Use of Theoretical Subjects to Develop a Method for Assessing Equivalence of Dietary Vitamin A in a Mixed Diet.

BACKGROUND: Although the vitamin A (VA) equivalency of provitamin A carotenoids from single foods or capsules has been studied using several approaches, there is currently no reliable method to determine VA equivalency for mixed diets. OBJECTIVES: To reach the objective of identifying a method to determine the VA equivalency of provitamin A carotenoids in mixed diets, we tested a new approach using preformed VA as proxy for provitamin A. METHODS: We studied 6 theoretical subjects who were assigned physiologically plausible values for dietary VA intake, retinol kinetic parameters, plasma retinol pool size, and VA total body stores. Using features in the Simulation, Analysis and Modeling software, we specified that subjects ingested a tracer dose of stable isotope-labeled VA on day 0 followed by 0-µg supplemental VA or 200, 400, 800, 1200, 1600, and 2000 µg VA daily from day 14 to day 28; we assigned VA absorption to be 75%. For each supplement level, we simulated plasma retinol specific activity (SAp) over time and calculated the mean decrease in SAp relative to 0 µg. Group mean data were fitted to a regression equation to calculate predicted VA equivalency at each supplement level on day 28. RESULTS: For each subject, higher VA supplement loads resulted in lower SAp, with the magnitude of the decrease differing among subjects. The mean predicted amount of absorbed VA was within 25% of individual subjects' assigned amount for 4 of the 6 subjects, and the mean ratio of predicted to assigned amount of absorbed VA over all supplement loads ranged from 0.60 to 1.50, with an overall mean ratio of 1.0. CONCLUSIONS: Results for preformed VA suggest that this protocol may be useful for determining VA equivalency of provitamin A carotenoids in free-living subjects if mixed diets with known provitamin A content were substituted for the VA supplements.

Carotenoid and Tocopherol Profiling in 18 Korean Traditional Green Leafy Vegetables by LC-SIM-MS.

Fruits and vegetables are a vital source of redox-active phytochemicals in the diet. Traditional green leafy vegetables (GLVs) are a rich source of carotenoids, dietary fiber, minerals, phenols, vitamins, and tocopherols and are commonly consumed in rural areas worldwide. In traditional Korean medicine, many GLVs are used to treat various ailments. However, data on the carotenoid and tocopherol content of many traditional GLVs consumed in the Republic of Korea are insufficient. The current work aims to compare the carotenoid and tocopherol profiles of 18 traditional GLVs by utilizing a single ion monitoring LC-MS approach to identify the potential GLVs for commercial cultivation and healthy diet formulations. Among the traditional GLVs investigated, (all-E)-lutein was the most abundant carotenoid, ranging from 44.4% in Glehnia littoralis to 52.1% in Heracleum moellendorffii. It was followed by (all-E)-violaxanthin and (all-E)-ß-carotene. The highest contents of (all-E)-violaxanthin (75.6 µg/g FW), 9-Z-neoxanthin (48.4 µg/g FW), (all-E)-luteoxanthin (10.8 µg/g FW), (all-E)-lutein (174.1 µg/g FW), total xanthophylls (310.5 µg/g FW), (all-E)-ß-carotene (69.6 µg/g FW), and total carotenoids (380.1 µg/g FW) were recorded in Pimpinella brachycarpa. Surprisingly, Taraxacum mongolicum also showed the highest contents of (all-E)-violaxanthin, (all-E)-lutein, and total carotenoids, which were statistically non-significant (p > 0.05, Tukey HSD) with P. brachycarpa. The highest concentration of (all-E)-zeaxanthin (14.4 µg/g FW) was recorded in Solidago virga-aurea. Among the studied herbs, 13.9 (H. moellendorffii)-133.6 µg/g FW (Toona sinensis) of α-tocopherol was recorded. Overall, the results suggest that P. brachycarpa and T. mongolicum are rich sources of carotenoids. On the other hand, T. sinensis is a rich source of α-tocopherol. These GLVs can be utilized in the diet to enhance the intake of health-beneficial carotenoids and α-tocopherol.

Rice callus as a high-throughput platform for synthetic biology and metabolic engineering of carotenoids.

