This is the old United Nations University website. Visit the new site at http://unu.edu
Materials and methods
Results
References
Viveka Persson, Ted Greiner, Sirajul Islam, and Mehari Gebre-Medhin
Viveka Persson, Ted Greiner, and Mehari Gebre-Medhin are affiliated with the Section for International Child Health (ICH) in Uppsala University, Uppsala, Sweden. Sirajul Islam is affiliated with the non-governmental organization Worldview International Foundation in Dhaka, Bangladesh.
Abstract
A recent innovation in assessing community vitamin A status is the Helen Keller International food-frequency method, which is based on weekly intakes of key foods among pre-school children. Since it excludes breastmilk, we investigated whether the amount of breastmilk received by 40 children aged one to three years in a rural area of Bangladesh contributed significantly to their vitamin A intake. Vitamin A intake was indirectly calculated from the consumption of breastmilk, which was quantified over a 9-hour period by a test-weighing technique. The estimated mean 24-hour milk intake was 548 g for the 97% who were breastfed at 12 to 23 months and 312 g for the 73% who were breastfed at 24 to 36 months. This represents an average daily intake of 41% and 23% of the safe recommended daily intake (400 RE) for vitamin A, respectively. The Helen Keller International food-frequency method should be revalidated for settings where breastfeeding is sustained beyond infancy.
Introduction
Vitamin A deficiency is a major health problem in the less-developed countries. It is estimated that 250 million children are at risk [1]. Correcting mild to moderate vitamin A deficiency at the community level is thought to lead to at least a 23% reduction in mortality rates among young children [2]. At the International Conference on Nutrition jointly convened by the Food and Agriculture Organization and the World Health Organization in 1992, it was declared that efforts should be made to eliminate vitamin A deficiency before the end of this decade [3].
The planning and implementation of programmes to reduce vitamin A deficiency require simple and reliable methods of assessing the risk of vitamin A deficiency at the community level. However, conventional quantitative methods of assessing the prevalence of vitamin A deficiency in the community, including xerophthalmia prevalence surveys, dietary assessment, and biochemical analyses of serum indicators, pose important financial, logistical, and technical constraints. This has constrained how much attention governments and non-governmental organizations can give to vitamin A deficiency.
Perhaps the simplest and most innovative method to assess community risk of vitamin A deficiency now coming into frequent use is the Helen Keller International food-frequency method [4]. This method is based on diets of children one to six years of age. A score is assigned to each child based on the number of animal versus plant sources rich in vitamin A that were consumed during the past week, ignoring amounts. Nearly all the foods taken into consideration contain at least 100 retinol equivalents (RE) per 100 g. The Helen Keller International food-frequency method is intended for use in assessing whether or not vitamin A deficiency is a public health problem in a population. However, it may also prove useful in monitoring large-scale shifts in consumption of these foods, for example, in response to campaigns promoting dietary improvement. Also, in areas where both short-term and long-term strategies to ameliorate vitamin A deficiency are running concurrently, diet-based monitoring indicators are needed to tell decision makers when untargeted distribution of vitamin A capsules can be phased out as diets improve [5, 6].
The Helen Keller International food-frequency method approach has certain advantages. General eating habits are easier to remember and, therefore, are more reliably reported than specific quantities of foods. A seven-day food-frequency method also captures eating patterns over a whole week, increasing the likelihood that holidays and market days will be included. It has been shown that estimating the exact nutrient intake in individuals is not always necessary to predict the prevalence of nutritional deficiency in a community [7, 8]. Food-frequency methods have also been shown to have predictive power in relating the intake of food to risk of disease [9].
The Helen Keller International food-frequency method excludes breastmilk, on the grounds that it is only a minor source of vitamin A after the first year of lactation, i.e., the one- to six-year-old target group. The vitamin A content of breastmilk of deprived mothers in Bangladesh at 12 months and more post-partum has been estimated to be 30 RE per 100 g of milk consumed [10, 11].At this level, breastfed children are less likely to develop xerophthalmia than non-breastfed children [12, 13], even at older ages [14, 15].
The Helen Keller International food-frequency method has been validated against serum retinol in three countries: the Philippines, Guatemala, and Tanzania [16]. However, the majority of vitamin A deficiency is located in South Asia, where such studies have not yet been conducted. At the same time, the tradition of sustaining breastfeeding beyond the first year is stronger in this region than anywhere else in the world. In Bangladesh, for example, the 1996-1997 Demographic and Health Survey found that the mean duration of any breastfeeding was 28 months, based on current status data for children less than three years of age [17], and the median was 36 months. This is comparable to the mean of 27 months reported in 1975-1976 [181, suggesting that no decline in duration has occurred since then.
