Objectives:
Infections may play a role in the etiology of childhood cancer and immunizations may be protective because vaccinations stimulate the immune system. Observational studies reported inconsistent associations between vaccination and risk of childhood cancer. Therefore, this review article has been conducted.

Objectives:

Objectives:
Previous population studies on the associations between dietary fatty acids (FAs), plasma FAs levels and the risk of age-related macular degeneration (AMD) have yielded inconclusive results. Therefore, this review article (meta-analysis) has been conducted.

Objectives:
Does asthma increase risk of severe COVID-19, mortality and other poor outcomes in patients with COVID-19?

Study design:
This review article included 11 studies with a total of 6,046 patients.

Objectives:
Migraine is a common disease worldwide and migraine prevention is primarily currently based on pharmaceuticals. The mechanism of vitamin B2 may positively contribute to migraine. Therefore, this review article has been conducted.

Objectives:
Regular physical activity is the prime modality for the prevention of numerous non-communicable diseases and has also been advocated for resilience against COVID-19 and other infectious diseases. However, there is currently no systematic and quantitative evidence synthesis of the association between physical activity and the strength of the immune system. Therefore, this review article has been conducted.

Objectives:
Approximately 7.3 million births occur annually among adolescents in low- and middle-income countries. Pregnant adolescents constitute a nutritionally vulnerable group that could benefit from intervention to mitigate the mortality and adverse birth outcomes associated with adolescent pregnancy. Therefore, this review article (meta-analysis) has been conducted.

Objectives:
Previous meta-analyses, with some methodological controversies, have assessed the relation between nut consumption and type 2 diabetes (T2D) risk and pointed to contradictory results. Therefore, this review article has been conducted.

Does nut consumption reduce risk of type 2 diabetes?

Study design:
This review article included 5 prospective cohort studies and 3 cross-sectional studies.
The certainty of the evidence using NutriGrade was very low for all the exposures.

Objectives:
Several comorbidities have been shown to be associated with coronavirus disease 2019 (COVID-19) related severity and mortality. However, considerable variation in the prevalence estimates of comorbidities and their effects on COVID-19 morbidity and mortality have been observed in prior studies. Therefore, this review article has been conducted.

Objectives:
Do magnesium intakes reduce risk of all-cause, cancer and cardiovascular disease (CVD) mortality?

Study design:
This review article included 19 prospective cohort studies with a total of 1,168,756 participants (52,378 deaths from all causes (all-cause mortality), 23,478 from cardiovascular disease (CVD) and 11,408 from cancer).
The follow-up period was 3.5 to 32 years.