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Breastfeeding and vitamin D supplements for infants and bigger children prevent asthma and allergies

Breastfeeding and vitamin D supplements for infants and bigger children prevent asthma and allergiesAllergic diseases such as asthma, hay fever, food allergies and contact dermatitis are becoming increasingly common. It makes a big difference to breastfeed for at least six months because breast milk contains various compounds that strengthen the child’s gut flora and immune defense. Vitamin D supplements are also important, and Icelandic research suggests that is pays off to continue giving them to children until the age of six years. Unfortunately, many parents forget to give their children vitamin D until the age of two, as recommended. Also, many children get too little sunlight during the summer period and don’t get vitamin D supplements when it is winter, and that is something we all need at these latitudes.

According to the Nordic Nutrient Recommendations, infants should only be breastfed during the first six months after birth. From that point and onward, the parents can gradually introduce them to solid foods and continue with partial breastfeeding until one year of age, possibly a little longer. Breastmilk is quite unique in that it contains a variety of compounds that are needed for proper development of the child. Breastfeeding also offers comfort, and the mother’s milk protects against many infections and gastrointestinal disturbances. It even appears that breastmilk lowers the risk of diabetes of overweight later in life. However, there is limited proof that breastfeeding protects against allergies and asthma.
Most infants in Nordic countries are breastfed, and many get additional foods until the age of six months. However, only 23-63% of the infants are breastfed entirely at four months of age, and most mothers stop breastfeeding when the child is six months. Some infants may need additional food before they reach this age, but the Danish health authorities recommend waiting with this until the child is at least four months old. Nevertheless, there is still a lot of discussion about the right time to stop breastfeeding.
Vitamin D is also relevant in terms of allergy risk, because there is very little of the nutrient in breastmilk and the diet. Therefore, scientists from the University Hospital in Reykjavik, Iceland, wanted to study the diet and vitamin D’s influence on the production of IgE antibodies, which are responsible for the allergic reactions. The researchers studied infants during their first year of life and followed up for six years.

  • Increased production of IgE antibodies causes type 1 allergies or classic allergies with symptoms such as asthma, hay fever, hives, and diarrhea that occur immediately after contact with the allergen. The symptoms are caused by the reaction to histamine.
  • Asthma is a common disorder among children and teenagers in the Western world.
  • 5-7 percent of all children develop food allergies.
  • The most common childhood allergy is cow milk’s allergy, followed by allergies towards eggs, peanuts, nuts, fish, and shellfish.
  • One can also develop allergies towards food sources of IgE antibodies such as gluten and milk protein (there is a huge grey zone)

The Icelandic study and its methods

The scientists gathered data from 144 healthy, Icelandic infants of Caucasian (white) heritage, all of whom were preterm. Blood samples were taken when the children were infants and when they were around six years of age. The samples were analyzed for IgE antibodies and vitamin D. Also, the children’s weight was noted.
The mothers were asked to provide detailed information about their children’s nutrition and breastfeeding habits, the time of introducing baby formula and solid food, and supplementation with vitamin D and other nutrients. The babies’ birth months were categorized as “winter/spring” (Nov-April) and “summer/autumn” (May-Oct) based on the expected contribution of sunlight exposure to maternal vitamin D status around the time of birth.
Maternal smoking habits, BMI, age, and social status were also taken into account. As part of the six-year follow-up, the parents were asked to fill in questionnaires with information about their child’s use of anti-histamines and asthma inhalers.

At the norther latitudes, humans can only synthesize vitamin D from sunlight during the summer period where the sun sits sufficiently high in the sky.

Early introduction of solid food increases the risk of allergies

It turned out that 14 (10%) of the children in the study had become IgE-sensitive during the six years follow-up. Eight of the children had become hypersensitive to cow’s milk, and some of the children had developed allergies towards eggs, peanuts, wheat, and soy.
The majority of allergic children in the study used antihistamines or asthma inhalers. Those, who had become IgE-sensitive, gained more weight during the first two months, and their head circumference was significantly larger, but after 6-12 months there was no major difference. Still, rapid infant growth is associated with an increased risk of allergic rhinitis, asthma, and impaired pulmonary function.
The average breastfeeding rate was high. After four months, 60 percent of those children that had not developed allergies were still breastfed only. The children, who got more than breastmilk before their fourth month, had an increased risk of developing allergies. This is because their intestinal microflora and immune defense were not fully developed. The study therefore supports the Danish health authorities’ recommendation about not giving infants solid foods before they have reached an age of six months, especially if it is dairy products, eggs, wheat, peanuts, and others foods that are known to trigger allergic reactions.

New recommendations for infants regarding cow’s milk

The Danish health authorities recommend that you do not give cow’s milk (or other dairy products) but only breastmilk or baby formula to infants until they have reached an age of one year. The reason is that cow’s milk contains a lot of protein (casein) and other growth-stimulating substances that may lead to allergies and overweight later in life.

Lack of vitamin D increases the risk of allergy

Vitamin D is important for bones, the immune system, the nervous system, and many other functions. Maternal vitamin D status has vital importance for fetal development and the child’s vitamin D status at birth. The Icelandic study showed that the total vitamin D intake was lower among the children, who had developed IgE-allergic reactions after 12 months. The same was the case at six years of age. Although it is a small study, its strength lies in the fact that the researchers followed the children during the first six years of their lives. Therefore, the researchers recommend that Nordic infants and older children get plenty of vitamin D from their diet, from sun exposure, and from supplements.
The health authorities already recommend that white, Caucasian children in the ages 0-2 years get a 10 microgram/day supplement of vitamin D. Dark-skinned children should continue taking vitamin D, as the vitamin D synthesis in dark skin at our latitudes is less effective compared with light skin. Actually, a lot of available research suggests that all children, adolescents, and adults should continue taking vitamin D during the winter and in situations, where their vitamin D status is inadequate.

How vitamin D counteracts infections and asthma

Vitamin D has a number of functions in the immune defense. It helps the white blood cells fight infections swiftly and effectively, and prevents chronic inflammatory conditions like asthma.

It is better to give your child vitamin D routinely

Even though the Danish health authorities advise infants to get a daily vitamin D supplement, nearly half of Danish parents forget to follow this advice, according to a study. Not only does this increase the risk of weak bones, it also increases the risk of infections, allergies, asthma, and autism. Since many parents apparently have difficulty with remembering to give their children vitamin D, it may be a good idea to introduce a routine of giving the supplement at mealtime.


Birna Thorisdottir et al. Infant feeding, Vitamin D and IgE Sensitization to Food Allergens at 6 Years in a Longitudinal Icelandic Cohort. Nutrients 2019

Vibeke Mikkel Hansen. Forældre glemmer, at give deres småbørn D-vitamin. DR Ligetils nyheder 05-09-2017

Khaled Sall et al. Randomized controlled trial og vitamin D supplementation in children with autism spectrum disorder. Journal of Child Psychology and Psychiatry. 2016

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