10.1

Atherosclerosis, 31 (1978) 101-104 0 Elsevier/North-Holland Scientific Publishers, Ltd.

Preliminary

Note

THE EFFECT OF GARRI ON RAT PLASMA CHOLESTEROL

IKPENDU C. ONONOGBU and I. EMOLE Department

of Biochemistry,

University of Nigeria, Nsukka (Nigeria)

(Received 28 May, 1978) (Revised, received 22 May, 1978) (Accepted 26 May, 1978)

Summary Plasma cholesterol concentrations were measured in rats after incorporation of garri in their diet; control animals were fed a diet without garri. Cholesterol concentrations decreased with incorporation of garri in the diet, but a saturation point was reached after which garri had no further lowering effect on plasma cholesterol. Histology of the kidney and liver revealed cellular vacuolation and cytoplasmic sweliing in garri-fed animals. Key words:

Cassava - Cereal - Cholesterol -Diet

Introduction Diet has been recognized as one of the factors affecting plasma lipid concentration. Cholesterol-lowering diets have been regarded as necessary for the control of cardiac atherosclerosis. Garri is the flour prepared from cassava (M&hot utilissina), and is equivalent to ground-up tapioca - a staple food in urban communities in Nigeria. Its toxicity is caused by its content of cyanogenie glycosides [l] and its goitrogenic tendency has been previously reported [ 21. Garri may contain as much as 35 mg of hydrocyanic acid (HCN) in an average daily consumption of 750 g [ 31. Although the body can detoxify this HCN, concern has arisen that certain adverse biochemical and physiopathological changes may be caused by prolonged consumption of garri. Even when cassava is properly processed, the amount of unremovable cyanide present in the flour is still comparatively high. More elegant processing methods are, however, being introduced to reduce the cyanide content. Most of the previous dietary reports on garri have concentrated on cyanide poisoning and goitrogenicity. No data are available on its This investigation

was supported

by a gmmt from the University

of Nigeria, Nsukka.

102

effect on plasma cholesterol. Garri is mainly consumed in urban communities. Since a few cases of cardiac atherosclerosis have been found in urban Nigerian communities, we decided to investigate the effect of garri on plasma cholesterol. The background of the problem is whether or not garri contributes to the incidence of atherosclerosis in Nigeria. Methods Three groups of rats, consisting of 4 adult male albino rats in each group, were housed at 25°C in stainless steel cages with raised wire gauze. The rats weighed between 270 and 300 g. The rats were maintained on a diet of groundnut cake, fish meal and maize (Table 1) for 4 weeks. The control group (Group 0) was maintained on the diet without garri incorporation. The first experimental group (Group 1) had 16% garri incorporated in the diet, while the other group (Group 2) had 32% garri incorporated (Table 2). Garri was obtained from the Agricultural Farm of the University of Nigeria, Nsukka. The rats were weighed before the experiment and initial plasma cholesterol concentration was determined. The rats were fed 200 g of the powdered feed daily; water was allowed ad libitum. At weekly intervals the rats were weighed, and plasma cholesterol concentrations determined. At the end of the 4th week the rats were killed, and the liver and kidney were removed for histological examination. Total cholesterol was determined by the method of Zak [4] utilizing the Liebermann-Burchard reaction. Samples of kidney and liver were processed into paraffin and stained with haematoxylin and eosin.

TABLE 1 DIETARY

COMPOSITION

Food

Maize Garri Fishmeal Groundnut cake

Protein

Liiid

Carbohydrate

Water

VQ

(%)

(%)

(%)

5

67 21 6

18 77 57 53

10 2 42 13

1 28

TABLE 2 FEEDING REGIME GeXi

Maize

Groundnut cake

Fishmeal

@)

(%I

(%)

(%)

16 32

67 50 32

23 24 26

10 10 10

Group 0 (Control) Group 1 Group 2

103 TABLE 3 CHANGE IN MEAN WEIGHTS OF RATS DURING FEEDING (g) Group

Before feeding

1st week

2nd week

3rd week

4th week

Control Group I Group II

273.5 273.7 273.0

304.4 302.8 308.0

316.9 319.9 328.8

321.0 323.0 333.6

327.1 328.3 339.6

TABLE 4 PERCENTAGE

INCREASE

IN WEIGHT WITH REFERENCE

TO WEIGHT BEFORE FEEDING

Group

1st week

2nd week

3rd week

9th week

Control Group I Group II

11.3 10.6 12.8

15.9 16.9 20.4

17.4 18.0 22.2

19.6 19.9 24.4

TABLE 5 CHOLESTEROL Control Group 1 Group 2

100-

CONCENTRATION

(n = 4) (n = 4) (n = 4)

