An investigation of factors affecting changes in health behaviours during the COVID-19 pandemic in a UK population-based cohort study.

OBJECTIVES: The COVID-19 pandemic has led to changes in behaviours, which may have different health effects in population subgroups. We investigated whether within-individual changes in health behaviours from before to during the pandemic differ by socio-economic deprivation, age or sex. STUDY DESIGN: Prospective cohort study. METHODS: Participants were recruited from the existing UK Fenland cohort study with measurements of health behaviours twice prepandemic (2005 to February 2020) and three times during the pandemic (July 2020 to April 2021). Health behaviours included daily servings of fruit and vegetables, units of alcohol consumed per week, smoking status, sleep duration and total and domain-specific physical activity energy expenditure. Sociodemographic information (English indices of multiple deprivation, education, occupation and ethnicity) and COVID-19 antibody status were also collected. Participants were grouped into three categories based on their English indices of multiple deprivation score: most, middle and least deprived. RESULTS: Participants were included if they had completed at least one measurement during the pandemic and one prepandemic (n = 3212). Fruit and vegetable consumption, total physical activity energy expenditure and smoking prevalence decreased during the pandemic compared with prepandemic, whereas average sleep duration increased and alcohol consumption did not change. Decreases in fruit and vegetable intake and physical activity energy expenditure were most pronounced in the most deprived group compared with the least deprived group and were greater in women than men. CONCLUSIONS: Socio-economic inequalities in health behaviours have worsened during the pandemic. As the country emerges from the COVID-19 pandemic, strategies to reduce health inequalities need to be put at the forefront of recovery plans.

The aetiology of rickets-like lower limb deformities in Malawian children.

UNLABELLED: Debilitating rickets-like lower limb deformities are common in children throughout the world, particularly in Malawi, Africa where the causes are unknown. We have identified that Blount disease and calcium deficiency rickets are the likely causes of these deformities and propose calcium supplementation as a potential treatment of Malawian rickets. INTRODUCTION: Surgical correction of rickets-like lower limb deformities is the most common paediatric operation performed at Beit Cure Orthopaedic Hospital, Malawi. The aim of this study was to investigate the aetiology of these deformities. METHODS: Children with a tibio-femoral angle of deformity >20° were enrolled (n = 42, 3.0-15.0 years). Anthropometric and early life and well-being data were collected. Early morning serum and urine samples were collected on the morning of the operation for markers of calcium and phosphate homeostasis. Knee radiographs were obtained, and the children were diagnosed with either Blount (BD, n = 22) or evidence of rickets disease (RD, n = 20). As BD is a mechanical rather than metabolic disease, BD were assumed to be biochemically representative of the local population and thus used as a local reference for RD. RESULTS: There were no differences in anthropometry or early life experiences between BD and RD. Parathyroid hormone (PTH), 1,25-dihydroxyvitamin D, total alkaline phosphatase and urinary phosphate were significantly higher and serum phosphate, 25-hydroxyvitamin D (25OHD) and tubular maximal reabsorption of phosphate significantly lower in RD than BD. There was no difference in serum calcium, fibroblast growth factor 23 or markers of iron status between groups. All children had 25OHD > 25 nmol/L. CONCLUSIONS: Vitamin D deficiency is not implicated in the aetiology of RD or BD in Malawian children. The cause of RD in Malawi is likely to be dietary calcium deficiency leading to elevated PTH resulting in increased losses of phosphate from the bone and glomerular filtrate. The causes of BD remain unclear; there was no evidence in support of previously suggested risk factors such as being overweight or starting to walk early. Prior to surgical intervention, supplementation with calcium should be considered for children with RD.

The effects of maternal iron deficiency on infant fibroblast growth factor-23 and mineral metabolism.

Fibroblast growth factor-23 (FGF23), a phosphate(Phos)-regulating hormone, is abnormally elevated in hypophosphataemic syndromes and an elevated FGF23 is a predictor of mortality in kidney disease. Recent findings suggest iron deficiency as a potential mediator of FGF23 expression and murine studies have shown in utero effects of maternal iron deficiency on offspring FGF23 and phosphate metabolism. Our aim was to investigate the impact of maternal iron status on infant FGF23 and mineral metabolites over the first 2years of life. Infants born to mothers with normal (NIn=25,) and low (LIn=25) iron status during pregnancy, from a mother-infant trial (ISRCTN49285450) in rural Gambia, West Africa, had blood and plasma samples analysed at 12, 24, 52, 78 and 104weeks (wk) of age. Circulating intact-FGF23 (I-FGF23), Phos, total alkaline phosphatase (TALP) and haemoglobin (Hb) decreased and estimated glomerular filtration rate increased over time [all P≤0.0001)]. C-terminal-FGF23 (C-FGF23) and TALP were significantly higher in LI compared with NI, from 52wk for C-FGF23 [Beta coefficient (SE) 18.1 (0.04) %, P=0.04] and from 24wk for TALP [44.7 (29.6) U/L, P=0.04]. Infant Hb was the strongest negative predictor of C-FGF23 concentration [-21% (4%) RU/mL, P≤0.0001], Phos was the strongest positive predictor of I-FGF23 [32.0(3.9) pg/mL, P≤0.0001] and I-FGF23 did not predict C-FGF23 over time [-0.5% (0.5%), P=0.3]. In conclusion, this study suggests that poor maternal iron status is associated with a higher infant C-FGF23 and TALP but similar I-FGF23 concentrations in infants and young children. These findings further highlight the likely public health importance of preventing iron deficiency during pregnancy. Whether or not children who are born to iron deficient mothers have persistently high concentrations of these metabolites and are more likely to be at risk of impaired bone development and pre-disposed to rickets requires further research.

Vitamin D binding protein genotype is associated with plasma 25OHD concentration in West African children.

Vitamin D is well known for its role in promoting skeletal health. Vitamin D status is determined conventionally by circulating 25-dihydroxyvitamin D (25OHD) concentration. There is evidence indicating that circulating 25OHD concentration is affected by variation in Gc, the gene encoding the vitamin D binding protein (DBP). The composite genotype of two single nucleotide polymorphisms (rs7041 and rs4588) results in different DBP isotypes (Gc1f, Gc1s and Gc2). The protein configurational differences among DBP isotypes affect DBP substrate binding affinity. The aims of this study were to determine 1) Gc variant frequencies in a population from an isolated rural region of The Gambia, West Africa (n=3129) with year-round opportunity for cutaneous vitamin D synthesis and 2) the effects of Gc variants on 25OHD concentration (n=237) in a genetically representative sub-group of children (mean (SD) age: 11.9 (4.8) years). The distribution of Gc variants was Gc1f: 0.86, Gc1s: 0.11 and Gc2: 0.03. The mean (SD) concentration of 25OHD was 59.6 (12.9) nmol/L and was significantly higher in those homozygous for Gc1f compared to other Gc variants (60.7 (13.1) vs. 56.6 (12.1) nmol/L, P=0.03). Plasma 25OHD and 1,25(OH)2D concentration was significantly associated with parathyroid hormone in Gc1f-1f but not in the other Gc variants combined. This study demonstrates that different Gc variants are associated with different 25OHD concentrations in a rural Gambian population. Gc1f-1f, thought to have the highest affinity for 25OHD, had the highest 25OHD concentration compared with lower affinity Gc variants. The considerable difference in Gc1f frequency observed in Gambians compared with other non-West African populations and associated differences in plasma 25OHD concentration, may have implications for the way in which vitamin D status should be interpreted across different ancestral groups.