Reina Engle-Stone

Plasma Retinol-Binding Protein Predicts Plasma Retinol Concentration in Both Infected and Uninfected Cameroonian Women and Children

Variation in the relationship between plasma retinol-binding protein (RBP) and retinol (ROH) has implications for vitamin A (VA) status assessment using RBP. Our objectives were to identify factors affecting the RBP:ROH relationship and to derive and evaluate population-specific RBP cutoffs for VA deficiency (VAD) in Cameroon. Plasma RBP, C-reactive protein (CRP), α1-acid-glycoprotein (AGP), and ROH concentrations were compared in a subsample of women 15-49 y (n = 121) and children 12-59 mo (n = 123) included in a national survey conducted in 2009. Plasma RBP and ROH were highly correlated (r = 0.94 for women; r = 0.96 for children; P < 0.001). Pregnancy and lactation altered the RBP:ROH relationship in women, but obesity, elevated CRP and AGP, age, and VA status did not. Among children, age altered the RBP:ROH relationship, but sex, stunting, VA status, and elevated CRP and AGP did not. Cutoffs for VAD derived using regression analysis were <1.17 μmol RBP/L for women (corresponding to <1.05 μmol ROH/L) and <0.83 μmol RBP/L for children (corresponding to <0.70 μmol ROH/L). The sensitivity and specificity of derived cutoffs were 81.8 and 93.0% for women and 94.7 and 88.9% for children, respectively. The infection-adjusted prevalence of low VA status (<1.17 μmol RBP/L) was 21.9% (95% CI = 18.7-25.0%) among women. Among children, the infection-adjusted prevalence of VAD (<0.83 μmol RBP/L) was 35.0% (95% CI = 31.1-39.0%). In conclusion, VAD remains a public health problem in Cameroon. The RBP:ROH relationship should be considered in surveys using RBP to assess VA status, and use of population-specific cutoffs may be advisable.

Dietary Intervention Strategies to Enhance Zinc Nutrition: Promotion and Support of Breastfeeding for Infants and Young Children:

Breastmilk is the only dietary source of zinc for exclusively breastfed young infants, and it remains a potentially important source of zinc for older infants and young children who continue breastfeeding beyond early infancy. Therefore, we examined available information on breastmilk zinc concentration and total milk consumption to develop estimates of the amount of zinc transferred in breastmilk to children of different ages. Breastmilk zinc concentration declines rapidly during the first few months postpartum and more slowly thereafter. Breastmilk supplies all of the theoretical zinc needs for at least the first several months of life, although the period during which breastmilk alone remains sufficient is uncertain. Breastmilk continues to provide more than half of childrens estimated zinc requirements after the introduction of complementary foods, even into the second year of life. Public health programs to promote and support breastfeeding should be included among the strategies to ensure adequate zinc status of young children.

Plasma Ferritin and Soluble Transferrin Receptor Concentrations and Body Iron Stores Identify Similar Risk Factors for Iron Deficiency but Result in Different Estimates of the National Prevalence of Iron Deficiency and Iron-Deficiency Anemia among Women and Children in Cameroon

Available iron status indicators reflect different aspects of metabolism. We compared the prevalence and distribution of iron deficiency (ID) and iron-deficiency anemia (IDA) among Cameroonian women and children, as measured by plasma ferritin, and soluble transferrin receptor concentrations, body iron stores (BIS), and hemoglobin, and evaluated the impact of adjustments for inflammation on these measures. In a nationally representative survey, we randomly selected 30 clusters in each of 3 zones (north, south, and large cities) and 10 households/ cluster, each with a child aged 12-59 mo and a woman 15-49 y. Ferritin and BIS were mathematically adjusted for inflammation, using plasma C-reactive protein and α(1)-acid glycoprotein both as continuous and categorical variables. Inflammation was present in 48.0% of children and 20.8% of women and anemia was diagnosed in 57.6% of children and 38.8% of women. Depending on the iron status indicator applied, the prevalence of ID ranged from 14.2 to 68.4% among children and 11.5 to 31.8% among women, and the prevalence of IDA ranged from 12.0 to 47.4% among children and 9.0 to 19.4% among women; the proportion of anemia associated with ID ranged from 20.8 to 82.3% among children and 23.2 to 50.0% among women. The different iron indicators generally identified similar groups at greatest risk of deficiency, using both conventional and derived cutoffs: younger children, pregnant women, and women and children in the north and rural areas. Research is needed to clarify the relationships between iron status indicators, particularly in the presence of inflammation, to harmonize global data on prevalence of ID.

