34. Snedecor GW & Cochran WG (1967): Statistical Methods. Ames, IA: Iowa State University Press.

    Google Scholar 

  35. Stamp TCB & Round JM (1974): Seasonal changes in human plasma levels of 25 (OH) vitamin D. Nature 247, 563–565.

    CAS  Article  Google Scholar 

  36. Van Der Wielen RPJ, Lowik MRH, Van Den Berg H, De Groot LCPGM, Haller J, Moreiras O & Van Staveren WA (1995): Serum vitamin D concentrations among elderly people in Europe. Lancet 346, 207–210.

    CAS  Article  Google Scholar 

  37. Van Leeuwen JPTM, Van Den Bemd G-JCM, Van Driel M, Buurman CJ & Pols AP (2001): 24,25-Dihydroxyvitamin D3 and bone metabolism. Steroids 66, 375–380.

    CAS  Article  Google Scholar 

  38. Vieth R (1999): Vitamin D supplementation, 25-hydroxyvitamin D concentrations, and safety. Am. J. Clin. Nutr. 69, 842–856.

    CAS  Article  Google Scholar 

  39. Webb AR, Kline LW & Holick MF (1988): Influence of season and latitude on the cutaneous synthesis of vitamin D3: exposure to winter sunlight in Boston and Edmonton will not promote vitamin D3 synthesis in human skin. J. Clin. Endocrinol. Metab. 67, 373–378.

    CAS  Article  Google Scholar 

  40. Zittermann A (2003): Vitamin D in preventive medicine: are we ignoring the evidence? Br. J. Nutr. 89, 552–572.

    CAS  Article  Google Scholar 

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Acknowledgements

This work was supported by funding made available by the Irish Government under the National Development Plan 2000–2006.

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Correspondence to K D Cashman.

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Guarantor: KD Cashman.

Contributors: TH contributed to design, execution, analysis and writing of the study. AC contributed to dietary assessment and analysis. MOB and AF contributed to design, execution and analysis of the study. MK contributed to design and writing of the study. KDC contributed to design, analysis and writing of the study.

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Hill, T., Collins, A., O'Brien, M. et al. Vitamin D intake and status in Irish postmenopausal women. Eur J Clin Nutr 59, 404–410 (2005). https://doi.org/10.1038/sj.ejcn.1602088

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Keywords

  • vitamin D
  • intake
  • status
  • postmenopausal women
  • Irish

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