This study examined whether rural Bangladeshi children, at least at the lower end of the one- to six-year age group, might receive enough breastmilk to contribute significantly to their total vitamin A intake, or whether breastmilk intake can indeed be ignored in applying the Helen Keller International food-frequency method.
Study area and study population
The study was conducted in five villages in rural Thakurgaon District, Bangladesh, in November and December 1996. Breastmilk intakes were measured in 40 children selected by quota sampling. Women volunteers working in the Worldview International Foundation Comprehensive Nutrition and Blindness Prevention Program were instructed to recruit a predetermined number of breastfed children one to three years old within their programme areas. This gave a sample with a mean age of 18 ± 8.4 months, with equal numbers of one- to two-year-olds and two- to three-year-olds and equal numbers of boys and girls.
Breastmilk intake
The consumption of breastmilk over a 9-hour period was quantified by a test-weighing technique. Children were weighed immediately before and after all feedings from 9 a.m. to 6 p.m. on a UNICEF beam balance accurate to 5 g. The change in body weight during the feeding was assumed to be equal to the weight of the milk consumed. From these data, the 12-hour intake was derived as 1.33 of the 9-hour intake, and the 24-hour consumption was extrapolated using the correction factor 12-hour consumption/0.53 previously determined for Bangladeshi women [19]. The scales were calibrated on a daily basis. Four women volunteers were selected to perform the test weighing in the homes of the breastfeeding women. They were trained in weighing and record-keeping techniques. The day before the last weighing, the mothers were asked to keep track of the frequency of breastfeeding for the period from 6 p.m. the day before test weighing until 9 a.m. the day of test weighing, allowing a 24-hour suckling frequency to be estimated.
Breastmilk intake
As shown in table 1, the mean 9-hour intake of breastmilk for the whole sample was 171 ± 126 g (range, 20-470). The mean intake of breastmilk for girls (166 g) was not significantly different from that for boys (176 g; p =.8). The intake of breastmilk in the 12- to 23-month age group was 218 ± 129 g, significantly higher than the 124 ± 106 g value for the older group (p =.015). Using the correction factors, the estimated mean 24-hour intake would be 548 g for the 12- to 23-month-old group and 312 g for the 24- to 36-month-old group.
Frequency of breastfeeding
The mean suckling frequency was 6.3 ± 2.3 per 9 hours. The mean was 6.0 for girls and 6.5 for boys (p =.45) (table 2). In the 12- to 23-month-old group, the mean frequency was 6.8 ± 2.2, and in the older age group, 5.8 ± 2.3 (p =.19). For the period between 6 p.m. and 9 a.m., the mothers’ estimations of suckling frequency yielded a mean of 4.3 ± 1.6 (range, 1-8). The overall estimated total was 10.6 ± 3.5.
Table 1. Measured nine-hour breastmilk intake (g) according to age group (mean ± SD)
|
Age (mo) |
Boys |
Girls |
All |
|
12-23 |
216 ± 132 |
221 ± 134 |
218 ± 129a |
|
24-36 |
136 ± 123 |
111 ± 91 |
124 ± 106 |
|
Total |
176 ± 131 |
166 ± 125 |
171± 126 |
Table 2. Suckling frequency according to age group (mean ± SD)
|
Age (mo) |
9-h measurement |
Mothers’ 15-h record |
Total |
|
12-23 |
6.8 ± 2.2 |
4.9 ± 1.6a |
11.6 ± 3.1 |
|
24-36 |
5.8 ± 2.3 |
3.8 ± 1.6 |
9.6 ± 3.6 |
|
Total |
6.3 ± 2.3 |
4.3 ± 1.6 |
10.6 ± 3.5 |
Vitamin A intake from breastmilk
By multiplying the values for breastmilk intake shown in table 1 by the estimated retinol concentration of 30 RE/100 g, the total intake of retinol from breastmilk is calculated as 164.4 RE in the younger and 93.6 RE in the older age group. This corresponds to 41% and 23% of the safe recommended daily intake (RDI) of 400 RE for children at those ages, or 82% and 46%, respectively, of the basal RDI of 200 RE [20].
Conclusions and discussion
There is no doubt that breastmilk is important in the nutrition of young children in Bangladesh. In Gaibandah and other districts located in the same region as Thakurgaon, 97% of children 12 to 23 months of age, 73% of those 24 to 35 months of age, 32% of those 36 to 47 months of age, and 10% of those 48 to 59 months of age were still being breastfed [21].
