Skip to main content Accessibility help
×
Home
Hostname: page-component-747cfc64b6-rtmr9 Total loading time: 0.534 Render date: 2021-06-15T20:22:25.156Z Has data issue: true Feature Flags: { "shouldUseShareProductTool": true, "shouldUseHypothesis": true, "isUnsiloEnabled": true, "metricsAbstractViews": false, "figures": true, "newCiteModal": false, "newCitedByModal": true, "newEcommerce": true }

Vitamin D status in Greenland is influenced by diet and ethnicity: a population-based survey in an Arctic society in transition

Published online by Cambridge University Press:  08 June 2012

Stig Andersen
Affiliation:
Arctic Health Research Centre, Aalborg University Hospital, Hobrovej 42D, 9000Aalborg, Denmark Department of Medicine, Queen Ingrids Hospital, Nuuk, Greenland
Peter Laurberg
Affiliation:
Department of Endocrinology, Aalborg University Hospital, Aalborg, Denmark
Bodil Hvingel
Affiliation:
Department of Surgery, Queen Ingrids Hospital, Nuuk, Greenland
Kent Kleinschmidt
Affiliation:
Department of Medicine, Queen Ingrids Hospital, Nuuk, Greenland
Lene Heickendorff
Affiliation:
Department of Clinical Biochemistry, Aarhus University Hospital, Aarhus, Denmark
Leif Mosekilde
Affiliation:
Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark
Corresponding
E-mail address:
Rights & Permissions[Opens in a new window]

Abstract

Vitamin D status as measured by plasma 25-hydroxyvitamin D (25(OH)D) is important to human health. Circumpolar people rely on dietary sources and societal changes in the Arctic are having profound dietary effects. The objective of the present study was to determine plasma 25(OH)D status and factors important to plasma 25(OH)D in populations in Greenland. Inuit and non-Inuit aged 50–69 years in the capital in West Greenland (latitude 64°15′N) and in a major town and remote settlements in East Greenland (latitude 65°35′N) were surveyed. Supplement use and lifestyle factors were determined by questionnaires. Inuit food scores were computed from a FFQ of seven traditional Inuit and seven imported food items. 25(OH)D2 and 25(OH)D3 levels were measured in the plasma. We invited 1 % of the population of Greenland, and 95 % participated. 25(OH)D3 contributed 99·7 % of total plasma 25(OH)D. Non-Inuit had the lowest median plasma 25(OH)D of 41 (25th–75th percentile 23–53) nmol/l compared with 64 (25th–75th percentile 51–81) nmol/l in Inuit (P< 0·001). Plasma 25(OH)D was below 20 and 50 nmol/l in 13·8 and 60·1 % of participants, respectively, with Inuit food item scores below 40 % (P< 0·001), and in 0·2 and 25·0 % of participants, respectively, with higher scores (P< 0·001). The Inuit diet was an important determinant of plasma 25(OH)D (P< 0·001) and its effect was modified by ethnicity (P= 0·005). Seal (P= 0·005) and whale (P= 0·015) were major contributors to plasma 25(OH)D. In conclusion, a decrease in the intake of the traditional Inuit diet was associated with a decrease in plasma 25(OH)D levels, which may be influenced by ethnicity. The risk of plasma 25(OH)D deficiency in Arctic populations rises with the dietary transition of societies in Greenland. Vitamin D intake and plasma 25(OH)D status should be monitored.

Type
Full Papers
Copyright
Copyright © The Authors 2012

Vitamin D deficiency is associated with adverse health outcomes and increases the risk of osteoporosis, falls and fractures(Reference Mosekilde18). Epidemiological evidence has linked low plasma 25-hydroxyvitamin D (25(OH)D) to a number of inflammatory, infectious, cardiovascular and metabolic disorders, and with cancers(Reference Holick9Reference Sharma, Barr and Macdonald19). Thus, vitamin D is important for human health.

The endogenous production of 25(OH)D depends on the UVB-mediated conversion of 7-dehydrocholesterol to previtamin D3 and further isomerisation to vitamin D3 in the skin(Reference Adams and Hewison10). This depends on exposure to sunlight and plasma 25(OH)D levels in groups of Caucasian individuals decrease with increasing latitude(Reference Holick9, Reference Adams and Hewison10, Reference Sharma, Barr and Macdonald19, Reference Hagenau, Vest and Gissel20). Thus, low plasma levels of 25(OH)D are seen in, for example, Scandinavian populations(Reference Brot, Vestergaard and Kolthoff21, Reference Dalgård, Petersen and Schmedes22) even during the summer(Reference Sharma, Barr and Macdonald19). Very low levels of 25(OH)D may be found in Arctic populations characterised by low sun exposure and heavy outdoor clothing.

Diet provides yet another source of plasma 25(OH)D, with free-living fish and sea mammals being particularly rich in vitamin D(Reference Holick9, Reference Sharma, Barr and Macdonald19, Reference Kleiver, Draper and Ronald23, Reference Lu, Chen and Zhang24). These dominate the traditional Inuit (Eskimo) diet(Reference Sharma, Barr and Macdonald19, Reference Kuhlein, Receveur and Soueida25, Reference Andersen, Hvingel and Kleinschmidt26) and the Inuit consider seal and whale blubber to be of particular dietary value. This may compensate for the lack of exposure to the sun and thus of dermal vitamin D production in Arctic residents.