Carotenoids are a large class of important lipid-soluble phytonutrients that are widely used as nutritional supplements due to their health-promoting activities. For example, ß-carotene is the precursor for vitamin A synthesis, and astaxanthin is a powerful antioxidant. However, these carotenoids cannot be synthesized de novo by humans. These properties of ß-carotene and astaxanthin make them attractive targets for metabolic engineering in rice (Oryza sativa) endosperm because rice is an important staple food in developing countries, and rice endosperm is devoid of carotenoids. In this chapter, we introduce an assay based on rice embryogenic callus for the rapid functional characterization of genes involved in carotenoid biosynthesis and accumulation. The system is also an ideal platform to characterize cereal endosperm specific promoters. Four diverse cereal endosperm specific promoters were demonstrated to be active in rice callus despite their restricted activity in mature plants. The use of endosperm specific promoters that are expressed in rice callus, but remain silent in regenerated vegetative tissue, directs accumulation of carotenoids in the endosperm without interfering with plant growth. Rice callus is a useful platform for improving gene editing methods and for further optimizing pathway engineering. Thus, the rice callus platform provides a unique opportunity to test strategies for metabolic engineering of synthetic carotenoid pathways, leading to novel carotenoid-biofortified crops.

Clinical Factors Affecting the Serum Retention of a Teratogenic Etretinate after the Acitretin Administration.

Etretinate, an acitretin metabolite, has a long retention duration in adipose tissues with a teratogenic potential. FDA advises a contraceptive period of at least three years after discontinuing acitretin. However, the effect of accumulated etretinate in adipose tissues on fetus is unknown. Although the teratogenic threshold for serum concentration of etretinate has been presented as higher than 2 ng/mL, that of acitretin is unknown. To examine factors affecting body retention of acitretin and etretinate, effects of acitretin dosage, acitretin-taking duration, elapsed time after stopping acitretin, age, sex, concomitant alcohol consumption, and foods and supplements rich in vitamin A intake on serum concentrations of acitretin and etretinate were analyzed in 14 acitretin-taken patients and 58 controls without taking acitretin or etretinate. Serum concentrations of acitretin, but not etretinate, tended to be inversely related to the discontinuation duration. They were also related to old age. Different from a published result that alcohol consumption could promote the metabolism of acitretin into etretinate, alcohol intake did not affect serum concentrations of etretinate. Unexpectedly, more frequent intake of vitamin A or provitamin A-rich food and supplements was associated with higher serum acitretin, whereas less frequent intake of vitamin A or provitamin A-rich food and supplements was associated with higher serum levels of etretinate in acitretin-taken patients. Despite preliminary data, inter-individual variations in serum retention of etretinate suggest the necessity of further research before applying the same guidelines to everyone to minimize unnecessary contraception.

Natural diversity in the carotene, tocochromanol and fatty acid composition of crude palm oil.

Crude palm oil (CPO) is extracted from the mesocarp of oil palm (Elaeis guineensis) fruits. CPO is widely consumed in many African countries. Due to its high provitamin A carotenoid content, it is also widely used in programmes designed to prevent vitamin A deficiency. Elaeis guineensis occurs naturally across a wide geographical range in Africa. We investigated the carotene, tocochromanol (vitamin E) and fatty acid composition of a large set of genotypes representative of this genetic and geographic diversity. We found considerable intraspecific diversity in most lipid traits. Populations from Côte d'Ivoire were distinguished from other origins by their very low palmitate content and high tocochromanol content. Genotypes from Benin, Côte d'Ivoire and Nigeria were characterized by high carotene contents. Finally, hybrids of crosses between genotypes from Côte d'Ivoire and Nigeria produce CPO with exceptionally high provitamin A and vitamin E contents together with low palmitate content.

Multinutrient Biofortification of Maize (Zea mays L.) in Africa: Current Status, Opportunities and Limitations.

