K. Hart

Comparison of vitamin D2 and vitamin D3 supplementation in raising serum 25-hydroxyvitamin D status: a systematic review and meta-analysis

Background: Currently, there is a lack of clarity in the literature as to whether there is a definitive difference between the effects of vitamins D2 and D3 in the raising of serum 25-hydroxyvitamin D [25(OH)D]. Objective: The objective of this article was to report a systematic review and meta-analysis of randomized controlled trials (RCTs) that have directly compared the effects of vitamin D2 and vitamin D3 on serum 25(OH)D concentrations in humans. Design: The ISI Web of Knowledge (January 1966 to July 2011) database was searched electronically for all relevant studies in adults that directly compared vitamin D3 with vitamin D2. The Cochrane Clinical Trials Registry, International Standard Randomized Controlled Trials Number register, and clinicaltrials.gov were also searched for any unpublished trials. Results: A meta-analysis of RCTs indicated that supplementation with vitamin D3 had a significant and positive effect in the raising of serum 25(OH)D concentrations compared with the effect of vitamin D2 (P = 0.001). When the frequency of dosage administration was compared, there was a significant response for vitamin D3 when given as a bolus dose (P = 0.0002) compared with administration of vitamin D2, but the effect was lost with daily supplementation. Conclusions: This meta-analysis indicates that vitamin D3 is more efficacious at raising serum 25(OH)D concentrations than is vitamin D2, and thus vitamin D3 could potentially become the preferred choice for supplementation. However, additional research is required to examine the metabolic pathways involved in oral and intramuscular administration of vitamin D and the effects across age, sex, and ethnicity, which this review was unable to verify.

The ability of habitual exercise to influence appetite and food intake in response to high- and low-energy preloads in man.

The present study tested the hypothesis that habitual exercisers demonstrate an increased accuracy of regulation of food intake in compensation for previous dietary energy intake. Twenty-three lean healthy male subjects were divided into two groups on the basis of their habitual exercise levels: non-exercisers (no exercise sessions/week, n 9), and exercisers (>two exercise sessions of 40 min or more/week, n 14). The appetite response to covert liquid preloads of high (2513 kJ) energy (HE) and low (1008 kJ) energy (LE) was investigated Sixty minutes after the preload subjects were offered an ab libitum buffet-style meal and energy intake (EI) was calculated. Subjective hunger and satiety were assessed throughout using self-rated visual-analogue scales. Buffet EI in non-exercisers was not significantly different following the LE or HE preloads (mean compensation 7 %), but the exercise group significantly reduced their energy intake following the HE, compared with the LE, preload (mean compensation 90 %; P=0.0035). A broadly similar pattern of response was observed for both moderate (two to three sessions/week, n 7) and high exercisers (>four sessions/week, n 7). There were no significant differences between hunger or satiety ratings following HE or LE preloads for either group. However non-exercisers scored significantly higher on their self-ratings of hunger at the start of the study, before preload consumption, compared with the exercisers (P<0.01). These findings demonstrate that habitual exercisers have an increased accuracy of short-term regulation of food intake in compensation for preload manipulation, and provide additional support for advocating regular exercise in the prevention of overweight and obesity.

Habitual dietary intake, eating pattern and physical activity of women with polycystic ovary syndrome

Background/Objective:Diet and lifestyle modifications may be of benefit in the management of polycystic ovary syndrome (PCOS), but there is a paucity of data on these behaviours in women with PCOS. This study aims to address this through a comprehensive investigation of the habitual diet and activity patterns of UK women with PCOS and their alignment with dietary recommendations for health.Subjects/Methods:A 7-day-estimated food and activity diary and questionnaire was completed by 210 women with PCOS for calculation of activity levels, energy and nutrient intakes and dietary glycaemic index (GI).Results:Mean (s.d.) body mass index (BMI) was 27.4 (7.3) kg/m2 (n=183), with 53% of women with PCOS having a BMI>25 kg/m2. Of the overweight women, approximately half were not achieving sufficient physical activity to promote weight loss. More frequent eating episodes and a lower BMI were weakly associated (r=−0.158, P=0.034). Mean percentage energy from fat was 38 (7)% (12% energy from saturated fat), with 68% of women with PCOS consuming > 35% energy from fat. Mean dietary GI was higher in obese women with PCOS, compared with healthy weight women with PCOS (55.7 (3.4) and 53.8 (4.0), respectively; P=0.043).Conclusion:Many women with PCOS are not achieving dietary intakes and levels of physical activity that optimise symptom management and disease prevention. Advice should focus on fat quality and quantity and carbohydrate modification. There is a need for further robust research into the role of dietary GI in the PCOS population.

