Vitamin A insufficiency linked to hand, foot and mouth disease

By Sarah Guy

Vitamin A status is associated with immunity to, and pathogenic condition of, hand, foot, and mouth disease (HFMD) in children, say researchers whose study results show that the majority of those with the infectious disease also had vitamin A insufficiency.

Furthermore, the complication rate was higher and duration of hospitalization longer among children with HFMD and vitamin A levels of 0.7 µmol/L or less - the level generally considered to indicate deficiency - compared with those whose levels were higher, remarks the team in Clinical Nutrition.

Vitamin A is "an essential micronutrient with established roles in embryogenesis, growth, reproduction, maintenance of epithelial integrity, and optimal function of the immune system," explain Weiping Wang, from the Children's Hospital of Fudan University in Shanghai, the People's Republic of China, and co-investigators.

The last two functions are particularly concerning when considering the potential impact of vitamin A deficiency on HFMD infection, which is characterized by pathologic damage to the skin and mucous membranes, they add.

The team assessed dietary intake and serum concentrations of vitamin A in a group of 450 hospitalized HFMD patients aged a median 25 months at disease onset. Participants all weighed in the normal range for their age and none were malnourished.

The cohort had a mean serum vitamin A concentration of 0.73 µmol/L, measured by blood test, and 52.7% of patients presented with concentrations of 0.70 µmol/L or lower, a "remarkably high number," say Wang and colleagues.

Mean length of hospital stay was significantly longer among vitamin A deficient than sufficient HFMD patients, at 3.5 versus 3.2 days. When the cohort was categorized according to vitamin A deficiency, the rate of disease complications was significantly higher in the deficiency group, at 46% versus 29% in the nondeficient group.

Results of an enzyme-linked immunosorbent assay showed that serum concentrations of interferon (IFN)-α were significantly lower in patients with complications than in those without, at 67.1 versus 87.7 pg/mL. More importantly, serum IFN-α concentration positively associated with vitamin A concentration, remark Wang et al.

"The mechanisms are unclear, but low vitamin A levels may be due to decreased intake, increased consumption, or increased catabolism," write the authors.

They suggest that further studies are needed to determine the reasons for their findings, so that "appropriate interventions can be implemented to improve the vitamin A status of individuals with HFMD."

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