The objectives of the present study were to (i) develop and validate a norm-referenced performance-rating scale to interpret a nutrition knowledge test developed for urban adolescents and (ii) develop a prototype for other researchers to follow when developing nutrition knowledge tests.

For norm development the nutrition knowledge test (questionnaire) was administered to a sample representative of the questionnaire target group, referred to as the norm group. These included 512 adolescents in grades 8 (n 158), 10 (n 149) and 12 (n 205) at three randomly selected schools in Soweto and Johannesburg. The performance scores (in percentages) obtained by the norm group were transformed to Z-scores which were categorised into stanines using established Z-score cut-off points. For validation purposes the questionnaire was completed by 148 volunteers: sixty university dietetics students, nineteen non-nutrition university students and sixty-nine primary-school teachers.

As required of an ideal norm group, the Z-scores formed a normal distribution (a bell-shaped curve). To facilitate interpretation of the results, the Z-score cut-off points for these categories were transformed back to performance scores (percentages) so that the performance of a testee could be interpreted directly from his/her performance in percentage. As is recommended, the nine stanine categories were reduced to five: very poor, fair/below average, good/average, very good/above average and excellent. The discriminatory validity of the norms was substantiated by showing that groups with known nutrition knowledge levels were rated appropriately and that the performance ratings of these groups differed significantly, with university dietetics students scoring 98·3 %, primary-school teachers 20·3 % and non-nutrition university students 31·6 %.

The norm-referenced performance-rating scale can be used with confidence to interpret the performance score achieved by a testee on the nutrition knowledge test developed for urban adolescents in South Africa. The methodology used in the study serves as a prototype for other researchers who are developing knowledge tests.

Multivitamin supplements are used by nearly half of middle-aged women in the USA. Despite this high prevalence of multivitamin use, little is known about the effects of multivitamins on health outcomes, including cancer risk. Our main objective was to determine the association between multivitamin use and the risk of breast cancer in women.

We conducted a population-based case–control study among 2968 incident breast cancer cases (aged 20–69 years), diagnosed between 2004 and 2007, and 2982 control women from Wisconsin, USA. All participants completed a structured telephone interview which ascertained supplement use prior to diagnosis, demographics and risk factor information. Odds ratios and 95 % confidence intervals were calculated using multivariable logistic regression.

Compared with never users of multivitamins, the OR for breast cancer was 1·02 (95 % CI 0·87, 1·19) for current users and 0·99 (95 % CI 0·74, 1·33) for former users. Further, neither duration of use (for ≥10 years: OR = 1·13, 95 % CI 0·93, 1·38, P for trend = 0·25) nor frequency (>7 times/week: OR = 1·00, 95 % CI 0·77, 1·28, P for trend = 0·97) was related to risk in current users. Stratification by menopausal status, family history of breast cancer, age, alcohol, tumour staging and postmenopausal hormone use did not significantly modify the association between multivitamin use and breast cancer.

The current study found no association between multivitamin supplement use and breast cancer risk in women.

To explore explicit beliefs about the controllability of obesity and the internalisation of negative weight-related stereotypes among public health trainees.

Cross-sectional online survey assessing explicit beliefs about the controllability of obesity using the Beliefs About Obese Persons Scale (BAOP) and internalisation of weight bias using the Modified Weight Bias Internalization Scale (WBIS-M). Bivariate associations between BAOP and WBIS-M scores and demographic characteristics were examined using t tests or ANOVA with post hoc Tukey’s tests.

School of Public Health at a large, Midwestern University.

Public health students (n 322).

Relative to students who identified as male, those who identified as female had a stronger belief that obesity is not within the control of the individual (P = 0·03), yet had more internalisation of weight bias (P < 0·01). Greater weight bias internalisation was also seen among students who perceived themselves to be of a higher weight status (P < 0·001) and those who were at risk for food insecurity (P < 0·01).

Public health trainees may be more attuned to the complexities of weight relative to trainees in other health-related fields, but are still susceptible to internalisation of negative weight-related stereotypes.

To assess the folate status of US women in a study of a folate-fortified oral contraceptive (OC) using the Short Folate Food Frequency Questionnaire and plasma and red blood cell (RBC) folate samples.

Sub-analysis from a multi-centre, randomised, double-blind, controlled contraceptive trial with assessments at baseline and 6 months. We calculated dietary folate equivalents (DFE) consumed and the proportion of participants meeting folate adequacy benchmarks.