Transition of Greenlandic societies started around 1960 and has occurred at different paces in different parts of Greenland(Reference Bjerregaard and Young27), so that, today, settlements, towns and the capital city display different degrees of Westernisation(Reference Andersen, Hvingel and Kleinschmidt26, Reference Bjerregaard and Young27). This has influenced the use of the traditional Inuit diet, which has decreased(Reference Andersen, Hvingel and Kleinschmidt26, Reference Bjerregaard and Young27), and this in turn has the potential to influence plasma 25(OH)D(Reference Kuhlein, Receveur and Soueida25). Furthermore, obesity rates in Inuit have increased in parallel with transition(Reference Andersen, Mulvad and Pedersen28). This is associated with lower plasma 25(OH)D in other populations(Reference Adams and Hewison10) and may have a similar effect in Inuit.

This led us to study dietary habits and plasma 25(OH)D in cohorts living in the capital city Nuuk in West Greenland and in the rural Ammassalik district in East Greenland. We evaluated the impact of dietary components on plasma 25(OH)D in Arctic population groups. In addition, we assessed the influence of ethnicity on plasma 25(OH)D.

Subjects and methods

Area of investigation

Nuuk (64°15′N, 51°35′W) in West Greenland is the capital city of Greenland with 13 000 inhabitants of whom 75 % are Inuit (Eskimo) and 25 % non-Inuit (Caucasians). Nuuk was established as a trading post under the Danish crown in 1728 and is now a modern city with access to a wide variety of food items including fast food, Italian food, Thai food and takeaways, supplementary to traditional Greenlandic food items. Furthermore, a wide variety of food items imported from Denmark is available in a number of stores.

The Ammassalik district (65°35′N, 38°00′W) in East Greenland was isolated until 1884 and is still today difficult to access by sea due to pack ice from the northern ice cap. It is sparsely populated with 2943 inhabitants (93 % Inuit) spread over an area of 243 000 km2. Tasiilaq is the main town of the Ammassalik district, which has seven settlements. Tasiilaq has one store with a limited food selection and five minor shops. Each of the settlements has one store with a limited selection depending on access by sea and air.

Subjects and procedures

Participants and procedures have been described in detail previously(Reference Andersen, Hvingel and Kleinschmidt26). We invited 50–69-year-old men and women, both Greenlanders (all Inuit) and non-Greenlanders (all Caucasian Danes), recorded and living at the address. The places selected for the investigation were Nuuk, Tasiilaq, and the settlements Tiniteqilaaq, Sermiligaaq, Kulusuk and Kuummiut in the Ammassalik district. Only the settlements with more than fifteen inhabitants in the selected age group were included. In Nuuk, names and addresses were obtained from the hospital registration system that keeps records of all inhabitants of Nuuk. A random sample of 25 % of the total population aged 50–69 years was selected. The hospital registration system had not been regularly updated and for the investigation in Ammassalik, names and addresses were obtained from the National Civil Registration System in which every person living in Denmark, the Faeroe Islands and Greenland is registered. We invited 225 persons in Nuuk, 184 in Tasiilaq, nineteen in Tiniteqilaaq, twenty-eight in Sermiligaaq, fifty-two in Kulusuk, fifty-three in Kuummiut, and 95 % participated. A Greenlander (Inuit) was defined as an individual born in Greenland with both parents born in Greenland.

The present study was conducted according to the guidelines laid down in the Declaration of Helsinki and all procedures were approved by the Commission for Scientific Research in Greenland (reference no. 2010-8). All subjects gave informed written consent in Danish or Greenlandic by the participant's choice.

The local hospital porter or the nursing station attendant delivered a letter of invitation. The investigation took place at the local hospital or nursing station or by request as home visits. A physical examination was performed including height without shoes, weight in indoor clothing and recording of major disabilities. Participants were interviewed by a Greenlandic interpreter or by one of the investigating doctors (S. A., P. L. and B. H.), completing a questionnaire in either Danish or Greenlandic as appropriate for the participant. Information regarding age and sex was obtained from the National Civil Registration System. Information on lifestyle patterns and dietary habits was obtained by questionnaires. Questions were asked as written in the questionnaires. The same interpreter was used in Nuuk, Tasiilaq and all settlements.

Dietary habits

An interview-based FFQ was used to assess dietary habits. It included seven traditional Inuit (seal, whale, wild fowl, fish, reindeer, musk ox and hare) and seven imported food items (pre-cooked meals, potatoes, vegetables, butter, cheese, eggs and fresh fruit). These food items had been selected because they were typical to the diet in Greenland and they have been used previously(Reference Andersen, Hvingel and Kleinschmidt26). For each food item, six different frequency categories were given from ‘never’ to ‘daily intake’. A frequency score was calculated based on the average number of days per month the food item was ingested(Reference Andersen, Hvingel and Kleinschmidt26). Inuit food items scored positively and imported food items scored negatively. The sum of frequency scores for all food items consumed by each participant was calculated and individuals were categorised as follows: diet group 1, >80 %; diet group 2, 60–80 %; diet group 3, 40–60 %; diet group 4, 20–40 %; diet group 5, < 20 % Inuit food item scores on a scale where 100 % was purely Inuit foods and 0 % was purely imported food. We did not assess portion size for practical reasons but food-frequency scores were validated by cross-check questions as well as by a biomarker of the intake of traditional Inuit foods(Reference Andersen, Hvingel and Kleinschmidt26).

