Background There is a paucity of data on the prevalence of food allergy (FA) in Vietnam. A cross‐sectional, population‐based study was conducted to evaluate the current prevalence of FA among 2‐ to 6‐year‐old children in two different regions in Vietnam. Method A structured, anonymous questionnaire, modified from published FA epidemiologic studies and based on EAACI guidelines, was distributed to parents/guardians of participating children in Hue City (urban area) and Tien Giang Province (rural area). Data collected from the survey were statistically analyzed to generate the prevalence of self‐reported and doctor‐diagnosed FA and overarching pattern of food allergens. Results A total of 8620 responses were collected (response rate 81.5%). Children in Tien Giang reported more than twice the food‐induced adverse reactions seen in children in Hue (47.8% vs. 20.5%). In contrast, children in Hue showed higher self‐reported FA (9.8%) and doctor‐diagnosed FA rates (8.4%) than children in Tien Giang (7.9% and 5.0%, respectively). Crustacean was the predominant allergy‐inducing food in both areas (330 of 580 cases, 56.9%), followed by fish, mollusk, beef, milk, and egg. However, substantial variations of FA patterns were seen between the study sites. Geographic location and co‐morbidities of other allergic diseases were key risk factors for FA (P < 0.001). Conclusions The prevalence of FA in Vietnamese children seems to be higher than previously reported from other Asian countries. Crustacean is the predominant allergy‐inducing food among participating preschool children in Vietnam. The variation of reported food allergen sources across different socio‐economic locations could imply different eating habits or the participation of indoor and outdoor allergen exposure.

BackgroundWeb-based surveys (WBS) are increasingly applied in epidemiological studies as an appealing alternative to traditional survey methods. Rapid data collection, reduced expenditure and ease of access to large populations are some of the clear advantages of online surveys. However, WBS are still subject to limitations in terms of sample size, response rate and other additional biases compared to traditional survey methods. In the present study, we seek to validate data on food allergy (FA) in two independent sample populations collected from a WBS, and compare it to a paper-based survey (PBS).MethodsData collected from two survey modes were compared by hypothesis testing for independent sample population. The WBS included 1185 respondents, while the PBS included 9039 respondents.ResultsOverall, the data from the WBS were comparable to the PBS conducted over the same period of time in Vietnamese adults. There were no effects of different survey modes on the lifetime prevalence of doctor-diagnosed FA (5.7%; P = 0.7795, β = 0.05) and IgE-mediated FA (5.8%; P = 0.9590, β = 0.05). Both surveys showed the dominance of seafood allergy in this population (up to 2.6%), followed by beef allergy. Close correlation was seen in the patterns of FAs and different clinical symptoms. The contribution of family history of allergic diseases and place of residence to FA were confirmed in both surveys.ConclusionsThe consistency of the WBS results with the PBS indicates a promising application of online surveys as an economic and validated model for future epidemiological studies, specifically in developing countries.Electronic supplementary materialThe online version of this article (10.1186/s40413-018-0195-2) contains supplementary material, which is available to authorized users.

Sodium benzoate and potassium sorbates are the two typical preservatives widely used in Vietnam and other countries. The maximum level (ML) of sodium benzoate and potassium sorbate in processed meat products imposed by Ministry of Public Health is 1000 ppm. Although there are warnings about overusing of these preservatives that related to human health, many manufacturers do not follow the regulations. The aim of this study was to survey and consider the amounts and presence of these preservatives in processed meat products by using High-performance liquid chromatography (HPLC) method. 90 samples of brands and no brands including Vietnamese pork rolls, pâtés, hams, sausages, and fermented pork rolls that available at markets in Ho Chi Minh City were analysed for these two preservatives. There was a preference for using sodium benzoate in all samples. Moreover, Vietnamese pork roll samples had the highest percentage of samples with preservatives concentrations exceeding the ML. Among 90 samples, sodium benzoate was detected in 52.2% of samples and 17.8% of them exceeded the ML, while potassium sorbate was found in 24.4% of samples and only 2.2% of them exceeded the regulated amount. 46.4% of Vietnamese pork rolls, 12.5% of pâtés, and 9.1% of fermented pork rolls had sodium benzoate exceeded the ML, whilst ham and sausage samples contained the concentrations inside the safety limits. Furthermore, only one sample of Vietnamese pork rolls and one sample of sausages had potassium sorbate concentrations surpassing the ML with the level of 1,717.57 mg/kg and 1,814.00 mg/kg, respectively. Furthermore, branded samples showed a significantly different result in compared with no branded samples. Of branded samples, exceeding sodium benzoate level ML was detected in 10% of samples and none of the samples found surpassing potassium sorbate limit amount. Nevertheless, 27.5% and 5% of unbranded samples had sodium benzoate and potassium sorbate higher than the authorized amounts, respectively. New strategies should be established to monitor the food safety issues.

