. 2017 Sep 14;75(10):798–829. doi: 10.1093/nutrit/nux037

Table 5.

Predicted adoption of biofortified crops as evidenced by consumer willingness to pay in low- and middle-income countries

Reference	Country	Study Population	Method and Study Design	Results	Conclusion
Sweet potato
Low and van Jaarsveld (2008)³⁷	Mozambique	Consumers: Bakers in 3 rural villages; n = 8–10 (per village)	Calculation of costs and revenues of producing bread buns with 38% of wheat flour replaced by boiled and mashed OFSP (golden bread)	Calculated net return to labor was 3 times higher for golden bread buns vs white wheat flour buns due to lower costs	Small-scale golden bread production is an economically viable option for creating a market for OFSP
Naico and Lusk (2010)⁸¹	Mozambique	Consumers: Adults at local markets, rural and urban, M (40%) + F (60%), mean age: 30 y; n = 308	Choice experiment: 9 choice sets of the attributes pulp color (white/ orange), dry matter content (low/ medium/high), size (small/medium/large), and price (M7.5/10/15/kg) with treatment 1 and 2: visual exposure to a bag of sweet potato of each variety. One bag was given to each participant based on their preference from the choice questions. Treatment 3 and 4: no exposure	Price correlated negatively with preference. Dry matter was the most important attribute to the participants. Small-sized roots were more preferred in the rural area but not in the urban area. Consumers are willing to pay 51.3% more for OFSP relative to WFSP	Dry matter is a key factor driving consumer acceptance. When dry matter, price, and size are equal, orange pulp color is preferred over white pulp color
Chowdhury et al. (2011)⁴³	Uganda	Consumers: Rural (4 villages from each Kamuli and Luweero Districts; 40 random households per village) and urban (random at 2 marketplaces in Kampala) sweet potato consumers; M + F; n = 467	Valuation by choice experiment (17 scenarios) of 4 varieties of: 1 white sweet potato; 2 OFSP; and 1 yellow sweet potato, after (1) no nutritional info and asked to make real choices and commitments (n = 121); (2) nutritional info about OFSP and asked to make real choices and commitments (n = 115); (3) nutritional info and hypothetical assessments (n = 118); (4) nutrition information and “cheap talk” script and hypothetical assessments (n = 113)	In scenario (1) no difference in WTP for deep-orange vs white was found, whereas WTP for orange and yellow sweet potato was lower (−22% and −30%, respectively) compared with white. In (2) a premium was found for deep-orange variety relative to white (+25%). In (3) higher WTP for yellow (+40%), orange (+43%), and deep orange (+48%) vs white. In (4) higher WTP for yellow (+26%), orange (+26%), and deep orange (+52%) vs white. Respondents who preferred a variety in the sensory assessment were willing to pay more for that variety. Rural consumers had a higher WTP for OFSP varieties compared with urban consumers.	Consumers in Uganda are willing to pay similarly for biofortified (deep orange) varieties as for the traditional white variety, even without a promotional campaign. Provision of nutritional information translates into an increase in WTP for deep OFSP. Taste is an important attribute in WTP. Hypothetical scenarios translate into biased WTP; therefore, experiments with real transactions are superior
Maize
Tschirley and Santos (1995)⁶⁵	Mozambique	Consumers: Low-income urban households; n = 400	Price game assessing the percentage of respondents switching from white to yellow maize after a given discount rate	At a 14% discount, 25% of consumers would switch from white grain to yellow grain, whereas at a discount of 43%, 70% of consumers would switch. Lower-income consumers are more likely to switch at modest price discounts. At higher discount (> 43%), higher-income consumers are just as likely to switch to yellow maize	Reduced price is an important determinant of consuming yellow maize
Rubey and Lupi (1997)⁷⁷	Zimbabwe	Consumers: Urban households; n = 512	Focus group discussions and preference ranking (refinedness, product price, color, travel time for obtaining meal, product packaging)	The predicted share of households consuming yellow maize was 25% when sold at a 10% discount compared with white maize	Yellow maize is well accepted, provided that it is sold at a lower price than white maize and widely available
Stevens and Winter-Nelson (2008)⁴⁹	Mozambique	Consumers: Marketplace shoppers, 69% F, 14–70 y; n = 201	Trading experiments based on acceptance to trade white maize for orange maize at different prices and willingness to trade white maize with tomatoes, orange, and white near-isogenic lines of maize	Acceptance rate of orange maize meal at all trade ratios was 44%; factors reducing acceptance for trade are being male, being a nonshopper, being a bad taste judger, finding local maize tastes better than orange maize, and frequently eating meat/fish. Household size, the presence of small children, dietary diversity, and perceived taste were determinants of trade acceptance	Existing preferences for white maize do not preclude acceptance of orange biofortified varieties