The mean intake of breastmilk was about 550 g in the 12- to 23-month age group and 300 g in the 24- to 36-month age group. For the 12- to 17-, 18- to 23-, and >24-month age groups, Brown et al. [19] estimated 24-hour breastmilk intakes to be 563, 501, and 368 g, respectively. Our estimate for the younger age group was similar to theirs, and for the older age group ours was slightly lower. These levels are in turn similar to, although slightly higher than, Jelliffe and Jelliffe’s [22] estimates for poorly nourished populations of 300 to 500 ml/day at 12 to 23 months and 270 to 350 ml/day for children over 24 months. Although breastmilk production is only slightly affected by malnutrition, women in Bangladesh are among the most malnourished in the world (56% of women of child-bearing age have a body mass index less than 18.5) [23], and thus these results are likely to be conservative, applying to most places where breastfeeding is common among older children.
The mean observed suckling frequency in the study was 6.3 times per 9-hour period for 12- to 36-month-old children. The recalled suckling frequency was only 4.3 for a 15 -hour evening period, very likely an underestimate. Women in the study area sleep beside their babies and may not remember or be fully aware of all nighttime feedings.
Our observed values were compatible with the findings of two previous studies using observational techniques. Huffman et al. [24] observed five to six suckling episodes per 8-hour observation period for 18- to 36-month olds, as compared with our 6.3 episodes for a slightly younger group 12 to 36 months of age. Our value of 6.8 episodes per 9 hours for 12- to 23-month-olds was slightly higher than the finding by Guldan et al. [25] of four to six suckling episodes per 9-hour period among 16- to 24-month olds. The fact that suckling frequency declines with age would explain much of this small difference.
The daily vitamin A intake from breastmilk in the younger and older age groups was found to be about 160 and 90 RE/100 g, respectively, corresponding to approximately 80% and 40% of the basal requirement of 200 RE, which is equivalent to about 25% of the basal requirement for the entire age group one to six years of age covered by the Helen Keller International food-frequency method. Taking into account the actual percentage of children being breastfed, according to regional rates cited above, it would then correspond to approximately 10% of the basal requirement for the entire one- to six-year-old age group.
In this study, dietary intake was not assessed quantitatively, and thus the contribution of breastmilk to the children’s total vitamin A intake could not be calculated. Brown et al. [10] estimated it to be more than 70% in children 18 to 30 months of age. Zeitlin et al. [26] estimated that when breastmilk was included, overall dietary intakes for children 25 to 27 months of age came close to the RDI of 300 RE. They concluded that the only other significant source of vitamin A for children was seasonally available mangoes.
The bioavailability of b-carotene from various dietary sources is currently being debated. In 1967 WHO/FAO estimated the retinol conversion factor for P-carotene to be 6:1, but this is now being questioned. Recent studies in Indonesia and Viet Nam suggest that it should be 12:1 for yellow and orange fruits and 27:1 for vegetables [27]. If confirmed, this would increase the relative importance of breastmilk in the nutrition of young children, particularly in low-income areas.
In conclusion, this study showed, in agreement with earlier findings, that breastmilk is an important source of vitamin A in rural Bangladesh, even in the second and third year of life. Thus, we recommend that it be taken into account in rapid dietary assessments in settings where breastfeeding is commonly continued for longer than one year. One way of doing so would be to include breastmilk in the category of “animal food.” Another might be to assume that children one to two years old in Bangladesh are largely protected from clinical vitamin A deficiency by breastfeeding and to use the food-frequency method on the two- to six-year age group, since breastmilk will have less overall importance as a source of vitamin A and can be ignored more safely. One question in either case is whether the scales used in the Helen Keller International food-frequency method will need to be revalidated once again against serum retinol values to determine the sensitivity and specificity of the new approach.
Acknowledgments
We express our sincere appreciation to the Swedish International Development Cooperation Agency (Sida) for financing this research and to the Worldview International Foundation for providing needed assistance.
1. World Health Organization. Global prevalence of vitamin A deficiency. Micronutrient Deficiency Information System (MDIS) Working Paper No. 2. Geneva: WHO, 1995.
2. Beaton G, Martorell R, L’Abbe K. Effectiveness of vitamin A supplementation in the control of young child morbidity and mortality in developing countries. Toronto, Canada: University of Toronto, 1993.