Macro and micronutrient deficiencies pose serious health challenges globally, with the largest impact in developing regions such as subSaharan Africa (SSA), Latin America and South Asia. Maize is a good source of calories but contains low concentrations of essential nutrients. Major limiting nutrients in maize-based diets are essential amino acids such as lysine and tryptophan, and micronutrients such as vitamin A, zinc (Zn) and iron (Fe). Responding to these challenges, separate maize biofortification programs have been designed worldwide, resulting in several cultivars with high levels of provitamin A, lysine, tryptophan, Zn and Fe being commercialized. This strategy of developing single-nutrient biofortified cultivars does not address the nutrient deficiency challenges in SSA in an integrated manner. Hence, development of maize with multinutritional attributes can be a sustainable and cost-effective strategy for addressing the problem of nutrient deficiencies in SSA. This review provides a synopsis of the health challenges associated with Zn, provitamin A and tryptophan deficiencies and link these to vulnerable societies; a synthesis of past and present intervention measures for addressing nutrient deficiencies in SSA; and a discussion on the possibility of developing maize with multinutritional quality attributes, but also with adaptation to stress conditions in SSA.

Development of multinutrient-rich biofortified sweet corn hybrids through genomics-assisted selection of shrunken2, opaque2, lcyE and crtRB1 genes.

Sweet corn has gained worldwide popularity. Traditional sweet corn possesses low concentration of essential nutrients such as lysine (0.15-0.25%), tryptophan (0.03-0.04%) and provitamin-A (proA 3-4 ppm), and deficiency leads to serious health problems in humans. Here, stacking of shrunken2 (sh2), opaque2 (o2), lycopene epsilon cyclase (lcyE) and ß-carotene hydroxylase (crtRB1) genes  were undertaken in the parents of four hybrids viz., APQH1, APHQ4, APHQ5 and APHQ7 using marker-assisted backcross breeding (MABB). Gene-linked markers (umc2276 and umc1320) for sh2, while gene-based markers for o2 (umc1066 and phi057), lcyE (5'TE-InDel) and crtRB1 (3'TE-InDel), were used for genotyping in BC1F1, BC2F1 and BC2F2. Selected backcross progenies showed high recovery of recurrent parent genome (92.4-97.7%). The reconstituted sweet corn hybrids possessed significantly high lysine (0.390%), tryptophan (0.082%) and proA (21.14 ppm), coupled with high kernel sweetness (brix 18.96%). The improved sweet corn hybrids had high cob yield (12.22-15.33 t/ha) across three environments. These newly developed biofortified sweet corn hybrids possess great significance in providing balanced nutrition. This is the first report of combining sh2, o2, lcyE and crtRB1 genes for enrichment of sweet corn hybrids with multiple essential nutrients.

Child acceptability of a novel provitamin A carotenoid, iron and zinc-rich complementary food blend prepared from pumpkin and common bean in Uganda: a randomised control trial.

BACKGROUND: Ugandan children are fed homemade complementary foods (CFs) which are usually deficient in vitamin A, iron and zinc. Novel homemade CFs rich in vitamin A, iron and zinc need to be developed, and assessed for their acceptability among target children. OBJECTIVE: Homemade provitamin A carotenoids (PVACs), iron and zinc-rich complementary food (CF), common bean pumpkin blend (BPB) formulated from pumpkin (Sweet cream) and common bean (Obwelu) and PVAC-rich pumpkin blend (PB) from Sweet cream were prepared by expert peer mothers. This study compared child acceptability of BPB and PB (control). METHODS: The crossover acceptability study randomly assigned Ugandan children 6 to 24 months old to either receive 100 g of BPB (n = 35) or 100 g of PB (n = 35) on day one. After a washout period of one day, children crossed over to receive either BPB (n = 35) or PB (n = 35). The amount of CF consumed, duration of consumption, and micronutrient intake were assessed. The CF was acceptable if children consumed ≥50 g (50%) of served food (100 g). A paired t-test was used to determine the mean differences within participants between BPB and PB. The level of statistical significant difference was set at a probability value of 5% (p = 0.05). RESULTS: The mean consumption of BPB and PB was 53.9 g and 54.4 g, respectively. The mean duration for consumption of BPB and PB was 20.6 and 20.3 min, respectively. There was no significant difference in the amounts consumed, and duration of consumption in BPB and PB (p > 0.05). The mean intake of vitamin A was significantly higher (p < 0.00001) in PB (152.5 µgRAE) compared to BPB (100.9 µgRAE). The mean iron intake was significantly higher in BPB (1.1 mg) (p < 0.00001) compared to PB (0.3 mg). Furthermore, zinc intake was significantly higher (p < 0.00001) in BPB (0.58 mg) compared to PB (0.13 mg). CONCLUSION: A homemade complementary food, BPB, made from locally available common bean and pumpkin is rich in PVACs, iron and zinc and is acceptable to children in the age range of complementary feeding in Uganda. TRIAL REGISTRATION: Pan African Clinical Trials Registry www.pactr.org as PACTR202002576768667 . Retrospectively registered. Date of registration: 29/January/2020.

