Characteristics of incidence hip fracture cases in older adults participating in the longitudinal AGES-Reykjavik study.

Poor physical function and body composition my partly predict the risk of falls leading to fracture regardless of bone mineral density. INTRODUCTION: To examine the relationship between body composition, physical function, and other markers of health with hip fractures in older community-dwelling Icelandic adults. METHODS: A prospective cohort of 4782 older adults from the AGES-Reykjavik study. Baseline recruitment took place between 2002 and 2006, and information on hip fractures occurring through 2012 was extracted from clinical records. Using multivariate regression analyses, baseline measures of bone health, physical function, and body composition were compared between those who later experienced hip fractures and to those who did not. Associations with the risk of fractures were quantified using Cox regression. RESULTS: Mean age was 76.3 years at baseline. After adjustment for age, regression showed that male hip fracture cases compared with non-cases had (mean (95% confidence interval)) significantly lower thigh muscle cross-sectional area - 5.6 cm2 (- 10.2, - 1.1), poorer leg strength - 28 N (- 49, - 7), and decreased physical function as measured by longer timed up and go test 1.1 s (0.5, 1.7). After adjustment for age, female cases had, compared with non-cases, lower body mass index - 1.5 kg/m2 (- 2.1, - 0.9), less lean mass - 1.6 kg (- 2.5, - 0.8), thigh muscle cross-sectional area - 4.4 cm2 (- 6.5, - 2.3), and worse leg strength - 16 N (- 25, - 6). These differences largely persisted after further adjustment for bone mineral density (BMD), suggesting that body composition may contribute to the risk of fracture independent of bone health. When examining the association between these same factors and hip fractures using Cox regression, the same conclusions were reached. CONCLUSIONS: After accounting for age and BMD, older adults who later experienced a hip fracture had poorer baseline measures of physical function and/or body composition, which may at least partly contribute to the risk of falls leading to fracture.

Correction to: Characteristics of incidence hip fracture cases in older adults participating in the longitudinal AGES-Reykjavik study.

The original version of this article, published on 18 august 2020 contained a mistake. An author's name was misspelled.

Milk consumption throughout life and bone mineral content and density in elderly men and women.

UNLABELLED: Association between bone mineral density and bone mineral content in old age and milk consumption in adolescence, midlife, and old age was assessed. The association was strongest for milk consumption in midlife: those drinking milk daily or more often had higher bone mineral density and content in old age than those drinking milk seldom or never. INTRODUCTION: The role of lifelong milk consumption for bone mineral density (BMD) and bone mineral content (BMC) in old age is not clear. Here we assess the association between hip BMD and BMC in old age and milk consumption in adolescence, midlife, and current old age. METHODS: Participants of the Age, Gene/Environment Susceptibility-Reykjavik Study, aged 66-96 years (N = 4,797), reported retrospective milk intake during adolescence and midlife as well as in current old age, using a validated food frequency questionnaire. BMC of femoral neck and trochanteric area was measured by volumetric quantitative computed tomography and BMD obtained. Association was assessed using linear regression models. Differences in BMC, bone volume, and BMD in relation to milk intake were portrayed as gender-specific Z-scores. RESULTS: Men consuming milk ≥ once/day during midlife had 0.21 higher Z-scores for BMD and 0.18 for BMC in femoral neck (95 % confidence interval 0.05-0.39 and 0.01-0.35, respectively) compared with < once/week. Results were comparable for trochanter. For women the results were similar, with slightly lower differences according to midlife milk consumption. For current and adolescent milk consumption, differences in Z-scores were smaller and only reached statistical significance in the case of BMD for current consumption in men, while this association was less pronounced for BMC. CONCLUSIONS: Our data suggest that regular milk consumption throughout life, from adolescence to old age, is associated with higher BMC and BMD in old age, with no differences seen in bone volume. The strongest associations are seen for midlife milk consumption in both genders.

Maternal milk consumption, birth size and adult height of offspring: a prospective cohort study with 20 years of follow-up.

