Orange sweet potato bread and beta-carotene
What it found
Bread made with orange-fleshed sweet potato puree contained more beta-carotene as the puree level rose, and lab tests showed some of it could be taken in by the body.
The bread also digested more slowly than plain wheat bread.
What they found
Animal and lab studies
Beta-carotene taken in
In lab tests that mimic digestion, only a small share of the beta-carotene became micellarized, meaning available to be taken in. For all-trans beta-carotene it was 1.4% to 6.4%, for 13-cis beta-carotene 1.4% to 7.2%, and for 9-cis beta-carotene 1.1% to 6.9%.
More puree, more taken in
The amount of micellarized beta-carotene went up in a straight line with the sweet potato puree level in the bread.
Starch digestion
In lab tests, starch digestion of the bread went down. The rapidly digestible starch fell, while the slowly digestible starch and resistant starch fractions rose.
Other findings
Beta-carotene in bread
Total beta-carotene rose with the amount of sweet potato puree. It was 4.3, 9.2, 16.5, 23.3 and 33.6 micrograms per gram in bread with 10, 20, 30, 40 and 50% puree.
Vitamin A value
The calculated retinol activity equivalents were 30.9, 66.4, 119.5, 170.4 and 246.2 RAE per 100 g for the same breads.
What the authors conclude
“Overall, OFSP-wheat composite bread holds adequate amount of provitamin A carotenoids.”
Also in their conclusions
- They say the orange-fleshed sweet potato wheat bread holds an adequate amount of provitamin A carotenoids.
- They say the bioaccessible beta-carotene and the changed starch digestion make the bread useful as a new functional food.
- They say it could address vitamin A deficiency and blood sugar issues to improve human health.
How it was done
Vitamin A is needed for vision, growth, immune function and reproduction, and not getting enough causes anaemia, eye damage and poor growth in children. Foods rich in natural carotenes, like orange-fleshed sweet potato, could help address this.
The researchers made bread with wheat flour and 10% to 50% orange-fleshed sweet potato puree. They measured the beta-carotene in each bread and used lab tests to mimic oral, gastric and small intestinal digestion.
What it can’t tell you
- We summarised it from the abstract only.
- The digestion tests were done in the lab, not in people, so they cannot show how much beta-carotene a person actually absorbs from this bread.
- The starch digestion results come from lab tests, so they cannot show what happens to blood sugar in people who eat the bread.
Who paid
- Authors work at
- Biosciences for East and Central Africa at International Livestock Research Institute (ILRI), Kenya
The paper
- Title
- Starch digestibility and β-carotene bioaccessibility in the orange- fleshed sweet potato puree-wheat bread
- Type
- Study
- Evidence
- Animals and lab studies
- Summarised from
- Abstract only
- Cite
- Mbogo D, Muzhingi T, Janaswamy S (2021). Starch digestibility and β-carotene bioaccessibility in the orange- fleshed sweet potato puree-wheat bread. Journal of food science. doi:10.1111/1750-3841.15620PubMed 33565638DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error