The effect of ß-cyclocitral treatment on the carotenoid content of transgenic Marsh grapefruit (Citrus paradisi Macf.) suspension-cultured cells.

This work reports the development of suspension culture system of transgenic Marsh grapefruit (Citrus paradisi Macf., Rutaceae) callus overexpressing bacterial phytoene synthase; and the use of this suspension culture to investigate the effects of ß-cyclocitral on carotenoid content and composition. At a ß-cyclocitral concentration of 0.5 mM and after ten days cultivation, analysis of the carotenoids showed a significant increase in the content of ß-, α-carotene, and phytoene predominantly. The maximal increase in total provitamin A carotenoids content following ß-cyclocitral application was ~2-fold higher than the control, reaching 245.8 µg/g DW. The trend for increased transcript levels of biosynthetic genes PSY and ZDS correlated with the enhancement of the content of these carotenes following ß-cyclocitral treatment and GC-MS based metabolite profiling showed significant changes of metabolite levels across intermediary metabolism. These findings suggest that ß-cyclocitral can act as a chemical elicitor, to enhance the formation of carotenes in citrus suspension-cultured cells (SCC), which could be utilized in studying the regulation of carotenoid biosynthesis and biotechnological application to the renewable production of nutritional carotenoids.

Caregiver Perceptions and Acceptability of a Provitamin A Carotenoid, Iron and Zinc Rich Complementary Food Blend Prepared from Common Bean and Pumpkin in Rural Uganda.

Ugandan children are vulnerable to vitamin A deficiency (VAD), iron deficiency (ID) and zinc deficiency (ZnD) because they are fed on complementary foods (CFs) low in vitamin A, iron and zinc. This study developed a novel provitamin A carotenoid (PVAC), iron and zinc rich common bean pumpkin blend (BPB) complementary food (CF) from locally available pumpkin and common bean in Uganda and aimed to determine its acceptance, compared to a control pumpkin blend (PB). Seventy caregivers participated in the study. The sensory attributes (taste, colour, aroma, texture and general acceptability) of BPB and PB were rated using a five-point facial hedonic scale (1 = very bad, 2 = bad, 3 = neutral, 4 = good, 5 = very good). Focus group discussions (FGDs) were conducted to assess the perceptions of caregivers about the BPB. The chi square test was used to detect the proportion difference for each sensory attribute between BPB and PB, whilst FGD data were analysed by thematic analysis. A proportion of 64% to 96% of the caregivers rated both BPB and PB as acceptable (good to very good) for all the sensory attributes. There was no significant difference in caregiver acceptability for all attributes between BPB and PB (p > 0.05). Caregivers had positive perceptions about the taste, texture, aroma and colour of the BPB. Caregivers were keen to know the specific varieties of common bean and pumpkin used to formulate the PVAC, iron and zinc rich BPB. In conclusion, BPB was acceptable to caregivers, and they were interested to know how to prepare and use it as a CF.

Intervention Studies in Humans.

Intervention studies in humans provide the highest level of evidence in the assessment of the effect of nutrients or bioactive food components on human health /disease. There are different intervention study designs, and their selection depends on the objectives of the study. Here we present the main designs and the factors that should be considered when selecting and developing them.

Nutritional Properties and Consumer's Acceptance of Provitamin A-Biofortified Amahewu Combined with Bambara (Vigna Subterranea) Flour.