Dietary management of women with polycystic ovary syndrome in the United Kingdom: the role of dietitians

BACKGROUND Polycystic ovary syndrome (PCOS) is a common endocrine condition associated with hyperandrogenism, infertility and metabolic dysfunction. Weight management through diet and lifestyle modifications are fundamental to its management; however, presently, there are no official dietary guidelines. The present study aimed to explore the dietary and lifestyle strategies followed by women with PCOS and the contribution of dietitians to its management. METHODS A questionnaire was completed by 105 UK dietitians focused on the service provided and a patient questionnaire and 7-day food diary were completed by women with PCOS (n = 206 and n = 196, respectively). Food diaries were analysed for energy and macronutrient intake and the questionnaire focused on the dietary advice received. RESULTS Advice provided by dietitians focused on a reduction in energy intake (78%) and dietary glycaemic index (77%), often in combination. Of the women with PCOS who were following a diet specifically for their PCOS (57%), regimes included a low glycaemic index (34%), weight loss diets (16%) or a combination (26%). Of interest, 73% of overweight women were not following a diet to promote weight loss. Nutritional information predominately came from books, with only 15% of women having seen a dietitian. Eighty-four percent of women with PCOS who had increased physical activity (48%) self-reported an improvement in their symptoms. CONCLUSIONS Women with PCOS recognise the importance of diet, but few received dietary advice from a registered dietitian. The dietary information women with PCOS received was often from an unregulated source. A consensus statement of evidence-based dietary advice for women with PCOS is needed and would be a useful resource for dietitians.

Daily supplementation with 15 μg vitamin D2 compared with vitamin D3 to increase wintertime 25-hydroxyvitamin D status in healthy South Asian and white European women: a 12-wk randomized, placebo-controlled food-fortification trial

Background: There are conflicting views in the literature as to whether vitamin D2 and vitamin D3 are equally effective in increasing and maintaining serum concentrations of 25-hydroxyvitamin D [25(OH)D], particularly at lower doses of vitamin D.Objective: We aimed to investigate whether vitamin D2 or vitamin D3 fortified in juice or food, at a relatively low dose of 15 μg/d, was effective in increasing serum total 25(OH)D and to compare their respective efficacy in South Asian and white European women over the winter months within the setting of a large randomized controlled trial.Design: A randomized, double-blind, placebo-controlled food-fortification trial was conducted in healthy South Asian and white European women aged 20-64 y (n = 335; Surrey, United Kingdom) who consumed placebo, juice supplemented with 15 μg vitamin D2, biscuit supplemented with 15 μg vitamin D2, juice supplemented with 15 μg vitamin D3, or biscuit supplemented with 15 μg vitamin D3 daily for 12 wk. Serum 25(OH)D was measured by liquid chromatography-tandem mass spectrometry at baseline and at weeks 6 and 12 of the study.Results: Postintervention in the 2 ethnic groups combined, both the vitamin D3 biscuit and the vitamin D3 juice groups showed a significantly greater absolute incremental change (Δ) in total 25(OH)D when compared with the vitamin D2 biscuit group [Δ (95% CI): 15.3 nmol/L (7.4, 23.3 nmol/L) (P < 0.0003) and 16.0 nmol/L (8.0, 23.9 nmol/L) ( P < 0.0001)], the vitamin D2 juice group [Δ (95% CI): 16.3 nmol/L (8.4, 24.2 nmol/L) (P < 0.0001) and 16.9 nmol/L (9.0, 24.8 nmol/L) (P < 0.0001)], and the placebo group [Δ (95% CI): 42.3 nmol/L (34.4, 50.2 nmol/L) (P < 0.0001) and 42.9 nmol/L (35.0, 50.8 nmol/L) (P < 0.0002)].Conclusions: With the use of a daily dose of vitamin D relevant to public health recommendations (15 μg) and in vehicles relevant to food-fortification strategies, vitamin D3 was more effective than vitamin D2 in increasing serum 25(OH)D in the wintertime. Vitamin D3 may therefore be a preferential form to optimize vitamin D status within the general population. This trial was registered at www.controlled-trials.com as ISRCTN23421591.

