Background: Childhood and adolescent obesity is a growing global health issue linked to noncommunicable diseases such as cardiovascular disease and type 2 diabetes. Digital health technologies, including mobile apps and web-based programs, offer scalable tools to improve health behaviors, but their effectiveness in young populations remains unclear. Objective: This systematic review aimed to evaluate the effectiveness of mobile and web-based digital interventions in promoting healthy diets, reducing obesity risk, increasing physical activity, and improving nutrition-related knowledge and attitudes among children and adolescents. Methods: A systematic search was conducted across PubMed, Scopus, Web of Science, and Google Scholar databases, along with hand-searching reference lists of key systematic reviews. The search encompassed records published up to September 30, 2024. Eligible studies were randomized controlled trials targeting dietary intake, anthropometric measurements, physical activity, or nutrition-related attitudes and knowledge among participants aged ≤18 years. Screening, full-text eligibility assessment, and data extraction were done partly in duplicate (20%; κ=0.86 for title or abstract screening, κ=0.71 for full-text eligibility assessment, and κ=0.78 data extraction). Risk of bias was evaluated using the Cochrane Risk-of-Bias tool (κ=0.71 for interrater reliability of 20% duplicate evaluation). Data were synthesized narratively. Results: From 300 records screened, a total of 37 articles (34 studies) were included. Interventions included games, (in 21/34 studies, 62%), mobile apps, web-based programs, and other digital tools. Among the 34 included studies, 23 (68%) studies reported positive outcomes for at least 1 measured variable. Fruit intake improved in 17 of 34 studies (50%) assessing fruit intake, while 7 of 34 studies (21%) targeting sugar-sweetened beverage consumption showed reductions. Improvements in nutrition knowledge were reported in 23 of 34 (68%) studies, but changes in anthropometric measures and physical activity outcomes showed no effect. Risk of bias was low for random sequence generation but high or unclear in other domains for many studies. Conclusions: Mobile- and web-based interventions, particularly game-based tools, show promise for promoting healthy dietary behaviors and increasing nutrition knowledge in children and adolescents. However, the evidence for long-term sustainability and impact on anthropometric and physical activity outcomes remains limited. Future research should focus on understanding which digital features drive effectiveness, extending follow-up periods, and exploring the role of family involvement in interventions. Trial Registration: PROSPERO CRD42023423512; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=423512

The safety considerations of food-based solutions for vitamin D deficiency prevention, such as fortification and supplementation, are critical. On the basis of collective data from 20 randomized controlled trials (RCTs) and 20 national healthy surveys, as well as prospective cohort studies (PCSs) across the ODIN project (“Food-based solutions for optimal vitamin D nutrition and health through the life cycle”, FP7-613977), we analyzed the potential safety issues arising from vitamin D intakes and/or supplementation. These adverse consequences included high serum 25-hydroxyvitamin D (S-25(OH)D) concentrations (>125 nmol/L), high serum calcium concentrations, and vitamin D intakes in excess of the tolerable upper intake levels (ULs). In the RCTs (n = 3353, with vitamin D doses from 5–175 µg/day), there were no reported adverse effects. The prevalence of high S-25(OH)D was <10% when vitamin D supplements were administered, and <0.1% for fortified foods. Elevated serum calcium was observed among <0.5% in both administration types. No ODIN RCT participants exceeded the age-specific ULs. In observational studies (n = 61,082), the prevalence of high 25(OH)D among children/adolescents, adults, and older adults was 125 nmol/L were rare in the RCTs and PCSs, and no associated adverse effects were observed.