Eight centres in the USA.

Healthy women aged 18–40 years requesting contraception with no contraindications for OC use.

Overall, 385 participants were randomised to either a novel folate-fortified OC or a marketed OC. The 262 (68 %) participants compliant with the protocol were included in the analysis set. Baseline daily DFE consumption was 529·8 (sd 342·1) μg and similar in both groups. At follow-up, the fortified OC group had higher intake than the conventional OC group (1225·9 (sd 346·2) μg compared with 500·6 (sd 361·2) μg). Mean plasma folate level increased from 44·5 (sd 17·2) to 55·8 (sd 21·1) nmol/l. Mean RBC folate level increased from 996·7 (sd 369·8) to 1311·9 (sd 436·0) nmol/l. The proportion meeting selected folate adequacy benchmarks increased in the fortified OC group (P < 0·001).

Lack of adequate folate intake in reproductive-aged women from dietary sources or supplements alone suggests the need for novel approaches. Use of folate-fortified OC ensures adequate folate levels and meeting of folate benchmarks.

To examine the association between overweight and obesity and serum ferritin among women of reproductive age (15–49 years) in Nicaragua, considering the effect of α1-acid glycoprotein (AGP), a marker of inflammation.

We analysed data from the 2004–05 Nicaraguan Integrated Surveillance System for Nutrition Interventions. Three logistic regression models were analysed with low serum ferritin (<15 μg/l) as the dependent variable: (i) overweight or obese status and covariates; (ii) model 1 plus AGP; and (iii) model 1 restricted to only women with normal AGP levels (≤1·0 g/l).

Nicaragua.

Included in this analysis were 832 non-pregnant mother/caregivers (15–49 years) surveyed in 2004–2005.

In the sample, prevalence of overweight and obesity was 31·8 % and 19·2 %, respectively, and 27·6 % had low serum ferritin. In model 1, the adjusted OR of low serum ferritin was 0·74 (95 % CI 0·52, 1·05) for overweight women and 0·42 (95 % CI 0·26, 0·65) for obese women. In model 2, AGP was significantly independently associated with low serum ferritin (adjusted OR=0·56, 95 % CI 0·34, 0·92) while the adjusted OR for overweight and obesity were largely unchanged. Excluding women with elevated AGP did not appreciably affect the relationship between overweight or obesity and low serum ferritin (model 3).

Overall, in this population of reproductive-age women, obese women were less likely to have low serum ferritin levels, and this was independent of inflammation as measured by AGP.

To determine whether the literature filtering process, a vital initial component of a systematic literature review, could be successfully completed by nutrition professionals or non-professionals.

Using a diet–disease relationship as the guideline topic, inter-rater agreement for the title and abstract filtering processes between and among professionals and non-professionals was assessed and compared with an expert reference standard. Predetermined eligibility criteria were applied by all raters to 185 titles and 90 abstracts. Filtering decisions were initially made independently and then revised after a within-pair consensus meeting.

The raters were six dietitians (RD) and six nutrition graduate students (Grad). To assess inter-rater agreement (reliability), each group was divided into three pairs.

Weighted and unweighted kappa statistics and percentage agreement were calculated to determine the inter-rater agreement within pairs. Sensitivity and specificity estimates were determined by comparing responses with those of an expert reference standard. Overall, Grad pairs demonstrated greater inter-rater agreement than RD pairs for title filtering (P < 0.05); no differences were observed for abstract filtering. Compared with the expert reference standard, every rater and pair had false-negative responses for both title and abstract filtering.

After consensus meetings, both RDs and Grads were comparable in their agreement on title and abstract filtering, although important differences remained compared with the expert reference standard. This study provides preliminary findings on the value of utilising a non-expert pair in developing guidelines, and suggests that the literature filtering process is complex and quite subjective.

To assess the applicability and use of infant nutrition and health indicators during emergencies.

Indicators recommended by international health and nutrition organisations for assessing infant feeding practice were compiled and analysed to evaluate their consistency and applicability for use in surveys of emergency-affected populations. These indicators included measures of breast-feeding status, use of artificial feeding, anthropometric status and morbidity. Health and nutrition surveys performed on the resident or refugee population of Kosovo during the years 1996–1999 were then reviewed and the use of infant feeding and morbidity indicators were compared.

A number of recommended indicators exist for assessing infant and child feeding practice which have been generated by different international organisations. A comparison of these indicators revealed a number of inconsistencies, both in target population and measurement method. Their use during the Kosovo crisis was likewise inconsistent and prevented conclusions being drawn about the effectiveness of the international response in protecting infant health and nutrition.

