Health Implication Of Steroid Fattened Livestock And The Implication Of Their Lipid Profile For Human Nutrition
1.1 Background of Study
Hormones are chemicals produced by animals to co-ordinate their physiological activities. They acts as messengers, produced in and released from one kind of tissue to gradually stimulate or inhibit some process in a different tissue over a long period. The importance of individual hormones varies between sexes and age and a disruption of the endocrine equilibrium may result in multiple actions e.g the male hormone testosterone controls many processes from the development offoetus to libido in the adult. Alternatively, one function may be controlled by multiple hormones, e.g. the menstrual cycles involves estradiol, progesterone, follicle stimulating hormone and luteinizing hormone. Hormones are vital innormal development, maturation and physiological functioning of many vital organs and processes in the body (Annamaria, 2012).
However, like any other chemicals of natural or synthetic origin, hormones may be toxic to living organisms under certain circumstances. The toxicity may be due to an excess of its normal (physiological) action. Hormones, like other chemicals, may also exert direct toxic actions not related to their endocrine (physiological) actions (Annamaria, 2012).
Besides the endogenous corticosteroids (cortisol, cortisone) and those suspected to be endogenous (prednisone, prednisolone), there are synthetic exogenous corticosteroids (dexamethasone, betamethasone), developed because of their anti-inflammatory properties.
Estrogens, androgens, gestagens and corticosteroids are steroids which act as hormones. The parent compound from which all steroids are derived is cholesterol. The classification of steroid hormones can be done according to their biological activity and pharmacological effects which includes the sex steroids, a subset of hormones producing sex differences and reproduction such as estrogen, gestagens and androgens. The second group is the corticosteroids which are glucocorticosteroids, involves in metabolism and immune function and mineralocorticosteroids, involves in the regulation of the blood volume and electrolyte content.
They can also be classified upon their endo or exogenous origin. Steroid hormones that are biosynthetically present in the body are the endogenous hormones and they are chemical messengers from one cell (or group of cells) to another e.g (estradiol). Exogenous steroids are also called xenobiotics are foreign compounds that are naturally or synthetically produced e.gmethyltestosterone (Noppeet al., 2008).
Apart from the endogenous corticosteroids (cortisol, cortisone) and those suspected to be endogenous (prednisone, prednisolone), there are the synthetic exogenous corticosteroids ‘old’ structures. Well-known examples of these drugs with a steroids structures are tetrahydrogestrinone (THG), norbolethoneanddesoxymethyltestosterone (DMT) (Noppeet al., 2008).
Cholesterol is a waxy substance made by animal liverand also supplied in diet through animal products suchas meats, poultry, fish and dairy products. Cholesterol isneeded in the body to insulate nerves, make cellmembranes and produce certain hormones, and it is animportant lipid in some membranes. However, the bodymakes enough cholesterol, so any dietary cholesterol
isn’tneeded. Cholesterol plays a major role in human heart health but can be both good and bad. High-densitylipoprotein (HDL) is good cholesterol and low-density lipoprotein (LDL) is bad cholesterol.
Triglycerides are another fat in the bloodstream, the most common type of fat in the body. High levels oftriglycerides is also linked to heart disease and diabetes.A high triglyceride level combined with low HDL cholesterol or high LDL cholesterol seems to speed up atherosclerosis, which is the buildup of fatty deposits in artery walls that increase the risk for heart attack and stroke (Hongbao, 2006).
1.2 Statement of Problem
Due to the important role of hormones in several body functions, they also have been exogenously applied to animals and humans for productivity and growth development. Focusing on the veterinary field, due to the obvious ability to improve weight gain and feed efficiency in meat producing animals, natural hormones and/or the synthetic surrogates have been used in agricultural practice for several decades by farmers and this imposes several risks on human health. Also, corticosteroids can be illegally used in animal fattening, this is because it has been described that they may have a synergetic effect when combined with anabolic steroids or agonists. (Courtheynet al., 2002; Noppeet al., 2007).