BACKGROUND/OBJECTIVES: Previous studies have suggested that milk consumption during pregnancy may have growth-promoting effects on the offspring in utero. Whether this effect tracks beyond the prenatal period remains unclear. We examined whether milk consumption during pregnancy is associated with infant size at birth and offspring's height- and growth-related biomarkers at ∼20 years of age. SUBJECT/METHODS: A prospective cohort of 809 Danish pregnant women was recruited in 1988-1989, with offspring follow-up at ∼20 years of age (n=685). Milk consumption was assessed at gestational week 30 using a food frequency questionnaire. Birth weight and birth length were measured according to standard procedures at delivery and converted to specific z-scores, adjusted for gestational age and gender. RESULTS: In adjusted models, maternal milk consumption of ≥150 ml/day vs <150 ml/day was associated with 0.32 higher z-scores for birth weight (95% confidence interval (CI) 0.06; 0.58) and 0.34 higher z-scores for birth length (95% CI 0.04; 0.64). At follow up, ∼20 years later, those offspring whose mothers had consumed < 150 ml milk/day tended to have 0.19 higher z-scores for height (P=0.16), ∼8% higher levels of insulin-like growth factor I (P=0.12) and ∼14% higher insulin levels (P=0.11) compared with offspring whose mothers consumed <150 ml milk/day. CONCLUSIONS: Our findings add to recent observations that maternal milk consumption may have a growth-promoting effect with respect to weight and length at birth. Furthermore, the results provide some suggestion that this effect may even track into early adult age, although further studies with more statistical power are needed for that purpose.

Validity of retrospective diet history: assessing recall of midlife diet using food frequency questionnaire in later life.

OBJECTIVES: Limited information exists on the validity of dietary information given by elderly people on their past diet. Here we test the relative validity of a food frequency questionnaire asking older persons about their midlife diet. DESIGN: Retrospective food intake of 56-72-year-old subjects was estimated using a food frequency questionnaire designed for the AGES-Reykjavik Study (AGES-FFQ), an epidemiological study of older individuals. Results were compared with detailed dietary data gathered from the same individuals 18-19 years previously, i.e., in midlife, as part of a national cohort. Spearman correlation and cross-classifications were used to assess the ability of the AGES-FFQ to rank subjects according to their intake. SETTING: Nationwide, Iceland. PARTICIPANTS: Subjects, born 1937-1952 (n=174), who participated in the 1990 Icelandic National Dietary Survey. MEASUREMENTS: Dietary intake, estimated by the AGES-FFQ (2008-2009), and dietary history obtained from the 1990 Icelandic National Dietary Survey as a reference method. RESULTS: The strongest correlation between the AGES-FFQ and the reference method was found for cod liver oil, r=0.53, p<0.001 and r=0.56, p<0.001, for men and women, respectively. For men the corresponding correlation coefficient for milk and dairy products was r=0.43, p<0.001. The correlation coefficients were lower but within a reasonably acceptable range (r=0.26-0.40) for meat, fish and potatoes for both genders, as well as fresh fruits and milk/dairy products for women and whole-wheat bread, oatmeal/muesli and blood/liver-sausage for men. No correlation was found between the AGES-FFQ and the dietary history for rye bread and vegetable consumption. Subjects were categorized into five groups according to level of consumption by the two methods. Cross-classification showed that 16-59% were classified into same group and 43-91% into same or adjacent group, 0-14% were grossly misclassified into opposite groups. CONCLUSION: The AGES-FFQ on midlife diet was found suitable to rank individuals by their intake of several important food groups.

Iodine status of adolescent girls in a population changing from high to lower fish consumption.

