Lack of Correspondence between Experimentally Determined Values of Vitamin E in Carrot (Daucus carota L.) and Those Reported in the USDA National Nutrient Database

Abstract

Vitamin E compounds, known collectively as tocochromanols, are essential nutrients found in plant tissues. These compounds are present in fruits and vegetables at lower levels than in nuts and oils. However, since fruits and vegetables are frequently consumed in the diet, they represent important contributions to vitamin E intake. Knowledge of nutrient levels in fruits and vegetables is important in making dietary recommendations and in planning menus. The U.S. Department of Agriculture (USDA) National Nutrient Database (NNB) reports levels of vitamin E in carrot of 6.6 µg·g−1 on a fresh weight basis and similar levels of vitamin E for food products containing carrots, such as baby food and carrot juice. We collected data on four tocochromanol compounds using reverse-phase high-performance liquid chromatography (HPLC) with fluorescence detection on both fresh carrots and on commercially available food products containing carrots. Our data revealed that levels of vitamin E in fresh carrot and food products containing carrot were in the range of 0.007–0.12 µg·g−1 converted to a fresh weight basis. These levels were consistent with several published research studies for carrot, lower than several other published studies, and significantly lower than values reported in the NNB. Data from our studies show actual vitamin E values for this vegetable may be significantly lower than levels published in the NNB, but large discrepancies exist in the published reports for measurement of tocochromanol levels for this vegetable. Dietary guidance based on vitamin E values for carrot reported in the NNB could lead to inaccurate nutrient recommendations and should be clarified and standardized.