This month, researchers from several institutions including the University of Oulu in Finland and the Imperial College in London reported the results of a study which found an association between high-dose vitamin D supplementation in infancy and an increased risk of atopy, allergic rhinitis, and asthma later in life. Atopy, or atopic syndrome, is an allergic hypersensitivity affecting parts of the body not in direct contact with an allergen. It may involve eczema (inflammation of the upper skin layers), allergic conjunctivitis, allergic rhinitis and asthma.

The team started collecting data in 1967. That year, every mother in the two most northern provinces of Finland – a group of mothers referred to as the Northern Finland Birth Cohort (NFBC) – who had given birth to a child during the previous year was required to report the level of vitamin D they were giving their infant. At the time, Finnish government recommendations stated that mothers should supplement their infants with 50 ug of vitamin D. Mothers were asked to report if they were giving their infant the recommended dose of vitamin D, no vitamin D, or an irregular dose of vitamin D. An irregular dose of vitamin D usually reflected the fact that the infant was given high levels of vitamin D rich cod liver oil.

The infants were then tracked over the next 31 years of their lives. The exact age at which the study participants started to develop allergies and asthma was not specifically documented. However, the team did check in with subjects when they were 14 years old. At that point, subjects who had been taking the requisite 50 µg of vitamin D as infants were found to suffer from a higher prevalence of asthma and allergies. When the researchers checked in with the subjects at 31 years of age – the presence of atopy was determined by skin-prick test – the trend persisted. Prevalence of asthma and allergic rhinitis was greater in participants who had received vitamin D supplementation regularly than in those who had received it irregularly or not at all.

Although the team did not keep track of specific levels of vitamin D supplementation higher than 50 µg, their data did suggest increases in the occurrence of allergic rhinitis and asthma among those participants who had taken the highest doses of vitamin D.

The researchers believe that the NFBC population lends itself to a highly accurate study on the effects of vitamin D. Since during the Northern Finnish winter, daylight last for only 2 hours a day, the infants analyzed may have produced less vitamin D from sunlight. Also, during 1966, infant formula in Finland was not yet supplemented with vitamin D, meaning that lack of information on infant feeding was not likely to have affected estimates of vitamin D intake.

Compliance to vitamin D supplementation recommendations (i.e., child received 50 µg regularly) was associated with several social and behavioral characteristics of the mother. It turns out that mothers who were more proactive, better educated, and of higher social class were most likely to correctly follow the government specified vitamin D supplementation guidelines for their infants. Ironically, the children born to such mothers were found to suffer from higher levels of asthma, atopy, and rhinitis by age 31. This means that, ironically, those children born to mothers who did not correctly comply with the supplementation guidelines were actually healthier 31 years later. As the team states, “Many of the same characteristics that were predictive of worse compliance to vitamin D recommendations were associated with reduced risk of allergies.”
Of course, those of us familiar with the work of biomedical researcher Trevor Marshall understand why those infants given extra vitamin D during the first years of life were more likely to develop asthma and allergies as adults. Molecular and clinical data support the fact that the vitamin D derived from diet and supplements in a secosteroid that, at high levels, blocks the activity of the vitamin D Receptor – a fundamental receptor of the body that controls the activity of the innate immune system. A wide body of research has also confirmed that asthma and allergies are caused by chronic intraphagocytic biofilm-like bacteria. Thus, the innate immune function of those infants given extra vitamin D was depressed at an early age. The subsequent immunosuppression almost certainly made it easier for the infants to acquire the pathogens that cause asthma and allergies. Since L-form and biofilm bacteria grow very slowly, it took many years before the symptoms of their diseases became overt and problematic.

When Dr. S.O. Shaheen of the National Heart and Lung Institute at the Imperial College London was alerted to the results of the above study, he wrote a letter to two researchers (A.A. Litonjua and S.T. Weiss of the Brigham and Women’s Hospital in Boston) who, unaware of the long-term immunosuppressive effects of vitamin D, are urging researchers to conduct more trials in which infants are administered high doses of vitamin D.

“I would argue… that the vitamin D story is, at present, rather more confused than Weiss and Litonjua suggest, and that before rushing into prenatal nutrient supplementation trials, we need more convincing data to support their hypothesis, and greater confidence that such an intervention would be safe, states Shaheen. “Given the failure to translate observational associations between antioxidant deficiency and asthma into beneficial interventions in adults, we need to be more sure that observational links with prenatal nutrition are not confounded, and that longer term follow-up of birth cohorts does not reveal a positive relation between prenatal vitamin D status and [asthma].”