Promotion of dietary diversification encourages target populations to consume diets that naturally provide sufficient VA. The effectiveness of this approach depends on the availability and accessibility of VA-rich foods, prevailing dietary patterns, socioeconomic status and purchasing power, as well as nutrition knowledge and awareness of the importance of diversified diets [3]. Because animal-source foods are generally scarce in sub-Saharan Africa [17], alternative VA-rich foods include dark green leafy vegetables, carrots, and pumpkins [18]. In Kenya, these crops are not widely consumed, and the main staples, such as maize, Irish potatoes, beans, and sweet potatoes, contain little or no pro-VA carotenoids [19].

The Kenya National Demographic and Health Surveys reported that 77% of children aged 6–35 months consumed VA-rich foods in 2008, and 72% in 2014 (Table 2). The 2022 survey did not separately collect data on VA-rich food consumption. In these two surveys, VA-rich foods included both animal-source and plant-based foods. Given the typical composition of Kenyan household diets, the VA-rich foods consumed by children were likely dominated by plant-based sources. As with VAS coverage, geography, maternal education, and household wealth quantile influenced children’s consumption of VA-rich foods (Table 2) [11, 12].

Children living in urban areas, particularly around the capital city, Nairobi, with well-educated mothers and in the highest wealth quantile consumed more VA-rich foods compared to those in rural or northeastern regions, with mothers lacking education, and in the lowest wealth quantile [11, 12]. Similarly, a study found that maternal education, household wealth, marital status, and media exposure were significant predictors of VA-rich animal-source food consumption among children aged 6–23 months in sub-Saharan Africa [17]. In East Africa, older, more educated, employed, wealthier, literate women with greater media exposure were also more likely to consume VA-rich foods than their counterparts [4]. These women may have better access to VA-rich foods and more resources to obtain and use VA-relevant information. In principle, promoting the consumption of VA-rich foods is an effective and sustainable strategy to reduce VAD. In practice, however, the primary target group, the less educated rural poor in remote areas, often lacks the means to do so. Therefore, these populations need social support, such as food vouchers and nutrition education, to improve access to diversified VA-rich diets in the Kenyan context.

Food fortification refers to the practice of adding micronutrients to commonly consumed staples and condiments during processing to increase their nutritional value [20]. As of October 2024, 143 countries had mandated the fortification of at least one staple food, such as rice, maize flour, wheat flour, oil, sugar, or salt [3, 21]. Because it requires little change in habitual dietary patterns, food fortification is considered a low-cost, high-impact strategy for addressing VAD [22].

For fortification programs to be effective, several conditions must be met. First, there should be appropriate food vehicles, i.e., widely consumed food items to which nutrients can be added [23]. Second, food distribution networks and processing industries must function effectively at scale [3]. Third, the majority of the population must purchase and consume processed foods, and fourth, well-established regulatory systems must be in place. In addition, the fortificant, the chemical form of the added micronutrient, must be safe, stable, sufficient, and effective for target groups [24]. Critics of fortification argue that uneven access to fortified foods, especially among VAD-vulnerable households in remote rural areas, undermines its effectiveness [9]. They also note that efficacy can only be assessed at the point of consumption because sufficient quantities of fortified foods must be consumed and the fortificant must remain adequately active [25].

In Kenya, food fortification began in 1972 with voluntary salt iodization [5]. Building on this success, the Government of Kenya expanded fortification programs over time. In 2005, the Kenya National Food Fortification Alliance (KNFFA) was established to coordinate efforts, bringing together the Ministry of Health, the Kenya Bureau of Standards, research institutions, development partners, industry associations, and consumer organizations [5]. By 2012, legislation mandated the fortification of maize flour, wheat flour, and edible oils. The Food, Drugs and Chemical Substances Act was amended in 2012 and 2015 to align standards and labeling requirements for fortified foods with East African Community regulations [5, 26]. Specifically for VA, the law required fortification of wheat flour, maize flour, and vegetable oil (Table 3). These commodities were selected because of their wide consumption and affordability across all wealth quintiles in Kenya [24].

Compared to wheat flour, maize flour is fortified at a significantly lower rate (Table 3). Maize is Kenya’s most important staple, with annual per-capita consumption estimated at 98–100 kg [19, 27]. Large-scale mills, with daily processing capacities above 50 tons, dominate the maize flour market and account for 76% of total daily production. One study found that 51.4% of surveyed mills implemented mandatory fortification: all large-scale mills fortified 100% of their maize flour, whereas medium-scale mills fortified 45.8% and small-scale mills only 24.1% [27]. Reviews identified the weak engagement of small- and medium-scale mills as a major barrier to effective fortification [20]. Their limited participation is often attributed to financial constraints, lack of equipment, and insufficient technical capacity for quality assurance, all of which hinder consistent compliance with standards [15]. To encourage greater participation, financial incentives such as tax credits may be required.