The intake of vitamin D-containing supplements was evaluated by asking the frequency of intake. Supplements were presented to one of the investigating doctors for evaluation. Contents and type of vitamin D differed between supplements available. Vitamin D content was evaluated based on the interview if no supplement was presented. Subjects were classified by daily intakes (yes/no).

Plasma 25-hydroxyvitamin D assay

Plasma 25(OH)D levels were analysed by isotope dilution liquid chromatography–tandem MS (LC–MS/MS) as described earlier(Reference Hojskov, Heickendorff and Moller29). Calibrators traceable to a NIST standard reference material (SRM972) were used (ChromSystems).

Statistics

Results are presented as medians with 25th and 75th percentiles. The plasma 25(OH)D groups were compared using non-parametric statistics: Mann–Whitney U test for comparison of two groups; Kruskal–Wallis test for comparing several groups; Kendall's τ for the relationship between the groups. Plasma 25(OH)D followed the normal distribution (P= 0·17), and linear regression models were used with plasma 25(OH)D as the dependent variable. Interaction was tested in multivariate logistic regression analysis. Explanatory variables were diet group, participant group, ethnic origin, use of supplements, BMI, age, sex and alcohol intake (average number of units per week). Diet, participant group and origin were investigated individually in the multivariate linear regression analysis due to covariance between these. Random selection of participants in Nuuk was performed using MedStat (Astra). Data were processed and analysed using Corel Quattro Pro 8 (Corel Corporation) and the Statistical Package for the Social Sciences version 13.0 (SPSS, Inc.). A P value of less than 0·05 was considered significant.

Results

For the present study, 1 % of the population of Greenland was invited and the participation rate was 95 %. The characteristics of the participants are given in Table 1. In the case of non-Inuit, seven had one parent born in Greenland while ninety-four had neither parent born in Greenland. Non-Inuit were more frequent users of vitamin preparations than Inuit (Table 1). Non-Inuit were skilled labour from Denmark and included more men than women (P< 0·001). Also, there were fewer non-Inuit than Inuit in the age group of 60–69 years and the mean age was lower (men P= 0·001, women P= 0·005; Table 1) because some leave Greenland when retiring. The study cohorts represented different levels of Westernisation as illustrated by hunting habits (Table 1). The two participants categorised as non-Inuit who reported hunting as a trade were of mixed origin.

Table 1 Descriptive information on participants in the diet and vitamin D survey in East and West Greenland (Number of participants and percentages)

* Including seven participants of mixed origin.

χ2 test for comparing proportions among all groups.

χ2 test for comparing proportions among Inuit.

§ BMI increased from settlement to town to city in Inuit men (trend, P= 0·010) but not in women (trend, P= 0·39).

Information missing for one participant.

Estimated units of alcohol per week. Information missing for nine participants.

** Information missing for seven participants.

Dietary habits

Dietary habits differed between the participant groups (Fig. 1). Of the participants, 93 % of Inuit in settlements had a food-frequency score of more than 60 % traditional foods compared with 86 % of Inuit in Tasiilaq, 59 % of Inuit in Nuuk and 3 % of non-Inuit. Conversely, 83 % of non-Inuit reported a food-frequency score of more than 60 % imported foods, while this was 14 % of Inuit in Nuuk and 1·4 % of Inuit in both Tasiilaq and settlements. Differences in dietary habits were marked between Inuit and non-Inuit (P< 0·001) as well as between the Inuit groups (P< 0·001). No seasonal differences in Inuit food frequency were reported.

Fig. 1 Food-frequency scores among the population groups in the capital city Nuuk (latitude 64°15′N) in West Greenland and in the Ammassalik district (latitude 65°35′N) in rural East Greenland. Classification was based on frequencies of intake of seven traditional Inuit (seal, whale, wild fowl, fish, reindeer, musk ox and hare) and seven imported food items (pre-cooked meals, potatoes, vegetables, butter, cheese, eggs and fresh fruit). Six different frequency categories were given for each food item from ‘never’ to ‘daily intake’ and a frequency score was calculated. Individuals were categorised based on frequency scores on a scale where 100 % is purely Inuit foods and 0 % is purely imported foods. □, Non-Inuit; , Inuit in city; , Inuit in town; , Inuit in settlement.

Vitamin D

Plasma 25(OH)D3 contributed 62·30 nmol/l (99·7 %) to the overall mean of 62·50 nmol/l of total 25(OH)D in the plasma, while 25(OH)D2 contributed only 0·3 %. This proportion was 0·2 % in Inuit and 1·4 % in non-Inuit not taking vitamin D-containing supplements (P= 0·005).

Diet and vitamin D

Fig. 2 shows that there was a significant (P< 0·001) difference in plasma 25(OH)D levels between the participants in the five diet groups. A diet based on mainly imported foods was associated with a mean total plasma 25(OH)D level of 36 nmol/l. This increased gradually (P< 0·001) to 68 nmol/l in the group with a diet comprising mainly traditional Inuit food items. The dietary components reported by Inuit that contributed markedly to plasma 25(OH)D were seal (P= 0·005) and whale (P= 0·015).

Fig. 2 Plasma 25-hydroxyvitamin D (25(OH)D) in each food-frequency group where 100 % is purely Inuit foods and 0 % is purely imported foods. Values are medians, with 25th and 75th percentiles represented by vertical bars.

The occurrence of plasma 25(OH)D below 50 nmol/l decreased with a higher intake of Inuit foods (Fig. 3) and 25(OH)D below 20 nmol/l was seen only in those with a low intake of traditional Inuit foods.

