We examined cross-sectional and longitudinal associations of dietary factors with caries experience in a population sample of 487 children aged 6–9 years at baseline examinations of the Physical Activity and Nutrition in Children (PANIC) Study. Altogether, 406 of these children attended 2-year follow-up examinations. Food consumption and eating frequency were assessed using 4-day food records, diet quality using the Baltic Sea Diet Score (BSDS) and eating behaviour using the Children’s Eating Behavior Questionnaire. Caries experience was examined clinically. The cross-sectional associations of dietary factors with caries experience at baseline were analysed using linear regression and the longitudinal associations of dietary factors with a change in caries experience over follow-up using generalised mixed-effects regression adjusted for other risk factors. A higher consumption of high-fibre grain products (standardised regression coefficient β = −0·16, P = 0·003) and milk (β = −0·11, P = 0·025) and higher BSDS (β = −0·15, P = 0·007) were associated with lower caries experience, whereas a higher consumption of potatoes (β = 0·11, P = 0·048) and emotional overeating (β = 0·12, P = 0·025) were associated with higher caries experience. Higher snacking frequency (fixed coefficient β = 0·07, P = 0·033), desire to drink (β = 0·10, P = 0·046), slowness in eating (β = 0·12, P = 0·027) and food fussiness (β = 0·12, P = 0·018) were associated with higher caries experience, whereas enjoyment of food (β = −0·12, P = 0·034) and higher BSDS (β = −0·02, P = 0·051) were associated with lower caries experience.

Increased vitamin D fortification of dairy products has increased the supply of vitamin D-containing products with different vitamin D contents on the market in Finland. The authors developed a ninety-eight-item FFQ with eight food groups and with a question on supplementation to assess dietary and supplemental vitamin D and Ca intakes in Finnish women (60ºN). The FFQ was validated in subgroups with different habitual vitamin D supplement use (0–57·5 µg/d) against the biomarker serum 25-hydroxyvitamin D (S-25(OH)D) and against 3-d food records (FR) (n 29–67). Median total vitamin D intake among participants was 9·4 (range 1·6–30·5) µg/d. Spearman’s correlations for vitamin D and Ca ranged from 0·28 (P 0·146, FFQ v. S-25(OH)D, persons not using supplements) to 0·75 (P<0·001, FFQ v. FR, supplement use included). The correlations between the FFQ and S-25(OH)D concentrations improved within increasing supplement intake. The Bland–Altman analysis showed wide limits of agreement between FFQ and FR: for vitamin D between −7·8 and 8·8 µg/d and for Ca between −938 and 934 mg/d, with mean differences being 0·5 µg/d and 2 mg/d, respectively. The triads method was used to calculate the validity coefficients of the FFQ for vitamin D, resulting in a mean of 1·00 (95 % CI 0·59, 1·00) and a range from 0·33 to 1·00. The perceived variation in the estimates could have been avoided with a longer FR period and larger number of participants. The results are comparable with earlier studies, and the FFQ provides a reasonable estimation of vitamin D and Ca intakes.

Secondary hyperparathyroidism (SHPT) is one of the outcomes of vitamin D deficiency that negatively affects bone metabolism. We studied the ethnic differences in vitamin D status in Finland and its effect on serum intact parathyroid hormone (S-iPTH) concentration and bone traits. The study was done in the Helsinki area (60°N) during January–February 2008. A total of 143 healthy women (20–48 years of age) from two groups of immigrant women (Bangladeshi, n 34 and Somali, n 48), and a group of ethnic Finnish women (n 61) were studied in a cross-sectional setting. Serum concentrations of 25-hydroxyvitamin D (S-25OHD) and S-iPTH were measured. Peripheral quantitative computed tomography measurements were taken at 4 and 66 % of the forearm length. In all groups, the distribution of S-25OHD was shifted towards the lower limit of the normal range. A high prevalence of vitamin D insufficiency (S-25OHD < 50 nmol/l) was observed (89·6 %) in the Somali group. The prevalence of SHPT (S-iPTH>65 ng/l) was higher (79·1 %) in Somali women than in Finnish women (16 %). There was a significant association between S-25OHD and S-iPTH (r − 0·49, P < 0·001). Ethnicity and S-25OHD together explained 30 % of the variation in S-iPTH. The total bone mass at all sites of the forearm, fracture load and stress–strain index was higher (P < 0·001) in Bangladeshi and Finnish women than in Somali women. The high prevalence of hypovitaminosis D, SHPT and low bone status in Somali women indicates a higher risk of osteoporosis.

Due to little outdoor activity and low dietary intake of vitamin D (VD), Bangladeshi low-income women are at risk for osteoporosis at an early age. The present study assessed the effect of VD, Ca and multiple micronutrient supplementation on VD and bone status in Bangladeshi young female garment factory workers. This placebo-controlled 1-year intervention randomly assigned 200 apparently healthy subjects (aged 16–36 years) to four groups: VD group, daily 10 μg VD; VD and Ca (VD-Ca) group, daily 10 μg VD+600 mg Ca; multiple micronutrient and Ca (MMN-Ca) group, 10 μg VD and other micronutrients+600 mg Ca; a placebo group. Serum 25-hydroxyvitamin D (S-25OHD), intact parathyroid hormone (S-iPTH), Ca, phosphate and alkaline phosphatase were measured. Bone mineral density and bone mineral content were measured by dual-energy X-ray absorptiometry. All measurements were made at baseline and at 12 months. Significantly (P < 0·001) higher S-25OHD concentrations were observed in the supplemented groups than in the placebo group after the intervention. Supplementation had an effect (P < 0·001) on S-iPTH in the VD-Ca and MMN-Ca groups compared with the placebo group. Bone mineral augmentation increased at the femur in the supplemented groups. Supplementation with VD-Ca should be recommended as a strategic option to reduce the risk of osteomalacia and osteoporosis in these subjects. MMN-Ca may have analogous positive health implications with additional non-skeletal benefits.

The importance of the seasonal variation of calcitropic hormones to growing skeleton has not been established. We studied whether there exists a seasonal variation in calcitropic hormones, bone mineral density (BMD) and bone remodelling markers in early puberty girls. One hundred and ninety-six girls, mean age 11·4 (sd 0·4) years, in Tanner stage 2 (early puberty) and 3 (mid-puberty) were studied during September to March. The BMD was measured from the lumbar vertebrae and the left femur by dual-energy X-ray absoptiometry. Their serum 25-hydroxyvitamin D (S-25-OHD), serum intact parathyroid hormone (S-iPTH), serum osteocalcin, urinary pyridinoline and urinary deoxypyridinoline were analysed from fasting samples. The concentration of S-25-OHD and serum osteocalcin differed among months (p<0·01), reflecting a seasonal variation. The parathyroid hormone correlated negatively with S-25-OHD (r −0·325, p<0·001). Moreover, the BMD in the femur (p=0·047) and to a lesser extent in vertebrae (p=0·057) differed between months in early puberty girls but this was not seen in mid-puberty. Seasonal variation in S-25-OHD and bone remodelling markers accompanied by negative correlation between S-25-OHD and S-iPTH was seen in this cross-sectional study of adolescent girls. In addition, the seasonal rhythm contributed 7·0–7·6% difference in the BMD of lumbar vertebrae and left femur in early puberty girls. This variation should be avoided since it could hamper peak bone mass attainment.