"This study shows that cardiovascular risk starts far earlier in life than we ever realised," said lead study author Jonathan Silverberg from Northwestern University in the US.
"Given how common these allergic diseases are in childhood, it suggests we need to screen these children more aggressively to make sure we are not missing high cholesterol and high blood pressure," Silverberg added.
Asthma, hay fever and eczema -- increasingly common in children -- are associated with chronic inflammation, impaired physical activity, sleep disturbance and significant morbidity. But little has been known about the cardiovascular risk factors in children with these diseases so far.
"There may be an opportunity to modify their lifestyles and turn this risk around," Silverberg said.
Silverberg studied the association of asthma, hay fever, eczema and cardiovascular risk factors using data from the 2012 National Health Interview Survey of 13,275 children. Asthma occurred in 14 percent of children, eczema in 12 percent and hay fever in 16.6 percent. Asthma, hay fever and eczema were all associated with higher rates of overweight or obesity.
The association with hypertension and high cholesterol exists separately from obesity. Inflammation occurring in asthma and hay fever might contribute to the higher rates of cardiovascular disease.
Also, children with profound asthma are typically more sedentary, which also may have a harmful effect and drive up blood pressure and cholesterol, Silverberg said.The study was published in the Journal of Allergy & Clinical Immunology.