الفهرس 
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Abstract
The modern pharmacological therapy is costly and associated with multiple side effects resulting in patient non-compliance. Thus there is a need to explore alternative therapies particularly from natural sources as these are cost effective and possess minimal side effects. In this attention, Oats, formally named Avena sativa, is a type of cereal grain from the Poaceae grass family of plants. While oats are suitable for human consumption as oatmeal and rolled oats, one of the most common uses is as livestock feed. Oats are usually considered a secondary crop, i.e., derived from a weed of the primary cereal domesticates, then spreading westward into cooler, wetter areas favorable for oats, eventually leading to their domestication in regions of the Middle East and Europe. Oats are best grown in temperate regions. They have a lower summer heat requirement and greater tolerance of rain than other cereals, such as wheat, rye, or barley, so they are particularly important in areas with cool, wet summers, such as Northwest Europe and even Iceland. The grain refers specifically to the edible seeds of oat grass, which is what ends up in our breakfast bowls. Whether loved or hated for their mushy yet hearty texture when cooked, oats are most prized for their nutritional value and health benefits. The Food and Drug Administration (FDA) allows the use of a health claim on food labels associating a reduced risk of coronary heart disease with the consumption of β-glucan soluble fiber from whole grain oats. Oatmeal is also a desired asset to those trying to lose weight and control hunger levels due to its high water and soluble fiber content.
Obesity is an abnormal accumulation of body fat. The prevalence of overweight and obesity is commonly assessed by using body mass index (BMI), defined as the weight in kilograms divided by the square of the height in meters (kg/m2). A BMI over 25 kg/m2 is defined as overweight, and a BMI of over 30 kg/m2 as obese. These markers provide common benchmarks for assessment, but the risks of disease in all populations can increase progressively from lower BMI levels. According to World Health Organization, more than 1.9 billion adults worldwide were overweight, including 650 million who were obese, in 2016. The prevalence of obesity tripled worldwide between 1975 and 2016. In Egypt, the estimated annual deaths due to obesity was about 115 thousand (19.08% of the total estimated deaths in 2020. DALYs attributable to obesity may have reached 4 million in 2020. The economic burden imposed by obesity is around 62 Billion Egyptian pounds annually.This value is the cost of treating diseases attributable to obesity in adults.
Excessive body weight i.e. obesity, is associated with various diseases, particularly cardiovascular diseases, diabetes mellitus type 2, obstructive sleep apnea, certain types of cancer, osteoarthritis and asthma. Also, obesity increases the risk of many physical and mental conditions. These co-morbidities are most commonly shown in metabolic syndrome, a combination of medical disorders which includes: diabetes mellitus type 2, high blood pressure, high blood cholesterol, and high triglyceride levels. Complications are either directly caused by obesity or indirectly related through mechanisms sharing a common cause such as a poor diet or a sedentary lifestyle.
Oats contain several components that have been proposed to exert health benefits. The primary type of soluble fiber in oats is β-glucan, which has been researched to help slow digestion, increase satiety, and suppress appetite. Beta-glucan can bind with cholesterol-rich bile acids in the intestine and transport them through the digestive tract and eventually out of the body. Whole oats also contain plant chemicals called phenolic compounds and phytoestrogens that act as antioxidants to reduce the damaging effects of chronic inflammation that is associated with various diseases like cardiovascular disease and diabetes. Oats are associated with heart health benefits, but research shows differing degrees of benefit. A systematic review of nine randomized controlled trials did not find adequate evidence to show that whole grain diets including oats reduced the risk of cardiovascular disease or lower blood cholesterol or blood pressure. β-glucan fiber found by high level in oat may help to prevent sharp rises in serum glucose and insulin levels after eating a meal, and may benefit gut health as the fiber is broken down and fermented by intestinal bacteria. Fiber in oat (soluble and insoluble) contributes to bowel regularity and the prevention of constipation. It has the ability to increase the weight and water content of stool, making them easier to pass. Cereal fibers, as found in wheat bran and oat bran, are considered more effective than fiber from fruits and vegetables. The breakdown and fermentation of β-glucan oat fiber has also been reported to increase the diversity of gut microbiota. This may in turn improve certain digestive issues such as diarrhea, constipation, and irritable bowel syndrome. However, more research is needed to evaluate the role of various microbiota on digestive conditions. β-glucan fiber attracts water and increases the viscosity (or thickness) of digested food, which increases the volume of food in the gut. This slows down digestion and the rate that nutrients are absorbed, which in turn increases satiety. Short-chain fatty acids produced from bacteria that ferment beta-glucan fibers may also increase satiety through a chain reaction of events that regulate appetite hormones. Although several randomized controlled trials have shown that intake of β-glucan oat fiber can increase satiety, other studies have not consistently shown that intake of oats produces the desired outcome of significant weight loss.
Aim of study
Despite the several studies that dealt with the relationship between eating oats and obesity, many aspects related to this topic are still not fully understood. Therefore, the current study aims to conduct chemical and nutritional studies on oat flour. Also, the study of the relationship of consumption on oat flour and obesity, and the interpretation of some of the mechanisms related to this problem, will be in the scope of this study.