Both exogenous hormones and synthetic compounds mimicking their effects may change the endogenous balance of human body, disturbing their natural functions. Children are extremely sensitive to exogenous steroid hormones because of their low endogenous levels, small variation in their blood levels might trigger serious pubertal development effects and even future adult life problems (Aksglaedeet al., 2006; Alveset al., 2007). An unexpected advance in timing of puberty in both African-American and white American girls (Herman-Giddenset al., 1997).
In adults, an association between the risk of breast cancer and persistently elevated blood levels of oestrogen and androgen has been found in many studies (Kaakset al., 2005; Yager& Davidson, 2006). Also, data published by Swan et al., in 2007 suggested that maternal beef consumption may alter males’ testicular development in utero and adversely affect his adult reproductive capacity.
In the human diet, meat is seen as a major source of fat and especially of saturated fatty acids (SFAs), which havebeen implicated in diseases associated with modern life,mostly in developed countries. Coronary heart diseaseand arteriosclerosis are among the most importantcauses of human mortality, and are strongly associatedwith dietary intake of cholesterol and saturated fatty acids(Simopoulos, 2002, 2004). In addition,HDL is considered to be beneficial as higher levels have been correlated with reduced risk of negative cardiovascular event (American heart Association, 2007). Elevated LDL and triglycerides are considered detrimental as their increased concentration is well is well correlated with poor cardiovascular outcomes (American heart Association, 2007; Segrest, 2002).
1.3 Significance of Study
As regards to hormonal content, all foodstuff of animal origin contains steroids hormones and metabolites, but their concentrations vary with the kind of food, gender, age and physiological stage of the animal. (Daxenbergeret al., 2001; Poelmanset al., 2005a, 2005b). In fact meat is clearly one of the most naturally contaminated foods. (Maumeet al., 2001, 2003; Poelmanset al., 2005a). Regarding potential toxicological substances used in animal husbandry and their derivatives the US Food and Drugs Administration (FDA) concluded that ‘safety can be assured’ because they are endogenous in both food-producing animals and people.
However, to show the safety of an endogenous sex steroid, it should be demonstrated under the proposed conditions of use, the concentration of residue of the endogenous steroid in treated food-producing animals is such that the increase will not exceed this 1% permitted increase. In 1988, the Joint Food and Agricultural Organisation/World Health Organisation (FAO/WHO) Expert on Food Additives (JECFA) and the US Food and Drugs Administration (FDA) that the residues found in meat from treated animals were safe for the consumers.
The World Health Organization recommends that the daily fat intake be reduced to 30% of the total energy intake, and that saturated fats should be limited to 10% of this caloric intake. It is also advised that cholesterol intake should not exceed 300 mg per day. Dietary intake of unsaturated fatty acids (UFA) has been shown to reduce the risk of cardiovascular diseases (CVD) and possibly the incidence of some cancers, asthma and diabetes among others. In fact, clinical trials have shown that it is unnecessary to completely substitute fish or poultry for lean red meat choices to achieve desirable blood lipid profiles (Davidson et al., 1999; Hunninghakeet al., 2000).
The concentration of dexamethasone will be analyzed in order to know if the use its use is being abused in animal husbandry by local farmers and the residual concentration in meat matrix will be known at the end of this study. The lipid profile of the selected animals will also be determined.
1.4 Aim of the Study
To identify the health implication of steroid fattened livestockin Lagos market and the implication of their lipid profile for human nutrition.
1.5 Objective of the Study
- To determine the presence of dexamethasone (steroid) in blood samples of chicken, mutton, pork, chevon and beef.
- To determine the Lipid profile (cholesterol, triglyceride, high density lipoprotein (HDL), low density lipoprotein (LDL) of the blood samples of the above named meat samples.