Standard indicators need to be agreed and promoted for use during surveys of emergency-affected populations. Failure to do so will lead to a continued inability to monitor the health and nutrition of infants at a population level during international relief operations.

To evaluate the utility of three validated food responsiveness scales in measuring recall of, and responsiveness to, food marketing exposure on social media.

Cross-sectional survey among adolescents and adults who used the social media platform Twitch.tv (Twitch). Responsiveness to food marketing was self-reported as craving or purchasing any brands participants observed on Twitch. Participants completed three validated scales of food responsiveness: the revised 18-question Three Factor Eating Questionnaire (TFEQ), the external eating subscale of the Dutch Eating Behavior Questionnaire (DEBQ) and the External Food Cue Responsiveness (EFCR) scale. Adjusted linear regression models assessed the predictive ability of each scale on recall and responsiveness outcomes.

Online survey.

Five hundred and sixty-eight Twitch users (90·1 % male, 60·6 % White, 43·7 % aged 18–24, 25·9 % under 18).

In separate adjusted linear regression models, scores on the TFEQ were not related to any outcome, while DEBQ scores related to product cravings (OR: 1·10, 95 % CI 1·01, 1·19, P = 0·02). In contrast, scores on the EFCR scale were significantly associated with higher brand recall (incident rate ratio: 1·42, 95 % CI 1·20, 1·68, P < 0·001), product craving (OR: 3·93, 95 % CI 2·22, 7·17, P < 0·001) and purchasing behaviour (OR: 3·97, 95 % CI 1·99, 8·26, P < 0·001). A subset of three EFCR scale items related to influencer marketing were similarly associated with each outcome with greater precision in the point estimates than the overall EFCR.

The EFCR scale predicted recall of and responsiveness to food marketing via Twitch, suggesting its utility in monitoring the effects of food marketing on social media.

To understand the different Na menu labelling approaches that have been considered by state and local policymakers in the USA and to summarise the evidence on the relationship between Na menu labelling and Na content of menu items offered by restaurants or purchased by consumers.

Proposed and enacted Na menu labelling laws at the state and local levels were reviewed using legal databases and an online search, and a narrative review of peer-reviewed literature was conducted on the relationship between Na menu labelling and Na content of menu items offered by restaurants or purchased by consumers.

Local and state jurisdictions in the USA

Not applicable.

Between 2000 and 2020, thirty-eight laws – eleven at the local level and twenty-seven at the state level – were proposed to require Na labelling of restaurant menu items. By 2020, eight laws were enacted requiring chain restaurants to label the Na content of menu items. Five studies were identified that evaluated the impact of Na menu labelling on Na content of menu items offered by restaurants or purchased by consumers in the USA. The studies had mixed results: two studies showed a statistically significant association between Na menu labelling and reduced Na content of menu items; three showed no effects.

Data suggest that Na menu labelling may reduce Na in restaurant menu items, but further rigorous research evaluating Na menu labelling effects on Na content of menu items, as well as on the Na content in menu items purchased by consumers, is needed.

About one-third of under-five Filipino children are stunted, with significant socio-economic inequality. This study aims to quantify factors that explain the large gap in stunting between poor and non-poor Filipino children.

Using the 2015 Philippine National Nutrition Survey, we conducted a linear probability model to examine the determinants of child stunting and then an Oaxaca-Blinder decomposition to explain the factors contributing to the gap in stunting between poor and non-poor children.

Philippines.

1881 children aged 6–23 months participated in this study.

The overall stunting prevalence was 38·5 % with a significant gap between poor and non-poor (45·0 % v. 32·0 %). Maternal height, education and maternal nutrition status account for 26 %, 18 % and 17 % of stunting inequality, respectively. These are followed by quality of prenatal care (12 %), dietary diversity (12 %) and iron supplementation in children (5 %).

Maternal factors account for more than 50 % of the gap in child stunting in the Philippines. This signifies the critical role of maternal biological and socio-economic circumstances in improving the linear growth of children.

To investigate whether maternal/caregiver’s age, infant age (0–6 months) and discarding colostrum affects timely initiation of breast-feeding (TIBF) and exclusive breast-feeding (EBF) in Ethiopia.