Fortified maize flour in Kenya also shows high rates of non-compliance with legal standards. Evidence indicates that only one third of fortified maize flour samples met fortification requirements, with substantial regional variation: 29.6% compliance in Nairobi/Central compared with only 3.7% at the Coast [24]. These differences are partly explained by environmental conditions. The Nairobi/Central region is relatively dry, whereas the coastal region is hot and humid. Temperature and humidity affect micronutrient stability, including VA, leading to degradation and loss of VA in fortified foods [24].

Research on VA-fortified wheat flour in Kenya is limited. However, evidence from Nigeria shows that VA stability in wheat flour ranged from 21% to 61% of fortification standards, with compliance rates as low as 6% [25]. Given similar production and regulatory challenges, VA-fortified wheat flour in Kenya is likely to face comparable issues, including poor quality and low population coverage [15].

Furthermore, a study found that 10% of mills in Kenya using the food fortification logo did not actually fortify their products [27]. The logo, introduced in 2006, was intended to be displayed on the packaging of fortified foods [26]. This fraudulent practice may result from limited monitoring and surveillance and weak law enforcement. The Kenya Bureau of Standards and the Food Safety Unit of the Ministry of Health are the principal regulatory bodies; however, one study estimated that they conducted micronutrient analyses at only 37% of mills nationwide [27].

Ambiguities in penalties further contribute to non-compliance. Kenya’s food fortification law does not specify clear penalties for violations; instead, penalties are left to the discretion of local officials [26]. This lack of clarity weakens enforcement, making it inconsistent and ineffective. Overall, available studies highlight major loopholes in Kenya’s food fortification regulations and underscore the need for a comprehensive evaluation of VA fortification programs and related policies.

The success of VA fortification also depends on consumer participation, which requires adequate awareness and nutritional knowledge. However, awareness of food fortification in Kenya remains low; only 28% of surveyed respondents reported being aware of fortification [28]. Awareness was higher among women, older individuals, the more educated, and those in formal employment [28]. Other studies reported similar findings; only 27% of respondents knew how to identify fortified products in the market [26], and 26% were aware of the importance of VA in the diet [29]. Therefore, limited consumer awareness of fortified foods and their health benefits remains a significant barrier to generating sufficient market demand.

The WHO defines biofortification as the process of enhancing the nutritional quality of food crops through agronomic practices, conventional plant breeding, or modern biotechnology [3]. Compared to VAS and food fortification, biofortification is often viewed as a more sustainable approach to addressing VAD, particularly for populations in remote rural areas [30]. The rural poor, who rely heavily on subsistence farming, typically have limited access to VA supplements delivered through health facilities and to VA-fortified foods available in markets [20, 31]. Given the predominance of smallholder subsistence farming in Kenya, the adoption and consumption of VA-biofortified staple crops could play a critical role in improving VA status.

The success of VA-biofortified crops depends on their acceptance by both producers and consumers. Farmers adopt new varieties based on comparative agronomic advantages, while consumers focus on sensory attributes such as taste, color, and texture [18]. If VA-biofortified varieties do not perform as well as conventional crops, adoption is unlikely. Moreover, the efficacy of pro-VA carotenoids can be compromised by post-harvest handling, processing, and cooking. Owing to their highly unsaturated structure, carotenoids are vulnerable to degradation by heat, oxygen, and light [31]. For example, one study found that VA-biofortified cassava retained only 27–56% of VA after drying, whereas drying had minimal effects on VA-biofortified sweet potatoes. The same study reported that processed flours from VA-biofortified maize, cassava, and sweet potato retained as little as 20% of VA after up to four months of storage [31]. These findings indicate that the effectiveness of VA-biofortified crops can vary markedly at the point of consumption.

As of 2025, Kenya has officially released VA-biofortified sweet potato varieties, commonly known as orange-fleshed sweet potatoes (OFSP), while VA-biofortified maize and cassava varieties remain under testing prior to release [32]. The following sections focus on these three VA-biofortified crops most relevant to Kenya.

Sweet potatoes (Ipomoea batatas) are widely cultivated in Kenya for both household consumption and livelihoods, with an estimated annual yield of 0.87 million tons [33]. The crop can be harvested year-round and thrives across diverse agro-ecological zones [34]. Traditionally considered a women’s crop, sweet potatoes are easily integrated into kitchen gardens [30, 35]. However, the dominant varieties grown in Kenya are white- and yellow-fleshed types, which contain low levels of pro-VA carotenoids. These characteristics made sweet potatoes a strategic target for VA-biofortification.

