Dietary vitamin D intake among university students and their habits concerning daily sunlight exposure – a cross-sectional study

Aim: To evaluate students’ dietary vitamin D intake according to characteristics and habits concerning daily sunlight exposure. Methods: The study included 403 students of the University of Rijeka, Croatia that fulfilled questionnaire about their characteristics, habits, physical activity, supplement use, diet, and their daily sunlight exposure. For assessing diet quality, the Dietary inflammatory index (DII®) was used. Results: Average dietary vitamin D intake was 2.76 μg/day, statistically highest among men (p<0.01), medical sciences universities’ students (p<0.01), students with obesity (p=0.03), highly physically active (p=0.02) and smokers (p=0.01). Major dietary vitamin D sources were fish (42%, p<0.01) and meat and meat products (31%). Students that more frequently expose themselves to the sunlight were mostly men, overweight, moderately physically active, dietary supplements users, and had a diet with more anti-inflammatory potential, higher dietary vitamin D intake and its major dietary sources. Those who rarely and never used a sunscreen had a more anti-inflammatory diet and higher vitamin D and its major food sources intakes. Diet with more pro-inflammatory potential had students that rarely or never directly expose themselves to the sunlight, likewise the students that frequently used sunscreen. Those subgroups also had the lowest dietary vitamin D intake. Conclusions: The average dietary vitamin D intake by investigated university students satisfied only the fifth of the recommended daily vitamin D intake. Students with habits that can influence the lower synthesis of vitamin D may increase the risk of diseases related to bone health, immunity and inflammation in their future life. Provided results about students’ habits of their exposure to the sunlight might be useful for public health messages toward sufficient sunlight exposure, diet quality with more anti-inflammatory potential, vitamin D supplements use, and vitamin D deficiency prevention.

Relationship between Serum 25OH-Vitamin D2 Level and Vitamin D Status of Children Aged 3–5 Years in China

Background: Vitamin D deficiency is prevalent globally and there is lack of evidence as to how 25(OH)D2 contributes to vitamin D status. The aim of this study was to describe vitamin D status and to assess the role of vitamin D2, a dietary vitamin D source, against the vitamin D status of children aged 3–5 years in China. Methods: Data were extracted from the Chinese National Nutrition and Health Surveillance (CNNHS) in 2013. The concentration of serum 25(OH)D2 and 25(OH)D3 was measured by using LC-MS/MS. Results: A total of 1435 subjects were enrolled and serum 25(OH)D were analyzed. The prevalence of total serum 25(OH)D < 30 nmol/L was 8.9%. Serum 25(OH)D2 was detected in 10.9% of the studied children. After adjusting for confounding factors, total 25(OH)D concentration was 8.48 nmol/L lower and odds ratio of vitamin D deficiency was 4.20 times (OR (95%CI): 4.20 (1.64, 10.77)) in children without 25(OH)D2 than those with 25(OH)D2 detected. Conclusions: Vitamin D deficiency was common among children aged 3–5 years in China. Vitamin D2 may play a role in preventing vitamin D deficiency in Chinese children aged 3–5 years.

Assessment of the Effects of Dietary Vitamin D Levels on Olanzapine-Induced Metabolic Side Effects: Focus on the Endocannabinoidome-Gut Microbiome Axis

Vitamin D deficiency is associated with poor mental health and dysmetabolism. Several metabolic abnormalities are associated with psychotic diseases, which can be compounded by atypical antipsychotics that induce weight gain and insulin resistance. These side-effects may be affected by vitamin D levels. The gut microbiota and endocannabinoidome (eCBome) are significant regulators of both metabolism and mental health, but their role in the development of atypical antipsychotic drug metabolic side-effects and their interaction with vitamin D status is unknown. We studied the effects of different combinations of vitamin D levels and atypical antipsychotic drug (olanzapine) exposure on whole-body metabolism and the eCBome-gut microbiota axis in female C57BL/6J mice under a high fat/high sucrose (HFHS) diet in an attempt to identify a link between the latter and the different metabolic outputs induced by the treatments. Olanzapine exerted a protective effect against diet-induced obesity and insulin resistance, largely independent of dietary vitamin D status. These changes were concomitant with olanzapine-mediated decreases in Trpv1 expression and increases in the levels of its agonists, including various N-acylethanolamines and 2-monoacylglycerols, which are consistent with the observed improvement in adiposity and metabolic status. Furthermore, while global gut bacteria community architecture was not altered by olanzapine, we identified changes in the relative abundances of various commensal bacterial families. Taken together, changes of eCBome and gut microbiota families under our experimental conditions might contribute to olanzapine and vitamin D-mediated inhibition of weight gain in mice on a HFHS diet.