A systematic search of PubMed, SCOPUS, EMBASE, CINHAL, Web of Science and WHO Global Health Library electronic databases was done for all articles published in English from 2000 to January 2018. Two reviewers independently screened, extracted and graded the quality of studies using Newcastle–Ottawa Scale. A weighted inverse-variance random-effects model meta-analysis, cumulative meta-analysis and mixed-effects meta-regression analysis were done.

All observational studies conducted in Ethiopia.

Mothers of children aged less than 2 years.

A total of forty articles (fourteen studies on TIBF and twenty-six on EBF) were included. TIBF was associated with colostrum discarding (OR=0·38; 95 % CI 0·21, 0·68) but not with maternal/caregiver’s age (OR=0·98; 95 % CI 0·83, 1·15). In addition, colostrum discarding (OR=0·53; 95 % CI 0·36, 0·78) and infant age (OR=1·77; 95 % CI 1·38, 2·27) were significantly associated with EBF but not maternal/caregiver’s age (OR=1·09; 95 % CI 0·84, 1·41).

There was no association between maternal/caregiver’s age and breast-feeding practice (EBF and TIBF). Colostrum discarding was associated with both EBF and TIBF. This evidence could be helpful to counsel all mothers of reproductive age and who discard colostrum.

Dietary recommendations (DR) in the USA may be inadequate at improving diets in racial/ethnic minority communities and may require redesign of the systems driving their development over the long term. Meanwhile, cultural adaptation of evidence-based DR may be an important strategy for mitigating nutrition disparities, but less is known about the adaptability of these recommendations to meet the needs of diverse groups. We examined the content and origin of major DRs – aspects that provide context on their potential universality across populations and evaluated their potential for cultural adaptation.

Case studies of Dietary Approaches to Stop Hypertension (DASH), the Mediterranean diet (MD), the EAT-Lancet diet (EAT) and the NOVA classification system.

United States.

Racial/ethnic minority populations.

Current DR differ in their origin/evolution but are similar in their reductionist emphasis on physical health. DASH has been successfully adapted for some cultures but may be challenged by the need for intensive resources; MD may be more beneficial if applied as part of a broader set of food procurement/preparation practices than as just diet alone; EAT-Lancet adaptation may not honor existing country-specific practices that are already beneficial to human and environmental health (e.g. traditional/plant-based diets); evidence for cultural adaptation is limited with NOVA, but classification of levels of food processing has potential for widespread application.

For DR to equitably support diverse populations, they must move beyond a Eurocentric or ‘general population’ framing, be more inclusive of cultural differences and honour social practices to improve diet and reduce disparities.

Alternative food sources (AFS) such as local markets in disadvantaged areas are promising strategies for preventing chronic disease and reducing health inequalities. The present study assessed how sociodemographic characteristics, physical access and fruit and vegetable (F&V) consumption are associated with market use in a newly opened F&V market next to a subway station in a disadvantaged neighbourhood.

Two cross-sectional surveys were conducted among adults: (i) on-site, among shoppers who had just bought F&V and (ii) a telephone-based population survey among residents living within 1 km distance from the market.

One neighbourhood in Montreal (Canada) with previously limited F&V offerings.

Respectively, 218 shoppers and 335 residents completed the on-site and telephone-based population surveys.

Among shoppers, 23 % were low-income, 56 % did not consume enough F&V and 54 % did not have access to a car. Among all participants living 1 km from the market (n 472), market usage was associated (OR; 95 % CI) with adequate F&V consumption (1·86; 1·10, 3·16), living closer to the market (for distance: 0·86; 0·76, 0·97), having the market on the commute route (2·77; 1·61, 4·75) and not having access to a car (2·96; 1·67, 5·26).

When implemented in strategic locations such as transport hubs, AFS like F&V markets offer a promising strategy to improve F&V access among populations that may be constrained in their food acquisition practices, including low-income populations and those relying on public transportation.

Previous studies from European countries noted that food products promoted on TV for children did not comply with international guidelines, including the World Health Organization European Nutrient Profile Model (WHO-ENPM) and the EU Pledge Nutrition Criteria (EU-PNC, an initiative developed by leading food companies). We aim to provide new data from Italy.

Evaluation of Italian TV advertisements. Data on nutritional values for food product advertised were compared with nutritional standards issued by the WHO-ENPM and the EU-PNC.

In total, 180 h of TV programmes from six Italian channels, 2016–2017.

Eight hundred and ten consecutive advertisements during children’s programmes.

