Template:Chapter 9.16

9.16 - Biofortified Sweet Potatoes

Alvaro Llamosas-Ibanez,University of Guelph,Canada

Suggested citation for this chapter.

Llamosas-Ibanez,A. (2025) Biofortified Sweet Potatoes. In Farmpedia, The Encyclopedia for Small Scale Farmers. Editor, M.N. Raizada, University of Guelph,Canada. http://www.farmpedia.org

What is vitamin A

A diet that meets the minimum macronutrients and micronutrients necessary for human health, especially for child development, is still significantly lacking in most equatorial and subtropical countries, especially among subsistence-level farmers. The World Health Organization (WHO) estimates that micronutrient deficiency affects more than 2 billion people worldwide, with vitamin A deficiency being one of the most widespread (Bouis & Welch, 2010).

Vitamin A deficiency is especially harmful to children and pregnant women: it lowers their immune response and resistance to common respiratory and diarrheal diseases, as well as to malaria. (Laurie et al., 2015). All of these are leading causes of infant mortality. Vitamin A deficiency weakens the skin, making it more prone to injury and infection (Laurie et al., 2015; Low et al., 2017). It also plays a crucial role in eyesight: it is estimated that over 40% of children under five in Sub-Saharan Africa suffer from vitamin A deficiency , which leads to night blindness that, in severe cases, can result in total loss of eyesight, with nearly 50% of affected children dying within a year (Mulongo et al., 2021).

What is Biofortification?

Biofortification is the name given to the process of selectively breeding a plant to increase its nutritional value, which can be achieved through conventional breeding methods (Bouis et al., 2013; Laurie et al., 2015). It allows smallholder farmers to increase the nutrient value of their crops, granting some economic benefits, but principally. enhanced nutrition, which can help avoid many diseases related to nutrient deficiency and improve child health and early development.

Click on the image to access a higher resolution image as well as lessons adapted for different geographic regions.

Figure 1. Biofortified sweet potatoes. Note. Many high-yielding varieties are now available, suited to different regions, climates, and disease pressures. Source: (Dembélé, 2017)

Biofortified orange-fleshed sweet potatoes (OFSP) are bred mainly to increase their available stores of beta-carotene, and increased yield and disease resistance ( Bouis & Welch, 2010; Low et al., 2017). They are a relatively low-cost and effective way to address malnutrition, synergizing well with other methods such as fortified foods or vitamin supplements, which often depend on government oversight and distribution to far rural areas ( Bouis & Welch, 2010). A key advantage is that it empowers local farmers, especially women, to control their nutrition rather than relying on external aid, which may be unreliable or come with conditions. The surpluses can also be sold at higher prices than regular non-biofortified produce to peri-urban and urban areas, increasing farmer profits ( Bouis & Welch, 2010; CPAD, 2021).

Click on the image to access a higher resolution image as well as lessons adapted for different geographic regions.

Figure 2. Biofortified crop availability worldwide. Note. Countries where biofortified crops have been made available or are in testing phases in blue. Source: HarvestPlus (https://bcr.harvestplus.org/varieties_released#)

Why sweet potatoes

Sweet potatoes (Ipomoea batatas), while native to South America, are a popular and hardy staple food, well known to farmers and consumers across the world (FAO, n.d.). They can be harvested during the lean months at the start of the rainy season in the subtropics, providing a nutritious food source while other crops mature (CPAD, 2021). The plants can be vegetatively propagated, so farmers can readily multiply and distribute them once initial cuttings are obtained. Sweet potatoes are an excellent source of calories, fiber, macro and micronutrients (Laurie et al., 2015) and can be further processed into many other food products, such as flour, dried chips, juice, bread, noodles, candy, and traditional dishes, all while retaining most of their nutritional value after cooking (Laurie et al., 2015). Its sweetness also makes it palatable to small children. All of these qualities make it an ideal way to introduce vitamin A into diets that would otherwise be deficient in it.

Orange fleshed sweet potatoes (OFSP) are one of the richest vitamin A sources available in the form of beta-carotene, a plant pigment responsible for its distinctive orange and yellow hues, which the human body can convert into vitamin A (Laurie et al., 2015; Low et al., 2017). Between 70% and 95% of beta-carotene is retained after cooking and a single medium-sized biofortified tuber (100 g) can provide a child with their daily vitamin A requirements (400 Retinol Activity Equivalents) (Low et al., 2017).