Consumption of Potentially Fortifiable Foods by Women and Young Children Varies by Ecological Zone and Socio-Economic Status in Cameroon

In preparation for a proposed large-scale food fortification program in Cameroon, we completed a nationally representative, cross-sectional, cluster survey to assess the consumption patterns of four potentially fortifiable foods (refined vegetable oil, wheat flour, sugar, and bouillon cube) by women and children. Thirty clusters were randomly chosen in each of three ecologic zones (south, north, and large cities) and 10 households (HH) per cluster were selected, each with a child 12-59 mo old and a primary female caregiver 15-49 y old (total 1002 HH). Blood samples were collected and food consumption was assessed by FFQ and 24-h dietary recall. Anemia (39% of women, 58% of children) and deficiencies of iron (15-32%, 21-70%), zinc (77%, 70%), vitamin A (22%, 35%), and vitamin B-12 (28%, 27%) were common, especially in the north and among HH with lower socio-economic status (SES). Oil was consumed by 54% of HH, whereas >75% of HH consumed wheat flour, sugar, and bouillon cube. For most foods, coverage was lower among HH with lower SES. On average, oil, wheat flour, and sugar were consumed once per day and bouillon cube was consumed twice per day. Median intakes of oil, wheat flour, sugar, and bouillon cube (among consumers) were 19.8, 79.4, 30.0, and 1.9 g/d for women and 12.0, 49.4, 19.4, and 0.9 g/d for children, respectively. Food consumption patterns of high risk population subgroups must be considered, along with technical feasibility and cost, for the selection of appropriate vehicles for food fortification.

Stunting Prevalence, Plasma Zinc Concentrations, and Dietary Zinc Intakes in a Nationally Representative Sample Suggest a High Risk of Zinc Deficiency among Women and Young Children in Cameroon

Before initiating a mass zinc fortification program, this study assessed the prevalence of and risk factors for low zinc status among Cameroonian women and children. In a nationally representative survey, we randomly selected 30 clusters in each of 3 strata (North, South, and Yaoundé/Douala) and 10 households per cluster, each with a woman aged 15-49 y and a child aged 12-59 mo (n = 1002 households). Twenty-four-hour dietary recalls (with duplicates in a subset) and anthropometric measurements were conducted, and non-fasting blood was collected to measure plasma zinc concentration (PZC) and markers of inflammation. PZC was adjusted for methodologic factors (time of collection and processing, and presence of inflammation). The prevalence of stunting was 33% (32% South; 46% North; 13% Yaoundé/Douala). Among women, 82% had low adjusted PZC (<50 μg/dL for pregnant women; <66 μg/dL for others; 79% South, 89% North, 76% Yaoundé/Douala). Among children, 83% had low adjusted PZC (<65 μg/dL; 80% South, 92% North, 74% Yaoundé/Douala). Risk factors for low PZC among women and children and for low height-for-age Z-score among children were similar and included residence in the North region and rural areas and households with low socioeconomic status. Using estimated average requirement values from the International Zinc Nutrition Consultative Group (IZiNCG), 29 and 41% of women had inadequate zinc intakes, assuming moderate and low bioavailability, respectively, but only 8% of children had inadequate zinc intake. Depending on the estimated physiologic zinc requirement applied, 17% (IZiNCG) and 92% (Institute of Medicine) of women had inadequate absorbable zinc intakes. Total zinc intakes were greatest in the North region, possibly because of different dietary patterns in this area. Zinc deficiency is a public health problem among women and children in Cameroon, although PZC and dietary zinc yield different estimates of the prevalence of deficiency. Large-scale programs to improve zinc nutrition, including food fortification, are needed.