Fig. 3 Fraction of participants with plasma 25-hydroxyvitamin D below 20 nmol/l (), between 20 and 50 nmol/l () and above 50 nmol/l (□) for each food-frequency group where 100 % is purely Inuit foods and 0 % is purely imported foods.

Ethnicity and vitamin D

Inuit had a higher plasma 25(OH)D than non-Inuit (Fig. 4). They also had the highest intake of traditional Inuit foods (Fig. 1). Table 2 lists the factors important to plasma 25(OH)D levels. Diet, lifestyle and ethnicity influenced plasma 25(OH)D in the adjusted analysis. A plasma 25(OH)D level below 50 nmol/l was more likely with Inuit food scores below 60 % (P< 0·001; OR 5·4, 95 % CI 3·3, 8·8) and was modified by ethnicity (ethnicity × diet as an interaction term, P= 0·005) in the multivariate logistic regression analysis.

Fig. 4 Plasma 25-hydroxyvitamin D (25(OH)D) in Inuit and non-Inuit (Caucasian) men and women living in the capital city Nuuk in West Greenland and in the rural Ammassalik district in East Greenland.

Table 2 Factors important to plasma 25-hydroxyvitamin D (25(OH)D) in residents in Greenland (β Coefficients and P values)

* Dependent variable was serum 25(OH)D and explanatory variables were weight, age, sex, alcohol intake, and either ethnicity, lifestyle or diet.

β (Regression) coefficients were as follows: Inuit/non-Inuit; city/town/settlements; decreasing traditional Inuit diet; vitamin D supplement use − /+; increasing BMI; increasing age; men/women; increasing alcohol intake.

Lifestyle represented by participant groups at different levels of Westernisation: non-Inuit; Inuit in city; Inuit in town; Inuit in settlement (as in Table 1).

§ Diet based on the diet groups calculated from the frequency of intake of seven Inuit and seven imported food items: diet group 1, >80 %; diet group 2, 60–80 %; diet group 3, 40–60 %; diet group 4, 20–40 %; diet group 5, 0–20 % Inuit food-frequency scores.

Discussion

This is the first population-based study of the relationship between plasma 25(OH)D and the transition of societies in Greenland. We found that decreasing intake of the traditional Inuit diet was followed by a decrease in 25(OH)D in the plasma and an emerging vitamin D deficiency. Furthermore, seal and whale were major contributors to plasma 25(OH)D in populations in Greenland. Interestingly, ethnicity may influence the impact of dietary habits on plasma 25(OH)D.

Vitamin D synthesis in humans requires UVB exposure of the skin. In Caucasians, low UVB exposure in high-latitude countries is associated with an increased risk of low plasma 25(OH)D(Reference Mosekilde1, Reference Holick9, Reference Adams and Hewison10, Reference Sharma, Barr and Macdonald19Reference Brot, Vestergaard and Kolthoff21). Greenland hosts the most northern habitats on Earth with a high solar zenith angle and consequently a very low intensity of UVB as the radiation is absorbed through its oblique passage through the atmosphere. Also, Greenland is an Arctic environment defined by the mean temperature being below 10°C during the warmest month. This influences clothing habits also during summer. Hence, very limited dermal production of vitamin D is expected in populations in Greenland and dietary sources are crucial to maintain adequate plasma 25(OH)D levels(Reference Kuhlein, Receveur and Soueida25, Reference Kuhnlein and Receveur30Reference Egeland, Johnson-Down and Cao32).

Vitamin D plays a pivotal role in skeletal health and low levels are associated with rickets, osteomalacia and osteoporosis with an increased risk of fractures(Reference Mosekilde1, Reference Bischoff-Ferrari, Willett and Wong48, Reference Adams and Hewison10). Vitamin D may also be important for the functioning of other systems, such as the immune system(Reference Adams and Hewison10, Reference Bikle33). As for the latter, tuberculosis is frequent in Greenland but is associated with both low and high plasma 25(OH)D(Reference Nielsen, Skifte and Andersson34). As for the former, knowledge of Inuit skeletal health is limited. Bone mineral density did not differ between Inuit and non-Inuit in North Greenland(Reference Andersen, Boeskov and Laurberg35). On the other hand, more frequent hip fractures were reported in Alaska compared with southern states in the USA(Reference Pratt and Holloway36). However, that study did not take into consideration differences in hours of sunlight and icy pavements. Still, plasma 25(OH)D is associated with the risk of falls(Reference Bischoff-Ferrari, Dawson-Hughes and Willett2, Reference Larsen, Mosekilde and Foldspang3) and myopathy(Reference Mosekilde1, Reference Pfeifer, Begerow and Minne37, Reference Glerup, Mikkelsen and Poulsen38), even though reports on falls in Greenland are lacking, and a sufficient plasma 25(OH)D status is important to human health(Reference Mosekilde1, Reference Adams and Hewison10, Reference Autier and Gandini39).

