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LETTERS TO THE EDITOR |
Linus Pauling Institute
571 Weniger Hall
Oregon State University
Corvallis, OR 97331
E-mail: maret.traber{at}oregonstate.edu
Bell Institute of Health and Nutrition
General Mills Inc
Minneapolis, MN 55427
Dear Sir:
Landvik states that "results [of vitamin E studies] have been somewhat variable, ...most likely due to differences in the dosages and forms of the vitamin E supplements evaluated." We concur that the outcomes of vitamin E supplementation studies have been variable, but the question is why. Studies of patients with fat malabsorption have shown that vitamin E absorption requires normal digestive processes involved in the absorption of dietary fats (1). However, the amounts and forms of fat required for optimal vitamin E absorption are unknown, and the causes of the variability in responses to supplements are also unknown. The purpose of our study was not to compare the bioavailability of vitamin E consumed with different amounts or kinds of dietary fat, but to design a study to evaluate the bioavailability of vitamin E in commonly consumed sources of the vitamin, namely, supplements and fortified breakfast cereal (2). Indeed, we anticipated that fortified breakfast cereal might not be an ideal vitamin E source because of its low fat content; therefore, one arm of our study included cereal that was intentionally suprafortified with vitamin E (eg, 400 IU per serving).
In an effort to make our results applicable to typical consumers, we considered that many persons take vitamins as part of their definition of a healthy lifestyle and thus take vitamins with breakfast or in the morning while they remain fasting. Thus, vitamin and mineral supplements, including vitamin E, are commonly consumed on an empty stomach in the morning with juice, tea, coffee, or nonfat milk. On the basis of these observations, the question we wanted to answer was, Is there a difference in the bioavailability of vitamin E when consumed as part of a low-fat breakfast cereal compared with that of a supplement consumed with a nonfat drink?
Landvik also states that "it is recommended that vitamin E supplements be taken with a meal containing fat." Two studies in humans have shown that plasma vitamin E increases to a greater extent when vitamin E supplements are taken with fat-containing foods (3, 4). Our study showed that vitamin E supplements are not effectively absorbed if they are taken on an empty stomach with a glass of nonfat milk (2). Therefore, we believe that our data support the advice that vitamin E supplements should not be taken alone, but rather should be consumed with food, perhaps foods containing higher amounts of fat in an effort to improve absorption.
Landvik claims that "the physical form of the vitamin E added to the cereal differed from the vitamin E capsules." In point of fact, the same deuterium-labeled vitamin E (d9-all-rac-
-tocopheryl acetate) was added to the cereal as was in the capsule. The study cereal was fortified in a manner identical to the commercially available cereal (Total; General Mills Inc, Minneapolis, MN) and was prepared by the same manufacturer so that the results of the study would be applicable to cereal available for purchase by average consumers. The vitamin E used was dissolved in the commercially used emulsion (Hoffmann-La Roche, Nutley, NJ), sprayed on the cereal, and then dried. The emulsion applied to the cereal was not included in the encapsulated vitamin E, but neither is it in commercially encapsulated vitamin E supplements. The differences in vitamin E absorption when the pill was consumed along with cereal suggest that the emulsion on the surface of the cereal does not increase vitamin E absorption from the supplement. Moreover, Roxborough et al (5) also observed a large degree of variability in subjects who consumed deuterium-labeled vitamin E with toast for breakfast. Thus, our findings concerning the lack of consistency in vitamin E absorption when the supplement is consumed with a low-fat meal are not unique.
From our results, we conclude that consumers wishing to increase their vitamin E intakes would benefit from eating their vitamin E supplement after a fat-containing meal, eating a vitamin E–fortified food such as breakfast cereal, or a combination of both. Food fortification with vitamin E appears to optimize vitamin E bioavailability from a low-fat diet, because we showed that the breakfast, which contained <5% fat (consisting of vitamin E–fortified cereal plus fat-free milk), unexpectedly increased vitamin E bioavailability. These findings are significant because fortified breakfast cereals are a major source of vitamin E in the American diet (6, 7). Further efforts to educate consumers regarding the consumption of vitamin E through fortified foods or supplements should be considered.
REFERENCES
-tocopherol is limited among US adults. J Am Diet Assoc 2004;104:567–75.[Medline]
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