OBJECTIVES: During the last decades, fish and milk consumption has decreased considerably in Iceland, especially among adolescents. As these food items are important dietary iodine (I) sources, the aim of the study was to assess the iodine status and dietary pattern of adolescent girls in a population changing from a high to lower consumption of milk and fish. SUBJECTS/METHODS: Subjects were randomly selected adolescent girls (16-20 years old, n=112). A validated Food Frequency Questionnaire (FFQ) was used to evaluate food consumption and compare it with food-based dietary guidelines for milk and dairy products (2-3 portions/day) and fish (> or =2 times/week). Urine samples were collected for measuring urinary iodine (U-I) and creatinine (Cr) and blood samples for measuring serum thyroid-stimulating hormone (TSH). RESULTS: Milk and dairy products provided 43% and fish provided 24% of the total dietary I. More than 65% of the girls consumed fish less than twice a week, and 40% consumed less than two portions of milk and dairy products per day. The median U-I concentration was 200 microg/l and the U-I/Cr ratio 138 microg I/g Cr. High intake of milk was associated with higher urinary iodine concentration, but fish intake was not found to be directly associated with urinary iodine concentration. CONCLUSIONS: Iodine status of Icelandic adolescent girls is within the optimal range defined by the World Health Organization. It is important to monitor both iodine status and the iodine concentration of important sources of iodine, as both dietary habits and composition of food might change with time.

Combined effects of maternal smoking status and dietary intake related to weight gain and birth size parameters.

OBJECTIVE: To investigate the interaction of smoking status and dietary intake during pregnancy and its relationship to maternal weight gain and birth size parameters. DESIGN: An observational prospective study. SETTING: Free-living conditions. POPULATION: Four hundred and eight healthy pregnant Icelandic women. METHODS: Maternal smoking status, lifestyle factors and dietary habits were evaluated with questionnaires. Intake of foods and supplements was also estimated with a semiquantitative food frequency questionnaire for the previous 3 months. All questionnaires were filled out between 11 and 15 weeks and between 34 and 37 weeks of gestation. Smoking status in relation to optimal and/or excessive weight gain during pregnancy was represented with logistic regression controlling for potential confounding factors. MAIN OUTCOME MEASURES: Maternal weight gain, smoking status, dietary intake and birthweight. RESULTS: Women who smoked throughout pregnancy were unlikely to gain optimal weight or more (OR 0.51, 95% CI 0.27-0.97), whereas smoking cessation in connection with pregnancy ('former smokers') doubled the risk of excessive weight gain (OR 2.03, 95% CI 1.24-3.35). The latter association was no longer significant after adjustment for dietary factors and other confounding factors. Former smokers ate the least amount of fruit and vegetables (fruit: 129 versus 180 and 144 g/day (median), P= 0.038; vegetables: 53 versus 76 and 72 g/day, P= 0.026 for former smokers, nonsmokers and smokers, respectively). Birthweight was lowest among infants born to smokers, but birthweight was similar for former smokers and nonsmokers (3583 +/- 491 g versus 3791 +/- 461 g and 3826 +/- 466 g, respectively; P= 0.003). CONCLUSIONS: Smoking cessation in early pregnancy or pre-pregnancy is not associated with low birthweight. It is, however, associated with excessive maternal weight gain and a low fruit and vegetable intake.

Relationship between high consumption of marine fatty acids in early pregnancy and hypertensive disorders in pregnancy.

