The finding of this vegetable’s properties presents a plant-based approach to address a problem that blights Africa and South-East Asia. In 2011, the World Health Organisation (WHO) reported that vitamin A deficiency (VAD) affects around 190 million preschool-aged children and 19 million pregnant women in these regions.
Children in developing countries are at risk of consuming vitamin A deficient diets as those living in third world countries rely on cheap dark green-yellow local vegetables and fruits for vitamin A. Due to poor bioavailability plant foods that provide β-carotene are a substitute of preformed vitamin A.
The study set out to determine the total carotenoids, and trans- and cis-β-carotenes, present in raw and boiled orange-fleshed sweet potatoes. Carotenoid content was found to be higher in the raw potatoes compared to the boiled samples from the same variety.
Meanwhile, the trans-β-Carotene was found to be the major carotenoid in all of the raw potatoes, but boiling was associated with an increase in cis-β-carotene. The researchers believed the potato varieties, Kamalsundari, and BARI SP-5 orange-fleshed sweet potatoes had the potential to be used as food-based supplements to reduce vitamin A deficiency.
Vitamin A deficiency
The findings of the study have relevance to a region where micro-nutrient deficiencies are common and where food fortification programs are well established. Its impact on growth and development is most evident especially in young children, adolescents, and pregnant and lactating mothers.
Nearly 44–50% of preschool children in South and Southeast Asia are affected by severe vitamin A deficiency. Among the South Asian countries, India has the highest prevalence of clinical and subclinical vitamin A deficiency, the prevalence being as much as 62% in preschool children.
In Bangladesh, the prevalence of subclinical vitamin A deficiency in the preschool-aged children is 20.5%, although in slum areas the prevalence is as high as 38.1%
The study used seven varieties of sweet potatoes - three orange-fleshed, three yellowish-cream fleshed and one white-fleshed potato variety. Based at Institute of Nutrition and Food Science (University of Dhaka, BD) and the Nutritional Biochemistry Laboratory of International Centre for Diarrheal Disease and Research in Bangladesh, the researchers used potatoes with an average weight of 200g.
Three analytical samples for each variety (raw and boiled) were analysed for total carotenoids, using acetone-petroleum ether extraction followed by spectrophotometric analysis. Trans- and cis-β-carotene content was also determined.
Among the seven varieties of sweet potatoes, total carotenoid content, in both raw and boiled samples, was highest in Kamalasundari (61.94μg per g vs 58.32μg per g, respectively), followed by BARI SP-4 (36.23μg per g vs 32.29 μg per g) and BARI SP-5 (19.31μg per g vs 18.24 ± 0.32 μg per g). The other varieties were found to have relatively low amounts of carotenoids. Previous studies have also identified the Kamalasundari as being rich in carotenoids.
“These results indicate that boiling sweet potato decreases trans-β-carotene and increases cis-β-carotene,” the study noted.
“This means the the cis isomer is comparatively greater in boiled samples than in the raw potato. In general, cis-β-carotene content is very low or insignificant in sweet potato, although white- or yellowish-fleshed varieties have much more cis-β-carotene than the orange-fleshed variety,” the study added.
Source: Food Chemistry
First published online 15 May 2016, Vol 199, pp. 628–63, doi:10.1016/j.foodchem.2015.12.057
“Carotenoids and β-carotene in orange fleshed sweet potato: A possible solution to vitamin A deficiency”
Authors: Sheikh Nazrul Islama, Tania Nusrata, Parveen Beguma and Monira Ahsanb