Regional, Socioeconomic, and Dietary Risk Factors for Vitamin B-12 Deficiency Differ from Those for Folate Deficiency in Cameroonian Women and Children

BACKGROUND Representative data on folate and vitamin B-12 dietary intake and status in low-income countries are rare, despite the widespread adoption of folic acid fortification. OBJECTIVE The purpose of this study was to evaluate folate and vitamin B-12 intake, status, and risk factors for deficiency before implementation of a national fortification program in Cameroon. METHODS A nationally representative cross-sectional cluster survey was conducted in 3 ecologic zones of Cameroon (South, North, and the 2 largest cities, Yaoundé/Douala), and information on dietary intake was collected from 10 households in each of 30 randomly selected clusters per zone. In a subset of women and their 12- to 59-mo-old children (n = 396 pairs), plasma folate and vitamin B-12, as well as breast milk vitamin B-12, were analyzed. RESULTS Vitamin B-12 and folate dietary intake patterns and plasma concentrations were similar for women and children. In the subsample, 18% and 29% of women and 8% and 30% of children were vitamin B-12 (≤ 221 pmol/L) and folate (< 10 nmol/L) deficient, respectively. Mean dietary folate ranged from 351 μg dietary folate equivalents/d in the North to 246 μg dietary folate equivalents/d in Yaoundé/Douala; plasma folate was negatively associated with socioeconomic status (P = 0.001). Plasma vitamin B-12 deficiency was similar in the South and North, 29% and 40%, respectively, but was only 11% in Yaoundé/Douala, and was positively associated with socioeconomic status. Mean breast milk vitamin B-12 was statistically significantly lower in the North (101 pmol/L) than in the South (296 pmol/L) or Yaoundé/Douala (349 pmol/L). CONCLUSIONS Folate intake and status are inadequate among women and young children in Yaoundé/Douala, whereas low vitamin B-12 intake and status are more common in poor and rural areas, especially in the North. Different strategies may be needed to control deficiency of these nutrients in different regions of Cameroon.

Breast Milk Retinol and Plasma Retinol-Binding Protein Concentrations Provide Similar Estimates of Vitamin A Deficiency Prevalence and Identify Similar Risk Groups among Women in Cameroon but Breast Milk Retinol Underestimates the Prevalence of Deficiency among Young Children

Breast milk vitamin A (BMVA) has been proposed as an indicator of population vitamin A status but has rarely been applied in large-scale surveys or compared with conventional vitamin A biomarkers. We assessed the prevalence of, and risk factors for, low BMVA and its relation to vitamin A intake, plasma retinol-binding protein (pRBP), and markers of inflammation in a national survey in Cameroon. We randomly selected 30 clusters in each of 3 strata (South, North, and Cities). Casual milk samples were collected from approximately 5 women per cluster (n = 440). pRBP, plasma C-reactive protein (pCRP), plasma α1-acid glycoprotein (pAGP), and 24-h vitamin A intake were assessed in 10 women aged 15-49 y and 10 children aged 12-59 mo per cluster, including a subset of lactating women (n = 253). Low BMVA was infrequent: 7.2% (95% CI: 4.7, 9.8) of values were <1.05 μmol/L, and 9.3% (95% CI: 5.8, 12.7) were <8 μg/g fat, consistent with the low prevalence of pRBP <0.78 μmol/L among women (< 5%) but lower than the prevalence of pRBP <0.83 μmol/L among children (35%). Risk factors for both low BMVA and pRBP included living in the North and low maternal education. BMVA was positively associated with inflammation-adjusted pRBP among women in the lowest vitamin A intake tertile [<115 μg retinol activity equivalents (RAEs)/d, P < 0.01] but not in the highest tertile (>644 μg RAEs/d, P > 0.4). Controlling for milk fat, BMVA was negatively associated with pCRP (P < 0.02) but not pAGP (P > 0.5). BMVA and pRBP provide similar estimates of vitamin A deficiency prevalence and identify the same risk groups among women in Cameroon, but BMVA underestimates the prevalence of vitamin A deficiency among young children.

Simulations Based on Representative 24-h Recall Data Predict Region-Specific Differences in Adequacy of Vitamin A Intake among Cameroonian Women and Young Children Following Large-Scale Fortification of Vegetable Oil and Other Potential Food Vehicles