Insufficient vitamin D status (serum 25-hydroxyvitamin D (S-25(OH)D)<50 nmol/l) is common among immigrants living at the northern latitudes. We investigated ethnic differences in response of S-25(OH)D to vitamin D₃supplementation, through a 5-month randomised controlled trial, in East African and Finnish women in Southern Finland (60°N) from December 2014 to May 2015. Vitamin D intakes (dietary and supplemental) were also examined. Altogether, 191 subjects were screened and 147 women (East Africansn72, Finnsn75) aged 21–64 years were randomised to receive placebo or 10 or 20 µg of vitamin D₃/d. S-25(OH)D concentrations were assessed by liquid chromatography–tandem MS. At screening, 56 % of East Africans and 9 % of Finns had S-25(OH)D<50 nmol/l. Total vitamin D intake was higher in East Africans than in Finns (24·2 (sd14·3)v.15·2 (sd13·4) µg/d,P<0·001). Baseline mean S-25(OH)D concentrations were higher in Finns (60·5 (sd=16·3) nmol/l) than in East Africans (51·5 (sd15·4) nmol/l) (P=0·001). In repeated-measures ANCOVA (adjusted for baseline S-25(OH)D), mean S-25(OH)D increased by 8·5 and 10·0 nmol/l with a 10-µg dose and by 10·7 and 17·1 nmol/l with a 20-µg dose for Finns and East Africans, respectively (P>0·05 for differences between ethnic groups). In conclusion, high prevalence of vitamin D insufficiency existed among East African women living in Finland, despite higher vitamin D intake than their Finnish peers. Moderate vitamin D₃supplementation was effective in increasing S-25(OH)D in both groups of women, and no ethnic differences existed in the response to supplementation.

Aims: We evaluated the consumption of healthy foods among Russian, Somali and Kurdish immigrants in Finland, and examined the relationship between socio-demographic factors and food consumption. Methods: We used data from the Migrant Health and Wellbeing Study (Maamu), a population-based health interview and examination survey in six different municipalities in Finland between 2010 and 2012. Altogether, 635 men and 737 women, aged 18–64 years, of Russian (n = 527), Somali (n = 337) and Kurdish (n = 508) origin were included. The important socio-demographic determinants of healthy food consumption – sex, age, education, place of residence and household size – were assessed by logistic regression. Results: Based on the consumption frequencies of recommended healthy foods – fruits, berries, vegetables, fish and rye bread – immigrants of Russian origin had higher consumption of healthy foods than their peers of Kurdish and Somali origin. Low consumption of fresh vegetables, fruits and berries was found among Somali immigrants. Sex and age were the most important determinants of healthy food consumption, as women and older age groups had diets closer to the national nutrition recommendations. High educational level was also positively associated with healthy food consumption. Conclusions: We found ethnic differences in the consumption of healthy foods among the immigrant groups of Russian, Somali and Kurdish origin in Finland. Socio-demographic factors, especially age, sex and education, seem to also play an important role in immigrants’ food consumption. Further studies examining the consumption of fruits, berries and fresh vegetables among Somali immigrants in Finland are needed.

Objective: We investigated the determinants of serum 25-hydroxyvitamin D [S-25(OH)D] and dietary vitamin D sources among three immigrant groups in Finland and compared their S-25(OH)D to the general Finnish population.Design: Cross-sectional population-based Migrant Health and Wellbeing Study and the nationally representative Finnish Health 2011 Survey. S-25(OH)D was standardised according to the Vitamin D Standardisation Program. Vitamin D sources were assessed by interview.Setting: Six different municipalities in Finland (60°–63°N).Participants: Immigrants aged 18–64 years (446 Russians, 346 Somalis, 500 Kurds), 798 Finns aged 30–64 years.Results: The mean of S-25(OH)D was 64 (95 % CI 62, 66), 44 (95 % CI 41, 46), 35 (95 % CI 34, 37) and 64 (95 % CI 62, 66) nmol/l for Russians, Somalis, Kurds and Finns, respectively. S-25(OH)D among Somalis and Kurds was lower compared with Finns (P< 0·001). The prevalence of vitamin D deficiency (S-25(OH)D <30 nmol/l) and insufficiency (S-25(OH)D <50 nmol/l) was higher among immigrants than Finns (P< 0·001). Vitamin D-rich foods differed between the groups; vitamin D-fortified fat spread consumption was higher among Somalis (91 %) than among Russians (73 %) and Kurds (60 %); fish was less consumed among Kurds (17 %) than among Russians (43 %) and Somalis (38 %); and 57 % Russians, 56 % Kurds and 36 % Somalis consumed vitamin D-fortified dairy daily (P< 0·001 for all). Daily smoking, alcohol consumption and winter blood sampling were determinants of vitamin D insufficiency (P≤ 0·03). Older age, physical activity, fish and vitamin D-fortified dairy consumption were associated with lower odds of insufficiency (P≤ 0·04).Conclusions: Vitamin D status differed among immigrant groups and the determinants are, to some degree, associated with learned or existing cultural behaviours.