Liya Yan

Vitamin D Status Does Not Influence the Breast-Milk Calcium Concentration of Lactating Mothers Accustomed to a Low Calcium Intake

Plasma 25‐hydroxy‐vitamin D and breast‐milk calcium concentration were measured at 3 months of lactation in 60 Gambian mothers accustomed to a low calcium diet, of whom 30 were consuming a calcium supplement and 30 were receiving a placebo, and in 48 British mothers. The plasma 25‐hydroxy‐vitamin D concentration of the Gambian women was not affected by either calcium supplementation (supplemented, 64. 4 ± 2. 5 nmol 1‐1; placebo, 64. 9 ± 3. 5 nmol l‐1; mean ± SE) or season. The British average was lower (53. 9 ± 3. 0 nmol 1‐1, p= 0. 004), owing to marked seasonal effects. The breast‐milk calcium concentration was lower in The Gambia (supplemented, 5. 38 ± 0. 13 mmol 1‐1; placebo, 5. 10 ± 0. 13mmol 1‐1; British, 6. 93 ± 0. 15 mmol 1‐1, p < 0. 0001). There was no relationship between plasma 25‐hydroxy‐vitamin D and breast‐milk calcium concentration in any group. There was no trend towards lower breast‐milk calcium concentration in women with vitamin D status towards the bottom of the normal range or in British women during the winter. This study provides no support for the hypothesis that breast‐milk calcium concentration is influenced by vitamin D status or that lactating women with a low calcium intake are at particular risk of vitamin D deficiency.

Vitamin K status of older individuals in northern China is superior to that of older individuals in the UK

To explore whether differences in vitamin K nutrition might, at least in part, underlie differences in fracture incidence between Asian and European populations, the vitamin K status of older individuals in Shenyang, China (eighty-six men, ninety-two women) and in Cambridge, UK (sixty-seven men, sixty-seven women) was compared. Dietary information was collected by food questionnaire in Shenyang and food diary in Cambridge and used to estimate the intake and sources of phylloquinone. Fasting blood was analysed for phylloquinone, triacylglycerol, total osteocalcin (tOC) and undercarboxylated osteocalcin (expressed as percentage of tOC; %ucOC). The mean intakes of green leafy vegetables were 127 (SD 90) g/d in Shenyang and 39 (SD 48) g/d in Cambridge. The estimated phylloquinone intakes (geometric means) were 247 (95% CI 226, 270) microg/d in Shenyang and 103 (95% CI 94, 112) microg/d in Cambridge. Plasma phylloquinone concentrations (geometric means) were significantly higher in the Shenyang subjects (2.17 (95% CI 1.95, 2.42) nmol/l) than in the Cambridge subjects (0.69 (95% CI 0.63, 0.76) nmol/l; P<0.001). Plasma phylloquinone concentration was positively related to phylloquinone intake in both the Shenyang (coefficient 0.17 (SE 0.08); P=0.03) and Cambridge subjects (coefficient 0.29 (SE 0.10); P=0.005). tOC concentration and %ucOC (after adjusting for tOC) were significantly lower in the Shenyang than in the Cambridge subjects (tOC 25.2 (SE 4.2)% and %ucOC 68.5 (SE 10.0)% lower respectively; P<0.001). After adjusting for tOC and triacylglycerol, %ucOC was negatively related to plasma phylloquinone concentration in both the Shenyang (coefficient -0.41 (se 0.11); P=0.0003) and Cambridge subjects (coefficient -0.17 (SE 0.07); P=0.02). The present study demonstrates that older individuals in northern China have a better vitamin K status compared with their British counterparts in Cambridge, UK.

The effect of long-term calcium supplementation on indices of iron, zinc and magnesium status in lactating Gambian women

The effect of long-term supplementation with CaCO3 on indices of Fe, Zn and Mg status was investigated in a randomized, double-blind intervention study of sixty lactating Gambian women. The supplement contained 1000 mg Ca and was consumed between meals 5 d/week, for 1 year starting 1.5 weeks postpartum. Compliance was 100%. Plasma ferritin concentration, plasma Zn concentration and urinary Mg output were measured before, during and after supplementation at 1.5, 13, 52 and 78 weeks postpartum. No significant differences in mineral status were observed at any time between women in the supplement and placebo groups. Analysis of the longitudinal data series showed that plasma ferritin and Mg excretion were characteristic of the individual (P < 0.001). Within individuals, ferritin concentration was higher at 1.5 weeks postpartum than later in lactation (P = 0.002). Plasma Zn concentration was lower at 1.5 weeks postpartum than at other times (P < 0.001), an effect which disappeared after albumin correction. Low plasma concentrations of ferritin and Zn indicated that the Gambian women were at high risk of Fe and Zn deficiency. Measurements of alpha 1-antichymotrypsin suggested that the results were not confounded by acute-phase responses. The results of the present study indicate that 1000 mg Ca as CaCO3 given between meals does not deleteriously affect plasma ferritin and Zn concentrations or urinary Mg excretion in women who are at risk of Fe and Zn deficiency.