BACKGROUND The WHO recommends assessing food and nutrient intakes to design food-fortification programs, but nationally representative dietary data are seldom available in low-income countries. OBJECTIVE Prior to initiation of food fortification in Cameroon, we measured intake of vitamin A (VA) and fortifiable foods (vegetable oil, sugar, wheat flour, and bouillon cube) to simulate the effects of fortification with different foods and VA amounts on prevalence of inadequate and excessive VA intake. METHODS Twenty-four-hour recalls were conducted among 912 women and 883 children (with duplicates in a subset) in a nationally representative cluster survey stratified by region (North, South, Yaoundé/Douala). Usual intake distributions were estimated by the National Cancer Institute method. RESULTS Nationally, 53% of women had a usual intake of <500 μg retinol activity equivalents/d, and 59% of nonbreastfeeding children had an intake of <210 μg retinol activity equivalents/d, although VA intake varied by region. The current fortification program (12 mg/kg VA in oil) would decrease the prevalence of inadequate intakes to 35% among both women and children, without increasing the proportion with retinol intakes >3000 μg/d among women or >600 μg/d among children. However, inadequate VA intake would remain >50% in the North, where VA deficiency was most common. Increasing VA in oil or fortifying a second food (sugar, wheat flour, or bouillon cube) would further decrease the prevalence of inadequate intakes, but, depending on the food vehicle and region, would also increase the prevalence of retinol intakes above the tolerable upper intake level, mainly among children. CONCLUSIONS The current food-fortification program can be expected to improve dietary VA adequacy without increasing the risk of excessive intake among women and children in Cameroon. Modifications to the program must balance the potential to further increase VA intake with the risk of excessive intake among children.

Results of Fortification Rapid Assessment Tool (FRAT) surveys in sub-Saharan Africa and suggestions for future modifications of the survey instrument

Background Food fortification has been increasingly recognized as a promising approach to prevent micronutrient deficiencies. The Fortification Rapid Assessment Tool (FRAT) was developed to assist public health program managers to acquire the information needed to implement an effective mass food fortification program. Multiple countries have conducted FRAT surveys, but information on results and experiences with the FRAT tool has been available only at the national level. Objective To summarize the findings of the FRAT surveys previously conducted in sub-Saharan Africa. Methods Surveys from 12 sub-Saharan African countries (Burkina Faso, Cameroon, Congo, Guinea, Malawi, Mali, Mauritania, Mozambique, Niger, Rwanda, Senegal, Uganda) were identified. Information on consumption patterns for wheat flour, vegetable oil, sugar, and bouillon cubes was reviewed and summarized. Results Most surveys found that a moderate to high proportion of women reported consuming wheat flour (48% to 93%), vegetable oil (44% to 98%), sugar (55% to 99%), and bouillon cubes (79% to 99%) in the past 7 days, although consumption was more common and more frequent in urban areas than in rural areas. Similarly, the reported amounts consumed during the previous 24 hours were generally higher in urban settings. Conclusions The FRAT instrument has been successfully used in multiple countries, and the results obtained have helped in planning national food fortification programs. However, the recommended sampling scheme may need to be reconsidered, and the guidelines should be revised to clarify important aspects of fieldworker training, implementation, data analysis and interpretation, and reporting of the results.

Estimating the Effective Coverage of Programs to Control Vitamin A Deficiency and Its Consequences Among Women and Young Children in Cameroon

Background: To compare the cost-effectiveness of nutrition programs, the anticipated nutritional benefits of each intervention must be expressed using a common metric. Objective: We present the methodology for estimating the benefits of vitamin A (VA)-related interventions among women and children in Cameroon. Methods: We estimated “reach” (proportion of the population that receives a program), “coverage” (proportion that is deficient and receives a program), and “effective coverage” (proportion that “converts” from inadequate to adequate VA intake following an intervention) using dietary data collected during a national survey in 3 macro-regions of Cameroon (North, South, and Yaoundé/Douala). Effective coverage of programs such as (bio)fortification and micronutrient powders was estimated by adding the dietary VA contributed by the intervention to baseline VA intakes, including the contribution of increased maternal VA intake to infant VA intake through increases in breast milk VA. For interventions that provide VA-related benefits through other pathways (eg, periodic high-dose VA supplements and deworming), we developed alternative methods of estimating “daily VA intake equivalents.” Results: Baseline VA intakes and intervention reach varied by geographic macro-region. On average, estimates of program reach were greater than the effective coverage estimates by ∼50%. Effective coverage varied by intervention package and macro-region, ranging from <20 000 (deworming, Yaoundé/Douala) to >400 000 (micronutrient powder or VA supplement, North) children effectively covered per year. Conclusion: These estimates of effective coverage, along with macro-region-specific information on the costs of each intervention package, serve as inputs into an economic optimization model to identify the most cost-effective package of VA interventions for each macro-region of Cameroon.