De Groote and Kimenju (2008)⁷⁵	Kenya	Consumers: Urban maize consumers; n = 604	Contingent valuation in a semi-double-bounded model (acceptance of offered bids in 2 rounds)	Price, time saving, nutrient quality, and cleanliness were mentioned as factors determining choice for a particular maize product. Only 25% of respondents were willing to buy yellow maize at the same price as white maize. Acceptance increased with lower follow-up bids, with a maximum of 50%–58% of respondents being willing to pay for yellow maize at a 30% discount. Modeling showed 37% discount to be required for consumer acceptance (for supermarket respondents: 48%)	Consumers preferred white maize and would need a discount of 37% to buy yellow maize. People from western Kenya had the strongest preference for yellow maize. Consumers with higher education and income had a stronger preference for white maize. To market yellow maize for urban consumers in Nairobi, substantial price reductions would be necessary
De Groote et al. (2010)⁵⁰	Ghana	Consumers: Adults from Ashanti, Central, and Eastern Regions, 18–90 y; n = 703	Individual auctions (BDM) and choice experiments and group auctions after being exposed to no information and later to 5-min radio message about the benefits of eating orange maize	In Ashanti Region, consumers’ WTP is higher for white maize than for yellow and higher for yellow than for orange. In Central Region, WTP is higher for yellow than for white or orange. In the Eastern Region, WTP for yellow and orange maize is higher than for white. The difference in WTP between white and yellow maize was only significant in the Eastern Region. Provision of information increased WTP for orange maize relative to that for white maize and reduced WTP for white and yellow maize	A good information campaign based on radio message is likely to have an effect on consumer acceptance for orange maize
De Groote et al. (2011)⁷⁹	Kenya	Consumers: Rural and urban adults in western and eastern Kenya, 70% F, mean age: 46 y (rural) and 34 y (urban); n = 651	Experimental auction: price WTP for normal rice and willingness to buy biofortified or fortified maize for same or reduced price	Respondents were willing to pay 42.6 KES for white maize, 25% more for fortified maize, and 10% less for yellow maize. Location, familiarity with yellow maize (as in the west), and awareness raised the price by 6% and 7% for yellow maize	White maize is preferred, but WTP for fortified maize was higher and therefore with nutrition education yellow maize can be potentially accepted
De Groote and Kimenju (2012)⁸⁰	Kenya	Consumers: Urban adults, 45% F; n = 604	Experimental auction: willingness to buy biofortified maize for same or reduced price compared with normal maize	26% would buy yellow maize at same price as normal maize; even at discount, less than half would buy yellow maize. Price should be reduced by 37% for consumers to buy, with a larger discount for supermarket clients. Income and education had negative effect on WTP for yellow maize	Consumer preference for white maize is strong. For biofortified yellow maize to be accepted, a strong public awareness campaign is needed
Meenakshi et al. (2012)⁷⁶	Zambia	Producers and consumers: Small-scale rural farmers, mean age: 44 y; n = 478	Experimental auction: WTP for orange, yellow, or traditional maize with or without (radio or through community leaders) education	WTP is slightly higher for orange maize compared with white maize, whereas yellow maize was sold at a discount. Nutrition education improves acceptability and WTP, no difference between locations and no difference between channel of information receiving	Orange maize is perceived differently than yellow maize and can compete with white maize
Beans
Oparinde et al. (2015)⁴¹	Rwanda	Consumers: Adults in Northern Province, > 18 y; n = 572	Experimental auction: WTP for RIB, WIB, and a local variety (Mutiki) after exposure to no information; 1-time information (1-min radio message) on gains/benefits of iron; repeated information on gains/benefits of iron; 1-time information on negative effects/disadvantages of low iron; repeated information on negative effects/disadvantages of low iron	WTP was 476 RWF/kg for the local variety, 490 RWF/kg for RIB, and 387 RWF/kg for WIB with similar ranking in all treatment groups. Without information (control group), participants were willing to pay a 7% premium for RIB and needed a discount of 11% for WIB. With information, a premium of 13%–17% would be paid for RIB, whereas a discount of 6%–14% was needed for WIB compared with the local variety. Type of information did not affect the premiums for RIB, whereas the frequency of information increased the premium from 23% to 39% for RWF. The premium on WIB, increased significantly by 85% for the frequent negative effects/disadvantages of low iron information	Without nutritional information, participants were willing to pay a 7% premium for RIB, whereas a 11% discount for WIB was needed. RIB can compete well with the local variety, and this can be enhanced with repeated nutritional information
Pérez et al. (2015)⁴²	Guatemala	Consumers: Adults in northwest Guatemala, mean age: 35 y; n = 360	Price game with 1 lb of control and biofortified beans for home testing after exposure to no information, 1-time nutrition information, and repeated nutrition information	WTP for biofortified beans was marginally higher in all information groups, influenced by order of exposure, age of respondent, and education level	The biofortified bean variety is liked in a similar way as the traditional bean