3. World Health Organization/Food and Agriculture Organization. International Conference on Nutrition: final report of the conference. Rome: FAO, December 1992.
4. Rosen D, Haselow N, Sloan N. How to use the HKI food frequency method to assess community risk of vitamin A deficiency. New York: Helen Keller International, Vitamin A Technical Assistance Program, 1993.
5. Greiner T. Combining long- and short-term vitamin A deficiency control programs. News on Health Care in Developing Countries 1992;6:27-9.
6. United Nations Administrative Committee on Coordination/Sub-Committee on Nutrition. Working group on vitamin A, 22nd session. Geneva: ACC/SCN, 1995.
7. Block G. A review of validations of dietary assessment methods. Am J Epidemiol 1982; 115:492-505.
8. Hernandez-Avila M, Master C, Hunter D, Buring J, Phillips J, Willett W, Hennekens C. Influence of additional portion size data on validity of a semi-quantitative food frequency questionnaire. Am J Epidemiol 1988;128:891.
9. Willett W, Sampson L, Stampfer M. Reproducibility and validity of a semi-quantitative food frequency questionnaire. Am J Epidemiol 1985;122:51-65.
10. Brown K, Black R, Becker S, Nahar S, Sawyer J. Consumption of foods and nutrients by weanlings in rural Bangladesh. Am J Clin Nutr 1982;36:878-89.
11. Baruha S, Tarannurn S, Nahar L, Mohiduzzaman M. Retinol and alpha-tocopherol content in breast milk of Bangladeshi mothers under low socio-economic status. Int J Food Sci Nutr 1997;48:13-18.
12. Bloem MW, Hye A, Wijnroks M, Ralte AKPW, Sommer A. The role of universal distribution of vitamin A capsules in combatting vitamin A deficiency in Bangladesh. Am J Epidemiol 1995;142:843-55.
13. Tarwotjo I, Sommer A, Soegiharto T, Dietary practices and xerophthalmia among Indonesian children. Am J Clin Nutr 1982;35:574-81.
14. Cohen N, Measham C, Khanum M, Ahmed N. Xerophthalmia in rural Bangladesh. Acta Paediatr Scand 1983;72:531-6.
15. Mabalabanis D. Breast feeding and vitamin A deficiency among children attending a diarrhoea treatment centre in Bangladesh: a case control study. BMJ 1991;303:493-6.
16. Sloan N, Rosen D, de la Paz T, Arita M, Temalilwa C, Solomons N. Identifying areas with vitamin A deficiency: the validity of a semiquantitative food frequency method. Am J Public Health 1997;87:186-91.
17. Mitra and Associates. Demographic and health survey 1996-7. Dhaka, Bangladesh: National Institute of Population Research and Training and Macro International, 1997.
18. Ahamed M. Breastfeeding in Bangladesh. J Biosoc Sci 1986;18:425-34.
19. Brown K, Black R, Robertson A, Akhtar N, Ahmed G, Becker S. Clinical and field studies of human lactation: methodological considerations. Am J Clin Nutr 1982;35:745-56.
20. Food and Agricultural Organization. Requirements of vitamin A, iron, folate, and vitamin B12. Rome: FAO, 1988.
21. Greiner T. Breastfeeding in Bangladesh: a review of the literature. Bangladesh J Nutt 1997;10:37-50.
22. Jelliffe D, Jelliffe E. The volume and composition of human milk in poorly nourished communities: a review. Am J Clin Nutr 1978;31:492-515.
23. Institute of Nutrition and Food Science, Department of Statistics, Dhaka University, and National Institute of Preventive and Social Medicine. Health and nutrition baseline survey of 44 rural thanas in Bangladesh. Final report. Dhaka: Bangladesh Integrated Nutrition Project, Ministry of Health and Family Welfare, Government of the People’s Republic of Bangladesh, January 1998.
24. Huffman S, Chowdhury A, Chakraborty J, Simpson N. Breast-feeding patterns in rural Bangladesh. Am J Clin Nutr 1980;33:144-54.
25. Guldan G, Zeitlin M, Beiser A, Super C, Gershoff S, Datta S. Maternal education and child feeding practices in rural Bangladesh. Soc Sci Med 1993;36:925-35.
26. Zeitlin M, Megawangi R, Kramer E, Armstrong H. Mothers’ and children’s intakes of vitamin A in rural Bangladesh. Am J Clin Nutr 1992;56:136-47.
27. West C, Hautvast J. From “whither” to “wither” micro-nutrient malnutrition. Lancet 1997;350(suppl III):15.