OBJECTIVE: To investigate whether there is a relationship between maternal intake of cod-liver oil in early and late pregnancy and hypertensive disorders in pregnancy. DESIGN: An observational prospective study. SETTING: Free-living conditions in a community with traditional fish and cod-liver oil consumption. POPULATION: Four hundred and eighty-eight low-risk pregnant Icelandic women. METHODS: Maternal use of cod-liver oil, foods and other supplements was estimated with a semiquantitative food frequency questionnaire covering food intake together with lifestyle factors for the previous 3 months. Questionnaires were filled out twice, between 11 and 15 weeks of gestation and between 34 and 37 weeks of gestation. Supplements related to hypertensive disorders in pregnancy, i.e. gestational hypertension and pre-eclampsia, were presented, with logistic regression controlling for potential confounding. MAIN OUTCOME MEASURES: Gestational hypertension, pre-eclampsia, cod-liver oil and multivitamins. RESULTS: The odds ratio for developing hypertensive disorders in pregnancy for women consuming liquid cod-liver oil was 4.7 (95% CI 1.8-12.6, P= 0.002), after adjusting for confounding factors. By dividing the amount of n-3 long-chain polyunsaturated fatty acids (n-3 LCPUFA) into centiles, the odds ratio for hypertensive disorders across groups for n-3 LCPUFA suggested a u-shaped curve (P = 0.008). Similar results were found for gestational hypertension alone. Further, the use of multivitamin supplements without vitamins A and D in late pregnancy doubled the odds of hypertensive disorders (OR 2.4, 95% CI 1.0-5.4, P= 0.044). CONCLUSIONS: Consumption of high doses of n-3 LCPUFA in early pregnancy, or other nutrients found in liquid cod-liver oil, may increase the risk of developing hypertensive disorders in pregnancy.

Maternal diet in early and late pregnancy in relation to weight gain.

OBJECTIVE: To identify dietary factors related to the risk of gaining weight outside recommendations for pregnancy weight gain and birth outcome. DESIGN: An observational study with free-living conditions. SUBJECTS: Four hundred and ninety five healthy pregnant Icelandic women. METHODS: The dietary intake of the women was estimated with a semiquantitative food frequency questionnaire covering food intake together with lifestyle factors for the previous 3 months. Questionnaires were filled out at between 11 and 15 weeks and between 34 and 37 weeks gestation. Comparison of birth outcome between the three weight gain groups was made with ANOVA and Bonferroni post hoc tests. Dietary factors related to at least optimal and excessive weight gain during pregnancy were represented with logistic regression controlling for potential confounding. RESULTS: Of the women, 26% gained suboptimal and 34% excessive weight during pregnancy. Women in late pregnancy with at least optimal, compared with women with suboptimal, weight gain were eating more (OR = 3.32, confidence interval (CI)=1.81-6.09, P < 0.001) and drinking more milk (OR = 3.10, CI = 1.57-6.13, P = 0.001). The same dietary factors were related to excessive, compared with optimal, weight gain. Furthermore, eating more sweets early in pregnancy increased the risk of gaining excessive weight (OR=2.52, CI=1.10-5.77, P=0.029). Women with a body mass index of 25.0-29.9 kg/m(2) before pregnancy were most likely to gain excessive weight (OR = 7.37, CI 4.13-13.14, P < 0.001). Women gaining suboptimal weight gave birth to lighter children (P < 0.001) and had shorter gestation (P = 0.008) than women gaining optimal or excessive weight. CONCLUSION: Women who are overweight before pregnancy should get special attention regarding lifestyle modifications affecting consequent weight gain during pregnancy. They are most likely to gain excessive weight and therefore most likely to suffer pregnancy and delivery complications and struggle with increasing overweight and obesity after giving birth.

Physical activity in the post-pubertal period is associated with maintenance of pre-pubertal high bone density-- a 5-year follow-up.

OBJECTIVE: To evaluate the association between physical activity (PA) and skeletal growth in girls during adolescence. DESIGN: A 5-year, observational, population-based study (Reykjavik, Iceland). SUBJECTS: Seventy-eight Caucasian girls, mean age 13.4+/-1.0 (mean+/-SD) years at baseline. METHODS: Bone mineral density (BMD, g/cm2) and bone width (cm) were measured in the forearm by single-photon absorptiometry at baseline and with dual-energy X-ray absorptiometry after 3 and 5 years, when lumbar spine, femoral neck (FN) and total body were also evaluated. Half of the physically active girls were compared with the other half of less active girls. RESULTS: BMD in physically active girls was higher in the forearm at both baseline (P=0.001) and after 5 years (P=0.04) in comparison with less active girls. BMD was higher for the total body (P=0.0001), spine L2-L4 (P=0.02) and FN (P=0.002) in the active girls at age 18. The accrual of forearm BMD and bone width from age 13 to 18 was no different when comparing the two groups. CONCLUSIONS: Pre-pubertal PA is associated with high BMD at age 13 and continued PA is associated with maintenance of high BMD until age 18.