Experimental design
All the experiments were a complied with the rulings of the Institute of Laboratory Animal Resources, Commission on life Sciences, National Research Council (NRC, 1996). Rats (n=36 rats), 145-155g per each, were housed individually in wire cages in a room maintained at 27 ± 5 0C, relative humidity (55±5%), a 12-hr lighting cycle and kept under normal healthy conditions. All rats were fed on basal diet (BD) for one-week before starting the experiment for acclimatization. After one week period, the rats were divided into two main groups, the first group (group 1, 6 rats) still fed on BD and the other main group (36 rats) was with high fat diet (HFD, protein, 20%; carbohydrates, 35% and fat, 45% of total calories, Research Diets, Inc. NJ, USA) for 8 weeks which classified into sex sub groups as follow: group (2), fed on HFD as a positive control; group (3), fed on HFD containing 100 % flour (WF); groups (4-7) fed on HFD containing composite WF plus 5, 10, 15 and 20 % of oat flour (OF), respectively. Body weight gain (BWG, as percent of initial weight) was assayed every week in rats.
Results
Chemical composition of control and composite wheat flour
With the increasing addition of oat flour up to 20%, the value of crude fat, fiber, ash and carbohydrates in the sample were significant (p≤0.05) increasing in comparison with the control sample (wheat flour). Moisture and total protein contents were recorded the opposite direction. On the other side, nutritional properties of control and composite wheat flour samples may be altered as the result of such chemical composition alterations. These properties include the total energy (Kcal/100g), the daily requirement of adult man from energy (GDR/energy) and from protein (GDR/protein), percent satisfaction of the daily requirements of adult man in energy (P.S./energy) and protein (P.S./protein). With the increasing addition of oat flour up to 20%, the value of total energy, GDR/energy and GDR/protein in the sample were significant altering in comparison with the control sample.
Mineral composition of control and composite wheat flour
With the increasing addition of oat flour up to 20%, the value of several minerals including Ca, K,Mg, P, Fe, Zn, Na, Mn and Cu in the sample were significant (p≤0.05) increasing in comparison with the control sample (wheat flour). The high significant increasing was recorded for Mg, P and Fe which recorded 74.33, 65.53 and 175.66% when compared with the control wheat flour samples. Also, increasing was noticed for some important trace metals such Zn, Mn and Cu.
Vitamins content of control and composite wheat flour
With the increasing addition of oat flour up to 20%, the value of several vitamins including thiamine (B1), riboflavin (B2), niacin (B3), pyridoxine (B6), folate (B9), cyanocobalamin (B12) and vitamin E in the sample were significant (p≤0.05) increasing in comparison with the control sample (wheat flour). The rates of increasing was ranged 33.87 to 67.36% when compared with the control wheat flour samples.
Bioactive compounds and dietary fiber content in wheat and oat flours
Dietary fiber was the most largest compound (7.45 ± 0.67 and 12.44± 0.1.02 mg. 100 g-1) followed by carotenoids (2.76 ± 0.27 and 4.97 ± 0.18 mg. 100g-1), β-glucans , 0.45 ± 0.11and 4.46± 0.42 mg. 100g-1), flavonoids (1.98 ± 0.42 and 2.36 ± 0.30 mg catechin equivalent. 100 g-1), and Phenolics (2.14 ± 0.37 and 3.35 ± 0.28 mg gallic acid equivalent. 100 g-1) in wheat and oat flours, respectively.
Biological Activities
Antioxidant activities of aqueous control and composite wheat flour extracts
Oat flour samples sample showed high antioxidant activity (AA, 63.78 ± 1.12%) and wheat flour showed low one (AA, 29.78 ± 1.56%). With the increasing addition of oat flour up to 20%, the value of AA in the samples were significant (p≤0.05) increasing in comparison with the control sample (wheat flour) which ranged 34.75 ± 1.70 to 46.76 ± 0.87%. The AA in OF is correlated with the reasonable content of different bioactive compounds such as phenolics, flavonoids and carotenoids.
DPPH radical scavenging activity
Oar flour possessed the highest scavenging activity while wheat flour samples exhibit the lowest one.With the increasing addition of oat flour up to 20%, the value of RSA in the samples were significant (p≤0.05) increasing in comparison with the control sample (wheat flour) which ranged. At a concentration of 100 μg/mL, the RSA of wheat and Oat flours were 26.12 and 60.96, respectively, whereas at the same concentration, the standard BHT was 90.29%. For the IC50, the oat flour was recorded 44.80 μg/mL while the control and composite wheat flour samples not detected. The IC50 of BHT (standard) was 88.93 μg/mL. The free radical scavenging activity of different tested samples and standard was in the following order: standard (BHT) > oat flour > composite flour > wheat flour.
Biological studies
The effect of oat flour on body weight of obese rats
Feeding of rats on diet induced obesity (DIO) leads to increase the body weight (BW) than the control group. At the end of the experiment (8 weeks), rats of the normal group recorded 74.95% of baseline for the body weight while obese group was 128.50% of baseline. Alteration of diets starch with oat flour by the level of 5, 10, 15 and 20% exhibited significant (p≤0.05) decreasing on BW of the obese rats which recorded 109.53, 99.45, 91.78 and 79.18% of baseline, respectively. The higher effect on weigh decreasing was recorded dose-response effect for oat flour.
Effect of control and composite wheat flour on serum lipid profile of obese rats
Obesity induced a significant increased (p≤0.05) in TG (41.70%), TC (37.60%), LDL (116.89%), VLDL (41.70%) while significant decreased (p≤0.05) in HDL (-36.92%) compared to normal controls. Replacement of wheat flour with oat flour by 5, 10, 15 and 20% induced significant (p≤0.5) improvements on blood lipid profile through decreasing the TG, TC, LDL and VLDL by the ratio of 29.36, 22.00, 19.43 and 14.48%; 29.16, 24.00, 15.63 and 14.26%; 88.36, 73.26, 52.42, 44.62; and 29.36, 22.00, 19.43 and 14.48%, respectively. The opposite direction was observed for the HDL levels. The improving of the blood lipid profile disorders induced by obesity in rats was increased with the increasing of oat wheat levels.