Systematic Review: Nutrition and Physical Activity in the Management of Paediatric Nonalcoholic Fatty Liver Disease

Objectives: The aim of the study was to evaluate efficacy of nutrition and physical activity interventions in the clinical management of paediatric nonalcoholic fatty liver disease. The prevalence of paediatric nonalcoholic fatty liver disease continues to rise alongside childhood obesity. Weight loss through lifestyle modification is currently first-line treatment, although supplementation of specific dietary components may be beneficial. Methods: Medline, CINAHL, EMBASE, Scopus, and Cochrane Libraries were systematically searched to identify randomized controlled trials assessing nutritional and physical activity interventions. Primary outcome measures were changes to liver biomarkers assessed by imaging, histology, or serum liver function tests. Study quality was evaluated using the American Dietetic Association Quality Criteria Checklist. Results: Fifteen articles met eligibility criteria investigating nutritional supplementation (vitamin E [n = 6], probiotics [n = 2], omega-3 fatty acids [n = 5]), dietary modification (low glycaemic load [n = 1] and reducing fructose intake [n = 1]). No randomized controlled trials examining physical activity interventions were identified. Vitamin E was ineffective at improving alanine transaminase levels, whereas omega-3 fatty acids decreased hepatic fat content. Probiotics gave mixed results, whereas reduced fructose consumption did not improve primary outcome measures. A low glycaemic load diet and a low-fat diet appeared equally effective in decreasing hepatic fat content and transaminases. Most studies were deemed neutral as assessed by the American Dietetic Association Quality Criteria Checklist. Conclusions: The limited evidence base inhibits the prescription of specific dietary and/or lifestyle strategies for clinical practice. General healthy eating and physical activity guidelines, promoting weight loss, should remain first-line treatment until high-quality evidence emerges that support specific interventions that offer additional clinical benefit.OBJECTIVES The aim of the study was to evaluate efficacy of nutrition and physical activity interventions in the clinical management of paediatric nonalcoholic fatty liver disease. The prevalence of paediatric nonalcoholic fatty liver disease continues to rise alongside childhood obesity. Weight loss through lifestyle modification is currently first-line treatment, although supplementation of specific dietary components may be beneficial. METHODS Medline, CINAHL, EMBASE, Scopus, and Cochrane Libraries were systematically searched to identify randomized controlled trials assessing nutritional and physical activity interventions. Primary outcome measures were changes to liver biomarkers assessed by imaging, histology, or serum liver function tests. Study quality was evaluated using the American Dietetic Association Quality Criteria Checklist. RESULTS Fifteen articles met eligibility criteria investigating nutritional supplementation (vitamin E [n = 6], probiotics [n = 2], omega-3 fatty acids [n = 5]), dietary modification (low glycaemic load [n = 1] and reducing fructose intake [n = 1]). No randomized controlled trials examining physical activity interventions were identified. Vitamin E was ineffective at improving alanine transaminase levels, whereas omega-3 fatty acids decreased hepatic fat content. Probiotics gave mixed results, whereas reduced fructose consumption did not improve primary outcome measures. A low glycaemic load diet and a low-fat diet appeared equally effective in decreasing hepatic fat content and transaminases. Most studies were deemed neutral as assessed by the American Dietetic Association Quality Criteria Checklist. CONCLUSIONS The limited evidence base inhibits the prescription of specific dietary and/or lifestyle strategies for clinical practice. General healthy eating and physical activity guidelines, promoting weight loss, should remain first-line treatment until high-quality evidence emerges that support specific interventions that offer additional clinical benefit.

Vitamin D deficiency as a public health issue: using vitamin D 2 or vitamin D 3 in future fortification strategies

The role of vitamin D in supporting the growth and maintenance of the skeleton is robust; with recent research also suggesting a beneficial link between vitamin D and other non-skeletal health outcomes, including immune function, cardiovascular health and cancer. Despite this, vitamin D deficiency remains a global public health issue, with a renewed focus in the UK following the publication of Public Health Englands new Dietary Vitamin D Requirements. Natural sources of vitamin D (dietary and UVB exposure) are limited, and thus mechanisms are needed to allow individuals to achieve the new dietary recommendations. Mandatory or voluntary vitamin D food fortification may be one of the mechanisms to increase dietary vitamin D intakes and subsequently improve vitamin D status. However, for the food industry and public to make informed decisions, clarity is needed as to whether vitamins D2 and D3 are equally effective at raising total 25-hydroxyvitamin D (25(OH)D) concentrations as the evidence thus far is inconsistent. This review summarises the evidence to date behind the comparative efficacy of vitamins D2 and D3 at raising 25(OH)D concentrations, and the potential role of vitamin D food fortification as a public health policy to support attainment of dietary recommendations in the UK. The comparative efficacy of vitamins D2 and D3 has been investigated in several intervention trials, with most indicating that vitamin D3 is more effective at raising 25(OH)D concentrations. However, flaws in study designs (predominantly under powering) mean there remains a need for a large, robust randomised-controlled trial to provide conclusive evidence, which the future publication of the D2-D3 Study should provide (BBSRC DRINC funded: BB/I006192/1). This review also highlights outstanding questions and gaps in the research that need to be addressed to ensure the most efficacious and safe vitamin D food fortification practices are put in place. This further research, alongside cost, availability and ethical considerations (vitamin D3 is not suitable for vegans), will be instrumental in supporting government, decision-makers, industry and consumers in making informed choices about potential future vitamin D policy and practice.