Selection of relevant dietary indicators for health.

OBJECTIVE: To define a set of dietary components that are relevant determinants for health in Europe. The selected components are intended to serve as nutrition indicators for health in the European Health Monitoring Programme and, as such, must be limited in number, relevant to health in Europe and practical for all involved countries with respect to data gathering and comparability of data. DESIGN: Major nutrition factors were determined by reviewing relevant epidemiological and clinical literature in nutrition and health as well as referring to reports from international expert groups, including the report from the project Nutrition and Diet for Healthy Lifestyles in Europe. The selection of factors was also based on the relative ease and cost involved for participating countries to obtain comparable and valid data. RESULTS: The selected factors include foods or food groups as well as individual nutrients. Biomarkers are suggested for selected nutrients that pose the greatest difficulty in obtaining valid and comparable data from dietary studies. CONCLUSIONS: The following list of diet indicators for health monitoring in Europe was agreed upon by the EFCOSUM group in 2001, in order of priority: vegetables, fruit, bread, fish, saturated fatty acids as percentage of energy (%E), total fat as %E, and ethanol in grams per day. Biomarkers were suggested for the following nutrients: folate, vitamin D, iron, iodine and sodium. Energy has to be assessed in order to calculate %E from total fat and saturated fatty acids.

A European food consumption survey method--conclusions and recommendations.

OBJECTIVE: To discuss the general outcome and conclusions of a European project (EFCOSUM); to develop a method for a European food consumption survey that delivers internationally comparable data on a set of policy relevant nutritional indicators. DESIGN AND METHODS: The EFCOSUM project was carried out within the framework of the European Health Monitoring Programme by 14 Member States as well as nine other European countries. Activities of the project included plenary sessions, desk research and working group activities, building on existing experience from such projects as DAFNE, EPIC, FLAIR Eurofoods-Enfant project, COST Action 99 and others. All participating states took part in one or more working group activities, which were discussed, adapted and finally approved in plenary sessions. RESULTS AND CONCLUSIONS: For a limited number of countries available food consumption data can be made comparable at the food intake level, but not at the nutrient level. To achieve comparability at the food intake level, a considerable amount of work still has to be done. A minimum list of dietary indicators considered to be the most relevant to be collected for the Health information exchange and monitoring system was identified. As the most suitable method to get internationally comparable new data on population means and distributions of actual intake the 24 h recall was selected, to be conducted at least twice. This also allows for the estimation of usual intake by a modelling technique that separates intra- and inter-individual intake. For a number of micronutrients the use of biomarkers is recommended. Aspects of food classification and food composition were discussed thoroughly, as well as statistical and data collection aspects. For the implementation of a pan-European survey the establishment of a European co-ordinating centre is recommended. The standardization of field work work procedures and other aspects of operationalization have been discussed in detail. It is concluded that there is broad European consensus on the most suitable method for a pan-European dietary survey for the purposes of the EU Health Monitoring Programme. It is further concluded that such a pan-European survey is feasible, if the funds are made available.

[Trends in overweight and obesity in 45-64 year old men and women in Reykjavik 1975-1994.].

