Assessment of the potential of comfrey (symphytum asperrimum) as a source of vitamin a in a school feeding programme

Abstract

The study was carried out in Gitathuru Approved School, Nairobi, Kenya. A sample of 85 children (8-13 years) whose haemoglobin level was <14 gms/dl were identified from a total of 106 children. All the study subj ects were examined for the presence of parasitic infestation and later dewormed with mebendazole. Clinical examinations were carried out. The subjects were randomly allocated into an experimental group (CCD) whose diet was supplemented with 10 gms of comfrey powder/day and a control group (CFD) whose diet was not supplemented. The serum ~-carotene and serum retinol levels at the baseline and after 21 days of intervention were determined to assess the potential of comfrey as a source of vitamin A. Both pre- and post-intervention haemoglobin levels were not significantly different (P > 0.05) Analysis of ~-carotene content of fresh comfrey, blanched-oven dried comfrey powder, and solar dried comfrey powders were carried out. Storage studies on ~-carotene stability, sieve analysis and adsorption capacity of comfrey powder were also carried out. The E,-carotene content of whole unblanched, oven dried comfrey powder was significantly higher (49.03±0 .14mg/100gms than solar dried comfrey powder (34.3±1.9mg/100gms) by 30% with P<0.05. The content of whole steam blanched, oven dried powder was higher than that of chopped steam blanched powder. The loss of B-carotene after 5 minutes of cooking comfrey powder was 4.5% and 21.7% after 7 minutes of cooking. After 2 weeks of storage of comfrey powder in 200 gauge black polythene bags at 25°c under CO2, the loss was 27.8% (i.e. from 49.03±O.14 mg/100gms to about 35.4±0.24 mg/100gms) and fell gradually to about 55% after five weeks of storage. There were no significant differences in base levels of serum B carotene and retinol concentrations between the two groups of children. However, the serum B-carotene levels of the CCD group (4.99±1.28~mol/l) was significantly higher than those of the CFD group post intervention (P<O.05). On the other hand post intervention serum retinol levels for CCD group (0.29±0.18~mol/l) and those of the CFD group 0.37±0.17~mol/l) were not significantly different. Analyses of data and storage studies shows that appreciable amounts of B-carotene remained, indicate that comfrey powder has a potential for use in institutions where it can be stored for a relatively long period of time. The study indicates that further investigation on the bio-availability and bio-conversion of Bcarotene, into active form of vitamin A is needed. Nevertheless, it should be noted increasing B-carotene levels above baseline levels (4.39±1.28~mol/l) by supplementation is desirable.