Out of 810 advertisements, 90 (11·1 %) referred to food products. Among these, 84·5 % of the foods promoted did not meet the WHO-ENPM and 55·6 % the EU-PNC guidelines. Advertisements promoting sweet and salty snacks (i.e. ≥ 70 % of all foods) v. other food products showed higher non-compliance with both the WHO-ENPM (OR: 73·8; 95 % CI: 4·09, 1330) and the EU-PNC (OR: 9·21; 95 % CI: 2·82, 30·1).

In Italy, most food advertisements during children’s programmes are not compliant with European nutritional standards. Almost all the advertisements for snacks do not meet international guidelines. As the WHO-ENPM guidelines do not propose standards for all the food products, including meals, there is an urgent need to define independent and easy-to-read guidelines for food advertisements targeting children. As a first step towards the complete ban of food advertisements targeting children recommended by other researchers, these guidelines should be enforced by all the TV broadcasts.

To categorize the research topics covered by a sample of cohort studies exploring the association between nutrition and obesity; to describe their funding sources; and to explore the association between funding sources and research topics.

Cross-sectional study.

Cohort studies retrieved from MEDLINE and PubMed published between 2010 and 2016.

One hundred and twenty-one studies were included. Funding source and conflicts of interest were disclosed in 95·0 and 90·1 % of the studies, respectively. Food industry sponsorship was disclosed in 8·3 % of the studies. Half of the studies analysed the consumption of a single food or food groups, 18·2 % included an analysis of dietary patterns and 17·4 % focused on specific nutrients. Highly processed foods were considered in 48·8 % of the studies and 27·3 % considered dietary behaviours (e.g. eating away from home). No statistically significant differences in research topics were observed between industry- and non-industry-funded studies.

Cohort studies focused on more complex exposures (e.g. food or dietary patterns) rather than single nutrients. No significant differences in the research agenda by funding sources were observed. The analysis was limited by the low proportion of studies with disclosed food industry sponsorship.

This paper describes the first web-based self-completed 24-h recall designed to categorise food intake according to Nova groups – Nova24h – and its agreement with a reference tool in estimating the dietary relative contribution of the four Nova food groups (% of total energy intake).

Comparisons of estimates of dietary relative contributions of Nova groups obtained by Nova24h and one standard interviewer-led 24-h recall.

Nationwide adult cohort study in Brazil.

The subjects were 186 participants of the NutriNet Brasil Cohort Study (n 186).

No statistically significant differences were observed between the Nova24h and the reference tool mean contributions of unprocessed or minimally processed foods (52·3 % v. 52·6 %), processed culinary ingredients (11·6 % v. 11·9 %), processed foods (17·1 % v. 14·7 %) and ultra-processed foods (19·0 % v. 20·9 %). Intraclass correlation coefficients between individual estimates obtained for each Nova group showed moderate to good agreement (0·54–0·78). Substantial or almost perfect agreement between the tools was seen regarding the ability to rank participants according to quintiles of contribution of each Nova group (PABAK 0·69–0·81).

Nova24h is a suitable tool for estimating the dietary relative energy contribution of Nova food groups in the NutriNet Brasil cohort. New studies are necessary to verify its adequacy in other populations.

To evaluate the effect of a sugar-sweetened beverage (SSB) tax implemented in Oakland, California, in July 2017, on prices of beverages sold in fast-food restaurants 2-year post-tax.

Using a difference-in-differences (DID) approach, we analysed beverage price data collected from fast-food restaurants 1-month pre-tax and 2-year post-tax in Oakland (intervention site) and Sacramento, California (comparison site). Separate linear regression models were used to estimate the impact of the tax on prices of bottled regular soda, bottled diet soda, bottled unsweetened beverages and fountain drinks.

Oakland and Sacramento, California, USA.

Chain and non-chain fast-food restaurants (n 85).

DID estimates indicate that in fast-food restaurants, on average, the price of bottled regular soda increased by 1·44 cents/oz (95 % CI 0·50, 2·73) (tax pass-through rate of 144 %) and the price of bottled diet soda increased by 1·17 cents/oz (95 % CI 0·07, 2·13). No statistically significant differences were found between bottled regular and diet soda price increases. Price effects for unsweetened beverages and fountain drinks were not statistically significant. Further, the estimated price change for fountain drinks was nearly zero.

Findings suggest that the effectiveness of SSB taxes in discouraging SSB consumption may be limited in fast-food restaurants in Oakland, California, because there were similar price increases in taxed and untaxed bottled soda and no changes in fountain drink prices.