Vitamin D is ample in traditional Inuit foods that comprise mainly marine mammals and fish, with blubber from seal and whale considered to be of particular value, in addition to caribou and birds(Reference Kuhnlein and Receveur30). Hence, dietary assessment interviews in a large group of Canadian Inuit have reported an intake of vitamin D exceeding the recommended adequate intake by up to 100 %(Reference Kuhlein, Receveur and Soueida25). It has also been reported that days with meals of traditional Inuit foods provided 25 μg vitamin D(Reference Kuhnlein and Receveur30). In contrast, dietary record studies have reported low intakes of vitamin D in the majority of Canadian Inuit in Nunavut and Northwest Territories(Reference Sharma, Barr and Macdonald19, Reference Sharma, Cao and Roache40Reference Frost43). A contributor to this discrepancy could be dietary transition as the intake of traditional Inuit foods is lower in younger compared with older individuals(Reference Kuhnlein and Receveur30, Reference Kuhnlein, Receveur and Soueida44). This was supported by plasma 25(OH)D in Greenland Inuit in Nuuk and Denmark classified by a weekly intake of marine mammals (yes/no)(Reference Rejnmark, Jørgensen and Pedersen45).

We performed a detailed classification of the diet by including non-Inuit and Inuit living in both an urban area with ample market foods and rural areas with limited availability of these and dependency on hunting and fishing. Participants were categorised based on the frequency of intake of traditional Inuit and imported market foods. This method is limited to the frequency of intake of food items used for main meals and does not include, for example, cereal foods. Also, we did not assess portion size. This hampers the accuracy of our estimates of food intakes but an equal influence on imported and traditional Inuit foods may be anticipated and hence a limited influence on the extent to which groups of subjects were categorised as traditional Inuit or Westernised eaters. Also, the method has been validated for description of the degree of adherence to the traditional Inuit diet(Reference Andersen, Hvingel and Kleinschmidt26). The diet groups were associated markedly with plasma 25(OH)D and we found 88 % higher plasma 25(OH)D values in the group with the highest compared with the lowest intake of traditional Inuit foods. This is twice the difference found in the study with a more crude classification of the diet(Reference Rejnmark, Jørgensen and Pedersen45) but in keeping with the findings among Canadian Inuit(Reference Kuhnlein and Receveur30Reference Egeland, Johnson-Down and Cao32). Still, plasma 25(OH)D was 68 nmol/l in the group with the highest intake of traditional Inuit foods and thus not exceedingly high.

We found plasma 25(OH)D deficiency, defined as plasma 25(OH)D < 50 nmol/l, in one in four subjects in the group with an Inuit diet score below 20 %. This was absent when the diet score was above 40 %. These diet scores correspond to less than weekly intake of Greenlandic food items and an intake three times weekly or more, respectively. The group with an intake of traditional Inuit foods less than weekly had a 25(OH)D level that matched the finding in Nuuk using the more simple dietary classification(Reference Rejnmark, Jørgensen and Pedersen45). The validity of this crude classification was supported by the present finding of seal and whale as the two major food items in the Inuit diet that were important for plasma 25(OH)D. However, such crude classification could not detect a difference in plasma 25(OH)D in a more recent study(Reference Nielsen, Skifte and Andersson34). Thus, our more detailed classification of the traditional Inuit diet contributed to a more comprehensive description of the association between the traditional Inuit diet and plasma 25(OH)D, which is supported by the findings in Canadian Inuit(Reference Kuhnlein and Receveur30).

We also found a higher plasma 25(OH)D in Inuit, who have darker skin compared with non-Inuit(Reference Frost43). This is in keeping with the diet being the source of plasma 25(OH)D as whites tend to have higher 25(OH)D than do those with darker skin at lower latitudes, i.e. in the USA(Reference Yetley46), the UK(Reference Ashwell, Stone and Stolte47) and immigrants to Scandinavia(Reference Islam, Viljakainen and Kärkkäinen48). The study by Rejnmark et al. (Reference Rejnmark, Jørgensen and Pedersen45) found lower plasma 25(OH)D among Inuit than among non-Inuit in Denmark. This may relate to skin pigmentation but further ethnic differences are supported by the present finding that ethnicity modified the influence of diet on plasma 25(OH)D. Our indirect measure of the influence of ethnicity was distinct (P= 0·005) but should be confirmed in direct comparisons. Whether the difference relates to the bioavailability or metabolism of plasma 25(OH)D remains to be settled.

The capital city Nuuk hosts more obese subjects than does the town and settlements in East Greenland(Reference Andersen, Mulvad and Pedersen28). This could contribute to differences in plasma 25(OH)D levels as obesity reduces plasma 25(OH)D levels in other populations(Reference Adams and Hewison10, Reference Wortsman, Matsuoka and Chen49). However, plasma 25(OH)D levels did not associate with BMI or weight in Inuit.

There was an association between the intake of traditional Inuit food items, the differences in the way of living between the study areas, the availability of imported food items, the frequency of fishing and hunting, and the fraction of non-Inuit. This limited the use of linear regression, but similar results were obtained using logistic regression, though this was less sensitive.

We studied only subjects aged 50–69 years. This might underestimate the impact of the transition away from traditional foods as older people eat more traditional foods(Reference Kuhnlein and Receveur30, Reference Kuhnlein, Receveur and Soueida44). Still, the older age group contributed to a high participation rate of 95 %, which supports the validity of the findings in the present population-based survey. Furthermore, the study included populations at the extremes of transition of societies in Greenland from the capital city Nuuk in West Greenland to remote settlements in East Greenland. Data on plasma 25(OH)D among populations in other areas of the more heavily populated west coast of Greenland are relevant as differences may apply in diet, lifestyle and genetics. Also, follow-up on the populations included here is recommended both to examine the effect of low plasma 25(OH)D in Inuit, and to follow up on the impact of future transition in dietary habits. Finally, younger people have a lower intake of traditional Inuit food items with a higher risk of 25(OH)D deficiency(Reference Kuhnlein and Receveur30, Reference Kuhnlein, Receveur and Soueida44). Thus, younger groups should be included in future studies of vitamin D intake and plasma 25(OH)D in Greenland.

