Jennifer E Rockell

Vitamin D status and its association with parathyroid hormone concentrations in women of child-bearing age living in Jakarta and Kuala Lumpur

Objective:To describe the vitamin D status of women living in two Asian cities, – Jakarta (6°S) and Kuala-Lumpur (2°N), to examine the association between plasma 25-hydroxyvitamin D and parathyroid hormone (PTH) concentrations, and to determine a threshold for plasma 25-hydroxyvitamin D above which there is no further suppression of PTH. Also, to determine whether dietary calcium intake influences the relationship between PTH and 25-hydroxyvitamin D.Design:Cross-sectional.Setting:Jakarta, Indonesia and Kuala Lumpur, Malaysia.Participants:A convenience sample of 504 non-pregnant women 18–40 years.Main measures:Plasma 25-hydroxyvitamin D and PTH.Results:The mean 25-hydroxyvitamin D concentration was 48 nmol/l. Less than 1% of women had a 25-hydroxyvitamin D concentration indicative of vitamin D deficiency (<17.5 nmol/l); whereas, over 60% of women had a 25-hydroxyvitamin D concentration indicative of insufficiency (<50 nmol/l). We estimate that 52 nmol/l was the threshold concentration for plasma 25-hydroxyvitamin D above which no further suppression of PTH occurred. Below and above this concentration the slopes of the regression lines were −0.18 (different from 0; P=0.003) and −0.01 (P=0.775), respectively. The relation between vitamin D status and parathyroid hormone concentration did not differ between women with low, medium or high calcium intakes (P=0.611); however, even in the highest tertile of calcium intake, mean calcium intake was only 657 mg/d.Conclusion:On the basis of maximal suppression of PTH we estimate an optimal 25-hydroxyvitamin D concentration of ∼ 50 nmol/l. Many women had a 25-hydroxyvitamin D below this concentration and may benefit from improved vitamin D status.

Very high rates of vitamin D insufficiency in women of child-bearing age living in Beijing and Hong Kong.

We aimed to describe the vitamin D status of young women living in two Chinese cities in the spring--Beijing in the north (latitude 39 degrees north) and Hong Kong (latitude 22 degrees north) in the south. We also examined the relationship between serum 25-hydroxyvitamin D and parathyroid hormone (PTH) concentrations to determine a threshold for serum 25-hydroxyvitamin D above which there is no further suppression of PTH. Finally, we examined whether dietary Ca intake influences this relationship. Non-pregnant women aged 18-40 years (n 441) were recruited between February and June. Fasting blood was collected and dietary intakes were assessed using 5 d food records. Mean serum 25-hydroxyvitamin D concentration was lower in Beijing than Hong Kong women (29 v. 34 nmol/l; P < 0.001). Vitamin D deficiency (< or = 25 nmol/l) was indicated in 40% of Beijing and 18% of Hong Kong women, and over 90% of women in both cities were insufficient (< or = 50 nmol/l). Mean Ca and vitamin D intakes were 478 mg/d and 2.0 microg/d, respectively. The relationship between 25-hydroxyvitamin D concentration and PTH was linear throughout the range with a slope of -0.36 (different from 0; P < 0.001; R 0.26), with no apparent threshold. There was no influence of Ca intake on the relationship between 25-hydroxyvitamin D and PTH concentration. Vitamin D deficiency is common and insufficiency is very common in non-pregnant women in Hong Kong and Beijing during spring. Serum 25-hydroxyvitamin D was inversely associated with PTH with no apparent threshold. Strategies such as vitamin D fortification or supplementation may be required.

Nutrients and foods consumed by New Zealand children on schooldays and non-schooldays.

OBJECTIVE To describe and compare food and nutrient intakes in New Zealand (NZ) children on schooldays and non-schooldays. DESIGN Secondary analysis of cross-sectional data from the NZ 2002 Childrens Nutrition Survey. Dietary intake was assessed using computer-assisted multi-pass 24 h dietary recalls in the home. Data were adjusted for survey weightings to be representative of the NZ population. The effect of day category on nutrient intake, and likelihood of consumption of food categories were determined using linear and logistic regression. SETTING NZ homes and schools. SUBJECTS A total of 2572 children (538 non-schooldays and 2034 schooldays) at the age of 5-14 years. RESULTS There were differences in the proportion consuming some food groups between schooldays and non-schooldays, although the majority of nutrient intakes including energy did not differ by day category. Mean cholesterol intake was higher on non-schooldays; dietary fibre and available carbohydrate, in particular sucrose and fructose, were higher on schooldays. Hot chips were twice as likely to be consumed on a non-schoolday. Soft drink consumption was higher on non-schooldays for Māori/New Zealand European and others and powdered drinks/cordial consumption did not vary by day category. More children consumed snack bars (normal weight, obese), fruit, sandwiches, biscuits/crackers and snack foods on schooldays. There was no difference in consumption of pies/sausage rolls by day category. CONCLUSIONS The proportion of consumers of a variety of foods differed significantly between non-schooldays and schooldays; few nutrient intakes differed. The present study indicates that family food, wherever it is consumed, is the mainstay of nutrition for NZ schoolchildren.

What children eat during afternoons and evenings: is it important?

OBJECTIVE To complete a description of the dietary intakes of New Zealand schoolchildren by describing afternoon and evening foods and nutrients. DESIGN Twenty-four hour dietary recall data from the 2002 Childrens Nutrition Survey were analysed to describe food and nutrient intakes during the afternoon (14.00 to 16.59 hours) and evening (17.00 to 23.59 hours). SETTING New Zealand homes and schools. SUBJECTS Children (n 2875) aged 5-14 years. RESULTS Most children consumed something during the afternoon (79 %) and evening (98 %). Children were less likely to consume something during non-school day afternoons; if 11-14 years of age; and when of Pacific ethnicity. Afternoon food consumers had higher daily intakes for most nutrients. Afternoon intake accounted for much of this difference. In the afternoon, children consumed fruit (26 %) and biscuits/crackers (21 %). Evening eating contributed to daily intakes of energy (40 %), fat (43 %), carbohydrate (35 %), sucrose (20 %), glucose (24 %), vitamin A (47 %), Ca (26 %) and Fe (40 %). Children aged 5-6 years consumed a lower proportion of their daily energy intake during the evening than older children. In the evening, just one-third of children consumed vegetables (45 % if including potato/kumara/taro), 19 % fruit and 17 % ate hot chips. Children were more likely to consume vegetables if they also consumed potato/kumara/taro. Twenty-three per cent of children had powdered drinks/cordials, 21 % had soft drinks and 19 % had milk. CONCLUSIONS Consuming foods/drinks in the afternoon positively influenced macronutrient distribution, increasing the carbohydrate proportion. During the evening 40 % of energy intake was consumed but less than one-half of children consumed vegetables; thus inclusion of vegetables in the evening is important, particularly in meals without potato/kumara/taro.