INTRODUCTION
1.1 BACKGROUND
OF STUDY
A dietary factor is thought to be
responsible for constant non-genetic neutropenia in Africans (Ogunranti, 1993).
As early as 1941, Forbes et al; noted
that persons of African origin had lower white blood cell counts than
Caucasians. Subsequent studies of the total white blood cell counts and
neutrophil counts of healthy afro-American, east Africans and afro-Caribbean
adult have consistently demonstrated significantly lower values of both the
lower and upper limit of normal when compared with Caucasian adults (Bain,
1996, Pancham, et al. 2002. Rippey,
1967). It has also been observed that low neutrophil counts are uncommon for
Caucasians while high neutrophil counts are uncommon for blacks (Reed et al. 1991).
However, a comparative study of the
white blood cell counts of cord blood from 240 babies of five (5) different
ethnic group showed that there is “No ethnic” difference found in the total
white blood cell count, Neutrophil, lymphocyte monocyte or eosinophil count
(Chan et al. 1985). Thus, the lower
total white blood cell and neutrophil counts which has been observed in adults
of African and Afro-carribean origin is not present in neonates. Similarly
eosinophil counts did not differ between the different ethnic groups suggesting
that African are not born neutropenic (Chan et
al. 1985).
Neutropenia is a granulocyte
disorder characterized by an abnormal low number of neutrophil, the most
important type of white blood cell. It is sometimes used interchangeably with
the term leucopenia (deficit in the number of white blood cell). Neutrophil
usually makeup 50-70% of the circulating white blood cells and serve as the
primary defense against infection by destroying bacteria in the blood (Hsieh,
2007).
We are aware that the main
difference between traditional African diet and European diets is the absence
of high level of cholesterol and saturated fatty acids in the African diet
(Green et al, 1978, Fredickson,
1974). Present study shows that, if the diets of Africans changes to European
type, the frequency of neutroponia will drop noticeably and if Africans had
European diets from infancy neutropenia would probably disappear (Ezeilo,
1972). This is so because elevated dietary cholesterol is known to increase
blood total leucocyte (Higher neutrophil counts), total cholesterol concentration
low density lipoprotein concentration ( Meijer et al. 1996). This dietary components are also hypothesized to
influence cardiovascular disease risk by induction of atherosclerotic plaques
in the aorta and coronary arteries ( Meijer et
al. 1996).
Atherosclerosis is a complex chronic
disease of the cardiovascular system characterized by the accumulation of
lipids within arterial walls that eventually go on to form plaques which can cause
narrowing, hardening and/ or blockage of arteries (Pearson et al. 2002). One well known risk factor in human is
hypercholesterolemia (I.e. elevated total cholesterol Tc) and low density
lipoprotein cholesterol (LDL-c) (Pearson et
al. 2002, Martinez et al. 1988).
It is characterized by focal lesion of one of the following types: fatty streak,
fibrous plaques and complicated lesions. Hypothesis used to elucidate
pathogenesis of atherosclerosis includes, lipid hypothesis, thrombogenic
hypothesis and endothelial cell injury hypothesis (Abdelhalim et al. 1994).
Foods high in dietary saturated fats
(SF) and cholesterol (i.e. European type of diet ) have been liked to
elevations in circulating cholesterol levels (in particular LDL-c) ( Hegsted et al
1965) prompting the recommendation that human limit the intake of these
dietary constituents (Pearsons et al
2002). All living organisms need food (diet) for growth, source of energy and
replacement of worn out and damaged tissues. There are three,(3) classes of food
namely, carbohydrate, protein and fats, In addition to protein, carbohydrate
and fats, diets must contain vitamins, salt, water and vegetable fibers
(Ramlingam, 2001). A healthy diet supplies adequate but not excessive
quantities of all these nutrients. A diet can be defective or unbalanced
because it lacks one or more essential nutrients or because it contains too
much of certain type/kind of food (Ramlingam, 2001).
Traditional African diets are rich
in carbohydrate and low in protein and lipids. The oil or fat content of many
African diets tend to be very low. Total dietary fat provide on average 18% of
total food energy in sub-Saharan Africans, but populations in some countries
obtain as little as 7 to 15% of food
energy from fat (FAO, 1997, Tariq 2003). The content of animal protein
also tends to be quite low. This dietary deficiencies are often as a result of
the lack of money, customs, economic, social and culture (Hegsted et al. 1965,
Hershamann et al, 2003, Tariq 2003, FAO,
1997). The European diets on the other hand is rich in protein and lipids and
moderately low in carbohydrate (Hegsted et al. 1965, Eaton et al. 1985, Miller et al.