Challenges for the adoption of Biofortified sweetpotato

Efforts to promote biofortified, orange fleshed sweet potatoes among subsistence and smallholder farmers have been ongoing since the late 1990s and early 2000s. However, early varieties underperformed compared to conventional sweet potatoes: producing lower, more variable yields and proved ill-suited to the climate pressures and diseases present in other countries (Mulongo et al., 2021).

Another issue is that orange fleshed sweet potatoes have lower dry matter content, which makes them feel less filling, and their higher beta-carotene content gives their flesh a watery texture, compared to traditional, white-fleshed varieties which are high in dry matter and are thus firmer and more filling. Because these traits are linked to high beta-carotene levels, it is difficult to create a variety with a similar flavor profile of the more palatable white fleshed sweet potato (Low et al., 2017; Mulongo et al., 2021).

Breeding efforts are ongoing to address or mitigate these issues, and higher yielding, more disease and drought resistant varieties have already been released and are being developed with the assistance of organizations like the International Potato Center (CIP) and the Kenya Agriculture Research Institute (KARI) (Laurie et al., 2015; Mulongo et al., 2021)

Cultural Adoption

White-fleshed varieties remain popular in many regions like Sub-Saharan Africa and there some cultural stigma against sweet potatoes, especially the orange fleshed variety, in urban and peri-urban areas where it is seen as a food meant for low-income families. However, these white fleshed varieties almost entirely lack beta-carotene (Bouis et al., 2013).

Click on the image to access a higher resolution image as well as lessons adapted for different geographic regions.

Click on the image to access a higher resolution image as well as lessons adapted for different geographic regions.

Figure 3. Beta-carotene content in different sweet potato varieties. Note. (Mother’s Delight), has up to 48 mg/100 g of beta-carotene, while a white-fleshed variety (Blesbok) has 0 mg/100 g. Source: (International Potato Center, n.d.)

This is why educating smallholder farmers on the importance and many health benefits of vitamin A-rich foods and the existence of high-yielding biofortified varieties is also a key part of the efforts to combat malnutrition worldwide. Special focus must be given to women, who are often farmers themselves, responsible for food preparation and their children's primary caregivers (Laurie et al., 2015; Low et al., 2017). This education must be accompanied by easier access to planting materials, tubers, seeds, or cuttings through local nurseries, seed banks, government programs and international aid organizations.

Institutes like USAID (formerly), the CIP, and CGIAR, through HarvestPlus and many international partners, offer training and education programs on best farming and business practices, including preparation and marketing of biofortified, orange fleshed sweet potatoes.

Conclusion

Biofortified sweet potatoes are a powerful and versatile tool in the fight against chronic malnourishment in the developing world and have the potential to significantly reduce child mortality and disease due to vitamin A deficiency. It combines well with other existing forms of aid, helping raise and diversify income for smallholder farmers and women, and the ongoing efforts to develop new, improved varieties and educate the general populace on its many benefits continue to show promising results.

Additional Resources to Get Started

Video from the International Potato Center on biofortified sweet potato: https://www.youtube.com/watch?v=8oby32lIFYc

HarvestPlus video featuring a Ugandan farmer on the importance of women in adopting biofortified foods: https://www.youtube.com/watch?v=Iiq0-tM2MCA

HarvestPlus biofortification toolbox https://www.harvestplus.org/biofortification-hub/toolbox/

Technologies for African Agriculture Transformation e-catalogue – Orange fleshed sweetpotato https://e-catalogs.taat-africa.org/com/technologies/ofsp-orange-fleshed-sweet-potato-high-provitamin-a

CGIAR: biofortified sweet potato impact report https://www.cgiar.org/annual-report/performance-report-2019/biofortified-sweet-potato-fights-micronutrient-malnutrition-in-sub-saharan-africa/

CIP Farmer education & cultivation manual https://cipotato.org/wp-content/uploads/2014/11/006197.pdf

CGIAR varieties released database https://bcr.harvestplus.org/varieties_released_list?crop=Vitamin_A_Sweet_Potato

AgrowNet: smallholder resource platform https://www.agrownet.com/en-ca/index.html

Practical Links to get Started

I. How to grow cassava: https://www.youtube.com/watch?v=80_c8kmKRyo

II. Information on the detoxification process of cassava: https://www.fao.org/4/t0554e/t0554e06.htm#:~:text=Boiling%2FCooking,Cooke%20and%20Maduagwu%2C%201978

