Milk Allergy Tied to Lower Bone Density in Children

Troy Brown, RN

April 20, 2016

Children with persistent cow's milk allergy (CMA) have a lower bone mineral density (BMD) and calcium intake before puberty compared with prepubertal children with food allergies other than cow's milk (NCMA), according to a new study. The study also found that prepubertal children with persistent CMA have similar vitamin D levels and intake as children with NCMA.

"[B]one mass accretion during the years of rapid skeletal growth is a major determinant of adult bone health and...failure to achieve peak bone mass is associated with increased risk of osteoporosis and fracture later in life," the researchers write.

Genevieve Mailhot, PhD, RD, from the Department of Nutrition and the Centre Hospitalier Universitaire Sainte-Justine Research Center, Université de Montréal, Quebec, Canada, and colleagues report their findings in an article published online April 19 in Pediatrics.

CMA is the most common childhood food allergy and affects from 2% to 3% of children. Children with CMA must adhere to a strict diet that eliminates all dairy products until the allergy resolves. The allergy resolves by age 3 years in as many as 87% of children, but persists until adolescence in as many as 15% of cases, the authors note.

"Dairy products account for >50% of calcium and vitamin D intakes in children. The elimination diet thus increases the risk of nutrient inadequacy and renders calcium and vitamin D supplementation necessary in cases in which alternatives do not meet dietary requirements," Dr Mailhot and colleagues write.

They recruited 52 prepubertal children with immunoglobulin E–mediated CMA and 29 prepubertal children with NCMA at an allergy clinic in Montreal, Quebec, Canada, between 2011 and 2014. They conducted the study from October to April to limit the influence of sun exposure on 25-hydroxyvitamin D (25[OH]D) levels and excluded children with comorbidities that would affect bone development.

Children in the CMA and NCMA groups did not differ in height, lean body mass, or weight, but lumbar spine BMD z-scores were significantly lower in children who had CMA compared with children with NCMA. Low BMD, defined as 2 standard deviations below the mean, was found in 6% of the children with CMA compared with none of the children with NCMA.

Using validated quantitative food frequency questionnaire to assess dietary calcium and vitamin D intakes, the researchers found that just 39% of children with CMA met the calcium RDA of 1000 mg/day, and 21% had calcium intake that was less than two thirds of the RDA. None of the children with NCMA consumed less than two thirds of the RDA and 74% met the RDA.

Most of the children in both groups consumed much less than the RDA for vitamin D; only 11.5% and 7.4% of the children with CMA and NCMA met the RDA, respectively.

Fewer than half of the children with CMA reported taking a supplement that contained either calcium (37%) or vitamin D (44%). However, most (83%) of the children who reported taking these supplements were compliant, taking them an average of 5.5 days per week.

Intakes of calcium and vitamin D were not associated with any of the bone parameters in children with CMA; however, there was an unexpected negative association between vitamin D intake and lumbar spine BMD (r = −0.284; P = .04). In contrast, however, lumbar spine BMD (r = 0.526; P = .005) and volumetric BMD (r = 0.444; P = .02) were each positively associated with calcium intake in the children with NCMA.

"The prepubertal children with persistent CMA in this study displayed lower BMD >z scores despite normal growth, a finding that may arise from suboptimal calcium intake. Only follow-up studies will confirm a lower bone acquisition rate in these children," the authors conclude.

The authors have disclosed no relevant financial relationships.

Pediatrics. Published online April 19, 2016.

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