Allergy

Prenatal, perinatal, and childhood vitamin D exposure and their association with childhood allergic rhinitis and allergic sensitization

Bunyavanich S, Rifas-Shiman SL, Platts-Mills TA, Workman L, Sordillo JE, Camargo CA Jr, Gillman MW, Gold DR, Litonjua AA. J Allergy Clin Immunol 2016. doi: 10.1016/j.jaci.2015.11.031. [Epub ahead of print]

The link between early-life vitamin D and allergic disease is unclear

Vitamin D has recently been proposed to be a key mediator of the immune system and may play a role in allergic disease, particularly in childen. 1However, conclusive evidence on the benefits or risks of early-life vitamin D is lacking. 1A recent study in the Journal of Allergy and Clinical Immunology investigated the relationship between early-life vitamin D and the development of childhood allergic rhinitis (AR) and allergic sensitisation. 2

Vitamin D can affect both innate and adaptive immune responses. 2

Immune cells affected by vitamin D include: 1

• Lymphocytes
  
• T cells
  
• Dendritic cells
  
• Macrophages.

Vitamin D can also influence immune system development prenatally2 and inadequate vitamin D intake has been linked with an increased risk of respiratory infections. 1

Assessment of vitamin D exposure in early-life

As part of Project Viva, a US pre-birth cohort study, 1248 mother-child pairs unselected for any disease were recruited. 2First- and second-trimester vitamin D exposure was estimated by maternal diet assessments using a 166-item semi-quantitative food frequency questionnaire. Child health was recorded by in-person interviews and questionnaires at 6 months, 1 year, and annual intervals thereafter. Children were monitored until approximately school age (median age: 7.7 years). 2

Antigen sensitisation was assessed in 616 children at school age. Serum total immunoglobulin E (IgE) and allergen-specific IgE levels were measured. The specific environmental allergens included Dermatophagoides farinae, Aspergillus fumigatus, Alternaria alternata, rye grass, ragweed, cat dander, dog dander, and Blattella germanica. 2

Confounding factors included in the statistical model included maternal education, health, smoking habits, parental allergies and the child’s season of birth. 2

Maternal vitamin D reduces risk of childhood allergic rhinitis

The incidence of allergic rhinitis was determined during interview by each mother’s answer to the question: “Has your child ever been told by a health care professional that your child has hay fever, seasonal allergies or allergic rhinitis?” 2

At school age, the prevalence of ever being affected by AR was 23.8%. 2

The risk of ever being affected by AR was reduced by 21% for each additional 100 IU of food-based vitamin D in the maternal diet during the first trimester (Odds ratio [OR]: 0.79; 95% confidence interval [CI] 0.67–0.92). 2

Similarly, in the second trimester, each additional 100 IU of food-based vitamin D in the maternal diet reduced the risk of AR by 20% (OR 0.80, 95% CI 0.68–0.93). 2

Maternal intake of vitamin D supplements during first or second trimester did not reduce the incidence of AR at school age (OR 1.00, 95% CI 0.91–1.10, and OR 0.98, 95% CI 0.88–1.10, respectively).

Correlations between total maternal vitamin D intake and 25(OH)D (the biologically active form of vitamin D) concentrations in maternal, cord blood, and childhood serum were weak-to-moderate. 2

No association between maternal vitamin D intake and allergen sensitisation or total IgE levels in children at school age was found. 2

A higher maternal intake of vitamin D in food, but not from supplements, during pregnancy may reduce the risk of AR at school age.

Maternal diet choice may help prevent childhood allergic disease

The authors concluded that the intake of foods containing vitamin D during pregnancy may reduce childhood risk of AR. Supplements may not provide biologically available forms of vitamin D. Vitamins D2 and D3, which make up most supplements, must be activated in the liver to 25(OH)D, whereas many foods, such as meats, naturally contain 25(OH)D. 2

Report on: Prenatal, perinatal, and childhood vitamin D exposure and their association with childhood allergic rhinitis and allergic sensitization. Bunyavanich S, Rifas-Shiman SL, Platts-Mills TA, Workman L, Sordillo JE, Camargo CA Jr, Gillman MW, Gold DR, Litonjua AA. J Allergy Clin Immunol 2016. doi: 10.1016/j.jaci.2015.11.031. [Epub ahead of print].

Reference list

1. Della Giustina A, Landi M, Bellini F, Bosoni M, Ferrante G, Onorari M, et al. Vitamin D, allergies and asthma: focus on pediatric patients. World Allergy Organ J 2014; 7(1): 27.
   
2. Bunyavanich S, Rifas-Shiman SL, Platts-Mills TA, Workman L, Sordillo JE, Camargo CA Jr, et al. Prenatal, perinatal, and childhood vitamin D exposure and their association with childhood allergic rhinitis and allergic sensitization. J Allergy Clin Immunol 2016. doi: 10.1016/j.jaci.2015.11.031. [Epub ahead of print].