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3 University of Hawaii, Honolulu, HI 96813; 4 University of California, Los Angeles, CA 90095; 5 Wageningen University, Wageningen, The Netherlands; and 6 University of Nairobi, Nairobi, Kenya
* To whom correspondence should be addressed. E-mail: suzanne{at}crch.hawaii.edu.
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ABSTRACT |
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 TOP ABSTRACT LITERATURE CITED |
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The Child Nutrition Program (CNP)7 was a feeding study for school-age children conducted in 1998–2001 in Embu District, Kenya. The goal was to test the effect of school-based snacks on a variety of health outcomes, including school performance, growth, and nutritional status (1). The CNP was a randomized, controlled feeding trial that enrolled 
900 children (in 2 cohorts) from 12 schools. The children were 7 to 9 y of age. All protocols were approved by the Human Subjects Protection Committees at the University of California, Los Angeles, CA, and the University of Nairobi, School of Medicine, Kenya.
Designing snacks for the CNP
The school snacks were designed to address micronutrient deficiencies that had been previously identified by the Nutrition Collaborative Research Support Program (NCRSP), conducted from 1983 to 1986 in the same district of Kenya (2,3). A variety of micronutrients are likely to be low in the diets of children in this mildly to moderately malnourished region of Kenya, particularly iron, zinc, vitamin B-12, riboflavin, calcium, and vitamin A. Negative health outcomes are known to occur if intake of these nutrients is below requirements (4). The children's diets contained few animal products, and both macronutrients and micronutrients may be present at suboptimal levels in primarily vegetarian diets (5,6). Protein intake appeared to be adequate for almost all children, even after adjustment for protein quality, although intake of several micronutrients was clearly low (7).
Findings from the NCRSP also indicated that intake of animal-source foods (ASF) was associated with a higher-quality diet (3). ASF are the only source of vitamin B-12, which is lacking in plant-based diets that do not contain fortified foods. Meat can provide highly available iron, zinc, and vitamin A (4). Dairy products are a major source of calcium in children's diets and also are a good source of riboflavin. Thus, snacks for the CNP were designed to improve intakes of nutrients with a high prevalence of inadequacy and to focus on the potential positive effects of animal products in the diets of school-age children.
Through an iterative process, appropriate snacks were designed to be used in a school feeding trial (8,9) using locally available foods that were good sources of the targeted nutrients. Three equicaloric snacks were developed: a vegetarian snack designated the "energy snack," a snack that included beef, and a snack that included whole milk. Githeri (a stew of maize, beans, and vegetables) is a common food in Embu, and all snacks were designed to include this local staple. Table 1 shows the ingredients that were used in the 3 snacks that were prepared for the feeding study. The energy snack consisted of 230 g of a vegetarian githeri, whereas the meat snack contained 225 g of a githeri with 38% cooked minced beef, by weight. To include milk in a snack, the amount of vegetarian githeri was reduced to 100 g, and a glass of milk (250 g) was included in the snack. These snacks were first tested by the study staff to ensure an acceptable taste and ease of preparation and then tested among the children in schools outside the intervention communities.
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260 kcal (1088 kJ), or 15% of a schooler's requirement (10). The amount was increased to 315 kcal (1318 kJ) after the first 3 mo. The higher energy level supplied 20% of the child's average energy requirement, assuming an active level of physical activity. Children consumed the snack every day they attended school but not on weekends, school holidays, or days missed because of illness. Thus, the average daily energy intake from snacks averaged 130 kcal/d (544 kJ/d) over the 2 y of the study.
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38% of the recommended intake (11). Vitamin B-12 was high in both the milk and meat snacks, providing 83 and 106% of the recommended intake, respectively. For these analyses, the bioavailability of iron and zinc in the snacks was estimated using algorithms that consider both enhancing and inhibiting factors (12). Available iron and zinc were highest in the meat snack. As expected, snacks with ASF supplied a higher proportion of most nutrients than the vegetarian snack. Intakes at baseline and during the feeding period
Table 2 shows children's usual intakes based on 3 24-h recalls that were collected at baseline and up to 21 recalls collected during the feeding period. Nutrient intakes were estimated using the International Minilist that is part of the WorldFood Dietary Assessment System (13). As intended, snacks supplied a relatively constant percentage of the total energy intake, although total energy intake varied somewhat across the 3 feeding groups. Vitamin A in the energy and milk snacks contributed 19 and 23% of the total vitamin A intake, respectively, which is well above the 7% of energy intake that the 2 snacks supplied, on average. Vitamin A sources were the milk in the milk snack and the fortified fat that was highest in the energy snack. However, the energy snack did not supply a disproportionate amount of any of the other 4 nutrients shown in Table 2. By comparison, the milk snack also supplied substantial amounts of vitamin B-12 and calcium. Relative to energy intake, the meat snack supplied particularly high amounts of vitamin B-12, as well as higher levels of both available iron and available zinc. Analyses of serum nutrient levels, however, showed significant improvement in vitamin B-12 levels for children in the milk and meat snacks over time but no measurable increases in either iron or zinc status (14).