Background: Food allergy (FA) is a serious, costly and growing health problem worldwide. FA occurs in both children and adults; however, there is a paucity of information on FA prevalence and its clinical features in the adult population, especially in Asia. We sought to assess the prevalence of FAs in Vietnamese adults and the distribution of offending food items among different regions throughout Vietnam.Methods: A nationwide, cross-sectional, population-based survey was conducted among University students aged 16-50 years. We used a structured, anonymous questionnaire, which was modified from recently published FA epidemiologic studies and based on European Academy of Allergy and Clinical Immunology (EAACI) guidelines, to collect data on FA prevalence, clinical presentations, and implicated food groups. Statistical analysis was performed to generate the prevalence of self-reported and doctor-diagnosed FA and to examine the association of key environmental factors and FA incidence in this population.Results: Of the 14,500 surveys distributed, a total of 9,039 responses were returned, resulting in a response rate of 62.4%. Among participants who reported food-induced adverse reactions, 48.0% have repeated reactions. 18.0% of the participants perceived FA symptoms, but less than half of them sought medical services for confirmation (37.9%). Stratifying for true FA symptoms, the prevalence of self-reported FA was 11.8% and of doctor-diagnosed FA, 4.6%. The most common doctordiagnosed FA was to crustacean (3.0%; 95% CI, 2.6-3.3), followed by fish (1.6%; 95% CI, 1.3-1.8), mollusk (1.3%; 95% CI, 1.0-1.5) and beef (1.0%; 95% CI, 0.8-1.2). The prevalence of doctordiagnosed FA differed among participants living in urban (6.5%) and rural regions (4.9%) (P < 0.001). Atopic family history was the strongest predictor for FA (odds ratio 8.0; 95% CI, 6.2-10.4).Conclusions: Seafood allergy among adults is predominant in Vietnam, followed by beef, milk, and egg, while peanut, soy, and tree nut allergy are much less common. Populations in rural regions have considerably less FA; however, the protective environmental factors have yet to be identified.

The population of older people is increasing at a rapid rate, with those 80 years and older set to triple by 2050. This systematic review aimed to examine older people’s perceptions and behaviours against existing heatwaves prevention measures and systematically categorize and analyse those measures using the Ottawa charter for health promotion framework. Peer-reviewed published literature between 22nd September 2006 and 24th April 2018 was retrieved, according to the PRISMA guidelines, from five different databases. Eighteen articles were finally included. There is a lack of published studies from developing countries. Results were categorized and analysed using the Ottawa charter five action areas. Mitigation strategies from current heat action plans are discussed and gaps are highlighted. A lack of systematic evaluation of heat action plans efficacy was identified. Older people are not demonstrating all recommended preventative measures during heatwaves. Support personnel and health professionals are not being pro-active enough in facilitating prevention of adverse effects from heatwaves. Governments are beginning to implement policy changes, but other recommended support measures outlined in the Ottawa charter are still lacking, and hence require further action. Linkage between specific components of heat action plans and outcomes cannot be ascertained; therefore, more systematic evaluation is needed.