Oparinde et al. (personal communication, 2016)	Rwanda	Consumers: Adult visitors of urban bean market; n = 398	WTP by BDM (individual auctions) of raw and cooked beans of local variety, RIB, and WIB after no information and after nutrition information	Without nutrition information, consumers were willing to pay the same price for RIB as for the local variety and more for the WIB. Information improved the premium for both iron varieties by 13%–15%. Poverty did affect WTP for WIB but not for RIB	RIB could be targeted for the poor, whereas WIB could be targeted for the richer consumers. Nutritional information should be used to promote iron beans
Oparinde et al. (personal communication, 2016)	Rwanda	Consumers: Rural and urban adults, mean: 43 y; n = 578 (rural), n = 231 (urban)	Experimental auction: WTP for control and 2 iron biofortified (IB1 and IB2) beans, after no nutrition information, short nutrition information, short nutrition information + endorsement by village leader, long nutrition information, or long nutrition information with endorsement of village leader (for rural adults); and after no nutrition information or short information (for urban adults)	Overall, WTP was similar for the control and IB1 bean but was higher for IB2 bean. Nutrition information raised the WTP price by 9%–13% more for the IB2 than for the IB1 and was slightly higher in rural areas. Length of nutrition information or endorsement did not influence a premium pay	Biofortified beans were acceptable, and a program to promote these beans can use a short version of nutritional information
Rice
Deodhar and Chern (2008)³²	India	Consumers: Rural and urban adults in Gujarat, mean age: 37 y; n = 602 Students, academics, and businesspersons (via Internet), mean age: 29 y; n = 110	Contingent valuation consumer survey about golden rice (genetically engineered with provitamin A) with WTP based on sequential closed-ended binary choice questions by stated choice method	72% of group 1 and 28% of group 2 were somewhat or extremely willing to consume foods produced with genetically engineered ingredients. The middle-income class was most likely to accept genetically engineered foods, and females were more reluctant. Consumers were willing to pay a premium of 19.5% for golden rice	Most respondents were willing to consume genetically engineered foods, and a substantial premium would be paid for golden rice with enhanced nutritive value
Depositario et al. (2009)²⁹	Philippines	Consumers: University students in Los Banos, mean age: 19 y; n = 100	WTP by uniform-price auction after visual exposure to 500-g bag of regular rice or golden-colored rice (genetically engineered) with no information or with positive, negative, or 2-sided information	Without information, golden rice was bought at a premium of 40% above the normal market price. The marginal effect of information on WTP with no information as a reference was 0.06 for positive information, −0.40 for negative information, and −0.56 for 2-sided information	Golden genetically engineered rice was well accepted. The marginal effect of positive information vs no information on WTP for golden rice is minimal, whereas negative or 2-sided information decreases WTP substantially
De Steur et al. (2010)⁷⁸	China	Consumers: Adult rice consumers in Shanxi Province, > 20 y; n = 944	Willingness to accept, WTP for folate-rich genetically engineered rice	62% of respondents are willing to accept genetically engineered rice, 27% are indifferent, and 11% are reluctant. Respondents were on average willing to pay 34% more for 1 kg of genetically engineered rice than for conventional rice. Males, higher-educated people, and rural consumers were more likely to accept genetically engineered rice	Consumers are in general willing to accept genetically engineered rice and willing to pay a premium. Knowledge, sex, and sociodemographic indicators play a role in acceptance of genetically engineered rice
De Steur et al. (2012)³¹	China	Consumers: Student rice consumers, mean age: 21 y; n = 132 Nonstudent rice consumers, mean age: 39 y; n = 120	Experimental auction with nonrepeated information treatments: bidding value for regular rice, folate-rich genetically engineered rice, and rice supplemented with folic acid	Female rice consumers are prepared to pay 33.7% more for folate-rich rice compared with regular rice. Offering a genetically engineered free folate substitute did not result in significant differences in bidding behavior. Students are less likely to buy and pay more for folate-rich rice. WTP is mainly determined by consumers’ acceptance of genetic engineering and objective knowledge	Despite lower bids after information was provided about genetic engineering, the perceived benefits are high enough to compensate for potential negative reactions to genetically engineered food
De Steur et al. (2013)³⁰	China	Consumers: Female student rice consumers, mean age: 21 y; n = 132 Female nonstudent rice consumers, mean age: 39 y; n = 120	Experimental auction with nonrepeated information treatments: bidding value for folate-rich genetically engineered rice vs conventional rice	Female students and women in general are willing to pay 25.8% and 40% more for folate-rich rice compared with regular rice. Provision of information on the folate benefits increases WTP for folate-rich rice. Information on genetic engineering did not reduce WTP in the nonstudent sample, but students reduced their bid significantly. Negative information has a larger effect on WTP in students, whereas positive information is more effective in nonstudents. Information on high prevalence of folate deficiency increases the bid value in both groups	There is a general positive effect of folate-related information; nonstudents are less concerned about genetic engineering. Conflicting information will lead to primacy bias in nonstudent sample, but students have an alarmist reaction. This highlights a need for segmented, targeted communication strategies on biofortification
