In Response to Vuong and King, “A Method of Preserving and Testing the Acceptability of Gac Fruit Oil, a Good Source of β-Carotene and Essential Fatty Acids”

Vitamin A deficiency is a worldwide nutritional scourge, and the situation seems to be deteriorating in some parts of the world, such as sub-Saharan Africa [1]. The role of provitamin A carotenes in the control of hypovitaminosis A has been a particular interest at CeSSIAM [2], and a landmark event in gaining a valid perspective on the issue was the publication of the relevant section of the dietary reference intakes [3], which defined the retinol activity equivalent (RAE) in January 2001. Prior to that date, the value of provitamin A carotenes in food matrices had been overvalued by the application of the conventional 1:6 and 1:12 bioconversion factors, producing falsely high estimates of population vitamin A security and illusory aspirations to improve vitamin A status by promoting green and orange vegetables [2]. However, the potential for the carotenes in edible oils to contribute dietary vitamin A activity had been severely undervalued by the same factors, since the dietary reference intake RAE proposes a three-times-greater bioefficacy for emulsified provitamin A carotenes in an oil base [3]. The Food and Nutrition Bulletin has been in the forefront in providing information on the dietary context of oil-based provitamin A sources [4, 5], and an additional example was the recent publication by Vuong and King [6] on the chemical and nutritional context of the gac fruit (Momordica cochinchinensis Spreng). As stated in their text on p 228: “The total carotenoid concentration of gac fruit oil is 5,770 ppm, consisting mainly of two carotenes, β-carotene and lycopene” [6]. We were troubled, however, when trying to get a handle on the dietary vitamin A value of the oil of this fruit compared to that of the palm fruit (genus Elaeis) [6], encountering a host of internal and external inconsistencies. For the sake of clarity in the international discussion and toward an informed use of appropriate dietary approaches to hypovitaminosis A, we raise some of these inconsistencies. The confusion derives in part from internal inconsistencies in the concurrent expression of nutrient concentration both per milliliter of oil and per 100 ml of edible portion of oil. Table 2 from Vuong and King [6] provides values for “β-carotene and isomers” in units of micrograms per milliliter (ppm) as 2,710 μg/ml for freshly prepared gac oil and 1,622 μg/ml for the same oil after three months of storage. However, in their table 5 (a comparative table of nutritional quality of gac fruit oil and of other fat and oil sources), in which the expression is per 100 g of edible oil, there is a disconnect: the vitamin A activity in retinol equivalents for gac oil is presented as 40 RE for data from the same article [6]. The external inconsistency is a similarly invalid conversion factor calculation for the red palm oil (RPO), reported by Nagendran et al. [7] as 8 RE in Vuong and King’s composite table 5 [6]. We have created a table in this letter, comparing the values of Vuong and King [6] and those of Nagendran et al. [7], along with information on the molecular-distilled RPO product, Carotino, published by Scrimshaw [8]; all are expressed for 100 g (approximately 100 ml) of edible oil (table 1). Indeed, with a uniform denominator, fresh gac oil would still have about five times the vitamin A activity of crude RPO, but the RE value, itself, is over 100 times what Vuong and King [6] presented in their table 5. Retinol equivalents, however, use a 1:6 conversion efficiency Letters to the Editor