In conclusion, we found low plasma 25(OH)D in older people in Greenland who had a low intake of Inuit food items. This observation was associated with the transition of societies in Greenland in keeping with the findings in indigenous populations in the Canadian Arctic. Furthermore, the present study suggests that ethnicity may contribute to differences in plasma 25(OH)D.

Acknowledgements

We gratefully acknowledge Karoline Berglund for her enthusiasm and thorough interviewing of Inuit. We are grateful for invaluable support from lægeklinikken in Nuuk, from Hans Chr. Florian Sørensen and the staff at the hospital in Tasiilaq, and from the staff at the nursing stations in Tiniteqilaaq, Sermiligaaq, Kuummiut and Kulusuk. This study was supported by grants from the following: Greenland Home Government; Karen Elise Jensen Foundation; Northern Jutland Research Foundation; Aalborg City Christmas Lottery; Danish Hospital Foundation for Medical Research, Region of Copenhagen, the Faeroe Islands and Greenland. The authors' contributions are as follows: S. A. contributed to the project conception, study design, raising of funds, data collection, analysis of the data and writing of the manuscript; P. L. participated in the project conception, study design, raising of funds, data collection, analysis of the data and reviewing of the manuscript; B. H. was responsible for the data collection and reviewing of the manuscript; K. K. participated in the study design and reviewing of the manuscript; L. H. was responsible for the analysis of the data, reviewing of the manuscript; L. M. contributed to the conception of the idea and writing of the manuscript. The authors declare that there are no conflicts of interest.