Two released OFSP varieties, Kabode and Vitaa, are rich in pro-VA carotenoids, and a daily intake of 100–125 g can meet the recommended daily VA requirement for children [33-35]. OFSP varieties also possess favorable agronomic traits, including faster maturation, higher yields, and suitability for value addition [18, 30]. Promotion strategies in Kenya have included distributing OFSP vines to households, establishing OFSP school gardens, and integrating OFSP into school feeding programs [30, 35].

In 2010, the Sweet Potato Action for Security and Health in Africa Project was launched in western Kenya as a proof of concept. The project engaged farmers as vine multipliers and extension officers as crop management supporters, while caretakers received vouchers for OFSP vines alongside sensitization campaigns. Findings showed that OFSP production and consumption increased, mothers’ VA status improved, and children’s stunting rates declined [9]. Despite the drastic color shift from white to orange, OFSP was generally well accepted due to its soft texture as well [36].

As a VAD-mitigation measure, the efficacy of OFSP depends on sustained consumption and high replanting rates [30]. Integrated, multi-channel campaigns involving both caretakers and children have been highly effective in promoting OFSP production and consumption [30, 35]. In contrast, single-channel campaigns did not significantly increase the likelihood of caregivers retaining OFSP on their farms after the initial distribution of planting material [30]. Despite promising outcomes, challenges persist. Market brokers who influence traded varieties often hold negative views of OFSP [37]. Some consumers believe that OFSP has contraceptive effects [10]. Additionally, rural households face high transaction costs when vine multipliers are not located nearby [9].

Maize (Zea mays L.) is a primary food source in Kenya, consumed by 85% of the population and contributing roughly 20% of national agricultural production [38]. Smallholder farmers produce more than 80% of maize, but the dominant varieties are white and low in pro-VA carotenoids [38]. This made maize an appropriate target for VA-biofortification, especially for subsistence farmers. VA-biofortified maize has a deep yellow to orange color due to carotenoid accumulation in the endosperm. However, unlike OFSP, this color change is a major barrier to acceptance, as yellow maize in sub-Saharan Africa is often associated with relief food or animal feed and is therefore perceived as “food for the poor.” Overcoming this stigma is essential for improving acceptance of VA-biofortified maize [8].

Adoption is further constrained by farmer and market dynamics. Smallholders are often reluctant to adopt new varieties unless they align with their production priorities. Market prices also shape adoption decisions; if biofortified maize seeds are more expensive, or if the grain sells for less because of its orange color, farmers are unlikely to adopt them [8]. For these reasons, color stigma, reluctance to adopt unfamiliar varieties, and market uncertainty, the uptake of VA-biofortified maize in Kenya may be slow.

Concerns also exist regarding the efficacy of VA-biofortified maize. A study in Zambia found that routine consumption increased children’s beta-carotene concentrations but did not improve VA status as measured by serum retinol. Limited conversion of beta-carotene to VA, likely due to high infection rates among children, was a probable explanation [39]. This issue may be relevant to Kenyan children, many of whom face infectious morbidities. Additionally, the instability of carotenoids means that storage conditions directly affect the efficacy of VA-biofortified maize [8].

Cassava (Manihot esculenta Crantz) is a starchy staple widely grown and consumed in Kenya. It serves as a food reserve when other crops fail, as it is well adapted to arid areas and nutrient-poor soils. The predominant varieties in Kenya have white roots with minimal pro-VA carotenoid content [40]. Similar to OFSP and VA-biofortified maize, VA-biofortification changes cassava root color from white to deep yellow due to increased beta-carotene. Some evidence suggests that higher pro-VA carotenoid levels may also affect cassava’s taste because carotenoid accumulation is associated with lower dry matter content. However, unlike maize, the color change does not appear to hinder acceptance. In eastern Kenya, VA-biofortified cassava was perceived as favorable in both color and taste, with children preferring yellow over white varieties. Carotenoids may also reduce post-harvest physiological deterioration, potentially allowing longer storage of VA-biofortified cassava compared with white cassava [41]. A study in Nigeria similarly reported greater acceptance of VA-biofortified cassava products than white cassava, with the yellow color not perceived as a barrier [42].

Regarding efficacy, a study in Kenya found that daily consumption of boiled yellow cassava modestly increased serum retinol concentrations while substantially increasing beta-carotene levels. The modest rise in serum retinol, despite large increases in beta-carotene, suggests poor conversion of beta-carotene into active VA [40]. Another study in eastern Kenya showed that incorporating VA-biofortified cassava into school lunch programs improved dietary VA adequacy compared with lunches without cassava [43]. VA retention in VA-biofortified cassava varies by processing method; boiled cassava retained more than 90% of pro-VA carotenoids, whereas other preparation methods retained only 1–18% [44]. Beta-carotene retention ranged from 10–29.3% depending on storage duration and processing techniques [31]. As with other VA-biofortified crops, predictors of consumption include knowledge and awareness of pro-VA cassava, recognition of its health benefits, and recommendations from healthcare workers [41].