Corticosteroids such as dexamethasone are important in animal protein, carbohydrate and fat metabolism and for their role in controlling inflammation (Gerrardet al., 2004). Corticosteroids are illegally used in several countries as growth promoters in veal calves and beef cattle, either alone or in combination with anabolic agents, especially at low dosage and primarily through oral administration, in order to enhance carcasses and meat quality traits (Renavilleet al., 1994; Gottardoet al., 2008). These drugs are usually used in association with sex steroids and β-agonists to obtain higher proportion of lean meat (Meyer et al., 2001). The strong pharmacological activity of synthetic corticosteroids renders the residues of these molecules potentially dangerous for meat consumers. Hence, this present study evaluates the level of dexamethasone and its implication on the lipid profile of livestock in Lagos market.
In this study, dexamethasone was found present in the tissues of all livestock kinds. However, the level was above permissible limit given by the JOINT FAO/ WHO Expert committee on Food Additives based on the ADI (Acceptable daily intake) of 0-0.015µg per kg of body weight for parent drug, the acceptable intake of parent drug (dexamethasone) is 0.9µg/day for an average individual. The MRLs (Maximum Residue Limits) that satisfy the ADI criteria in cattle and pigs are 2.5µg/kg for liver, 0.5µg/kg for muscle and kidney and 0.3µg/l for cows’ milk and that dexamethasone is rapidly eliminated from muscle and milk and that the probability of exposure to residues from tissues is low. The theoretical maximum daily intake is 0.875µg, based on the recommended MRLs and ingestion of 300g of meat (as muscle), 100g of liver, 50g of kidney and 1.5/1 of milk.
This results is in agreement with the USDA reported in 2000 that almost 90% of steers and heifers weighing over 700 pounds and almost 86% weighing less than 700 pounds were implanted atleast once in their lifetime with synthetic or natural hormones.
In this study, the concentration of dexamethasone was analyzed in order to know if the use of dexamethasone is being abused in animal husbandry by local farmers, and to know its residual concentration in meat matrix. Analysis on the lipid profile of the selected animals was also carried out and compared to determine the concentration of lipids in the varieties of animals that are commonly consumed.
Report on the elevation in serum cholesterol has being indicated in high doses of dexamethasone. This could be responsible for the elevated cholesterol level in the animals. Based on the standard concentration of total cholesterol in Chicken which is 76mg/dl (USDA, 2001), there is a high administration of dexamethasone in Chicken. Serum triglyceride concentration was observed to be higher in chicken when compared to that found in goat, pig, cow and sheep. Toxicity of dexamethasone could be related to this elevation of triglyceride (Yan et al., 2007).The level of HDL- cholesterol was observed to be 109.9mg/dl in Pig, 75.51mg/dl in Cow, 43.92mg/dl in Sheep, 42.77mg/dl in Goat and 28.92mg/dl in Chicken at (P ≤ 0.05). The level of HDL- cholesterol was observed to be 109.9mg/dl in Pig, 75.51mg/dl in Cow, 43.92mg/dl in Sheep, 42.77mg/dl in Goat and 28.92mg/dl in Chicken at (P ≤ 0.05).
Health effects of concern for human exposure to these synthetic steroids include cancer, reproductive defects and other endocrine disruption outcomes. Study by Pandyaet al.(2013), indicate that the dexamethasone treatment significantly increased TPL, Cholesterol and individual phospholipids content during developmental period whereas adult group displayed an opposite effect and the observations on the increase in phospholipid content during developmental period have been indirectly supported by finding of other investigators. Several indirect observations support the possibility of upregulation of lipid synthesis or accumulation in liver during developmental period after chronic dexamethasone treatment in neonates.