References

1Mosekilde, L (2005) Vitamin D and the elderly. Clin Endocrinol 62, 265281.CrossRefGoogle ScholarPubMed
2Bischoff-Ferrari, HA, Dawson-Hughes, B, Willett, WC, et al. (2004) Effect of vitamin D on falls: a meta-analysis. JAMA 291, 19992006.CrossRefGoogle ScholarPubMed
3Larsen, ER, Mosekilde, L & Foldspang, A (2005) Vitamin D and calcium supplementation prevents severe falls in elderly community-dwelling women: a pragmatic population-based 3-year intervention study. Aging Clin Exp Res 17, 125132.CrossRefGoogle ScholarPubMed
4Bischoff-Ferrari, HA, Willett, WC, Wong, JB, et al. (2009) Prevention of nonvertebral fractures with oral vitamin D and dose dependency: a meta-analysis of randomized controlled trials. Arch Intern Med 169, 551561.CrossRefGoogle ScholarPubMed
5Chapuy, MC, Arlot, ME, Duboeuf, F, et al. (1992) Vitamin D3 and calcium to prevent hip fractures in the elderly women. N Engl J Med 327, 16371642.CrossRefGoogle ScholarPubMed
6Chapuy, MC, Arlot, ME, Delmas, PD, et al. (1994) Effect of calcium and cholecalciferol treatment for three years on hip fractures in elderly women. BMJ 308, 10811082.CrossRefGoogle ScholarPubMed
7Larsen, ER, Mosekilde, L & Foldspang, A (2004) Vitamin D and calcium supplementation prevents osteoporotic fractures in elderly community dwelling residents: a pragmatic population-based 3-year intervention study. J Bone Miner Res 19, 370378.CrossRefGoogle ScholarPubMed
8DIPART group. (2010) Patient level pooled analysis of 68 500 patients from seven major vitamin D fracture trials in US and Europe. (2010) BMJ 340, b5463.CrossRefGoogle Scholar
9Holick, MF (2007) Vitamin D deficiency. N Engl J Med 357, 266281.CrossRefGoogle ScholarPubMed
10Adams, JS & Hewison, M (2010) Update in vitamin D. J Clin Endocrinol Metab 95, 471478.CrossRefGoogle ScholarPubMed
11Jahnsen, J, Falch, JA, Mowinckel, ZP, et al. (2002) Vitamin D status, parathyroid hormone and bone mineral density in patients with inflammatory bowel disease. Scand J Gastroenterol 37, 192197.CrossRefGoogle ScholarPubMed
12Cutolo, M, Plebani, M, Shoenfeld, Y, et al. (2011) Vitamin D endocrine systems and the immune response in rheumatic diseases. Vitam Horm 86, 327351.CrossRefGoogle ScholarPubMed
13Van der Mei, IA, Ponsonby, AL, Dwyer, T, et al. (2003) Past exposure to sun, skin phenotype, and risk of multiple sclerosis: case–control study. BMJ 327, 316.CrossRefGoogle ScholarPubMed
14Pfeifer, M, Begerow, B, Minne, HW, et al. (2001) Effects of a short-term vitamin D(3) and calcium supplementation on blood pressure and parathyroid hormone levels in elderly women. J Clin Endocrinol Metab 86, 16331637.Google ScholarPubMed
15Zittermann, A, Schleithoff, SS & Koerfer, R (2005) Putting cardiovascular disease and vitamin D insufficiency into perspective. Br J Nutr 94, 483492.CrossRefGoogle ScholarPubMed
16Ma, Y, Zhang, P, Wang, F, et al. (2011) Association between vitamin D and risk of colorectal cancer: a systematic review of prospective studies. J Clin Oncol 29, 37753782.CrossRefGoogle ScholarPubMed
17Gissel, T, Rejnmark, L, Mosekilde, L, et al. (2008) Intake of vitamin D and risk of breast cancer – a meta analysis. J Steroid Biochem Mol Biol 111, 195199.CrossRefGoogle ScholarPubMed
18Bell, DS (2011) Protean manifestations of vitamin D deficiency, part 2: deficiency and its association with autoimmune disease, cancer, infection, asthma, dermopathies, insulin resistance, and type 2 diabetes. South Med J 104, 335339.CrossRefGoogle ScholarPubMed
19Sharma, S, Barr, AB, Macdonald, HM, et al. (2011) Vitamin D deficiency and disease risk among aboriginal Arctic populations. Nutr Rev 69, 468478.CrossRefGoogle ScholarPubMed
20Hagenau, T, Vest, R, Gissel, TN, et al. (2009) Global vitamin D levels in relation to age, gender, skin pigmentation and latitude: an ecologic meta-regression analysis. Osteoporos Int 20, 133140.CrossRefGoogle ScholarPubMed
21Brot, C, Vestergaard, P, Kolthoff, N, et al. (2001) Vitamin D status and its adequacy in healthy Danish perimenopausal women: relationships to dietary intake, sun exposure and serum parathyroid hormone. Br J Nutr 86, 97–s103.CrossRefGoogle ScholarPubMed
22Dalgård, C, Petersen, MS, Schmedes, AV, et al. (2010) High latitude and marine diet: vitamin D status in elderly Faroese. Br J Nutr 104, 914918.CrossRefGoogle ScholarPubMed
23Kleiver, KM, Draper, HH & Ronald, KJ (1988) Vitamin D metabolism in the hooded seal (Cystophora cristata). J Nutr 118, 332341.CrossRefGoogle Scholar
24Lu, Z, Chen, TC, Zhang, A, et al. (2007) An evaluation of the vitamin D3 content in fish: is the vitamin D content adequate to satisfy the dietary requirement for vitamin D? J Steroid Biochem Mol Biol 103, 642644.CrossRefGoogle ScholarPubMed
25Kuhlein, HV, Receveur, O, Soueida, R, et al. (2008) Unique patterns of dietary adequacy in three cultures of Canadian Arctic indigenous peoples. Publ Health Nutr 11, 349360.Google Scholar
26Andersen, S, Hvingel, B, Kleinschmidt, K, et al. (2005) Changes in iodine excretion in 50–69-y-old denizens of an Arctic society in transition and iodine excretion as a biomarker of the frequency of consumption of traditional Inuit foods. Am J Clin Nutr 81, 656663.CrossRefGoogle ScholarPubMed
27Bjerregaard, P & Young, TK (1998) The Circumpolar Inuit – Health of a Population in Transition. Copenhagen: Munksgaard.Google Scholar
28Andersen, S, Mulvad, G, Pedersen, HS, et al. (2004) Gender diversity in developing overweight over 35 years of westernization in an Inuit hunter cohort and ethno-specific body mass index for evaluation of body-weight abnormalities. Eur J Endocrinol 151, 735740.CrossRefGoogle Scholar
29Hojskov, CS, Heickendorff, L & Moller, HJ (2010) High-throughput liquid–liquid extraction and LCMSMS assay for determination of circulating 25(OH) vitamin D3 and D2 in the routine clinical laboratory. Clin Chim Acta 411, 114116.CrossRefGoogle ScholarPubMed
30Kuhnlein, HV & Receveur, O (2007) Local cultural animal food contributes high levels of nutrients for Arctic Canadian indigenous adults and children. J Nutr 137, 11101114.CrossRefGoogle ScholarPubMed
31Johnson-Down, L & Egeland, GM (2010) Adequate nutrient intakes are associated with traditional food consumption in Nunavut Inuit children aged 3–5 years. J Nutr 140, 13111316.CrossRefGoogle ScholarPubMed
32Egeland, GM, Johnson-Down, L, Cao, ZR, et al. (2011) Food insecurity and nutrition transition combine to affect nutrient intakes in Canadian arctic communities. J Nutr 141, 17461753.CrossRefGoogle ScholarPubMed
33Bikle, DD (2011) Vitamin D regulation of immune function. Vitam Horm 86, 121.CrossRefGoogle ScholarPubMed
34Nielsen, NO, Skifte, T, Andersson, M, et al. (2010) Both high and low serum vitamin D concentrations are associated with tuberculosis: a case–control study in Greenland. Br J Nutr 104, 14871491.CrossRefGoogle ScholarPubMed
35Andersen, S, Boeskov, E & Laurberg, P (2005) Ethnic differences in bone mineral density between Inuit and Caucasians in North Greenland are caused by differences in body size. J Clin Densitom 8, 409414.CrossRefGoogle ScholarPubMed
36Pratt, WB & Holloway, JM (2001) Incidence of hip fracture in Alaska Inuit people: 1979–89 and 1996–99. Alaska Med 43, 25.Google ScholarPubMed
37Pfeifer, M, Begerow, B, Minne, HW, et al. (2009) Effects of a long-term vitamin D and calcium supplementation on falls and parameters of muscle function in community-dwelling older individuals. Osteoporos Int 20, 315322.CrossRefGoogle ScholarPubMed
38Glerup, H, Mikkelsen, K, Poulsen, L, et al. (2000) Hypovitaminosis D myopathy without biochemical signs of osteomalacic bone involvement. Calcif Tissue Int 66, 419424.CrossRefGoogle ScholarPubMed
39Autier, P & Gandini, S (2007) Vitamin D supplementation and total mortality: a meta-analysis of randomized controlled trials. Arch Int Med 167, 17301737.CrossRefGoogle ScholarPubMed
40Sharma, S, Cao, X, Roache, C, et al. (2010) Assessing dietary intake in a population undergoing a rapid transition in diet and lifestyle: the Arctic Inuit in Nunavut, Canada. Br J Nutr 103, 749759.CrossRefGoogle Scholar
41Erber, E, Hopping, BN, Beck, L, et al. (2010) Assessment of dietary adequacy in a remote Inuvialuit population. J Hum Nutr Diet 23, 3542.CrossRefGoogle Scholar
42El Hayek, J, Egeland, G & Weiler, H (2010) Vitamin D status of Inuit preschoolers reflects season and vitamin D intake. J Nutr 140, 18391845.CrossRefGoogle ScholarPubMed
43Frost, P (2012) Vitamin D deficiency among northern Native Peoples: a real or apparent problem? Int J Circumpolar Health 71, 18001.CrossRefGoogle ScholarPubMed
44Kuhnlein, HV, Receveur, O, Soueida, R, et al. (2004) Arctic indigenous peoples experience the nutrition transition with changing dietary patterns and obesity. J Nutr 124, 14471453.CrossRefGoogle Scholar
45Rejnmark, L, Jørgensen, ME, Pedersen, MB, et al. (2004) Vitamin D insufficiency in Greenlanders on a westernized fare: ethnic differences in calcitropic hormones between Greenlanders and Danes. Calcif Tissue Int 74, 255263.Google ScholarPubMed
46Yetley, EA (2008) Assessing the vitamin D status of the US population. Am J Clin Nutr 88, 558s564s.CrossRefGoogle ScholarPubMed
47Ashwell, M, Stone, EM, Stolte, H, et al. (2010) UK food standards agency workshop report: an investigation of the relative contributions of diet and sunlight to vitamin D status. Br J Nutr 104, 603611.CrossRefGoogle ScholarPubMed
48Islam, MZ, Viljakainen, HT, Kärkkäinen, MU, et al. (2011) Prevalence of vitamin D deficiency and secondary hyperparathyroidism during winter in pre-menopausal Bangladeshi and Somali immigrant and ethnic Finnish women: associations with forearm bone mineral density. Br J Nutr 9, 17.Google Scholar
49Wortsman, J, Matsuoka, LY, Chen, TC, et al. (2000) Decreased bioavailability of vitamin D in obesity. Am J Clin Nutr 72, 690693.CrossRefGoogle ScholarPubMed
Figure 0

