Han Seok Choi, Han Jin Oh, Hoon Choi, Woong Hwan Choi, Jung Gu Kim, Kyoung Min Kim, Kwang Joon Kim, Yumie Rhee, Sung-Kil Lim, Vitamin D Insufficiency in Korea—A Better Menace to Youthful Era: The Korea Nationwide Well being and Diet Examination Survey (KNHANES) 2008, The Journal of Medical Endocrinology & Metabolism, Quantity 96, Subject 3, 1 March 2011, Pages 643–651, https://doi.org/10.1210/jc.2010-2133
It has lengthy been identified that vitamin D performs an essential position in bone and mineral metabolism with its deficiency being intently related to the prevalence of metabolic bone illness akin to rickets in kids and osteomalacia in adults. Just lately, vitamin D can also be drawing curiosity of medical researchers with its vast number of nonskeletal actions on mobile proliferation and differentiation, muscle perform, and immunity (1). Vitamin D receptors have been found in most cells and tissues all through the physique, and a few of them even have the enzyme, 25-hydroxyvitamin d-1α-hydroxylase, which converts the first type of vitamin D to the energetic type (1, 2). Earlier research have proven that vitamin D deficiency or insufficiency is related to a rise within the danger of a number of well being circumstances together with cardiovascular ailments (3–5), diabetes mellitus (6, 7), cancers (8–11), an infection (12–14), and autoimmune ailments (15). It was additionally reported that vitamin D supplementation might cut back the danger of those ailments (16–19).
As increasingly more individuals dwell within the cities spending a majority of their time indoors, individuals can hardly get sufficient daylight publicity for ample cutaneous manufacturing of vitamin D. Thus, vitamin D insufficiency has grow to be a significant well being concern in fashionable society. In a latest examine carried out in 7441 postmenopausal osteoporotic ladies from 29 international locations taking part in a medical trial on bazedoxifene, the prevalence of 25-hydroxyvitamin D [25(OH)D] lower than 20 ng/ml was as a lot as 35.3% in winter and 25.2% in summer time, whereas the prevalence of 25(OH)D of 30 ng/ml or better was 21.2% in winter and 27.5% in summer time (20). In one other examine primarily based on the info of Nationwide Well being and Diet Examination Survey (NHANES) within the U.S. inhabitants, Ginde et al. in contrast serum 25(OH)D ranges from NHANES III, collected throughout 1988 by means of 1994, with NHANES knowledge collected from 2001 by means of 2004 (NHANES 2001–2004), and located a marked lower in serum 25(OH)D ranges from the 1988–1994 to the 2001–2004 knowledge collections (21). The prevalence of serum 25(OH)D ranges of lower than 10 ng/ml elevated from 2% in NHANES III to six% in NHANES 2001–2004, whereas the prevalence of serum 25(OH)D ranges of 30 ng/ml or better decreased from 45% in NHANES III to 23% in NHANES 2001–2004 (21). In Korea, vitamin D insufficiency can also be quite common. In a global epidemiologic examine that investigated the vitamin D standing amongst postmenopausal osteoporotic ladies together with 101 Korean, the imply serum 25(OH)D stage of Korean contributors was 17.6 ng/ml, which was the bottom amongst 18 international locations, and the prevalence of 25(OH)D lower than 30 ng/ml was the best in Korea with a charge of 92.1% (22). Nevertheless, the vitamin D standing within the basic inhabitants of Korea has not been adequately decided.
On this examine, we investigated the vitamin D standing and the prevalence of vitamin D insufficiency within the Korean inhabitants primarily based on the Fourth Korea Nationwide Well being and Diet Examination Surveys (KNHANES IV) performed in 2008, and likewise recognized the predictors for vitamin D insufficiency in Korea. That is the primary nationwide epidemiologic examine for vitamin D standing in Korea.