Assessment of Diet and Physical Activity in Paediatric Non-Alcoholic Fatty Liver Disease Patients: A United Kingdom Case Control Study

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease in children, with prevalence rising alongside childhood obesity rates. This study aimed to characterise the habitual diet and activity behaviours of children with NAFLD compared to obese children without liver disease in the United Kingdom (UK). Twenty-four biopsy-proven paediatric NAFLD cases and eight obese controls without biochemical or radiological evidence of NAFLD completed a 24-h dietary recall, a Physical Activity Questionnaire (PAQ), a Dutch Eating Behavior Questionnaire (DEBQ) and a 7-day food and activity diary (FAD), in conjunction with wearing a pedometer. Groups were well matched for age and gender. Obese children had higher BMI z-scores (p = 0.006) and BMI centiles (p = 0.002) than participants with NAFLD. After adjusting for multiple hypotheses testing and controlling for differences in BMI, no differences in macro- or micronutrient intake were observed as assessed using either 24-h recall or 7-day FAD (p > 0.001). Under-reporting was prevalent (NAFLD 75%, Obese Control 87%: p = 0.15). Restrained eating behaviours were significantly higher in the NAFLD group (p = 0.005), who also recorded more steps per day than the obese controls (p = 0.01). In conclusion, this is the first study to assess dietary and activity patterns in a UK paediatric NAFLD population. Only a minority of cases and controls were meeting current dietary and physical activity recommendations. Our findings do not support development of specific dietary/ physical activity guidelines for children with NAFLD; promoting adherence with current general paediatric recommendations for health should remain the focus of clinical management.

Vitamin D in adolescents: Are current recommendations enough? ☆

Vitamin D is essential for bone development during adolescence and low vitamin D status during this critical period of growth may impact bone mineralization, potentially reducing peak bone mass and consequently increasing the risk of osteoporosis in adulthood. Therefore, the high prevalence of vitamin D inadequacy and deficiency in adolescent populations is of great concern. However, there is currently a lack of consensus on the 25-hydroxyvitamin D [25(OH)D] concentration, the widely accepted biomarker of vitamin D status, that defines adequacy, and the vitamin D intake requirements to maintain various 25(OH)D thresholds are not well established. While the current intake recommendations of 10-15μg/day may be sufficient to prevent vitamin D deficiency (25(OH)D<25-30nmol/l), greater intakes may be needed to achieve the higher threshold levels proposed to represent adequacy (25(OH)D>50nmol/l). This review will address these concerns and consider if the current dietary recommendations for vitamin D in adolescents are sufficient.

Vitamin D production in UK Caucasian and South Asian women following UVR exposure.

BACKGROUND It is known that skin pigmentation reduces the penetration of ultraviolet radiation (UVR) and thus photosynthesis of 25-hydroxvitamin D (25(OH)D). However ethnic differences in 25(OH)D production remain to be elucidated. OBJECTIVE The aim of this study was to investigate differences in vitamin D production between UK South Asian and Caucasian postmenopausal women, in response to a defined and controlled exposure to UVR. DESIGN Seventeen women; 9 white Caucasian (skin phototype II and III), 8 South Asian women (skin phototype IV and V) participated in the study, acting as their own controls. Three blood samples were taken for the measurement of vitamin D status during the run in period (9days, no sunbed exposure) after which, all subjects underwent an identical UVR exposure protocol irrespective of skin colour (9 days, 3 sun bed sessions, 6, 8 and 8min respectively with approximately 80% body surface exposed). Skin tone was measured four times during the study. RESULTS Despite consistently lower 25(OH)D levels in South Asian women, they were shown to synthesise vitamin D as efficiently as Caucasians when exposed to the same dose of UVR. Interestingly, the baseline level of vitamin D rather than ethnicity and skin tone influenced the amount of vitamin D synthesised. CONCLUSIONS This study have found no ethnic differences in the synthesis of 25(OH)D, possibly due to the baseline differences in 25(OH)D concentration or due to the small population size used in this study. Applying mixed linear model, findings indicated no effect of ethnicity and skin tone on the production of vitamin D; baseline level and length of exposure were the critical factors. To confirm that ethnicity and skin tone has no effect on 25(OH)D production, a larger sample size study is required that considers other ethnic groups with highly pigmented skin. Initial vitamin D status influences the amount of UVB needed to reach equal serum concentrations.