Increased dietary intake and serum levels of vitamin E – α-tocopherol – have been associated with decreased risk of cataract and AMD (See references listed below). Generally publications from these studies have reported odd's ratios - a kind of relative risk of having the disease - among those in the lowest quintile level (dietary intake or serum) compared to the highest quintile level. Obviously, the absolute average levels could conceivably differ among studies. The range or variation of vitamin E levels in a given study could also impact the ability to determine it's relationship with the disease. From a public health standpoint, knowing the status of the general population with respect to vitamin E levels would enhance interpretation of various studies. A recent publication from the Third National Health and Nutrition Survey (NHANES III) documents the epidemiology of vitamin E in the general population (1).

Methods:

The NHANES III survey used a complex multistage stratified sampling design with oversampling of certain demographic groups, resulting in a representative sample of the non-institutionalized U.S. population. Serum concentration of α-tocopherol was measured in participants using high performance liquid chromatography at CDC laboratories. The study was designed to measure possible correlates of vitamin E levels. These included age, sex, race, educational status, smoking status, systolic blood pressure, cholesterol levels, body mass index, physical activity, vitamin/supplement use, alcohol consumption, diabetes status, vitamin E dietary intake (single 24-hour recall), fruit and vegetable consumption and serum concentrations of other vitamins and nutrients.

Results:

16,295 participants 18-90 years of age had α-tocopherol levels measured. Mean concentration of α-tocopherol was 26.8 цmol/L. The 25th percentile was 19.6цmol/L and the 75th percentile was 30.4 цmol/L.

After age-adjustment, women had a mean concentration of serum α-tocopherol similar to that of men within each racial or ethnic group. However whites had significantly higher levels than did African Americans or Mexican Americans. Forty-one percent of African Americans vs 26% of white Americans had α-tocopherol levels below 20 цmol/L - i.e. about the 25th percentile for the population as a whole. Use of vitamin and mineral supplements was inversely associated with odds of a low ( Below 20 цmol/L) serum α-tocopherol level (odd's ratio=0.27 [95% CI=0.19, 0.39])

References

1. Ford ES, Sowell A. Serum α-Tocopherol Status in the United States Population: Findings from the Third National Health and Nutrition Examination Survey. Am J Epidemiol 1999;150:290-300.