Topics and Strategies
This examine relies on the info acquired within the second 12 months (2008) of KNHANES IV. The KNHANES has been performed periodically since 1998 to evaluate the well being and dietary standing of the civilian noninstitutionalized inhabitants of the Korea (23). The KNHANES IV was a cross-sectional and nationally consultant survey performed by the Division of Persistent Illness Surveillance, Korea Facilities for Illness Management and Prevention, from 2007 to 2009. The survey consists of a well being interview survey, a diet survey, and a well being examination survey. The survey collected knowledge by way of family interviews and by direct standardized bodily examinations performed in specifically outfitted cell examination facilities. The sampling body was primarily based on the 2005 inhabitants and housing census in Korea. A stratified, multistage likelihood sampling design was used for the collection of family models. Within the second 12 months (2008) of the KNHANES IV, there have been 264,186 main sampling models, every of which contained ≈60 households. 200 sampling frames from main sampling models had been randomly sampled, and 23 households from every sampling body (≈60 households) had been sampled utilizing a systemic sampling methodology. Lastly, 12,528 people in 4,600 households had been sampled, and 9,308 of them participated in well being interviews and well being examination surveys, and eight,641 participated in diet surveys. Amongst those that participated within the survey between February 2008 and December 2008, serum 25(OH)D ranges had been obtained for the investigation of vitamin D standing in Korea. Serum 25(OH)D ranges had been obtained in 3,047 males and three,878 females aged 10 yr and older from all 16 administrative districts of South Korea (Supplemental Desk 1 and Supplemental Fig. 1, revealed on The Endocrine Society’s Journals On-line web page at http://jcem.endojournals.org/). All of the contributors on this survey signed an knowledgeable consent type.
Measurement of serum 25(OH)D
For measurements of serum 25(OH)D ranges, blood samples of particular person topics had been collected in the course of the survey. Blood samples had been correctly processed, instantly refrigerated, and transported in chilly storage to the Central Testing Institute in Seoul, Korea. Blood samples had been analyzed inside 24 h after transportation. Serum 25(OH)D ranges had been measured utilizing a γ counter (1470 Wizard, Perkin-Elmer Finland) with a RIA (DiaSorin, Nonetheless Water, MN). The interassay coefficients of variation had been 11.7%, 10.5%, 8.6%, and 12.5% at 8.6, 22.7, 33.0, and 49.0 ng/ml. We reported the proportion of contributors with serum 25(OH)D stage of lower than 10, 10 to <20, 20 to <30, and 30 ng/ml or better. Vitamin D insufficiency was outlined as serum 25(OH)D stage of lower than 20 ng/ml. Statistical analyses Statistical analyses had been carried out utilizing SAS V9.1 (SAS Institute, Cary, NC). For analyses of the connection between doable predicting components and vitamin D standing, components had been categorized. Age was categorized by 10 yr to analyze the age-related change of serum 25(OH)D ranges. Physique mass index (BMI) had been categorized as <23, 23 to <25, and ≥25 kg/m2, that are the cut-off factors for regular (together with underweight), obese, and weight problems for Asian populations. Seasons had been categorized as spring (March to Could), summer time (June to August), fall (September to November), and winter (February and December). Area was categorized as city and rural. Among the many 16 administrative districts the place this survey was performed, Seoul (the capital metropolis of South Korea) and the encompassing metropolitan space (Gyeonggi), and 6 different metropolitan cities (Busan, Daegu, Incheon, Gwangju, Daejeon, and Ulsan) of South Korea had been grouped as city areas. The rest of the areas (Gangwon, Chungbuk, Chungnam, Jeonbuk, Jeonnam, Gyeongbuk, Gyeongnam, and Jeju) had been grouped as rural areas. As a result of virtually all areas of South Korea are positioned between 33 diploma N and 38 diploma N of latitude, the latitude of the realm was not thought of as a predicting issue for vitamin D standing on this examine. Within the grownup inhabitants, occupation was categorized into seven teams, A (agriculture, forestry, and fishery), B (handbook labor), C (engineering, assembling, and technical work), D (gross sales, and repair), E (administration, clerical work, and specialists), F (college students), and G (not relevant) primarily based on the presumption that every group has a special stage of daylight publicity. Unemployed state, home tasks, and different unclassifiable works had been grouped as G. Common strolling was indicated as ‘yes’ when the topic walks for greater than 30 min at a time and greater than 5 occasions per week, no matter indoor or outside strolling. Common train was indicated as ‘yes’ when the topic does average or extreme train regularly, no matter indoor or outside train (for greater than 30 min at a time and greater than 5 occasions per week in case of average train akin to swimming sluggish, tennis doubles, volleyball, badminton, desk tennis, and carrying gentle stuffs; for greater than 20 min at a time and greater than thrice per week in case of extreme train akin to operating, climbing, biking quick, swimming quick, soccer, basketball, soar rope, squash, tennis singles, and carrying heavy stuffs). To match the imply serum 25(OH)D ranges among the many classes in every doable predicting issue, Pupil's t checks or ANOVA had been used. Univariate logistic regression analyses had been used to judge the affiliation between doable predicting components and vitamin D insufficiency. Multivariate logistic regression analyses had been additionally used to seek out the impartial predictors for vitamin D deficiency. All checks are two-sided, and P < 0.05 was thought of statistically important.