OBJECTIVE: The aim of this study was to assess possible changes in the prevalence of overweight and obesity in Iceland during the last decades. Furthermore, the possible effect of dietary changes on the observed trend in obesity prevalence was evaluated. MATERIAL AND METHODS: Participants came from stages III-V in the Reykjavik Health Study and the Reykjavik part of the MONICA studies from the period 1975-1994. The age groups 45-54 years and 55-64 years were examined. Only the information from the first visit of each person was included. The body mass index (BMI) for the participants was calculated and the percentage of those subjects considered overweight and obese according to WHO standards evaluated, using 25BMI<30 kg/m(2) as the cut-off point for overweight and BMI30 kg/m(2) as the cut-off point for obesity. Also, the observed trend in obesity prevalence is compared to changes in diet that have occurred in the same period. RESULTS: The results show that the mean weight and height of both men and women have been increasing during the study period. However, weight has increased more than can be accounted for by increased height, resulting in increased BMI. At the same time, the prevalence of overweight and obesity have increased, the relative increase in obesity far exceeding the relative increase in overweight. The prevalence of obesity more than doubled in both age groups of women during the study period, according to trend analyses. At the end of the period, almost 15% (95% confidence interval (CI), 9-22%) in the younger group of women and 25% (95% CI, 17-34%) in the older group were classified as obese. In the younger group of men, the prevalence of obesity almost doubled, while the observed increase in the older group was not statistically significant, according to trend analyses. The prevalence of obesity in the final period was about 19% (95% CI, 13-27%) and 17% (95% CI, 11-25%) in the younger and older groups of men, respectively. According to the food supply statistics there have been insignificant changes in the consumption of energy nutrients during the period. CONCLUSIONS: Overweight and obesity are becoming more common among middle-aged men and women in Reykjavik, during the period 1975-1994 and the rate of increase being comparable to that observed in many Western countries. It is urgent to respond to this problem by promoting a healthier lifestyle, both with respect to diet and physical activity.

Different beta-casein fractions in Icelandic versus Scandinavian cow's milk may influence diabetogenicity of cow's milk in infancy and explain low incidence of insulin-dependent diabetes mellitus in Iceland.

OBJECTIVES: To compare children with insulin-dependent diabetes mellitus (IDDM) with controls in Iceland regarding their consumption of cow's milk in infancy, and to investigate the beta-casein fractions in Scandinavian and Icelandic cow's milk. The A1 variant of beta-casein has been shown to be diabetogenic in animal studies, and suggestions have been made that the B variant of beta-casein acts similarly. Differences in the relative proportions of beta-casein fractions might explain the lower incidence of IDDM in Iceland than in Scandinavia. METHODS: A retrospective case-control study on IDDM patients and matching controls was performed in Iceland to compare their diets in infancy. Fifty-five children with IDDM born in Iceland over a 16-year period and randomly collected controls (n = 165) were recruited to the study. Mothers of the children answered questions on breastfeeding habits and on when cow's milk products were introduced. Samples of cow's milk from randomly selected milk batches from the largest consumption areas in Iceland and Scandinavia were collected. The milk samples were freeze-dried and their beta-casein fractions were analyzed using capillary electrophoresis. RESULTS: No significant difference was found between IDDM patients and controls in the frequency and duration of breastfeeding or the first introduction of cow's milk products. The analyses of milk samples showed that the percentage of the A1 and B variants of beta-casein in Icelandic milk was significantly lower than in the milk from the Scandinavian countries. CONCLUSIONS: Cow's milk consumption in infancy is not related to IDDM in Iceland. The lower fraction of A1 and B beta-caseins in Icelandic cow's milk may explain why there is a lower incidence of IDDM in Iceland than in Scandinavia.

Association between trans fatty acid intake and cardiovascular risk factors in Europe: the TRANSFAIR study.