De Steur et al. (2014)³³	China	Consumers: Female student and nonstudent rice consumers, mean age: 21 y (students); 40 y (nonstudents); n = 126	Experimental auctions with nonrepeated information rounds: bidding value for folate-rich rice, folate-rich rice genetically engineered, and rice supplemented with folic acid	A general preference for folate biofortification is observed, regardless of whether genetically engineered. Premiums were: 33.9%, 36.5%, and 19%, respectively, for folate-rich rice genetically engineered, nongenetically engineered, and supplemented. Key determinants were the target group, the timing of auction, intention to consume genetically engineered food, and responsibility for rice purchases	Positive reactions to genetically engineered folate-rich rice support its potential as a complementary micronutrient intervention
Pearl millet
Birol et al. (2011)⁸²	India	Producers and consumers: Millet-producing adults, 95% M; n = 360	Choice experiments with attributes: days to maturity, color, added nutritional value, and price of seed of hypothetical HIPM	Respondents could be divided in 3 segments; the 1st scored highest for the nutrition attribute followed by color; the 2nd one were more sellers than consumers and had lower preferences for nutrition and color and higher preferences for the price of the seed; the last segment preferred nutrition and color attributes, but to a lesser degree than those in the 1st segment	HIPM is valued most by large households that produce for themselves and have lower-quality diets. Households producing for market derive lower benefits from consumption characteristics. Farmers should be offered a pool of varieties that provide different attributes to maximize uptake
Birol et al. (2015)⁵⁷	India	Consumers: Rural pearl millet consumers in Maharashtra, mean age: 40 y; n = 452	Experimental auctions: bidding value for LPM and HIPM after no information; simulated video message on the importance of iron and HIPM, with HarvestPlus as the brand (internationally certified); information with a fictional brand name (locally certified at state level)	Even in the absence of information, consumers were willing to pay more for HIPM (13.6 Rs) compared to LPM (12.8 Rs). After nutrition information, WTP for HIPM increases significantly by 12% (2nd information) and 7% (3rd information), whereas WTP for LPM significantly decreased by 9% (2nd information) and 11% (3rd information). Overall, after 2nd information respondents were willing to pay 32.4% more for HIPM, whereas this was 28.6% for after 3rd information	Consumers assign a small but significant premium to HIPM relative to the local variety, even in the absence of nutrition information. International branding and certification results in the highest premium
Cassava
Oparinde et al. (2014)⁵⁵	Nigeria	Consumers: Adults in rural areas, 65% M, > 18 y; n = 671	Incentive-compatible experimental auctions: WTP for (light and deep) yellow cassava relative to white (local) cassava varieties with and without information from national or international delivery institutions	In Imo, consumers are willing to pay the most for the local gari and require a discount of 28% and 25% for light yellow and deep yellow cassava. In Oyo, consumers were willing to pay more for light yellow cassava: they would pay a premium of 6% for light yellow cassava and require a discount of 9% for deep yellow cassava. When information is provided, the discount in Imo for light yellow cassava becomes a premium (19%–20%), In Oyo, the discount for deep yellow cassava becomes a premium (26%–27%). In Oyo, after information, the consumer premium is larger for deep yellow cassava compared with light yellow cassava (20%–25%). Consumers in the southeast are indifferent to the authority delivering the planting material, whereas consumers in the southwest prefer delivery through international authority	Without a nutrition information campaign, biofortified varieties are unlikely to be accepted in the southeast because they are associated with a substantial discount. Nutrition information results in a large and significant price premium for biofortified yellow cassava. The nature of delivery institution has only a small effect in 1 of the states
González et al. (2009)⁵⁸	Brazil	Consumers: Households in northeast Brazil, mean age: 40 y; n = 414	Cross-sectional study: structured questionnaire after explanation about genetically engineered yellow cassava	WTP is 60%–70% higher for genetically engineered yellow cassava than normal cassava	Attitudes toward genetically engineered biofortified yellow cassava are positive

Abbreviations: BDM, Becker deGroot Marchak method; F, female; HIPM, high-iron pearl millet; IB1, high-iron bean 1; IB2, high-iron bean 2; KES, Kenyan shilling; LPM, local pearl millet; M, male; OFSP, orange-fleshed sweet potato; RIB, iron biofortified red bean; Rs, Rupees; RWF, Rwandan Franc; WFSP, white-fleshed sweet potato; WIB, iron biofortified white bean; WTP, willingness to pay.