Outcomes
The baseline traits and serum 25(OH) ranges of topics are offered in Desk 1. The common age was 42.4 ± 19.6 yr with a variety of 10–91 in males, and 45.0 ± 19.3 yr with a variety of 10–93 in females.
Serum 25(OH)D stage and the prevalence of vitamin D insufficiency
The imply serum stage of 25(OH)D was 21.2 ± 7.5 ng/ml in males and 18.2 ± 7.1 ng/ml in females. Vitamin D insufficiency was present in 47.3% of males and 64.5% of females, whereas solely 13.2% of males and 6.7% of females had a serum 25(OH)D stage of better than 30 ng/ml (Desk 1).
The age-related change of serum 25(OH)D stage in female and male is illustrated in Fig. 1 and Supplemental Fig. 2. From the ages of 10–19, imply serum 25(OH)D stage decreased, reaching its lowest stage on the age vary of 20–29, then elevated, reaching its peak on the age of 60–69, then decreased once more in each sexes.
Determine 2 demonstrates the proportion of contributors with serum 25(OH)D ranges of lower than 10, 10 to <20, 20 to <30, and 30 ng/ml or better, stratified by 10-year age classes. In each sexes, the prevalence of vitamin D insufficiency elevated from the age of 10–19, reaching its peak on the age of 20–29 (65.0% in male and 79.9% in feminine), and decreased, reaching its lowest ranges on the age of 60–69 in male and 50–59 in feminine, then elevated once more. To exclude the impact of seasons, we additionally analyzed the prevalence of vitamin D insufficiency in every season, and will observe the same sample in every season (Supplemental Fig. 3).
In grownup contributors aged 20 yr or older, the prevalence of vitamin D insufficiency in varied occupation teams is illustrated in Fig. 3. As anticipated, topics in group A, who often work open air and due to this fact have extra likelihood of daylight publicity, had the bottom charge of vitamin D insufficiency in each males (19.7%) and females (34.9%), whereas those that often work indoors had a better charge of vitamin D insufficiency. Curiously, college students additionally had very excessive charges of vitamin D insufficiency in each male (69.1%) and feminine (75.8%). In contributors youthful than 20 yr of age, the prevalence of vitamin D insufficiency by faculty they attend is offered in Supplemental Fig. 4. Members in larger grades confirmed larger ranges of vitamin D insufficiency. Predictors for vitamin D insufficiency in adults We additionally performed statistical analyses to seek out the predictors for vitamin D insufficiency in adults aged 20 yr or older. Attainable predicting components in our examine included age, BMI, season, area, occupation, common strolling, and train. Desk 2 shows the doable predicting components for serum 25(OH)D ranges and the imply serum 25(OH)D ranges by totally different traits. ANOVA or Pupil t check confirmed that imply serum 25(OH)D ranges are considerably totally different between the teams of all components aside from BMI in males. Univariate logistic regression analyses had been used to find out predictors related to the prevalence of vitamin D insufficiency in adults (Supplemental Desk 2). All of the doable predicting components aside from BMI in males had been discovered to have statistically important associations with vitamin D insufficiency. Fig. 4 exhibits the outcomes of multivariate logistic regression analyses to find out impartial predictors for vitamin D insufficiency in each sexes. Within the multivariate logistic regression mannequin together with all of the doable predicting components in Desk 2, age teams (20–29, 30–39, and 40–49), season (spring and winter), area (city), occupations (B–G), and common train (no) had been discovered to be impartial predictors for vitamin D insufficiency in each sexes. As well as, age group (≥80) was additionally an impartial predictor in male, and BMI (<23) and common strolling (no) had been impartial predictors in feminine for vitamin D insufficiency.Dialogue