Amahewu is a fermented non-alcoholic cereal grain beverage, popular in Southern Africa. This study evaluates the possibility of producing an acceptable provitamin A (PVA)-biofortified maize amahewu, complemented with bambara flour, to contribute towards the alleviation of protein energy malnutrition (PEM) and vitamin A deficiency (VAD). Germinated, roasted, and raw bambara flours, were added at 30% (w/w) substitution level, separately, to either white maize or PVA-biofortified maize flour, and processed into amahewu. Wheat bran (5% w/w) was used as reference inoculum. Amahewu samples were analyzed for nutritional properties and acceptability. The protein and lysine contents of amahewu almost doubled with the inclusion of germinated bambara. Protein digestibility of amahewu samples increased by almost 45% with the inclusion of bambara. PVA-biofortified maize amahewu samples complemented with bambara were extremely liked for their color, aroma, and taste when compared with their white maize counterparts. The principal component analysis explained 96% of the variation and PVA-biofortified maize amahewu samples were differentiated from white maize amahewu samples. The taste of amahewu resulting from roasting and germination of bambara was preferred in PVA-biofortified maize amahewu, compared to white maize amahewu. We conclude that PVA-biofortified maize amahewu, complemented with germinated bambara, has the potential to contribute towards the alleviation of PEM and VAD.

Consumer Perceptions and Acceptability of Traditional Dishes Prepared with Provitamin A-Biofortified Maize and Sweet Potato.

Vitamin A deficiency (VAD) is prevalent in South Africa, particularly among predominantly poor rural communities. Provitamin A (PVA)-biofortified crops could be used to address VAD; however, there are challenges of poor consumer acceptability. This study investigated the effect of replacing white maize and cream-fleshed sweet potato (CFSP) with PVA-biofortified maize and orange-fleshed sweet potato (OFSP), respectively, on consumer acceptability and perceptions of traditional dishes of rural communities in South Africa. Consumer acceptability of PVA-biofortified phutu (a crumbly maize porridge) served with either curried cabbage, chicken or bambara groundnut, separately, and boiled OFSP was evaluated by black South African adults (n = 120) using a five-point facial hedonic scale. Focus group discussions (FGDs) were conducted with 56 subjects recruited from the consumer panel to assess consumer perceptions of the food samples. The majority of the participants rated the composite dishes containing PVA-biofortified phutu as "4 = good" and the acceptability of the composite dishes varied significantly (p < 0.05). Compared to other age groups, the 50-59-year age group showed higher preference for white phutu and chicken curry, whereas the 30-39-year age group showed higher preference for PVA-biofortified phutu and chicken curry. The acceptability of OFSP and CFSP was similar. The study participants showed positive perceptions of the OFSP, as well as PVA-biofortified phutu if served with either curried chicken or cabbage. The findings suggest that PVA-biofortified maize and OFSP can replace white maize and CFSP, respectively, in selected traditional dishes of the rural communities studied to alleviate VAD.

Improving the Dietary Vitamin A Content of Rural Communities in South Africa by Replacing Non-Biofortified white Maize and Sweet Potato with Biofortified Maize and Sweet Potato in Traditional Dishes.

Biofortification of staple crops has a potential for addressing micronutrient deficiencies, such as vitamin A deficiency (VAD), which are prevalent in South Africa. The poor acceptability of provitamin A (PVA)-biofortified foods could be improved by combining them with other food items to produce modified traditional dishes. The nutritional composition of the dishes could also be improved by the modification. The study aimed to investigate the effect of replacing white maize and cream-fleshed sweet potato (CFSP)] with PVA-biofortified maize and orange-fleshed sweet potato (OFSP) on the nutritional composition of South African traditional dishes. The protein, fibre, total mineral (ash), lysine, and iron concentrations of the PVA maize phutu (traditional porridge) composite dishes (control), were not significantly different (P > 0.05) from those of white maize phutu composite dishes. However, the PVA concentration of PVA maize phutu composite dishes was higher than that of the white phutu composite dishes (P > 0.05). The OFSP had a significantly lower protein concentration, but a significantly higher (P > 0.05) fibre, ash, lysine, isoleucine, leucine, and PVA concentration, relative to the CFSP. The findings indicate that composite dishes in which white maize is replaced with PVA-biofortified maize, and switching over from CFSP to OFSP, would contribute to combating VAD in South Africa, and in other developing counties.

Carrot Leaves Maintain Liver Vitamin A Concentrations in Male Mongolian Gerbils Regardless of the Ratio of α- to ß-Carotene When ß-Carotene Equivalents Are Equalized.

