South African indigenous fruits – Underutilized resource for boosting daily antioxidant intake among local indigent populations?

Abstract

Consuming more than seven portions of fruit and vegetables daily substantially lowers the risk of mortality from any cause, yet many South Africans living below the poverty line have a very low or even zero intake of fruit and vegetables. Advice on the importance of consuming a healthy, and at the same time affordable diet needs to be provided by suggesting alternatives among indigenous plants that are nutritionally superior to “exotic” fruits. But to what extent could antioxidant intake be boosted through the ingestion of selected indigenous fruits? Ten indigenous South African fruits were evaluated for their antioxidant activity and compared with blueberry and cranberry. An Antioxidant Potency Composite Index was drawn up based on the results of three equally weighted assays, namely Total Phenolic Content (FCR), Trolox Equivalent Antioxidant Capacity (TEAC) and Total Antioxidant Capacity (H-ORAC_FL+L-ORACF_FL). The antioxidant potency rankings obtained were as follows: wild plum > wild olive > colpoon > blueberry > christmas berry > crossberry > waterberry > cranberry > tortoise berry > bietou > num-num > sour fig. Blueberry and cranberry ranked 5th and 9th, respectively. It was shown that by introducing servings of as little as 25 g of wild plum, waterberry, num num or sour fig into the diet, the daily antioxidant intake can be boosted to within an acceptable range to support health. All of these freely available fruits are known and have been traditionally used by rural communities in South Africa.

Keywords: antioxidant capacity (AOC), antioxidant potency composite index, oxygen radical antioxidant capacity (ORAC), total phenolic content (TPC), trolox equivalent antioxidant capacity (TEAC)