Effect of apolipoprotein E genotype on vitamin K status in healthy older adults from China and the UK.

The vitamin K concentration in the circulation and the availability of vitamin K to bone may be affected by factors influencing lipoprotein metabolism, such as apoE genotype. The relationships between markers of vitamin K status, bone mineral content and apoE genotype were studied in healthy older men and women aged 60-83 years, 177 from Shenyang, China, and 132 from Cambridge, UK. Fasting plasma was analysed for vitamin K1, triacylglycerol, total osteocalcin, undercarboxylated osteocalcin (ucOC) and apoE genotype. Hip bone mineral content was measured using dual-energy X-ray absorptiometry. Subjects were grouped according to apoE genotype as E2/3, E3/3 and [E3/4+E4/4]. The mean plasma vitamin K1 concentration of the three genotype groups was significantly higher and the percentage ucOC was lower in the Chinese than in the British subjects (P<0.01). A higher vitamin K1 concentration was found in subjects with [E3/4+E4/4] than those with either E2/3 or E3/3 in Cambridge (32.2 (SE 14.6 ) %, P=0.03; 24.6 (SE 10.7 ) %, P=0.02). Similar trends were observed although were not statistically significant in Shenyang (26.5 (18.9) %, P=0.16; 23.1 (13.0) %, P=0.08). Subjects with [E3/4+E4/4] had a lower percentage ucOC (total osteocalcin adjusted) than did those with either E2/3 or E3/3 in Shenyang (65.1 (27.2) %, P=0.02; 49.6 (19.9) %, P=0.01 respectively) but not in Cambridge. This study demonstrates that a superior vitamin K status is associated with the apoE4 genotype in healthy older individuals from China and the UK.

Age- and gender-related differences in bone mineral status and biochemical markers of bone metabolism in Northern Chinese men and women

The aim of this study was to provide insight into the bone mineral status and biochemical markers of bone metabolism in a Chinese population from Shenyang, in the north of China, where hip fracture incidence is low. A total of 194 healthy men and women, aged 25-35 years and 65-75 years, were studied. Bone mineral density (BMD) at the lumbar spine (LS) and femoral neck (FN) was measured using dual-energy X-ray absorptiometry. Fasting blood and 24 h urine samples were collected for bone alkaline phosphatase (bAP), osteocalcin, calcium, phosphate, and free deoxypyridinoline (Dpd). Both older women and men had lower BMD compared with younger women and men by 27.2 +/- 3.0% (mean +/- SE) and 9.8 +/- 3.0% at the LS and 22.0 +/- 3.4% and 12.8 +/- 3.4% at the FN, respectively, after adjusting for bone and body size (p < 0.01). BMD at the two sites was lower in older women than in older men by 10.7 +/- 4.1% and 10.2 +/- 4.2%, respectively, after size correction (p < 0.05). Plasma bAP, osteocalcin, calcium, and phosphate concentrations were higher in older women than younger women by 69.3 +/- 9.7%, 77.2 +/- 11.1%, 7.5 +/- 2.3%, and 8.0 +/- 3.8%, respectively, and older men by 67.6 +/- 11.1%, 72.1 +/- 11.0%, 7.7 +/- 2.3%, and 23.8 +/- 3.8%, respectively (p < 0.01). However, plasma osteocalcin, calcium, and phosphate concentrations were lower in older men compared with their younger counterparts by 35.6 +/- 11.0%, 8.7 +/- 2.3%, and 14.1 +/- 3.8%, respectively (p < 0.05). Urinary calcium and phosphate output were lower in older men compared with younger men by 48.0 plus minus 10.3% and 27.6 +/- 6.9%, respectively (p < 0.01), whereas there were no differences between older and younger women. No differences in Dpd between older and younger groups were found. This study demonstrates that bone mineral status is lower in older people in Shenyang, as has been shown in populations elsewhere. The pronounced low bone mineral status in older women may be associated with increased bone turnover, which was not observed in older men.