Consumption patterns of traditional leafy Vegetables and Their contribution to recommended dietary intakes of Vitamins a and c, and iron in Kalama division, Machakos District, Kenya
This study was undertaken between March 2003 and June 2003 in Kalama division of Machakos district to establish the consumption patterns and nutrient contents of traditional vegetables. A household survey was carried out using a self-administered structured questionnaire to collect data on demographic characteristics of the population and production, utilization, preferences, preparation and preservation of the vegetables. Samples of raw commonly consumed vegetables were collected and cooked in simulated traditional methods. The raw and cooked vegetables were analysed for reduced ascorbic acid and beta-carotene. The data was used to calculate the contribution of the vegetables to the household dietary intakes of the two vitamins in the division. Results showed that the average household size in Kalama division was 4.9, the female to male ratio was 100:88, and the dependency ratio was 88. Majority of household heads were farmers. Literacy levels among the household heads were high, with more than 75% having some formal education. The study found that about 16 species of traditional vegetables were consumed in Kalama division. The highest ranked in terms of preference were Amaranthus spp, Vigna spp, and Cucurbita maxima in that order. The most common method of preparation was boiling then mashing the vegetables in a mixture with the staple food, isyo. However, the vegetables were also prepared for consumption as a side dish, in which case they were boiled then stewed. The average time for both methods of cooking ranged between 5-80 v minutes with a mean of about 31 minutes. while the proportion of cooking water ranged between the amounts retained after washing to 1000ml added per kilogram of vegetables. During preparation as a side dish, nearly one-third of the respondents drained the vegetables and discarded the water before stewing. Preservation of the traditional vegetables was practised by only 8.0% of the respondents though 17.0% reported consuming them whenever they accessed them, implying that consumption would be higher if more were availed. Reduced ascorbic acid contents in the raw vegetables ranged from 78.3 n:g/lOOg in V unguiculata to 102.3mgll OOgin Erucastrum arabicum. Raw samples of Solanum nigrum had the highest levels of beta-carotene (6770Jlg/l OOg), while V unguiculata had the lowest (5028 Jlg/IOOg). The percent beta-carotene retention after cooking was highest in Solanum nigrum (over 80%) and lowest in Cucurbita maxima (35%). For ascorbic acid, retention was below fifty percent in all vegetables, with Solanum nigrum having the highest retention at 48.8% and the lowest being in Cucurbita maxima at 12.5%. The mean intake of the study population was 944RE/cu/day for vitamin A, 68.8mg/cu/day for vitamin C and 16.2mg/cu/day for iron. For almost half of the study population, traditional vegetables contributed about 50% of the recommended dietary intake for all the three micronutrients. Only a third received more than 100% of the RDI for vitamin A and iron from traditional vegetables. VI The study revealed that a diversity of traditional vegetables are grown and consumed in Kalama division. Consumption of the vegetables would be increased by improving availability. Hardly any processing or preservation of the vegetables was practised. despite the prolonged cooking, the contribution of traditional vegetables to dietary intakes . of the three micronutrients was high. This implies that this contribution would even be higher if discarding of cooking water was not practiced at all and cooking time was shorter. The contribution of the vegetables to the dietary intake of Vitamins A and C, and iron was high. Consumption .of the cooking water would definitely increase the dietary intake of the three micronutrients.