Blog By: Manasi Joshi
There are 9 calories in 1 gram of Fat. The double of Carbs and Protein. That is why it was recommended earlier to cut down on your fat intake if you are into weight loss, as the total calorie of that food item comes down drastically if the oil is reduced. Dietary fat is important for many body processes. It helps in transportation of some vitamins and in production of some hormones. Fat-soluble nutrients, such as vitamins A, D, E, and K and the carotenoids, rely on fat for proper absorption. It gives the feeling of satiety; protective insulation is given by subcutaneous fat, which is below your skin, and protective cushioning by the thin layer of fat that covers the internal organs
Groups of Fats
Dietry fats can be classified into four groups:
Saturated Fatty Acids ( SFA ) :
They are solid at room temperature. Exception is coconut oil because of the short chain fatty acids. SFA contain the maximum number of Hydrogen that the chain can hold. The level of saturation determines the consistency of the fat at room temperature. Food sources are whole milk, cream, ice cream, butter, cheese, egg-yolk, red meat, lard, margarine, chocolates, rich desserts, coconut and coconut oil.
Mono Unsaturated Fatty Acids (MUFA) :
Contains only one double bond. Oleic Acid (n9 – omega9) is the most common MUFA. It is technically not an essential fatty acid as the body can produce a limited amount if the essential fatty acids – n3 and n6 are present. N9 plays an important role in lowering cholesterol levels. The oil made by our skin gland is the same n9 found abundantly in olive oil. Food sources are Olive Oil, canola oil, peanut oil, peanuts, almonds and avocados, poultry, eggs
Poly Unsaturated Fatty Acids ( PUFA ) :
Contain two or more double bonds. They are mainly of two types n3 and n6 fatty acids. They play many important functions in the body. They are essential fatty acids as they cannot be produced by the body
Trans Fatty Acids
Trans fats are made when liquid oil has hydrogen added. The process makes a more solid fat that is more versatile than liquid oils, aids in preserving the freshness of products, and, in commercially prepared foods, provides a taste and texture similar to regular fat. Despite these desirable characteristics, research has found trans fats are not heart-healthy fats, so in the past few years many food manufacturers have successfully removed or reduced trans fats in their food products. Sources of trans fats include some fried foods, stick margarine, many packaged cookies, cakes, pastries and snack food.
Omega-3 Fatty Acids
Research is ongoing, but the benefits of omega-3 fats in the diet seem to include that they:
- lower triglyceride levels and reduce blood pressure, which are important risk factors in cardiovascular disease
- improve blood vessel elasticity
- keep the heart rhythm beating normally
- ‘thin’ the blood, which makes it less sticky and less likely to clot
- reduce inflammation and support the immune system
- may play a role in preventing and treating depression
- contribute to the normal development of the foetal brain.
Sources of Omega3 fatty acids are Walnuts, Flax seeds, Sardines, salmon, shrimps, soya, Brussels sprouts,
Recommended intake of dietary fat (Visible and invisible) is 25 to 35% of daily calories intake. Most of it should come from healthy oils, limiting the saturated fat intake to less than 10%.
I have listed below the recommended ratio of SFAs to MUFAs to PUFAs which is stated in some of the articles I have found.
Dietary fat composition does, indeed, have a major impact on the plasma lipid profile. However, beyond the typical call for a better balance between SFA and PUFA, it is apparent that MUFA figures in the final outcome if one attempts to induce the best plasma LDL/HDL profile in humans. Between dietary fat intakes of 20–40% en, the ideal balance would seem to approximate 1:1.3:1 for SFA : MUFA : PUFA. Calories in fats
(From the article- Dietary fat and heart health: in search of the ideal fat by KC Hayes DVM, PhD Foster Biomedical Research Laboratory, Brandeis University, Waltham, MA, USA)
While it has long been known that linoleic acid (n6) and alpha-linolenic acid (n3) are essential fatty acids which must be obtained from the diet, the story is richer than once thought. For example, while very long chain omega-3 polyunsaturated fats (docosahexaenoic acid (DHA)and eicosapentaenoic acid (EPA), (found in fatty fish and certain algae) are the most protective against sudden cardiac death, n3, the precursor to EPA and DHA that is found in the oil portion of flaxseed, soybeans, walnuts, and other plants, may be heart-protective. While saturated fat in excess increases heart disease risk, stearic acid is one type of saturated fat that has no effect on blood cholesterol levels when substituted for saturated or trans fats. Finally, moderate dietary cholesterol intake is recognized as having little effect on heart disease risk in healthy individuals (although risk may increase in people with diabetes). Plant stanols and sterols are thought to play a role in the reduction of heart disease risk among those who consume a plant-based diet.
