Effects of Coconut (Cocos nucifera Linn.) Water and Oil on the Ileal Bacterial Flora of Apparently Healthy Wistar Albino Rats

Abstract

In this study, the biosafety of the consumption of coconut water and oil was investigated. This was carried out by assessing their effects on the types and population of bacterial flora in the ileum of Apparently Healthy Wistar (AHW) rats. Both the in vitro and in vivo assays were employed. The in vitro assay was used for the assessment of the antibacterial activity of coconut water and oil on the bacteria isolated from the ileum of AHW rats while the in vivo assay was carried out in AHW rats (n=100) orally administered either coconut water or oil to monitor the effect in situ. In the in vivo assay, the albino rats (n= 100) were divided into 8 groups (A-H) of 12 rats each while the remaining four rats were put in another group to serve as a control. The first four groups (A-D) were daily orogastrically administered different volumes of coconut oil, 0.5 ml, 1.0 ml, 1.5 ml, 2.0 ml respectively for 4 weeks while groups E-H were daily orogastrically administered different volumes of coconut water, 0.5 ml, 1.0 ml, 1.5 ml, 2.0 ml respectively for four weeks. The control rats (Group l) however were not administered either coconut water or coconut oil. All the rats were allowed free access to rat chow and water. Seven distinct bacterial species were isolated from the ileum of (AHW) rats used in this study. These are Escherichia coli, Proteus mirabilis, Pseudomonas aeroginosa, Klebsiella pneumoniae, Shigella flexneri, Serratia marscense, and Morganella morganii. Both the coconut water and oil used inhibited the growth of all the bacteria isolated from the ileum of the rats with diameter zones of inhibition ranging from 7.50±0.50 mm to 23.00±2.00 mm and 4.25±0.25 mm to 19.00±1.00 mm respectively. The growth inhibition exerted by both, however, was lower than that of the conventional antibiotic (Ciprofloxacin) used as control which ranged from 12.00±0.50 mm to 42.50±2.50 mm. In the in vivo assay, coconut oil reduced the population of the ileal bacterial flora of the rats with the highest effect on Escherichia coli from 2.39×106 to 8.3×105cfu/ml while coconut water had minimal growth inhibitory activity on the bacterial load from 2.39×106to 1.23×106cfu/ml after 28 days of administration. These growth inhibitions, however, did not become significant (p<0.05) on the population of most of the bacterial flora until after 7 d of administration of either coconut water or oil with a dose between 0.5 and 1.0 ml. On the other hand, the administration of either coconut water or oil did not alter the types of bacterial flora in the ileum of the rats throughout this study. In conclusion, the administration of coconut water or oil to AHW rats did not significantly (p≤0.05) affect the population of the bacterial flora in their ileum within the first 7 days of consumption and also did not affect the bacterial types, therefore when consuming either, the duration should not exceed 7 d at a stretch so that the bacterial flora inhabiting the gut of consumers will not be adversely affected.