III. Information on the implementation of biofortified crops in Nigeria, including biofortified cassava: https://www.youtube.com/watch?v=8VAIQ4ruNTc

IV. Detailed information on biofortification of cassava for Africa: https://www.youtube.com/watch?v=7gMML7dYpvQ

V. Brief overview of biofortification: https://www.youtube.com/watch?v=CWukNqjX7AQ

VI. Information on biofortification's impacts on hunger and nutrient deficiencies: https://www.youtube.com/watch?v=ldXj_O-Cyx8

VII. Information on improved nutrition from biofortified cassava: https://www.youtube.com/watch?v=80_c8kmKRyo

VIII. Information on intensification of cassava production: https://www.fao.org/4/i3278e/i3278e.pdf

IX. Further scientific reading on biofortification: https://doi.org/10.1201/9781032690636

IX. Link to request germplasm at CIAT: https://alliancebioversityciat.org/genebank-germplasm-requests#/?filter=v2yzae38jpK&p=0 or email: alliance-grp-distributions@cgiar.org

X. To request germplasm from Genesys: https://www.genesys-pgr.org/

XI. Other genebanks and sources for genetic material:

EMBRAPA (Brazil) - https://www.embrapa.br/en/international

CSIR-PGRR (Ghana) - https://pgrri.csir.org.gh/

SPGRC (Southern Africa) - https://www.sadc.int/

NPGRL, UPLB (Philippines) - https://agora.uplb.edu.ph/

References

1. Blesbok. (n.d.). Sweetpotato Catalogue. Retrieved April 17, 2025, from https://sweetpotato-catalogue.cipotato.org/sweetpotato_variety/blesbok/

2. Bouis, H. E., & Welch, R. M. (2010). Biofortification—A Sustainable Agricultural Strategy for Reducing Micronutrient Malnutrition in the Global South. Crop Science, 50(S1), Article S1. https://doi.org/10.2135/cropsci2009.09.0531

3. Bouis, H., Low, J., McEwan, M., & Tanumihardjo, S. (2013). Biofortification: Evidence and Lessons Learned Linking Agriculture and Nutrition. ICN2 Second International Conference on Nutrition. November 19-21, 2014, Rome, Italy.

4. CPAD. (2021, April 23). Biofortified Sweetpotato Improving Lives of Smallholder Farmers in Malawi. International Potato Center. https://cipotato.org/blog/biofortified-sweetpotato-improving-lives-smallholder-farmers-malawi/

5. Dembélé, D. (2017). Biofortified Sweet Potatoes [Photo]. https://www.flickr.com/photos/cgiarclimate/38370352212/

6. FAO. (n.d.). Food and Agriculture Organization of the United Nations. Retrieved April 17, 2025, from https://www.fao.org/faostat/en/#data/QCL

7. Foley, J. (2021, April 9). HarvestPlus Biofortified Crops Map and Table Updated with 2020 Data. HarvestPlus. https://www.harvestplus.org/harvestplus-biofortified-crops-map-and-table-updated-with-2020-data/

8. International Potato Center. (n.d.). CIP Sweetpotato Catalogue. Retrieved April 17, 2025, from https://sweetpotato-catalogue.cipotato.org/

9. Laurie, S., Faber, M., Adebola, P., & Belete, A. (2015). Biofortification of Sweet Potato for Food and Nutrition Security in South Africa. Food Research International, 76, 962–970. 10. https://doi.org/10.1016/j.foodres.2015.06.001

11. Low, J. W., Mwanga, R. O. M., Andrade, M., Carey, E., & Ball, A.-M. (2017). Tackling Vitamin A Deficiency With Biofortified Sweetpotato in Sub-Saharan Africa. Global Food Security, 14, 23–30. https://doi.org/10.1016/j.gfs.2017.01.004

12. Mother’s Delight. (n.d.). Sweetpotato Catalogue. Retrieved April 17, 2025, from https://sweetpotato-catalogue.cipotato.org/sweetpotato_variety/mothers-delight/

13. Mulongo, G., Munyua, H., Mbabu, A., & Maru, J. (2021). What is Required to Scale-Up and Sustain Biofortification? Achievements, Challenges and Lessons From Scaling-Up Orange-Fleshed Sweetpotato in Sub-Saharan Africa. Journal of Agriculture and Food Research, 4, 100102. https://doi.org/10.1016/j.jafr.2021.100102