For at least one of these immune-mediated skin conditions, weight loss reduced the risk.
Obesity and overweight in children increase the risk of developing immune-mediated skin disorders (IMSDs), according to a massive longitudinal study from Korea.
Previous studies have shown an association, according to the authors of the new study in the Journal of Investigative Dermatology, but most were only snapshots, leaving causal direction unclear.
This longitudinal study shows the obesity precedes the development of the skin disorders.
“The precise mechanisms responsible for this connection [between obesity and inflammatory skin diseases] remain uncertain; however, excessive adipose tissue has been hypothesised to trigger proinflammatory mechanisms that influence the development of skin diseases,” the authors write.
Obesity or weight gain “could be a risk factor for paediatric IMSDs by triggering proinflammatory activation and upregulating various inflammatory cytokines”.
They used a nationwide health database on infants and children to examine the relationship between BMI and BMI changes on the development of alopecia areata, atopic dermatitis and psoriasis. They followed the children up in three cohorts until development of the condition or for around five years.
They found linear dose-dependent relationships between BMI and incidence of all three conditions.
Compared to those with normal weight (fifth to 85th percentile BMI), those with obesity had a 15% higher risk of alopecia areata, 12% higher for eczema and 24% higher for psoriasis. The elevated risks persisted after adjusting for sex, breastfeeding status, household income, and birth weight.
Underweight children were 21% less likely than normal-weight ones to develop alopecia, 6% less likely to develop eczema and 13% less likely to develop psoriasis.
The study found, moreover, that weight gain during follow-up was correlated with an increased eczema risk and weight loss with a decreased eczema risk. There was no such evidence for psoriasis or alopecia areata, however, which had lower incidence and occurred at later ages, meaning the follow-up may have been too short to detect such effects.
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“Our findings support the importance of promoting weight maintenance among children who are already within the normal weight range because it may help reduce the AD risk,” the authors write. “In addition, prevention of excessive weight gain and purposeful weight loss, including adopting healthy diet strategies in children with obesity to prevent AD, particularly before school age, should be promoted.”
Dermatologist Dr Kurt Gebauer told TMR there was a well-known association between psoriasis and obesity in adults, adolescents and children.
He said losing weight – and maintaining it, which was very much harder when the body had spent significant time at a certain weight – was a preferable way to control skin disorders than drugs such as biologics, which might fix the skin but leave the other obesity-related comorbidities intact.
He said it was hard for clinicians such as dermatologists to bring up the subject of weight loss with a patient who had come to consult about a skin problem, as they tended to react badly – “but we need to do more about it”.
It was all the more reason to address obesity and childhood obesity upstream at the source, with policies to tax sugary drinks and other fattening foods.
“This is a public health issue,” he said. “That’s where the action needs to come.”
