P.R. von Hurst

Vitamin D supplementation suppresses age-induced bone turnover in older women who are vitamin D deficient.

There is a lack of evidence that improving vitamin D status, without changing calcium intake, has a positive effect on bone turnover as indicated by bone marker changes. The objective was to measure the effect of vitamin D supplementation, in vitamin D deficient women (25(OH)D concentration<50 nmol/L), on osteocalcin (OC) and C-telopeptide (CTX). The study design was a randomised controlled intervention administering 4000 IU vitamin D3 or placebo daily for 6 months to South Asian women, aged>20 years. Subjects were stratified by age and menopausal status. Median (25th, 75th percentile) serum 25(OH)D increased significantly from 21 (11, 40) to 75 (55, 84) nmol/L with supplementation. In women>49 years or postmenopausal (n=26), who were not supplemented (n=13), CTX and OC levels increased (P=0.001, P=0.004 respectively), indicating an increased rate of bone turnover. With supplementation CTX decreased (P=0.012) and there was no significant change in OC. In women who were under 49 years and premenopausal (n=55; 29 supplemented), there was no significant response to supplementation in either CTX or OC. We conclude that correcting vitamin D deficiency in older women suppresses the age-induced increase in bone turnover and reduces bone resorption which would normally be exacerbated in conditions of low serum 25(OH)D.

Inflammatory status modulates plasma lipid and inflammatory marker responses to kiwifruit consumption in hypercholesterolaemic men

BACKGROUND AND AIMS Kiwifruit has the potential to improve markers of metabolic dysfunction, but the response may be influenced by inflammatory state. We aimed to investigate whether inflammatory state would modulate the effect of consuming two green kiwifruit daily on plasma lipids and markers of inflammation. METHODS AND RESULTS Eighty-five hypercholesterolaemic men completed a 4-week healthy diet run-in, before randomisation to a controlled cross-over study of two 4-week interventions of two green kiwifruit/day plus healthy diet (intervention) or healthy diet alone (control). Anthropometric measures and fasting blood samples (plasma lipids, serum apolipoproteins A1 and B, high-sensitivity C-reactive protein (hs-CRP) and interleukin (IL)-6, tumour necrosis factor-alpha (TNF-α) and IL-10) were taken at baseline, 4 and 8 weeks. Subjects were divided into low and medium inflammatory groups, using pre-intervention hs-CRP concentrations (hs-CRP <1 and 1-3 mg/L, respectively). In the medium inflammatory group the kiwifruit intervention resulted in significant improvements in plasma high-density lipoprotein cholesterol (HDL-C) (mean difference 0.08 [95% CI: 0.03, 0.12] mmol/L [P < 0.001]), total cholesterol (TC)/HDL-C ratio (-0.29 [-0.45, -0.14] mmol/L [P = 0.001]), plasma hs-CRP (-22.1 [-33.6, -4.97]% [P = 0.01]) and IL-6 (-43.7 [-63.0, -14.1]% [P = 0.01]) compared to control treatment. No effects were seen in the low inflammatory group. There were significant between inflammation group differences for TC/HDL-C (P = 0.02), triglyceride (TG)/HDL-C (P = 0.05), and plasma IL-6 (P = 0.04). CONCLUSIONS Inflammatory state modulated responses to the kiwifruit intervention by improving inflammatory markers and lipid profiles in subjects with modestly elevated CRP, suggesting this group may particularly benefit from the regular consumption of green kiwifruit. Registered 16th March 2010, Australian New Zealand Clinical Trials Registry (no. ACTRN12610000213044), www.ANZCTR.org.au.

Preferred natural food of breeding Kakapo is a high value source of calcium and vitamin D

The Kakapo, a large NZ native parrot, is under severe threat of extinction. Kakapo breed only in years when the local podocarps, including rimu (Dacrydium cupressinum), are fruiting heavily, and the fruit are the preferred food both in the diet of breeding females and for provisioning chicks. Attempts to provide a supplementary food during years of poor fruit supply have failed to encourage breeding. Nutrient analysis of rimu berries reveals high calcium content (8.4mg/g dry matter) which would be essential for both egg shell production and the growing skeleton of the chick. Vitamin D is also critical for these processes and for the maintenance of calcium homeostasis, but the source of vitamin D for these nocturnal, ground-dwelling vegetarians is unknown. OBJECTIVE To examine the vitamin D status of adult Kakapo, and to investigate the possibility that rimu berries provide vitamin D as well as calcium, thus differentiating them from the supplementary foods provided to date. METHOD Previously collected and frozen serum from 10 adult birds (6 females, 4 males) was assayed for 25(OH)D3 and D2. Two batches of previously frozen rimu berries were analysed for vitamin D3 and D2. RESULTS Vitamin D status of the 10 adult birds was very low; mean 4.9nmol/l, range 1-14nmol/l 25(OH)D3. No 25(OH)D2 was detected in any of the birds. High levels of D2 and moderate levels of D3 were found in the rimu berries. CONCLUSION Traditionally it has been considered that the D3 isoform of this endogenously produced secosteroid is produced only in animals. However, D3 has been reported in the leaves of plants of the Solanacae family (tomato, potato, capsicum). The avian vitamin D receptor (VDR) is thought to have a much greater affinity for the D3 form. Therefore if rimu fruit are able to provide breeding Kakapo with D3, and are a plentiful source of calcium, they could be the perfect food package for breeding and nesting birds. Of wider importance, this finding challenges conventional understanding that D3 production is exclusive to animals, and that there are no high concentration food sources of vitamin D.

Predictors of vitamin D status in New Zealand preschool children

Vitamin D deficiency has adverse health effects in young children. Our aims were to determine predictors of vitamin D status and then to use these factors to develop a practical tool to predict low 25(OH)D concentrations in preschool New Zealand children. A cross-sectional sample of 1329 children aged 2 to <5 years were enrolled from throughout New Zealand in late-winter to spring 2012. 25-Hydroxyvitamin D (25(OH)D) was measured on dried blood spot (DBS) samples collected using finger-prick sampling. Caregivers completed a questionnaire. Mean (SD) DBS 25(OH)D concentration was 52(19)nmol/L. 25(OH)D < 25 nmol/L was present in 86(7%), 25(OH)D < 50 nmol/L in 642(48%), 25(OH)D 50- < 75 nmol/L in 541(41%) and 25(OH)D > 75 nmol/L in 146(11%) of children. Factors independently associated with the risk of 25(OH)D < 25 nmol/L were female gender (OR 1.92,95%CI 1.17-3.14), other non-European ethnicities (not including Māori or Pacific) (3.51,1.89-6.50), had olive-dark skin colour (4.52,2.22-9.16), did not take vitamin D supplements (2.56,1.06-6.18), had mothers with less than secondary-school qualifications (5.00,2.44-10.21) and lived in more deprived households (1.27,1.06-1.53). Children who drank toddler milk (vitamin D fortified cows milk formula marketed to young children) had a zero risk of 25(OH)D < 25 nmol/L. The predictive tool identified children at risk of 25(OH)D < 25 nmol/L with sensitivity 42%, specificity 97% and ROC area-under-curve 0.76(95%CI 0.67-0.86, p < 0.001). Predictors of low vitamin D status were consistent with those identified in previous studies of New Zealand children. The tool had insufficient predictive ability for use in clinical situations, and suggests a need to promote safe, inexpensive testing to determine vitamin D status in preschool children.