BACKGROUND: Carrots are an important horticultural crop that contain provitamin A carotenoids (PACs). Orange carrots have high concentrations of α-carotene, which upon central cleavage yields 1 retinal and 1 α-retinal molecule. The leaves of carrot plants are a source of PACs when consumed. OBJECTIVE: Male Mongolian gerbils aged 27-30 d were used to assess the bioefficacy of carrot leaves to maintain vitamin A (VA) status and investigate whether the ratio of α- to ß-carotene (α:ß-carotene) affected bioefficacy. METHODS: After 3 wk depletion, baseline gerbils were killed (n = 6) and the remaining gerbils (n = 60) were divided into 6 groups to receive 4 VA-deficient, carrot leaf-fortified feeds (1:1.4, 1:2.5, 1:5.0, and 1:80 α:ß-carotene ratio) equalized to 4.8 nmol/g ß-carotene equivalents (ßCEs), or VA-deficient feed with (VA+) or without (VA-) retinyl acetate supplements. Carrot-leaf powder from 4 carrot plants with differing α:ß-carotene ratios was used. After 4 wk, gerbils were killed and tissues were collected and analyzed for retinoids by HPLC. RESULTS: VA+ had higher total liver VA (means ± SD 0.91 ± 0.29 µmol) than all other groups (range: 0.40-0.62) (P ≤ 0.03), and the carrot leaf treatments did not differ from baseline (0.55 ± 0.09 µmol). VA- (0.40 ± 0.23 µmol VA/liver) did not differ from the leaf-fed groups, but 30% became VA deficient (defined as <0.1 µmol VA/g liver). α-Retinol accumulated in livers and lungs and was correlated to total α-carotene consumption (R2 = 0.83 and 0.88, respectively; P < 0.0001). Bioefficacy factors ranged from 4.2 to 6.2 µg ßCE to 1 µg retinol. CONCLUSIONS: Carrot leaves maintain VA status and prevent deficiency in gerbils regardless of the α:ß-carotene ratio. The bioconversion of PACs from carrot leaves to retinol is similar to what has been reported for other green leafy vegetables, making the consumption of carrot leaves a viable method to improve dietary PAC intake.

The development and release of maize fortified with provitamin A carotenoids in developing countries.

Micronutrient deficiencies have been identified as major public health problems affecting a large part of the world's population. Biofortification of staple crops like maize has been proposed as one of the most cost effective and feasible approaches to combat micronutrient deficiencies. Studies have shown that provitamin A from biofortified crops is highly bioavailable and has the capacity to improve vitamin A status of vulnerable groups. Most people in sub-Saharan Africa subsist on maize and many people may benefit from consumption of provitamin A carotenoid biofortified maize, especially women and children. With the exception of transgenic golden rice, biofortified crops have received considerable acceptance by most communities. Negative perceptions associated with yellow maize do not affect orange maize, which is, for example, well-liked in rural Zambia. With proper policy frameworks and full commercialization, provitamin A maize can address the problem of vitamin A deficiencies among poor nations with maize-based diets.

Molecular Breeding for Nutritionally Enriched Maize: Status and Prospects.

Maize is a major source of food security and economic development in sub-Saharan Africa (SSA), Latin America, and the Caribbean, and is among the top three cereal crops in Asia. Yet, maize is deficient in certain essential amino acids, vitamins, and minerals. Biofortified maize cultivars enriched with essential minerals and vitamins could be particularly impactful in rural areas with limited access to diversified diet, dietary supplements, and fortified foods. Significant progress has been made in developing, testing, and deploying maize cultivars biofortified with quality protein maize (QPM), provitamin A, and kernel zinc. In this review, we outline the status and prospects of developing nutritionally enriched maize by successfully harnessing conventional and molecular marker-assisted breeding, highlighting the need for intensification of efforts to create greater impacts on malnutrition in maize-consuming populations, especially in the low- and middle-income countries. Molecular marker-assisted selection methods are particularly useful for improving nutritional traits since conventional breeding methods are relatively constrained by the cost and throughput of nutritional trait phenotyping.

Carotenoid and Tocochromanol Profiles during Kernel Development Make Consumption of Biofortified "Fresh" Maize an Option to Improve Micronutrient Nutrition.

