The quantity and quality of fat in the diet play a critical role in maintaining human health. Several studies in literature have directly implicated the amount and type of fat intake to specific diseases such as cardiovascular disease, hypercholesterolemia, cancer, high blood pressure and obesity. The largest contributor to this is TRANS FAT.
› Fats and Oils as Nutrients
Countless reports concerning the negative effects of fats and oil consumption have shifted today’s dietary focus towards fat minimization. This is unfortunate, any student of nutrition knows that fats are essential dietary components. Except for trans fat which should be avoided as much as possible, other fats are essential nutrients in our balanced diet. Excessive fat intake is detrimental but the recent success of some diet programs such as the Atkins Diet has shown a reduction of carbohydrates and quality/quantity of fat and can have a positive effect on weight loss and general health.
The functional role of fat in the diet is at least threefold. First, fat provides calorie density to the diet. One gram of fat gives 9 Kcal of energy. Carbohydrates and proteins, provides only 4 Kcal of energy per gram. Hence fat provides calorie density to the diet. Secondly, fats are essential in the diet for the absorption and mobilization of fat-soluble vitamins such as vitamin A, E, & K and fat-soluble antioxidants. These vitamins are not utilized by the body, if fat is not available in the diet. Thus fat is a vehicle carrying the fat-soluble vitamins, nutrients and antioxidants in the body. Thirdly, vegetable oils are the only sources of essential fatty acids to the body.
Essential fatty acids (EFA) are those fatty acids, which the body cannot synthesize and need to be supplied through diet. EFA’s are the precursors for a group of chemically related compounds, known as prostaglandins that are synthesized in the body from EFA. If EFA is not supplied through diet to the body, the body cannot synthesize prostaglandins. Prostaglandins play a key role in regulating many physiological processes in the body, such as controlling blood pressure, vascular damage in the brain and the heart, preventing blood clot in the arteries, lowering cholesterol, uterine contractions during child birth and menstrual cycles, inflammation and other conditions. Fourthly, fat in the diet imparts certain textural qualities, taste and palatability to the food. Fats and oils are integral lubricants of foods in two ways: through use as release agents as a part of the cooking process and as a lubricant during mastication (chewing). Fats and oils modify flavour release and improve palatability.
› Functionality of Dietary Fats
The type of fat used impacts all the functional factors. Fat molecules consist of three fatty acids linked to a glycerol backbone, resulting in triglycerides. The fatty acids consist of varying carbon chains ranging from 12 carbon atoms to 18 carbon atoms, and with unsaturation raging from 0 to 3 double bonds. These triglycerides are termed as fat or oil. Depending on the nature of fatty acids, the fat can be a solid fat or liquid fat at room temperature. The solid fat will have more percentage of saturated fats in the triglycerides and the liquid fats will have more unsaturated fats. The term important to stability and health relate to the degree of saturated and unsaturated fatty acids present in oil or fat.
Saturated fatty acids (SFA) have no double bonds between carbon and hydrogen; unsaturated fatty acids are those, which have one, two or three double bonds between the carbon and hydrogen in the chain. When there is one double bond it is termed monounsaturated fatty acids (MUFA). More than one double bond is termed polyunsaturated fatty acids (PUFA). A Trans Fat is when unsaturated fat bonds have been deformed to resemble a saturated fat. Your body doesn't know how to process trans fat and it disrupts all your metabolic processes.
When a fat is rich in SFA, it is solid at room temperature, such as coconut and palm oil and when it is rich in MUFA and PUFA it is liquid at room temperature. All solid fats tend to increase cholesterol and liquid fats tend to favour cholesterol reduction.
› Fat Requirements Fat consumption primarily occurs through salad and cooking oils, followed by frying fats and bakery shortenings. Now let us look into the quality and quantity of fat required in a balanced diet. According to the American Heart Association (AHA) the optimum intake of fat for an adult is 30% of the total caloric intake, to come from fat. It means an adult ingesting 2000 calories of diet should be getting 600 calories (30%) or 60-65 grams of fat per day. This quantity of fat per day is required in a balanced diet to maintain good health.
Coming to the quality of fat, the 30% of fat should include, not more than 8-10% Saturated fat (SFA), 10-12% Monounsaturated fat (MUFA) and not more than 10% of Polyunsaturated fat (PUFA). Among the 10% PUFA at least 3% should come from n-3 fatty acids (Omega 3), which are part of the PUFA family and as 0% Trans Fat or as little as possible. Thus the quality and quantity of fat requirements to the body is well defined.
