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Nutrition and Food Sciences

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Bread with sweet potato may help control blood sugar as well as preventing vitamin deficiency

Sweet potato bread contained more resistant starch and less rapidly digestible starch.

Substituting sweet potato puree for up to 50% wheat flour in bread can produce a bread that has good levels of vitamin A precursors, low starch digestibility, and is good for gut health. reports a study in Journal of Food Science. This bread could help improve the vitamin and fibre intake of urban African populations. The slower release of starch from this bread during digestion could also make it useful for diabetics seeking to control blood sugar.

Vitamin A is important for vision, growth and immune function. Its deficiency is a leading cause of blindness in young children. WHO figures in 2013 suggested that 30% of children under 5 years old do not consume enough vitamin A. This deficiency is often addressed by supplement programmes and fortification of staple foods, including maize, wheat flour and rice. Previous studies have determined that sweet potato is a good source of the vitamin A precursor beta-carotene and that it can be incorporated into breads and other foods to boost their vitamin content. Its addition can affect the bread quality and texture although heat treatment helps (see Further Reading). These fortified breads are on sale in Kenya, according to Srinivas Janaswamy of University of South Dakota, senior study author.

The study was led by Daniel Mbogo and was a collaboration between Mbogo at the International Potato Center, and scientists at South Dakota State University and North Carolina State University in the USA.

The scientists made wheat-sweet potato breads with up to 50% sweet potato content. The breads were subjected to a barrage of tests to determine the availability of vitamin A in the bread and the digestibility of the starch.

Simulated digestion studies showed that wheat bread made with 50% sweet potato contained 33.6 microg/g of beta carotene while bread made with 10% sweet potato contained 4.3 microg/g. In terms of vitamin A requirements, a 100 g serving of the 50% sweet potato bread can provide 82% of a 1 to 3 year-old’s daily requirement for vitamin A and 62% of a 3-8 year old’s requirements, says Janaswamy in a press release.

Starch digestion studies suggested that the proportion of rapidly digestible starch was lower in the 50/50 wheat-sweet potato breads than in wheat bread (50% rather than 75%) and the proportion of starch that was resistant to digestion was higher at 41% compared with 9% in the wheat bread.


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Starch digestibility and β‐carotene bioaccessibility in the orange‐ fleshed sweet potato puree‐wheat bread. Daniel Mbogo, Tawanda Muzhingi, Srinivas Janaswamy. Journal of Food Science 2021.

Article details

  • Author(s)
  • I. Hoskins
  • Date
  • 06 April 2021
  • Subject(s)
  • Food science