Table 1 Descriptive information on participants in the diet and vitamin D survey in East and West Greenland (Number of participants and percentages)

Figure 1

Fig. 1 Food-frequency scores among the population groups in the capital city Nuuk (latitude 64°15′N) in West Greenland and in the Ammassalik district (latitude 65°35′N) in rural East Greenland. Classification was based on frequencies of intake of seven traditional Inuit (seal, whale, wild fowl, fish, reindeer, musk ox and hare) and seven imported food items (pre-cooked meals, potatoes, vegetables, butter, cheese, eggs and fresh fruit). Six different frequency categories were given for each food item from ‘never’ to ‘daily intake’ and a frequency score was calculated. Individuals were categorised based on frequency scores on a scale where 100 % is purely Inuit foods and 0 % is purely imported foods. □, Non-Inuit; , Inuit in city; , Inuit in town; , Inuit in settlement.

Figure 2

Fig. 2 Plasma 25-hydroxyvitamin D (25(OH)D) in each food-frequency group where 100 % is purely Inuit foods and 0 % is purely imported foods. Values are medians, with 25th and 75th percentiles represented by vertical bars.

Figure 3

Fig. 3 Fraction of participants with plasma 25-hydroxyvitamin D below 20 nmol/l (), between 20 and 50 nmol/l () and above 50 nmol/l (□) for each food-frequency group where 100 % is purely Inuit foods and 0 % is purely imported foods.

Figure 4

Fig. 4 Plasma 25-hydroxyvitamin D (25(OH)D) in Inuit and non-Inuit (Caucasian) men and women living in the capital city Nuuk in West Greenland and in the rural Ammassalik district in East Greenland.

Figure 5

Table 2 Factors important to plasma 25-hydroxyvitamin D (25(OH)D) in residents in Greenland (β Coefficients and P values)

You have Access
25
Cited by

Send article to Kindle

To send this article to your Kindle, first ensure no-reply@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about sending to your Kindle. Find out more about sending to your Kindle.

Note you can select to send to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

Find out more about the Kindle Personal Document Service.

Vitamin D status in Greenland is influenced by diet and ethnicity: a population-based survey in an Arctic society in transition
Available formats
×

Send article to Dropbox

To send this article to your Dropbox account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Dropbox.

Vitamin D status in Greenland is influenced by diet and ethnicity: a population-based survey in an Arctic society in transition
Available formats
×

Send article to Google Drive

To send this article to your Google Drive account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Google Drive.

Vitamin D status in Greenland is influenced by diet and ethnicity: a population-based survey in an Arctic society in transition
Available formats
×
×

Reply to: Submit a response

Please enter your response.

Your details

Please enter a valid email address.

Conflicting interests

Do you have any conflicting interests? *