Outdated age has been recommended as a danger issue for vitamin D insufficiency as a result of the cutaneous synthesis of vitamin D3 declines with age (1, 24, 25). It was reported that growing older can lower by >2-fold the capability of the pores and skin to supply previtamin D3 in response to UV radiation (24). Unexpectedly, nonetheless, our outcomes confirmed that the serum 25(OH)D stage will increase with age from 20–29 to 60–69 in each sexes, and vitamin D insufficiency was most prevalent within the age of 20–29. In statistical analyses to establish the predictors for vitamin D insufficiency in Korean adults, predictors for vitamin insufficiency included younger age teams, spring and winter seasons, dwelling in an city space, and indoor occupations. A lot to our remorse, KNHANES didn’t embody the questions on every topic’s quantity of daylight publicity. As a substitute, we obtained the info concerning contributors’ occupation, which presumably displays the every topic’s quantity of daylight publicity. Those that work in agriculture, forestry, or fishery often spend their working time open air, thereby having extra publicity of daylight than those that spend their working time indoors. As we anticipated, there have been associations between occupation and vitamin D standing. Those that often work indoors had been extra predisposed to vitamin D insufficiency, whereas those that work open air have comparatively larger serum ranges of vitamin D. Additional analyses of our knowledge additionally revealed that there exists a transparent distinction within the sorts of jobs occupied by younger and older generations (knowledge not proven). Younger adults are likely to have indoor jobs, whereas aged adults are likely to have outside jobs. This phenomenon, which may be noticed in different industrialized international locations, is said to the fast financial improvement over the previous three a long time in Korea. As Korea’s most important business has modified from agriculture and fishery to manufacturing and commerce, youthful generations have moved to and settled in city areas and purchased indoor jobs, whereas older generations have stayed in rural areas, working in agriculture, forestry, or fishery. This partially explains why the youthful era is at better danger for vitamin D insufficiency than older era in Korea. Nevertheless, even after adjusting for different confounders, youthful age teams had been nonetheless impartial predictors for vitamin D insufficiency in our examine. Though the reason for this discovering is just not clear, it could be on account of different behavioral components that we didn’t alter within the statistical analyses, which can embody indoor life-style, sunscreen use, outside exercise, or dietary habits. One other attention-grabbing end in our examine is a really excessive prevalence of vitamin D insufficiency in college students, particularly these in highschool or school. It’s possible that these college students might have comparable daylight publicity to indoor staff as a result of additionally they spend a lot time in indoor locations akin to faculty or library.
Beforehand, larger prevalence of vitamin D insufficiency in youthful age teams was additionally famous within the Nationwide Weight-reduction plan and Diet Survey (NDNS) 1992–2001 of the UK (26). The survey confirmed that vitamin D deficiency or insufficiency was most prevalent in younger adults aged 19–24 yr in addition to within the aged over the age of 85 yr. The examine by Ginde et al. (21) primarily based on NHANES database in U.S. inhabitants, which in contrast serum 25(OH)D ranges from NHANES III (1988–1994) with NHANES 2001–2004, additionally offers us some implications. Within the NHANES III (1988–1994), there was a particular pattern towards decrease serum 25(OH)D ranges with growing age. Nevertheless, within the NHANES 2001–2004 database, serum 25(OH)D ranges had been comparable throughout the age spectrum. Earlier variations of serum 25(OH)D ranges by age equalized. They speculated that the lack of age-related variations of serum 25(OH)D could be secondary to disproportionately better time spent indoors and fewer time spent open air amongst youthful in contrast with older people. Together with our examine, these research primarily based on the NDNS of the UK and NHANES of the USA additionally suggest that vitamin D insufficiency is just not solely an issue of older generations anymore but in addition an essential well being concern amongst youthful generations.