1994).
1.2 STATEMENT
OF PROBLEM
Several studies have reported that
Africans have blood leucocyte counts that are persistently below the normal
range for people of European descent, the difference was due principally to
lower granulocyte counts, whereas absolute lymphocyte counts were actually
higher in Africans. It has also been proposed that the reasons for this
disparity might be primarily due to social-economic, biological and nutritional
factor (Hershman et al. 2003, Oji
2011, Ezeilo 1972)
We are aware that the main
difference between traditional African diet and European diet is the absence of
high level of cholesterol and saturated fatty acids in the African diets (Green
et al 1978, Fredickson, 1974,
Ebrahim, 2002). However, it is already well known that predisposition to
cardiovascular disease is higher in subjects feeding on high lipid cholesterol,
high protein and low carbohydrate European diet. Therefore, the contradiction
of the effects of low carbohydrate, high protein and high cholesterol diet on
the blood leucocyte count and the cardiovascular system is a problem worth
considering.
1.3 AIMS
AND OBJECTIVES
1. To
investigate the effects of feeding rats on diets which mimic basic African
diets (High carbohydrate, low animal protein and saturated fats) and European
diet (low carbohydrate, high protein and saturated fats) on the blood leucocyte
pattern of albino wistar rat.
2. To
determine the plasma concentration of total cholesterol and high density
lipoprotein cholesterol of rats fed as in 1 above and any possible Histological
effect on the heart.
1.4 SIGNIFICANCE OF STUDY
The findings of this study will go a long way to
evaluate the effects of low carbohydrate, high protein and high lipid
cholesterol diet on the blood leucocyte count and on the cardiovascular system
(Heart).
Though many reports has been
recorded in the scientific literature regarding the striking effect of low
carbohydrate, high protein and high lipid cholesterol diet on the
cardiovascular system and the leucocyte pattern of Africans, more research is
still needed to consolidate these scientific record/findings. Proponents of
high carbohydrate, low protein and low fat diets contend that saturated fat and
cholesterol diets are the major dietary contributor to cardiovascular diseases by
increasing the building of cholesterol on arteries (blood vessel) putting human
at risk of heart attack, stroke and other major health problem. Heart disease
is a leading cause of death worldwide in men and women. In many countries, heart
disease is viewed as a 2nd epidemic replacing infectious disease as
the leading cause of death.
Neutropenia is common in many
apparently healthy Africans (Ezeilo,1972)
but whether Neutropenia is hereditary or acquired is not certain but according
to the works of Ezeilo, 1972 hematological values determined in 3 groups of
Africans on different diets were compared with those of groups of European and
Asians. Neutropenia was most common in Africans on native diets (82%), less
common on those who periodically had European diets (55%) and least common
(25%) in those having only European diet, this shows that neutropenia in Africans
is non-genetic but dietary.
Ancient Africans believed that a
healthy immune system is responsible for the health and healing of the human body.
From this premise, health problem occur as a result of “something” lacking in
our nutrition (diet) leaving the human body vulnerable to disease. Therefore a
diet and lifestyle deficient in nutrient makes us susceptible to opportunistic
infections and cellular disorganization (Tariq, 2003).
Since high saturated fat and protein
diets are known to raise total cholesterol, low density lipoprotein and high
neutrophil count which are associated with an increased incidence of
cardiovascular disease, there is need to moderate the level of dietary
cholesterol intake, engage in physical activities and yet maintain high neutrophil
count.
1.5 SCOPE
OF STUDY
The study will be limited to the
comparative study of the effects of African diet (rich in carbohydrate, low in
protein and lipids) and European diets (rich in lipid cholesterol, proteins and
low in carbohydrate) on the blood leucocyte pattern and the cardiovascular system
(Heart). The study will also be within
Ebonyi state university.
20 healthy albino wistar rats will be
used for this study. The wistar rat will be fed for 12 weeks on standard rat
feed and a compounded European diet consisting of red meat and egg yolk.
Haematological parameters will be
determined, plasma total cholesterol level and high density lipoprotein
concentration will be determined. Histological conditions of the heart will
also be examined after staining using photomicrograph examination under a light
microscope.