Since allergies and obesity are both rising at alarming rates, I think this interesting study recently presented at the Endocrine Society Annual Meeting warranted attention, even if it's not about infants but adolescents (remembering that both conditions can begin in infancy--as discussed in What to Feed Your Baby).
Researchers at the Walter Reed National Military Medical Center evaluated a small group of boys and girls between 10 and 18 years old.* Fifty-four were overweight (their body mass index, BMI, was at or above the 85th percentile for age) and another 32 normal weight children. Hormone levels were as expected for body size: leptin was increased, adiponectin was decreased in the heavier group and immune factors associated with allergies were also elevated in the those that were obese. But what was most interesting in this small, admittedly preliminary report, wasn't just that higher degrees of obesity correlated with greater vitamin D deficiency, but that the vitamin D levels were most in synch with the higher degree of allergy seen in these obese adolescents.
It doesn't mean that Vitamin D deficiency caused the allergy, but it could be a co-factor promoting allergy, or something else could be causing both problems. And once again, it emphasizes the vast importance of Vitamin D in immunity as well as bone health. Please see the section on Vitamin D in What to Feed Your Baby for a discussion on the controversy about the correct dose of vitamin D for babies and their pregnant and nursing mothers.
*Percival CS. #OR51-5. Presented at: The Endocrine Society Annual Meeting; June 15-18, 2013.