BACKGROUND: High intakes of trans fatty acids (TFA) have been found to exert an undesirable effect on serum lipid profiles, and thus may increase the risk for cardiovascular disease. OBJECTIVES: Investigation of the association between TFA intake and serum lipids. DESIGN: Cross-sectional study in eight European countries (Finland, France, Greece, Iceland, The Netherlands, Portugal, Spain, Sweden) among 327 men and 299 women (50-65 y). Using a dietary history method, food consumption was assessed and TFA intake was calculated with recent figures on TFA levels of foods, collected in the TRANSFAIR study. RESULTS: Mean (+/-s.d.) TFA intake was 2.40+/-1.53 g/day for men and 1.98+/-1.49 g/day for women (0.87+/-0.48% and 0. 95+/-0.55% of energy, respectively), with the highest consumption in Iceland and the lowest in the Mediterranean countries. No associations were found between total TFA intake and LDL, HDL or LDL/HDL ratio after adjustment for cardiovascular risk factors. Additional adjustment for other fatty acid clusters resulted in a significant inverse trend between total TFA intake and total cholesterol (Ptrend<0.03). The most abundantly occurring TFA isomer, C18:1 t, contributed substantially to this inverse association. The TFA isomers C14:1 t9, C16:1 t9 and C22:1 t were not associated or were positively associated with LDL or total cholesterol. CONCLUSIONS: From this study we conclude that at the current European intake levels of trans fatty acids they are not associated with an unfavourable serum lipid profile. SPONSORSHIP: Unilever Research Laboratorium, the Dutch Dairy Foundation on Nutrition and Health, Cargill BV, the Institute of Food Research Norwich Laboratory, the Nutrition Branch of the Ministry of Agriculture, Fisheries and Food, the International Fishmeal and Oil Manufacturers' Association, Kraft Foods, NV Vandemoortele Coordination Center, Danone Group, McDonalds Deutschland Inc, Danish Veterinary and Food Administration, Valio Ltd, Raisio Group. European Journal of Clinical Nutrition (2000) 54, 126-135

The association between parathyroid hormone, vitamin D and bone mineral density in 70-year-old Icelandic women.

Parathyroid hormone (PTH) may be an important determinant of cortical bone remodeling in the elderly. Vitamin D status is one of the determining factors in this relationship. The aim of this study was to quantify the relationship between serum PTH, vitamin D and bone mineral density (BMD) in elderly women in Reykjavik (64 degrees N), where daily intake of cod liver oil is common and mean calcium intake is high. In PTH correlated inversely with 25(OH)D (r = -0.26, p<0.0 1). In multivariate analysis PTH correlated inversely with whole body BMD (mostly cortical bone) (R2 = 2.2%, p = 0.04) but not with the lumbar spine BMD, reflecting more cancellous bone. No association was found between 25(OH)D levels and BMD at any site in univariate or multivariate analysis. Osteocalcin, a measure of bone turnover, was negatively associated with BMD and this association remained significant when corrected for PTH levels. In summary, in this fairly vitamin D replete population with high calcium intake, PTH was negatively associated with total body BMD. We infer that suppression of PTH may reduce cortical bone loss, but other factors are likely to contribute to age-related bone remodeling and osteoporosis.

[Vitamin D intake and serum 25-OH-vitamin D concentration in different age groups of Icelandic women.].

OBJECTIVE: The aim of this study was to evaluate the vitamin D intake and serum concentrations of 25-OH-vitamin D (25-OH-D) in different age groups of Icelandic women. The seasonal variation of 25-OH-D and its relationship with parathyroid hormone (PTH) level was evaluated but some studies have indicated that subclinical vitamin D deficiency may lead to osteoporosis because of secondary elevations of parathyroid hormone levels and subsequent bone mineral release. MATERIAL AND METHODS: 25-OH-D was measured (RIA, Incstar) in serum from the following age groups of women; 12-15 years (n=325), 16, 18 and 20 years (n=247), 25 years (n=86), 34-48 years (n=107) and in 70 years old (n=308). PTH (IRMA, Nichols) was measured only in the 70 years old. vitamin D intake was assessed by a standardized food frequency questionnaire. The seasonal variation of 25-OH-D was evaluated in the age group 12-15 years and 70 years old. RESULTS: In the different age groups the 25-OH-D concentration was positively correlated to vitamin D intake (r=0.2-0.54; p<0.05). The mean concentration of 25-OH-D in 12-15 years old was 34.6+/-22 nmol/L compared to 53.9120 nmol/L in the 70 years old, p<0.01. The levels of the other age groups were in between. A marked seasonal variation in 25-OH-D was obser notved in the 12-15 years old with low vitamin D intake whereas only a slight seasonal variation was noted in the 70 years old with a mean vitamin D intake of 15 ug/day. CONCLUSIONS: The vitamin D status amongst 70 years old women in Iceland is good because of common intake of codliveroil and vitamin D supplements (83%). The desirable level for 25-OH-D in this age group seems to be around 50 nmol/L and this level is achieved by the intake of 15-20 ug/day (600-800 units) of vitamin D. Vitamin D deficiency is however common amongst 12-15 years old during late winter. Low serum 25-OH-D levels are also common amongst the other age groups studied during late winter. From the results it seems reasonable to recommend that foods like milk should be fortified with vitamin D in Iceland, especially during winter time.