Vitamin D status and dietary intake in young university students in the UK

Purpose Vitamin D deficiency is prevalent worldwide. This paper aims to investigate the vitamin D status and dietary intake in young university students. Design/methodology/approach Forty-one healthy students aged 18–29 years from Coventry University UK were recruited during January-February 2019, including white Caucasians (n = 18), African-Caribbeans (n = 14) and Asians (n = 9). Plasma 25(OH)D concentrations were measured and dietary vitamin D intake was determined. Chi-square and simple linear regression were used to analyse the data. Findings The plasma 25(OH)D concentrations were (36.0 ± 22.2) nmol/L in all subjects, (46.5 ± 25.3) nmol/L in white Caucasians, (22.6 ± 7.4) nmol/L in African-Caribbeans and (37.4 ± 21.7 nmol/L) in Asians. The majority (85.7%) of African-Caribbeans were vitamin D deficient compared with 22.2% of white Caucasians and 33.3% of Asians (p = 0.001). Overweight/obese subjects showed a significant higher proportion of vitamin D deficiency (65%) than normal weight subjects (28.6%) (p = 0.04). The average dietary vitamin D intake in all subjects was (4.6 ± 3.9) µg/day. Only 12.1% of the subjects met the recommended dietary vitamin D intake of 10 µg/day. Dietary vitamin D intake (p = 0.04) and ethnicity (p = 0.01) were significant predictors of 25(OH)D levels and accounted for 13% and 18.5% of 25(OH)D variance, respectively. Research limitations/implications This small-scale study showed an alarmingly high prevalence of vitamin D deficiency among subjects from African-Caribbean origin during wintertime. Education programs and campaigns are urgently needed to fight the vitamin D deficiency in this population. Originality/value The targeted population were in a critical period of transition from adolescence toward adulthood involving in changes in behaviours and nutrition.

Super-doses of dietary vitamin D3 intake in aged laying hens illustrates limitation of 24,25-dihydroxycholecalciferol conversion

Background: Humans take vitamin D supplements to reduce risk of vitamin D deficiency and reduce the risk of osteoporosis. However, it is unclear how dietary super-dose (10,000x greater than requirement) can affect vitamin D status in aged animals. Aged laying hens could potentially be a model to compare with women in peri- or postmenopausal stages of life because their bone health is physiologically taxed from egg production and they are highly susceptible to osteoporosis. Objective: We investigated dietary super-dose impacts of cholecalciferol (vitamin D3) on vitamin D status in aged laying hens in production. Methods: Forty-eight 68-wk old Hy-Line Brown laying hens were individually housed in cages with eight hens per dietary treatment for eleven weeks. Hens were randomly assigned to one of six groups of dietary vitamin D3 supplementation and fed ad libitum. Supplementation levels were 400 (recommended dosage for hens), 800, 7,400, 14,000, 20,000, and 36,000 IU D3/kg of feed. At termination of the study, all hens were euthanized and we collected blood, feces, and tibia and humerus bones. Ionized (free) blood calcium, fecal calcium, bone calcium, and plasma vitamin D metabolites were measured. Results: We did not discern any dietary effects in tissue and fecal calcium. We observed that increasing dietary vitamin D3 increased plasma vitamin D3, 25-hydroxycholecalciferol, and 24,25-dihydroxycholecalciferol concentrations (p < 0.0001 for all 3 metabolites). We also observed super-dose fed hens had decreased kidney 24-hydroxylase expression (p = 0.0006). Conclusions: Although dietary vitamin D3 super-doses did not affect calcium status in our aged laying hens, it is possible there is an age-related effect of not being as sensitive to vitamin D efficacy. We suggest future research should explore how 24-hydroxylation mechanisms are affected by vitamin D supplementation. Further understanding of 24-hydroxylation can help ascertain ways to reduce risk of vitamin D toxicity.

