Study suggests benefit for UV light exposure, but not vitamin D supplementation

Higher exposure to sunlight during the first 3 months of life was associated with a lower incidence of pro-inflammatory immune markers for allergic disease and eczema during infancy, according to preliminary findings from a clinical trial involving high-risk infants.

The double-blind randomized trial is being conducted to examine the impact of early postnatal vitamin D supplementation and exposure to ultraviolet light from the sun on immune development and allergic outcomes during the first 2 and a half years of life.

Researcher Kristina Rueter presented preliminary findings from the ongoing study virtually last weekend at the annual meeting of the European Academy of Allergy and Clinical Immunology (EAACI), held July 10-12.

She noted that the early findings are the first to demonstrate a link between higher direct ultraviolet (UV)-light-exposures, but not vitamin D supplementation, and lower incidence of pro-inflammatory immune markers in infants.

Higher UV-light exposure was also associated with lower incidence of eczema in the infants, who were followed for 30 months. Twelve-month and 30-month outcomes have not yet been presented.

Rueter reported that the early findings suggest that “UV exposure and lifestyle changes rather than vitamin D status may have an influence on early immune development and eczema outcome in infancy.”

She said while there has been a significant rise in allergic disease prevalence over the last few decades, the reasons for this increase are not well understood.

Environmental changes, including the rise in obesity, less exposure to germs due to greater personal hygiene, and increased exposure to antibiotics and other drugs, have all been identified as possible contributors to the rising rates of asthma and allergy.

Vitamin D deficiency has also been widely studied in observational trials, with conflicting findings, Rueter noted.

She said because vitamin D is known to have certain immunomodulatory influences, it has been considered a key candidate for influencing vulnerability to allergic disease.

The researchers recruited 195 high-risk infants for their trial who were randomized to receive either 400 IU of vitamin D per day or placebo until they reached 6 months of age.

In a novel move, the babies also wore a personal dosimeter that measured direct UV light exposures (290-380 nm).

The study protocol called for vitamin D levels to be measured at 3 months, 6 months, 12 months and 30 months of age. Immune function outcomes were assessed at age 6-months, and the protocol calls for assessment of food allergy, eczema, and wheeze at 6, 12, and 30 months of age.

Among the main findings in the infants by the age of 6-months:

  • At 3 and 6 months of age, vitamin D levels were higher in the infants receiving vitamin D supplementation compared to the placebo group, but no difference was seen between the two groups in food allergy, eczema, wheeze, or allergic rhinitis during the first 2.5 years of life.
  • Infants with eczema occurring during the first 6 months of life were found to have less UV light exposure (median [IQR] 555 (95% CI, 322-1210) J/m2) compared to those without eczema (998, 95% CI, 676-1577 J/m2P=0.023).
  • UV light exposure was also inversely correlated with IL-2, granulocyte-macrophage colony stimulating factor and eotaxin production to Toll-like receptor ligands.

Rueter cited the small study size as a study limitation in a question-and-answer session following her presentation, noting that a larger study may have shown a benefit for vitamin D supplementation.

Asked what the mechanism might be for the finding of a possible benefit for UV-light exposure in preventing allergic disease, she said very little research has been done on this.

“A few studies in mice have found similar and supportive findings in that higher UV-light exposure induced skin changes in terms of eczema but also respiratory function,” she said, adding that these researchers suggested a role for nitric oxide, which is produced by sunlight, in facilitating the skin changes.

Asked about the risks versus benefits of UV exposure with regard to health, Rueter said this is an area that needs further study.

“There is a lot of research that needs to be done to find the right balance between what is a good amount (of UV exposure), which may influence the immune system in a positive way, and what, on the other hand, might be too much, because it can cause more harm than benefit. We would, of course, encourage everybody to strictly follow the (sun exposure) cancer guidelines.”

  1. Higher exposure to sunlight during the first 3 months of life was associated with a lower incidence of pro-inflammatory immune markers for allergic disease and eczema during infancy.

  2. The early randomized trial findings are the first to demonstrate a link between higher direct ultraviolet (UV)-light-exposures, but not vitamin D supplementation, and lower incidence of pro-inflammatory immune markers in infants.

Salynn Boyles, Contributing Writer, BreakingMED™

Researcher Kristina Reuter reported no relevant disclosures related to this research.

Cat ID: 99

Topic ID: 80,99,730,105,99,192,925