Cholesterol is essential fats manufactured in our liver and is an essential fat in production of some hormones and cell membranes and other functions. It is found only in animal foods. The normal level of blood cholesterol is 150 to 200mg/dl. Lipoproteins act as the carriers to transfer cholesterol to and from the cells. The Low Density Lipoprotein (LDL) carries cholesterol from the liver to the cell and the High Density Lipoprotein (HDL) carries it from the cell to the liver for excretion in bile. HDL in the arterial wall also blocks LDL oxidation, thereby preventing the local damage induced by LDL accumulation. So, the terms Good and Bad Cholesterols. The ratio of LDL to HDL should the less than 4.
Triglycerides are another type of fat, and they’re used to store excess energy from your diet. High levels of triglycerides in the blood are associated with atherosclerosis. Elevated triglycerides can be caused by overweight and obesity, physical inactivity, cigarette smoking, excess alcohol consumption and a diet very high in carbohydrates (more than 60 percent of total calories). Underlying diseases or genetic disorders are sometimes the cause of high triglycerides. People with high triglycerides often have a high total cholesterol level, including a high LDL cholesterol (bad) level and a low HDL cholesterol (good) level. Many people with heart disease or diabetes also have high triglyceride levels.
|Effect of partial replacement of visible fat by ghee (clarified butter) on serum lipid profile.
Department of Physiology, All India Institute of Medical Sciences, New Delhi, 110 029.
Indian Journal of Physiology and Pharmacology [2002, 46(3):355-360]
Type: Clinical Trial, Journal Article, Randomized Controlled Trial, Research Support, Non-U.S. Gov’t, Comparative Study
A randomised controlled trial with a parallel design was conducted on 24 healthy young volunteers who were divided into two groups. After a lead-in period of 2 wk, the experimental group (n = 11; 9 male, 2 female) had for 8 wk a lacto vegetarian diet providing about 25% of the energy intake in the form of fat, of which ghee provided 10 en% and the remaining fat energy came from mustard oil and invisible fat. The control group (n = 13; 8 male, 5 female) had a similar diet except that all visible fat was in the form of mustard oil. In neither group was there any significant change in the serum lipid profile at any point in time. At 8 wk, 2 volunteers in the experimental group, and 1 volunteer in the control group had more than 20% rise in serum total cholesterol as compared to their 0 wk values. There was also an appreciable increase in HDL cholesterol at 8 wk in the experimental group, but it was not statistically significant. Consuming ghee at the level of 10% in a vegetarian diet generally has no effect on the serum lipid profileof young, healthy, physically active individuals, but a few individuals may respond differently.
- contains 75% MUFA,(highest of all the oils), along with 15% saturated fat, 9% omega-6 linoleic acid and 1% omega-3 linolenic acid.
- The Extra virgin olive oil is also rich in antioxidants.
- Since extra virgin, cold pressed olive oil has comparatively lower smoking point, it is best used as salad dressings or for light sautéing and stir frying.
- Olive oil has indeed withstood the test of time and is still considered one of the best.
Groundnut/Peanut Oil (GNO)
- contains 48% MUFA, 18% saturated fat and 34% omega-6 linoleic acid.
- Like olive oil, groundnut oil is relatively stable but again it has a good percentage of omega-6, so use of groundnut oil should be limited.
- contains 42% MUFA, 15% saturated fat, and 43% omega-6 linoleic acid.
- Sesame oil is similar in composition to groundnut oil.
- It can be used for frying because it contains unique antioxidants that are not destroyed by heat.
- However, the high percentage of omega-6 is again a major drawback.
- Sesame oil (SO) is known to be stable against oxidative deterioration and its keeping quality is mainly attributed to the presence of endogenous unsaponifiable components such as sesamolin, sesamol and sesamin (absent in other vegetable oils). A study conducted by Central Food Technological Research Institute (CFTRI), Mysore showed that sesame oil is very stable against oxidative deterioration compared to sunflower (SFO) and groundnut oils (GNO) at room temperature over a period of time.
- Blending of SO with GNO and SFO increased the shelf life of blended oils at room temperature and heated oils and the oxidative stability of blended oils.(2)
Safflower, Corn, Sunflower, Soybean and Cottonseed Oils
- all contain over 50% omega-6 and, except for soybean oil, only minimal amounts of omega-3.
- They have much lesser MUFA’s. Of these, Safflower oil contains the most omega-6 (almost 80%).
- Researchers are just beginning to discover the dangers of excess omega-6 oils in the diet, whether rancid or not.
- Use of these oils should be strictly limited.
- They should never be consumed after they have been heated, as in cooking, frying or baking.
Canola Oil / Rapeseed / Mustard
Canola oil contains 5% saturated fat (the least among all commercially available oils), 57% oleic acid, 23% omega-6 and 10%-15% omega-3(so high MUFA along with beneficial omega-3) .
The original rapeseed plant was high in erucic acid, which is an unpalatable fatty acid having negative health effects in high concentrations. ‘Canola’ is genetically altered and improved version of rapeseed. ‘Canola’ is a registered trade mark of Canadian Oil Association and contains less than 1 percent erucic acid.