Serum 25-hydroxyvitamin D levels and bone mineral density in 16-20 years-old girls: lack of association.

OBJECTIVE: Hypovitaminosis D has been shown to be associated with low bone mineral density in middle-aged and elderly women. The aim of this study was to evaluate whether such an association might exist in adolescent and young adult girls, approaching peak bone mass. DESIGN: Cross-sectional study carried out in late winter. SETTING: Reykjavik area at latitude 64 degrees N. SUBJECTS: Two-hundred and fifty-nine Icelandic Caucasian girls, aged 16, 18 and 20 years, randomly selected from the registry of Reykjavik. MAIN OUTCOME MEASURES: Bone mineral density in lumbar spine, hip, distal forearm and total skeleton was measured with dual-energy X-ray absorptiometry (DEXA) and compared with 25-hydroxyvitamin D levels [25 (OH)D] in serum, measured by radioimmunoassay. Calcium and vitamin-D intake were also assessed by a questionnaire. RESULTS: 18.5% of the girls were below 25 nmol L-1 in serum 25 (OH)D which has been recognized as the lower normal limit for adults. No significant association was found between 25 (OH)D levels and bone mineral density. CONCLUSIONS: Normal calcium and phosphate concentrations in plasma and normal bone mineral density are maintained in adolescent and young adult girls at lower 25 (OH)D levels than published 'normal' levels for middle-aged and elderly.

[Peak bone mass of Icelandic women and associated factors.].

OBJECTIVE: The aim of this study was to evaluate at which age peak bone mass is reached among Icelandic women. Previous studies on this subject have been conflicting indicating that this might be reached sometime between the age of 16 and 35 years. We have also analyzed associated nutritional and physical factors which might be of use for preventive measures against osteoporosis. MATERIAL AND METHODS: A random sample of 16, 18, 20 and 25 years old women in Reykjavik were invited, altogether 335 women participated. Bone mineral density (BMD) was analyzed by Dual Energy X-ray Absorptiometry (DEXA) in the lumbar spine, hip, forearm and total skeleton. Calcium, protein and vitamin D intake was assessed by a semiquantitative food frequency questionnaire. The level of 25-OH-vitamin D in serum was measured by a radioimmunoassay. Physical activity was assessed by a questionnaire. Multivariate analysis was performed by multiple linear regression. RESULTS: Maximal bone mineral density was reached for total skeleton, hip and forearm at the age of 20 years, BMD for the lumbar spine was 1% higher at the age of 25 than at 20 years but this was not statistically significant. No significant association was found between the calcium intake and BMD except in the subgroup of 18 years old women with calcium intake below 1000 mg/day. 25-OH-vitamin D levels were low (<25 nmol/L) in 15-18.5% of the groups but still no significant relationship was found with the bone mineral density. The strongest correlation was found between total BMD and the lean mass (0.38-0.53, p<0.01) but physical activity was also a significant factor in the age groups 16-20 years. About 25-30% of BMD variability can be attributed to these modifiable factors. CONCLUSION: Peak bone mass seems to be reached at the age of 20 and measures to increase it should therefore be emphasized before that age. Our results indicate that modifiable factors, especially lean mass and physical activity, are of considerable importance in the attainment of peak bone mass in women.