Asthma, Inflammation, Lung Function and Vitamin E
The number of people with asthma in the US is growing every year. According to the CDC, roughly 25 million Americans have asthma, half of whom have had an asthma attack in the past year. Asthma is more prevalent among the poor and African Americans, Hispanics and Puerto Ricans than Caucasians. Worldwide, 235 million people have asthma. It is the most common chronic disease among children (WHO, 2011).
Asthma is caused by a combination of genetic and environmental factors. One protective factor seems to be vitamin E, possibly because most people - especially children, young adults, non-Hispanic Blacks have low blood α-tocopherol levels (Pfeiffer et al, 2013). Vitamin E is an overlooked nutrient. Except for people over 70y, almost everyone is likely to have blood vitamin E levels below 30 µmol/L – the level found to have the lowest total mortality in the Alpha-Tocopherol Beta-Carotene (ATBC) Cancer Prevention Study (Figure 2, Wright et al, 2006).
In a newly published review, Abdala-Valencia and colleagues report that α-tocopherol is protective against allergic lung inflammation whereas γ-tocopherol is not. Like dietary fatty acid balance is important for health, imbalances in dietary intakes of vitamin E isoforms need to be considered. Although all 8 vitamin E isomers have antioxidant capacity, the Institute of Medicine Recommended Dietary Allowance (RDA) for vitamin E is based exclusively on α-tocopherol because it is the most biologically active form retained in the body. Since our bodies require adequate amounts of vitamin C to recycle vitamin E and prevent it from acting a source of reactive oxygen species (ROS), we need to remember to measure vitamin C status when studying vitamin E.
The predominant form of vitamin E in soybean and corn oil is γ-tocopherol. Because we consume so much of these oils, it is prudent to incorporate α-tocopherol-rich oils in our diet as well. Some of the best sources of α-tocopherol (to balance high intakes of γ-tocopherol) are sunflower and safflower oils. Another approach is to supplement with a pure α-tocopherol source.
As Abdala-Valencia and colleagues conclude: understanding the differential regulation of inflammation by isoforms of vitamin E could lead to new dietary approaches to modulate inflammatory pathways and maintain healthy lung function. Wouldn’t that be great?
Abdala-Valencia H, Berdnikovs S, Cook-Mills JM. Vitamin E isoforms as modulators of lung inflammation. 2013 Nutrients doi:10.3390/nu5114347
Pfeiffer CM, Steinberg MR, Schleicher RL, Haynes BMH, Rybak ME, Pirkle JL. The CDC’s Second National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population is a valuable tool for researchers and policymakers. 2013 J Nutr doi:10.3945/jn.112.172858
Wright ME, Lawson KA, Weinstein SJ, Pietienen P, Taylor PR, Virtamon J, Albanes D. Higher baseline serum concentrations of vitamin E are associated with lower total and cause-specific mortality in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study. 2006 Am J Clin Nutr 84:1200-1207