But study results do not justify high-dose supplementation Children born to mothers with low vitamin E levels were more likely to suffer from wheeze, and to require asthma medication at 2 years, researchers said here. Analysis of more than 600 children found that those with wheezing had mothers with significantly lower postpartum concentrations of the vitamin E isoform alpha-tocopherol (68 μmol/L, IQR:42,96) compared with those who did not (75 μmol/L, IQR:50,106, P=0.02), reported Cosby A. Stone, MD, MPH, of Vanderbilt University in Nashville. Increasing maternal concentrations of alpha-tocopherol had a protective association with the risk of early life wheezing and the receipt of asthma medications, he said in a presentation at the American Academy of Allergy, Asthma & Immunology (AAAAI) annual meeting. However, increasing concentrations of maternal gamma-tocopherol, another vitamin E isoform, modified this protective benefit, he added. "Our study fits into a growing body of knowledge that has shown associations between respiratory outcomes with isoforms of vitamin E, and that each isoform may affect outcomes such as wheezing differently," Stone said in an interview with MedPage Today. But he cautioned that the results imply association and do not show causation. Stone's group examined data from the Nashville-based INSPIRE birth cohort on 652 children with maternal postpartum plasma vitamin E isoforms measured at study enrollment. Median age of the children at time of maternal sample collection was 50 days (IQR 16,81), 47% were female, and 61% were white. The researchers followed the children and their mothers for the first 2 years of the child's life and used validated questionnaires to ascertain one of the three outcomes: children who wheezed in the past 12 months, received asthma medication in the past 12 months, or ever received an asthma diagnosis from a clinician. Using multivariable regression analysis for interaction, Stone's group found that the relationship of alpha-tocopherol with wheezing was modified by gamma-tocopherol concentration in tertiles (P=0.014 for main effect of alpha tocopherol; P=0.06 for interaction). At the highest tertile of gamma tocopherol, the protective association of alpha tocopherol on child wheezing was modified, the authors found. The results serve as an important reminder that there are eight isotopes of vitamin E, all which have displayed differing effects on health in human studies and animal experiments, Stone noted. "Clinicians should be made aware that what is currently labeled in our foods and supplements as vitamin E or alpha-tocopherol is actually any of eight different isoforms, and alpha-tocopherol may not actually be the dominant isoform being provided," he explained to MedPage Today. Stone noted that the oils that we consume are the main sources of tocopherol in our diet, and they can widely vary in terms of their tocopherol isoforms. For example, sunflower and safflower oil provide predominantly alpha-tocopherol as their isoform of vitamin E, while corn and soy oil provide predominantly gamma-tocopherol. Other sources of vitamin E include nuts, fish, avocados, leafy greens, and sweet potatoes, he added. Stone called for further evaluation for associations with both alpha-tocopherol and gamma-tocopherol and wheezing and asthma. "We need a clinical trial to evaluate the effect of giving more alpha-tocopherol to mothers during pregnancy before anyone should jump to giving supplements. In fact, high-dose supplementation is not what we would encourage, but correcting maternal alpha tocopherol deficiency or gamma tocopherol excess through dietary counseling is possibly important, and may provide us with a future tool to prevent wheezing or asthma," he explained. AAAAI session moderator Caroline C. Horner, MD, of St. Louis Children's Hospital, agreed that a clinical trial is warranted. "Usually, we don't differentiate between the isotopes of vitamin E. It's interesting because [the research] points out that they do exist and there may be a clinical effect," she told MedPage Today. Source