Vitamin D Intake in Slovenian Adolescents, Adults, and the Elderly Population

Vitamin D is involved in calcium and phosphorus metabolism, and is vital for numerous bodily functions. In the absence of sufficient UV-B light-induced skin biosynthesis, dietary intake becomes the most important source of vitamin D. In the absence of biosynthesis, the recommended dietary vitamin D intake is 10–20 µg/day. Major contributors to dietary vitamin D intake are the few foods naturally containing vitamin D (i.e., fish), enriched foods, and supplements. The present study aimed to estimate the vitamin D intake in Slovenia, to identify food groups that notably contribute to vitamin D intake, and to predict the effects of hypothetical mandatory milk fortification. This study was conducted using data collected by the national cross-sectional food consumption survey (SI.Menu) in adolescents (n = 468; 10–17 years), adults (n = 364; 18–64 years), and the elderly (n = 416; 65–74 years). Data collection was carried out between March 2017 and April 2018 using the EU Menu Methodology, which included two 24-hour recalls, and a food propensity questionnaire. Very low vitamin D intakes were found; many did not even meet the threshold for very low vitamin D intake (2.5 µg/day). Mean daily vitamin D intake was 2.7, 2.9, and 2.5 µg in adolescents, adults, and the elderly, respectively. Daily energy intake was found to be a significant predictor of vitamin D intake in all population groups. In adolescents and adults, sex was also found to be a significant predictor, with higher vitamin D intake in males. The study results explained the previously reported high prevalence of vitamin D deficiency in Slovenia. An efficient policy approach is required to address the risk of vitamin D deficiency, particularly in vulnerable populations.

Association of Dietary Vitamin D Intake, Serum 25(OH)D3, 25(OH)D2 with Cognitive Performance in the Elderly

Background: As life expectancy increases, cognitive performance decline in the elderly has become one of the major global challenges. We aimed to evaluate the association of dietary vitamin D (VD), serum 25-hydroxyvitamin D3 (25(OH)D3), 25-hydroxyvitamin D2 (25(OH)D2), and total 25-hydroxyvitamin (25(OH)D) concentration with cognitive performance in older Americans. Methods: The data from the National Health and Nutrition Examination Survey (NHANES), 2011–2014 was used. The cognitive performance was assessed by the Consortium to Establish a Registry for Alzheimer’s Disease (CERAD) Word Learning sub-test, Animal Fluency test, and Digit Symbol Substitution Test (DSST). A binary logistic regression model was applied to evaluate the association between VD and cognitive performance, and restricted cubic spline model was adopted to evaluate the dose–response relationship. Results: While comparing to the lowest dietary VD intake group, the multivariate adjusted odds ratios (ORs) and 95% confidence intervals (CIs) of the highest dietary VD intake group were 0.51 (0.36–0.72) for the Animal Fluency test score and 0.45 (0.31–0.66) for DSST score, respectively; and those of serum total 25(OH)D and 25(OH)D3 concentration were 0.68 (0.47–0.97) and 0.62 (0.44–0.86) for DSST score. L-shaped relationships were identified for dietary VD intake, serum total 25(OH)D and 25(OH)D3 concentration with cognition performance. The associations between dietary VD intake, serum total 25(OH)D and cognitive performance were non-significant when stratified by gender. Conclusions: The study indicates that dietary VD intake, serum total 25(OH)D and 25(OH)D3 concentration were positively associated with cognitive performance. Further studies are needed to clarify the possible effects of dietary VD intake and serum 25(OH)D2, 25(OH)D3 on cognitive performance.