Actually, another name for canola oil is LEAR (Low Erucic Acid Rapeseed) oil. In India, the “Hyola” is only hybrid ‘canola’ quality gobhisarson notified by Govt. of India recently after extensive trials by Indian Council of Agricultural Research (I.C.A.R.).
The Indian kachi ghani mustard oil has a very close composition to canola oil (given below). It has anti-oxidants, allyl-isothiocynates, phenolics (anti-bacterial properties), phytins and also absence of trans fatty acids (as it is cold pressed oil) and presence of Vitamin E, makes the mustard oil heart healthy and one of the best oils for cooking
Flax Seed Oil contains 9% saturated fatty acids, 18% oleic acid, 16% omega-6 and 57% omega-3. With its extremely high omega-3 content, flax seed oil is an excellent top-up for the lack of n3 and n-6/n-3 imbalance so prevalent globally today. New extraction and bottling methods have minimized rancidity problems. It should always be kept refrigerated, never heated, and consumed in small amounts in salad dressings and spreads.
Ghee: Though Ghee has a higher percentage of SFA’s, its n6:n3 ratio is about 4, which is very good. A study on 63 healthy physically active adult volunteers (52 men and 11 women) was conducted at AIIMS, New Delhi following a randomized controlled parallel design. The experimental group was provided ghee and mustard oil in diet for 8 weeks. Their serum total cholesterol and HDL cholesterol level increased while LDL cholesterol level did not show any change. The study did not indicate any adverse effect of ghee on lipoprotein profile.
Tropical Oils are more saturated than other vegetable oils.
Coconut oil is 92% saturated with over two-thirds of the saturated fat in the form of medium-chain fatty acids (MCT). Of particular interest is lauric acid, found in large quantities in both coconut oil and in mother’s milk. This fatty acid has strong antifungal and antimicrobial properties. Coconut oil protects tropical populations from bacteria and fungus so prevalent in their food supply; as third-world nations in tropical areas have switched to polyunsaturated vegetable oils, the incidence of intestinal disorders and immune deficiency diseases has increased dramatically.A report published in the American Soc.for Nutritional Sciences, showed that MCT may increase energy expenditure, may result in faster satiety and facilitate weight control when included in the diet as a replacement for fats containing (Long Chain Triglycerides) LCT) However, more work is required to establish whether prolonged consumption of MCT helps decrease in body weight or helps control weight gain.
Palm oil is about 50% saturated, with 41% MUFA and about 9% linoleic acid. Currently palm oil is a major edible oil commodity in more than 132 countries worldwide.
Highly saturated tropical oils do not contribute to heart disease but have nourished healthy populations for millennia. Human beings have been consuming saturated fats from animals products (meat, milk, butter)and the tropical oils for thousands of years; In fact, it is the advent of modern processed vegetable oil accompanied with lack of physical activity that is associated with the epidemic of modern degenerative disease. The saturated fat scare has forced manufacturers to abandon these safe and healthy oils in favor of hydrogenated soybean, corn, safflower and sunflower oils.
Cooking with oil
Heating oil changes its characteristics. Oils that are healthy at room temperature can become unhealthy when heated above certain temperatures. When choosing cooking oil, it is important to match the oil’s heat tolerance with the cooking method.
A 2001 parallel review of 20-year dietary fat studies in the United Kingdom, the United States of America, and Spain found that polyunsaturated oils like soya, canola, sunflower, and corn oil degrade easily to toxic compounds when heated. Prolonged consumption of burnt oils led to atherosclerosis, inflammatory joint disease, and development of birth defects. The scientists also questioned global health authorities’ recommendation that large amounts of polyunsaturated fats be incorporated into the human diet without accompanying measures to ensure the protection of these fatty acids against heat- and oxidative-degradation.
Palm oil contains more saturated fats than canola oil, corn oil, linseed oil, soybean oil, safflower oil, and sunflower oil. Therefore, palm oil can withstand the high heat of deep frying and is resistant to oxidation compared to highly unsaturated vegetable oils. Since about 1900, palm oil has been increasingly incorporated into food by the global commercial food industry because it remains stable in deep frying or in baking at very high temperatures and for its high levels of natural antioxidants.
Have the reins been loosened on fat so much that “splurge” is the new health trend? No, calories from all sources count. As scientific evidence regarding the benefits and risks of particular fatty acids continues to evolve, the current consensus is that moderation applies to dietary fat as much as other nutrient and lifestyle choices. Importantly, fat is not to be feared; it is a critical component of a healthful diet. The Institute of Medicine notes the acceptable range for fat consumption among adults is 20 to 35 percent of total calories. For an adult consuming a 2,000-calorie diet, the range would be between 45 and 78 grams of fat per day.
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