Higher vitamin A linked to better lung function in sickle cell anemia
Study involved 70 children and adolescents with SCA
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Higher vitamin A levels in the blood were significantly associated with better lung function in children and adolescents with sickle cell anemia (SCA), the most common and severe form of sickle cell disease (SCD), a small study shows.
Given that vitamin A levels tend to be low in children with SCA and lung disease is a common and serious complication of SCA, the findings “open the potential door for the introduction of vitamin A supplements in the routine care of children with SCA to maintain normal pulmonary [lung] function,” the researchers wrote.
The study, “Serum Vitamin A levels in children with sickle cell anemia: relationship with pulmonary function indices,” was published in BMC Pediatrics.
Lung problems can affect SCA
SCD is caused by an abnormal form of hemoglobin, the oxygen-carrying protein in red blood cells. This abnormal hemoglobin causes red blood cells to take on a sickle-like shape, making them prone to early destruction, called hemolysis, and to clumping that can block blood vessels. Symptoms include anemia, or low red blood cell levels, pain episodes, and breathing difficulties.
Previous studies suggest that chronic lung disease, “an important cause of death in adults with SCA, results from a progressive event” that starts as reduced lung function in children and progresses to chronic lung disease with age, the researchers wrote.
Low blood levels of vitamin A, which helps maintain the health of the cells lining the airways, have been associated with acute and chronic lung disease in the general population. While lower vitamin A levels have been reported in children with SCA, “there is limited available data to ascertain if [a] relationship exists between [blood] vitamin A levels and pulmonary function in patients with SCA,” the researchers wrote.
To learn more, a team of researchers analyzed data from 70 children and adolescents with SCA, ages 6 to 17, who were followed at the University of Nigeria Teaching Hospital. The group included 45 children, or 64.3%, and 25 adolescents, or 35.7%.
Most participants were boys (60%), belonged to the middle socioeconomic class (62.8%), and attended primary school (55.7%). Most lived in an urban area — 47 participants, or 67.1%. None had acute or chronic lung disease.
Participants’ mean blood vitamin A levels were 20.22 micrograms (mcg)/dL, which is below the normal range (25 to 70 mcg/dL), consistent with previous reports of low vitamin A levels in children with SCA.
Higher vitamin A tied to lung function
Statistical analyses showed that none of the sociodemographic factors — age, sex, place of residence, and socioeconomic class — were significantly associated with blood vitamin A levels or with two measures of lung function.
These were forced expiratory volume in one second (FEV1), which measures how much air a person can exhale in the first second of a breath, and forced vital capacity (FVC), which measures the total volume of air that can be forcefully exhaled after taking the deepest possible breath.
Notably, higher blood vitamin A levels were significantly associated with higher FEV1 and FVC values, reflecting better lung function.
The researchers noted that a decline of 20% or more in predicted FEV1 or FVC values can indicate impaired lung function. Based on the association seen in this study, “early introduction of vitamin A as part of routine care may provide some clinical benefit in these children,” the team wrote.
The findings highlight “the need for further studies to elucidate the effect of vitamin A supplementation on pulmonary function abnormality already noted in children with SCA,” the researchers wrote, adding that previous studies have suggested that “vitamin A protects against the decline in pulmonary function in the general population.” The researchers noted that the study was small and cross-sectional, meaning it could not prove cause and effect. They also did not control for nutrition, which can affect vitamin A levels.
