12 January - 20 June 2016

Kamalsundari and BARI SP-5 orange-fleshed sweet potatoes have the potential to be used as food-based supplements to reduce vitamin A deficiency

13 January 2016

In many parts of the world, primarily Africa and South East Asia there is an endemic deficiency in vitamin A, affecting an estimated 190 million preschool-aged children and 19 million pregnant women (the two most at risk groups in terms of vitamin A deficiency). Although taken for granted in many areas, the deficiency of vitamin A in the diet can lead to numerous health problems during the early developmental stages of a child’s life, causing reduced immune function, growth and night blindness. Under normal circumstances breast milk is the primary significant source of vitamin A for infants, with those fed little or no breast milk in early life increasingly susceptible to infection. This coupled with a vitamin A deficient diet in childhood due to lack of abundant preformed vitamin A (retinol) from food (liver, eggs, milk and milk products), leads to reliance on local vegetables and fruits for a source of vitamin A.

A recent study by the University of Dhaka into this endemic health issue (44–50% of preschool children in South/Southeast Asia are affected by vitamin A deficiency) has shown that a home grown crop can be a solution.

The orange-fleshed sweet potato is known to contain the provitamin A β-carotene, containing up to 277 μg per g. A 125g serving of boiled sweet potatoes can therefore supply the daily requirement of vitamin A for preschool children and protect them from night blindness and reduced immune system function. In addition to being rich in β-carotene, significant amounts of protein, fat, carbohydrate and dietary fibre are also present. If this is used as a staple food a steady supply of vitamin A and energy can be achieved in resource-poor developing countries for relatively little cost.

The Dhaka study identified that BARI SP-2 (Kamalasundari) and BARI SP-5 orange-fleshed sweet potatoes contained significant amounts of β-carotene. These varieties, used as a food-based supplement to combat vitamin A deficiency, could help mitigate this problem in future. With the knowledge that maceration and heat processing improve β-carotene bio accessibility, due to rupture of plant tissue microstructure and subsequent release of nutrients, the analysts investigated orange-fleshed sweet potatoes for their content of total carotenoids and trans- and cis-β-carotene, precursors to Vitamin A.

Their approach consisted of three analytical samples for each variety (raw and boiled) being analysed for total carotenoids, trans and cis-β-carotenes, with analysis conducted by in the laboratory of the Institute of Nutrition and Food Science (University of Dhaka, BD) and the Nutritional Biochemistry Laboratory of International Centre for Diarrheal Disease and Research, Bangladesh.

Carotenoid isolation was performed using acetone-petroleum ether extraction followed by spectrophotometric determination. Trans- and cis-β-Carotenes were analysed by reversed-phase HPLC method using a mobile phase containing acetonitrile:methanol:2-propanol in the ratio of 85:15:33 with 0.01% ammonium acetate.

Seven varieties of sweet potatoes comprising three orange-fleshed, three cream fleshed and one white-fleshed potato variety were collected from the Tuber Crops Research Centre (TCRC) of Bangladesh Agricultural Research Institute (BARI), Bangladesh. The potatoes were harvested when they became matured at about four to five months; the average weight of each potato given as 200g.

In conclusion, the study showed significant differences in both total carotenoid content and percentages of trans- and cis-β-carotenes in the different varieties of sweet potato. The study showed that carotenoid content was higher in the raw compared to the boiled samples from the same variety, with the Kamalasundari, BARI SP-2 variation shown to contain the most carotenoids in both the raw and boiled samples. β-Carotene was higher in the Kamalsundari and BARI SP-5 varieties with trans-β-Carotene the major carotenoid in all the raw samples. Boiling was associated with an increase in cis-β-carotene and a decrease in trans. Kamalsundari and BARI SP-5 forms have the potential to be used as food-based supplements to reduce vitamin A deficiency when incorporated into the daily diet in childhood. These forms have the highest readily available vitamin A precursors.

RSSL's provides vitamin analysis in a wide range of matrices. This includes a full vitamin and mineral analysis service to assist with labelling, due diligence, claim substantiation and stability.

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