To evaluate the prevalence of ‘High Fat Sugar Salt’ (HFSS) products and front-of-pack nutrition labelling (FOPNL) characteristics across promoted products in UK online supermarkets.

A cross-sectional survey conducted (December 2021–January 2022) on promoted products. Data on ingredients, nutritional composition and display of FOPNL were collected from product webpages. The UK’s Nutrient Profiling Model and Multiple Traffic Light criteria were used to determine HFSS status and possession of inherent red traffic lights (iRTL), respectively. Data analysis determined the prevalence (i.e. percentage of products of the total number of products sampled) of HFSS; FOPNL and possession of iRTL. Chi-squared tests explored associations between these.

Three major UK online supermarket retailer websites.

Product ‘multibuy’ and ‘entrance’ promotions, from selected product categories.

Among the sampled 625 promoted products, the prevalence of HFSS was greater in entrance (73 %) compared with multibuy (41 %) promotions (χ2 (1) = 34, P < 0·05), with variations in the former across retailers (49–92 %). The prevalence of HFSS products in multibuy promotions offered by two retailers varied by category (i.e. Confectionery 94–97 %, Yogurts 20–20 %, Soft Drinks 16–33 %, Ready Meals 1·4–18 %). Not all promoted products displayed FOPNL on webpages (70 %) or images (52 %). A number of iRTL were found to be possessed by both HFSS and non-HFSS-promoted products.

Prior to the 2022 implementation of Regulations restricting these, HFSS products were promoted in online supermarkets with varying display of FOPNL and possession of iRTL. Findings support future policy evaluation and mandatory digital FOPNL.

We aimed to assess the feasibility of a simple new fifteen-item FFQ as a tool for screening risk of poor dietary patterns in a healthy middle-aged population and to investigate how the results of the FFQ correlated with cardiovascular risk factors and socio-economic factors.

A randomized population-based cross-sectional study. Metabolic measurements for cardiovascular risk factors and information about lifestyle were collected. A fifteen-item FFQ was created to obtain information about dietary patterns. From the FFQ, a healthy eating index was created with three dietary groups: good, average and poor. Multivariate logistic regression was used to assess relationships between dietary patterns and cardiovascular risk factors.

Sweden.

Men and women aged 50 years and living in Gothenburg, Sweden.

In total, 521 middle-aged adults (257 men, 264 women) were examined. With good dietary pattern as the reference, there was a gradient association of having obesity, hypertension and high serum TAG in those with average and poor dietary patterns. After adjustment for education and lifestyle factors, individuals with a poor dietary pattern still had significantly higher risk (OR; 95 % CI) of obesity (2·33; 1·10, 4·94), hypertension (2·73; 1·44, 5·20) and high serum TAG (2·62; 1·33, 5·14) compared with those with a good dietary pattern.

Baseline data collected by a short FFQ can predict cardiovascular risk factors in middle-aged Swedish men and women. The FFQ could be a useful tool in health-care settings, when screening for risk of poor dietary patterns.

Several meta-analyses have suggested the beneficial effect of vitamin D on patients infected with severe acute respiratory syndrome coronavirus-2. This umbrella meta-analysis aims to evaluate influence of vitamin D supplementation on clinical outcomes and the mortality rate of COVID-19 patients.

Present study was designed as an umbrella meta-analysis. The following international databases were systematically searched till March 2023: Web of Science, PubMed, Scopus, and Embase.

Random-effects model was employed to perform meta-analysis. Using AMSTAR critical evaluation tools, the methodological quality of the included meta-analyses was evaluated.

Adult patients suffering from COVID-19 were studied.

Overall, 13 meta-analyses summarising data from 4 randomised controlled trial and 9 observational studies were identified in this umbrella review. Our findings revealed that vitamin D supplementation and status significantly reduced mortality of COVID-19 [Interventional studies: (ES = 0·42; 95 % CI: 0·10, 0·75, P < 0·001; I2 = 20·4 %, P = 0·285) and observational studies (ES = 1·99; 95 % CI: 1·37, 2·62, P < 0·001; I2 = 00·0 %, P = 0·944). Also, vitamin D deficiency increased the risk of infection and disease severity among patients.

Overall, vitamin D status is a critical factor influencing the mortality rate, disease severity, admission to intensive care unit and being detached from mechanical ventilation. It is vital to monitor the vitamin D status in all patients with critical conditions including COVID patients.