145.8 v! 23.2 125.3 f 10.3 123.5 r 17.9

Control

e---Q

_

160-

(MEAN ?rSD mg/lOO ml)

/’

-

16x

CasMva

inwrporation

R-------X

32%

Cassavo

incorporation,~

D

Y’ /

140E 0 0

-

E

-Cholesterol

>120-

.s IOO-

40 t

20

t

0

1

Time

Fig. 1.

3

2 in

weeks

I

4

104

Results There was no appreciable weight difference between the groups at the start. Weight increased in the groups fed garri (Table 3) and was greatest in the group fed at the 32% level (Table 4). Plasma cholesterol concentrations decreased with time in groups fed garri (Fig. 1). Although the cholesterol concentration fell in garri-fed rats, analysis of variance gave a group difference of only F = 6.32 in cholesterol concentration. Thus, there was a trend towards a reduction in cholesterol concentration, but this did not reach a statistically significant level - possibly because of the small number of rats in each group. The mean cholesterol concentrations are shown in Table 5. Examination of the kidney and liver cells under the light microscope revealed swelling and vacuolation in the groups on the garri-enriched diet. Discussion Detoxification of cyanide from cassava is known to take place in the kidney and liver [5]. The rhodanase-mediated incorporation of cyanide with thiosulphate to form thiocyanate is the main detoxification process. Vacuolation of the kidney and the liver cells suggests that although the rat can detoxify the cyanide in cassava, prolonged cassava consumption results in degenerative and fatty changes in the liver [6] and kidney cells. Such vacuolation depends on the nutritional status of the animals [7]. Hypercholesterolaemia is associated with atherosclerosis [ 81, but our results indicate that garri does not cause hypercholesterolaemia. Consumption of garri is high among Nigerian urban dwellers. Hence, if rat-to-human extrapolation is acceptable, garri is not a responsible factor in urban heart disease in Nigeria. As an incidental finding, blood cholesterol tended to be lower in garri-fed than in control rats, but the results were not statistically significant. If later work confirms that this trend is real, it might reflect impaired lipoprotein synthesis [9] due to a toxic effect on the liver, as to some extent suggested by the histological observations. References 1 Osuntokun, B.O., Epidemiology of tropical nutritional neuropathy in Nigerians, Trans. ROY. Sot. Trap. Med. Hyg.. 65 (1971) 454. activity of cassava. Nature (Land.), 210 2 Ekpechi. O.L., Dimitrladou. A. and Fraser, R.. Goitrogenic (1966) 1137. 3 Seigler, D.S., Isolation and chsracterisation of naturally occurring cyanogenic compounds, Phytochemistry, 14 (1976) 9. 4 Zak. B., Simple rapid microtechnique for serum total cholesterol, Amer. .I. Clin. Path., 27 (1957) 583. 5 Smith, J.N.. Comparative biochemistry of detoxification. In: M. Florkin and H. Massln (Eds.), Comparative Biochemistry, Vol. 6. Academic Press, New York, NY, 1964. p. 403. 6 Adams, C.W.M., Femand. V.S.V. and Schnieden. H.. Histochemistry of a condition resembling Kwashiorkor produced in rodents by a low protein-high carbohydrate diet (cassava), Brit. J. Exp. Path., 39 (1958) 393. 7 Grandpierre, R. and Grognot. P.. Les modifications histologiques du foie dues a l’altitude, Med. Aeronaut., 2 (1947) 18. 8 Kennel. W.B.. Dawber. T.R., Friedman, G.D., Glonnon, W.E. and McNamara. P.M., Risk factors in coronary heart disease - An evaluation of serum lipids as predictors of coronary heart disease. Ann. Intern. Med., 61 (1964) 888. 9 Havel. R.J., Felts, J.M. and Van Duyne. C.M., Formation and fate of endogenous triglycerides in blood of Plasma of rabbits, J. Lipid Res., 3 (1962) 297.

The effect of garri on rat plasma cholesterol.

10.1 Atherosclerosis, 31 (1978) 101-104 0 Elsevier/North-Holland Scientific Publishers, Ltd. Preliminary Note THE EFFECT OF GARRI ON RAT PLASMA CH...
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