The oral administration of dexamethasone to rats and dogs shows that corticosteroid concentration in plasma and hepatic glycogen reduced with elevated levels of serum lipids (FAO/WHO, 1995). Yan Liu et al., 2007 reported that there is a significantly increased triglyceride accumulation within liver after dexamethasone treatment in neonatal age after 14 days (Liu et al., 2007). Dexamethasone treatment (100 mg/kg) for 5 days increased triglycerides retentionin the liver by decreasing their secretion (Latteronet al., 1997). The regulatory role of glucocorticoids in gluconeogenic and insulin resistance during development has being known (Amin et al., 1999). In hepatocytes, the effect of induction of gluconeogenesis after dexamethasone treatment was shown (Anan et al., 1984). This may possibly indicate the increased turnover of fatty acids and their metabolism in liver mitochondria during developmental period.
Kapitulniket al. (1986), have shown increased fluidity in developing fetal rat liver microsomal membranes with significant increase in contents of polyunsaturated fatty acids after early prenatal exposure to dexamethasone (Kapitulniket al., 1986). This may support observation of fluidized membrane during developmental process. However, it is possible that excess glucocorticoids may increase the formation of ketone bodies in liver as dexamethasone regulates ketogenesis as reported in hepatocyte culture (Agiuset al., 1986).
Cholesterol biosynthesis is undertaken by the body thus; excessive intake of cholesterol is non-essential as elevated blood cholesterol remains a major risk factor for atherosclerosis. More recent analysis suggests an association between elevated serum cholesterol and ischemic stroke. In the Honolulu Heart Program, data available from 6,352 men followed for an average of 15 years showed a continuous increase in risk of thromboembolic stroke and levels of serum cholesterol (Benfanteet al., 1994). In eastern Asian populations with a range of serum cholesterol levels corresponding to the lower two thirds of western populations, increasing cholesterol concentrations are associated with a higher risk of non-hemorrhagic stroke (Eastern stroke, 1998).
High levels of triglycerides in the blood could lead to hypertriglyceridemia (HTG) and it is commonly encountered in clinical practice as it is a common cause of acute pancreatitis (Amanda et al., 2013). Recent genetic research has elucidated the polygenic nature of most cases of HTG, although the rare monogenic forms cause severe HTG and are informative biologically and biochemically, epidemiologic evidence links HTG with Cardiovascular diseases risk (Amanda et al., 2013). Hypertriglyceridemia (HTG) is a common clinical diagnosis, sometimes defined when plasma triglyceride (TG) concentration rises above a threshold value, such as the 90th or 95th percentile for age and sex. HTG frequently co-exists with secondary conditions, including poor diet, alcohol use, obesity, metabolic syndrome, and type 2 diabetes (Yuan et al., 2007; Hegeleet al., 2009). HTG is sometimes classified as ―primary, when a familial or inherited basis is suspected, or ―secondary, when one or more secondary factors contribute to the clinical presentation (Yuan et al., 2007). Genetic factors can influence the severity of the plasma TG elevation in the presence of a secondary factor (Hegeleet al., 2009).
Xiong et al.(2015), found out that HDL-apoCIII has a positive and significant association with Coronary heart diseases (CHD). There were also some clinical studies found that HDL-apoCIII was significantly higher in CHD patients than in non-CHD patients, which can be used to predict the occurrence and progression of CHD, as well as the recurrent cardiovascular event (Sacks et al., 2000; Jensen et al., 2012; Chang et al., 2012) Oxidized LDL induces the formation of foam cells and fatty streaks in the vessel wall which is the hallmark of initiation of atherosclerosis (Riley et al., 2008).
Due to the increasing demand for livestock meat and the temptation to improve weight gain and feed efficiency in meat producing animals, the use and abuse of corticosteroids such as dexamethasone are being practiced by farmers for lucrative purposes. This, however, imposes several risks on human health.
Lipid profile (total cholesterol, triglycerides, HDL-cholesterol and LDL-cholesterol) was also seen to be abnormal in the dexamethasone fattened livestock due to the effect of the steroid. The elevation of the serum lipid profile poses several risks to human health which include; cancer, reproductive defects, cardiovascular diseases and other endocrine disruption outcomes. This observation makes the livestock hazardous for consumption.
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