› Rice Bran Oil (RBO)
Rice bran oil is popular in several countries such as Japan, India, Korea, China and Indonesia as cooking oil. It has been shown that RBO is an excellent cooking and salad oil due to its high smoke point and for its delicate flavour. RBO is known for reducing cholesterol and cardiovascular diseases. The nutritional qualities and health effects of rice bran oil are discussed below, and are compared with other commonly used cooking oils.
› Nutritional Qualities of Rice Bran Oil (RBO)
Fats and oils act as a heat transfer medium, but also become a component of the food. Because of this dual function, the oil must meet a number of requirements. It must have good thermal and oxidative stability. It must also have good flavour, good shelf life and acceptable cost. Finally, it must have consumer appeal.
There are two types of fats we consume in our daily diets. One is invisible fat, which comes from all natural fat present in vegetables, fruits, cereals, poultry, meat, fish and other foods. The other one is visible fat, which is the cooking medium, salad oils and other added sources of oils. We have no control over the invisible fat intake. However, the quantity and quality of visible fat intake need to be controlled to maintain better health.
Comparing known vegetable oils and rice bran oil to the fatty acid profile recommended by the American Heart Association, we find RBO is the closest to the AHA recommendations. AHA recommendations are that SFA in the diet above 10% is not good, as it tends to raise the cholesterol levels. SFA below this 10% level is good for health. MUFA at 10% and above is good as it maintains cholesterol levels, but below this level is not good for health. PUFA at the 10% level is good, but too much of PUFA is known to generate free radicals and aid carcinogenesis and hence is not good for health. PUFA below 10% is not good, as the body needs essential fatty acids for its metabolism.
Another component of fats and oils is the unsaponifiable fraction (unsap), which contains the antioxidants and micronutrients of the oil. RBO has 4.2% of unsap, whereas all other oils have unsap less than 1-2%. It is the combination of an excellent essential fatty acid profile and a high unsaponifiable fraction that brings about cholesterol reduction. In addition to this RBO does not produce any allergenic reactions when ingested, as does several oils. RBO has the highest cholesterol reduction capacity of any other oil.
RBO unsaponifiable fraction is rich in vitamin E complex, tocopherols and tocotrienols, a unique antioxidant known as gamma oryzanol, high quantities of phytosterols, polyphenols and squalene. RBO has a very good shelf life compared to other cooking oils because of these antioxidants. These compounds are nutritionally very valuable and it has been shown to be responsible for the hypocholesterolemic effect. RBO appears to be the richest source of tocopherols and tocotrienols. Hence RBO not only has a good fatty acid profile, but also is a rich source of antioxidants and micronutrients.
› Hypocholesterolemic Effect of RBO Studies have shown that RBO in the diet significantly reduces LDL cholesterol and triglycerides; it increases HDL cholesterol (good cholesterol), inhibits platelet aggregation and prevents cardiovascular diseases. Clinical studies from Japan, India and the U.S.A. have confirmed these results and named RBO as ”Health Oil”. In every 1% reduction in cholesterol, there was a 2% decrease in the risk of coronary heart disease. Thus RBO in the diet significantly reduces cholesterol without any side effects known to exist with pharmaceutical drugs and is the healthiest of all oils for human consumption.
› Safety of RBO
A safety evaluation of RBO was carried out by the FDA/WHO protocol. It was proved to be safe for human consumption, without any side effects. RBO has earned GRAS status in the U.S.A.
› Taste and Acceptability
Foods were prepared in several ways, such as deep fried, pan fried, baked foods and salad dressings in rice bran oil. Similar foods in peanut oil, palm oil, soybean oil, olive oil and corn oil were prepared and compared. Taste panel, color, appearance, smell and texture were the criteria for the acceptability of the products. RBO prepared foods scored highest in all the panels, also rated highest shelf life when compared to the other products. RBO was found to be more economical as less oil is absorbed in the food, almost 20% less when compared to other oils. This lower absorption rate is related to the viscosity of RBO, a physical quality of the oil, which makes it light and non-sticky. The high smoke point prevents the isomerization and polymerization of the fatty acids and also the generation of free radicals at high temperatures. There are many beneficial aspects of RBO that attracts consumers to utilize RBO in their diet.
Check product ingredients for shortenings and hydrogenated oil as these contain Trans Fats. Ask restaurants what they are using to fry or prepare your meal. It makes a difference and your good health depends on it.