The Meals and Diet Board on the Institute of Medication of The Nationwide Academies developed the dietary reference intakes (DRIs) for U.S. and Canadian populations in 1997. The DRIs of vitamin D, that are stratified by age, state that ample intakes of vitamin D are 200 IU every day for younger adults beneath 50, 400 IU every day for these aged between 51 and 70, and 600 IU every day for these aged over 70 (27). Nevertheless, a number of scientists and analysis teams have recommended that new evidences exhibit the necessity to revise the DRIs of vitamin D by growing the reference values (27, 28). The Nationwide Osteoporosis Basis presently recommends 400–800 IU of vitamin D every day for adults beneath 50 and 800-1000 IU of vitamin D every day for adults aged over 50. The Korean Diet Society additionally revealed the DRIs for Koreans in 2005 (29). The ample intakes of vitamin D had been established at 200 IU every day for younger Korean adults, and 400 IU every day for adults aged over 50 yr. Primarily based on the outcomes of our examine, nonetheless, we discovered that the present DRIs of vitamin D for Koreans aren’t sufficient to take care of adequate serum 25(OH)D ranges, particularly for younger adults. That’s as a result of every day consumption of 400 IU vitamin D would elevate serum 25(OH)D by solely 3.6–5.6 ng/ml in wholesome younger adults (30), whereas it may elevate the extent by as a lot as 14–16 ng/ml within the aged (31, 32). We additionally recommend that the present age stratification in suggestions for vitamin D consumption is probably not affordable at the very least in Korea. Our outcomes confirmed that younger adults at the moment are at better danger for vitamin D insufficiency than the aged. Thus, younger adults may have vitamin D supplementation as a lot as or much more than that for the aged. Additionally, occupation of every particular person ought to be thought of once we advocate vitamin D supplementation. Those that spend most of their time indoors may have extra dosage of vitamin D dietary supplements than those that spend their time open air.
The current examine has some limitations. First, we didn’t inquire into every particular person’s quantity of daylight publicity. We solely assumed that those that work open air would have extra daylight publicity, whereas those that work indoors would have much less. Thus, we couldn’t estimate how the extent of daylight publicity really differs among the many varied occupations. Second, we didn’t get hold of knowledge concerning behavioral components that would have an effect on cutaneous synthesis of vitamin D akin to sunscreen use or clothes. Third, we didn’t get hold of knowledge concerning every particular person’s vitamin D consumption by means of weight-reduction plan and dietary supplements, which could have affected the topic’s vitamin D standing to some extent. Fourth, serum 25(OH)D ranges in January, that are presumed to be among the many lowest within the 12-month cycle, weren’t included on this examine. Subsequently, it’s possible that the prevalence of vitamin D insufficiency within the 12 months was considerably underestimated in our examine.
In conclusion, we discovered that vitamin D insufficiency is a quite common well being drawback in Korea. Our examine additionally implies that vitamin D insufficiency is now a better risk to youthful era. Additional examine is critical to analyze whether or not this discovering is a more moderen worldwide pattern within the fashionable epidemic of vitamin D insufficiency. As our outcomes recommend, younger individuals who dwell in city areas working indoors are at better danger of vitamin D insufficiency, particularly in spring and winter. Primarily based on our outcomes, we propose that present suggestions for vitamin D intakes are insufficient for Koreans, particularly for the youthful inhabitants, and that age stratification in suggestions for vitamin D consumption is probably not affordable. Moreover, occupation and different behavioral components of every particular person should be thought of within the suggestions for vitamin D consumption.
Acknowledgments
Disclosure Abstract: The authors don’t have anything to declare.
Abbreviations: – “vitamin d korea”
References
Supplementary knowledge
“vitamin d korea”