Changes in intake
Figure 1 shows the percentage change in energy intake over the 2 y of the study. Children in the control group increased their energy intakes by only 18 kcal/d (75 kJ/d), whereas those in the energy, milk, and meat snack groups increased their energy intakes by 36, 90, and 128 kcal/d (150, 377, and 536 kJ/d), respectively. The energy content of snacks averaged 130 kcal/d (544 kJ/d) over the study period, so only children in the meat group added the full amount of the snack to their total energy intake. For children in the energy snack group, the energy content of the food consumed at home decreased by 95 kcal/d (398 kJ/d), which offset the energy received from the snacks. For those in the milk group, the energy content of the home diet decreased by 39 kcal/d (163 kJ/d). However, the energy of the food from home did not decrease on average for those in the meat group. Thus, there were important differences in the energy intake changes among the snack groups. The reasons for these differences are not known, but 1 possibility is that the children in the meat group were more active and/or were growing faster, and thus were hungrier. Also, most children were iron and zinc deficient at baseline, which may cause a degree of anorexia. With improved available iron and zinc intake, their appetites may have improved. We have previously reported that children in the meat group had a greater increase in arm muscle mass and higher activity on the playground at school (15,16).
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FOOTNOTES |
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2 Supported by the Global Livestock Collaborative Research Support Program, USAID Grant No. PCE-G-00-98-00036-00.
7 Abbreviations used: ASF, animal-source foods; CNP, Child Nutrition Program; NCRSP, Nutrition Collaborative Research Support Program.
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LITERATURE CITED |
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TOPABSTRACTLITERATURE CITED |
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1. Neumann CG, Bwibo NO, Murphy SP, Sigman M, Guthrie D, Weiss RE, Allen LH, Demment MW. Animal source foods improve dietary quality, micronutrient status, growth and cognitive function in Kenyan school children: background, study design and baseline findings. J Nutr. 2003;133(11 Suppl 2):3941S–9S.
2. Neumann C, Bwibo NO, Sigman M. Diet quantity and quality. Functional effects on rural Kenyan families. Los Angeles: UCLA School of Public Health; 1992.
3. Calloway DH, Murphy S, Balderston J, Receveur O, Lein D, Hudes M. Village Nutrition in Egypt, Kenya and Mexico: Looking Across the CRSP Projects. Berkeley, CA: The University of California. 1992.
4. Murphy SP, Allen LH. A greater intake of animal products could improve the micronutrient status and development of children in East Africa. In: East Africa Livestock Assessment Workshop Proceedings. Davis, CA: University of California. 1997.
5. Murphy SP, Allen LH. Nutritional importance of animal source foods. J Nutr. 2003;133(11 Suppl 2):3932S–5S.
6. Neumann C, Harris DM, Rogers LM. Contribution of animal source foods in improving diet quality and function in children in the developing world. Nutr Res. 2002;22:193–220.
7. Murphy SP, Calloway DH, Beaton GH. Schoolchildren have similar predicted prevalences of inadequate intakes as toddlers in village populations in Egypt, Kenya, and Mexico. Eur J Clin Nutr. 1995;49:647–57.[Medline]
8. Murphy SP, Gewa C, Liang LJ, Grillenberger M, Bwibo NO, Neumann CG. School snacks containing animal source foods improve dietary quality for children in rural Kenya. J Nutr. 2003;133(11 Suppl 2):3950S–6S.
9. Murphy SP, Gewa C, Grillenberger M, Bwibo NO, Neumann CG. Designing snacks to meet micronutrient deficiencies in rural Ken;ya. Proceedings of the 18th International Congress of Nutrition, Annals of Nutrition and Metabolism. 2005.
10. Institute of Medicine. Dietary reference intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids. Washington, DC: National Academy Press. 2002.
11. Institute of Medicine. Dietary reference intakes for calcium, phosphorus, magnesium, vitamin d, and fluoride. Washington, DC: National Academy Press. 1997.
12. Murphy SP, Beaton GH, Calloway DH. Estimated mineral intakes of toddlers: predicted prevalence of inadequacy in village populations in Egypt, Kenya, and Mexico. Am J Clin Nutr. 1992;56:565–72.
13. Calloway DH, Murphy SP, Bunch S, Woerner J. WorldFood Dietary Assessment System user's guides. Berkeley, CA: The University of California. 1994.
14. Siekmann JH, Allen LH, Bwibo NO, Demment MW, Murphy SP, Neumann CG. Kenyan school children have multiple micronutrient deficiencies, but increased plasma vitamin B-12 is the only detectable micronutrient response to meat or milk supplementation. J Nutr. 2003;133(11 Suppl 2):3972S–80S.
15. Grillenberger M, Neumann CG, Murphy SP, Bwibo NO, Van't Veer P, Hautvast JGAG, West CE. Food supplements have a positive impact on weight gain and the addition of animal source foods increases lean body mass in Kenyan schoolchildren. J Nutr. 2003;133(11 Suppl 2):3957S–64S.
16. Whaley S, Sigman M, Neumann CG, Bwibo N, Guthrie D, Weiss RE, Alber S, Murphy SP. The impact of dietary intervention on the cognitive development of Kenyan schoolchildren. J Nutr. 2003;133(11 Suppl 2):3965S–71S.
17. Institute of Medicine. Dietary reference intakes for thiamin, riboflavin, niacin, vitamin B6, folate, vitamin B12, pantothenic acid, biotin, and choline. Washington, DC: National Academy Press. 1998.
18. Institute of Medicine. Dietary reference intakes for vitamin C, vitamin E, selenium, and carotenoids. Washington, DC: National Academy Press. 2000.
19. Institute of Medicine. Dietary reference intakes for vitamin A, vitamin K, arsenic, boron, chromium, copper, iodine, iron, manganese, molybdenum, nickel, silicon, vanadium and zinc. Washington, DC: National Academy Press. 2001.
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