Biofortification is a strategy to reduce micronutrient malnutrition. The aim of this study was to investigate whether consumption of biofortified fresh maize can supply nutritionally meaningful amounts of provitamin A carotenoids (PVA), zinc, lysine, and tryptophan. The accumulation patterns for PVA and tocochromanol compounds in developing grain of 23 PVA hybrids was studied, and nutritionally meaningful amounts of those compounds were found in grain by milk stage, when fresh maize is eaten. The highest PVA and tocochromanol accumulation occurred by physiological maturity. The percent apparent retention in boiled fresh maize was 92%, 117%, 99%, and 66% for PVA, zinc, lysine, and tryptophan, respectively. Consumption of 0.5 to 2 ears of fresh maize daily could supply 33-62.2%, 11-24% and more than 85% of the estimated average requirement of PVA, tryptophan, and zinc, respectively. The results indicate that eating biofortified fresh maize can contribute to improved micronutrient nutrition.

The Potential of Integrating Provitamin A-Biofortified Maize in Smallholder Farming Systems to Reduce Malnourishment in South Africa.

Biofortification interventions have the potential to combat malnutrition. This review explored the use of provitamin A-biofortified maize (PVABM) as a vitamin A deficiency (VAD) reduction agricultural-based strategy. Maize has been identified as one of the key staple crops for biofortification to reduce hidden hunger in Africa. Most nutrition interventions have not been successful in reducing hunger because rural communities, who mainly rely on agriculture, have been indirectly excluded. The biofortification intervention proposed here aims to be an inclusive strategy, based on smallholder farming systems. Vitamin A is a micronutrient essential for growth, immune function, reproduction and vision, and its deficiency results in VAD. VAD is estimated to affect more than 250 million children in developing countries. In Africa, especially sub-Saharan Africa, maize is a staple food for rural communities, consumed by most household members. Due to carotenoids, PVABM presents an orange color. This color has been reported to lead to negative perceptions about PVABM varieties. The perceived agronomic traits of this maize by smallholder farmers have not been explored. Adoption and utilization of PVABM varieties relies on both acceptable consumer attributes and agronomic traits, including nutritional value. It is therefore important to assess farmers' perceptions of and willingness to adopt the varieties, and the potential markets for PVABM maize. It is essential to establish on-farm trials and experiments to evaluate the response of PVABM under different climatic conditions, fertilizer levels and soils, and its overall agronomic potential. For the better integration of PVABM with smallholder farming systems, farmer training and workshops about PVABM should be part of any intervention. A holistic approach would enhance farmers' knowledge about PVABM varieties and that their benefits out-compete other existing maize varieties.

Provitamin A biofortification of cassava enhances shelf life but reduces dry matter content of storage roots due to altered carbon partitioning into starch.

Storage roots of cassava (Manihot esculenta Crantz), a major subsistence crop of sub-Saharan Africa, are calorie rich but deficient in essential micronutrients, including provitamin A ß-carotene. In this study, ß-carotene concentrations in cassava storage roots were enhanced by co-expression of transgenes for deoxy-d-xylulose-5-phosphate synthase (DXS) and bacterial phytoene synthase (crtB), mediated by the patatin-type 1 promoter. Storage roots harvested from field-grown plants accumulated carotenoids to ≤50 µg/g DW, 15- to 20-fold increases relative to roots from nontransgenic plants. Approximately 85%-90% of these carotenoids accumulated as all-trans-ß-carotene, the most nutritionally efficacious carotenoid. ß-Carotene-accumulating storage roots displayed delayed onset of postharvest physiological deterioration, a major constraint limiting utilization of cassava products. Large metabolite changes were detected in ß-carotene-enhanced storage roots. Most significantly, an inverse correlation was observed between ß-carotene and dry matter content, with reductions of 50%-60% of dry matter content in the highest carotenoid-accumulating storage roots of different cultivars. Further analysis confirmed a concomitant reduction in starch content and increased levels of total fatty acids, triacylglycerols, soluble sugars and abscisic acid. Potato engineered to co-express DXS and crtB displayed a similar correlation between ß-carotene accumulation, reduced dry matter and starch content and elevated oil and soluble sugars in tubers. Transcriptome analyses revealed a reduced expression of genes involved in starch biosynthesis including ADP-glucose pyrophosphorylase genes in transgenic, carotene-accumulating cassava roots relative to nontransgenic roots. These findings highlight unintended metabolic consequences of provitamin A biofortification of starch-rich organs and point to strategies for redirecting metabolic flux to restore starch production.