Dietary fats


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  • Causes under investigation for insulin resistance
  • Dietary fats

    1. 1. Dr Shailendra Meena PG Student L N Medical College and J K Hospital Bhopal
    2. 2. Introduction  Fats are best known members of a chemical group called the lipids.  The term lipid is applied to a group of naturally occurring substances characterized by their insolubility in water, greasy feel and solubility in organic solvents like ether, chloroform, benzene or other fat solvents.  The term lipid was first used by the German biochemist Bloor in 1943
    3. 3. Introduction cont….  In normal human subjects, fats constitutes between 10-15 % of body weight.  Most of the body fat(99%) is stored in the adipose tissues.  Fat present in the diet or in human body are in the form of fatty acids, triglycerides, phospholipids and cholesterol.  Each fat molecule is made up of four compounds, one alcohol and three fatty acids.
    4. 4. Functions of Fats 1) Insulation and Padding:  Fats are deposited in adipose tissue, subcutaneous tissue and abdominal cavity  Fats surrounds the organs and laced throughout muscle tissue  Fats functions like insulating material against cold  Fats protects vital organs against physical injuries by forming a padding around them
    5. 5. Functions of Fats cont… 2. Energy:  The primary function of fat is to supply energy.  It is a very concentrated source of energy.  Each gram of fat when oxidized yields approximately 9 kcal, twice as much energy as one gram of carbohydrate or protein.  Fat specially supply energy in between the meals and during starvation.
    6. 6. Functions of Fats cont… 3. Carriers of fat soluble vitamins:  Dietary fat is a carrier of the fat soluble vitamins-A,D,E and Vitamin K  Fat is also necessary for the absorption of Vitamin A and its precursor, carotene.
    7. 7. Functions of Fats cont… 4. Satiety function:  Fats improves the palatability of the diet.  It slows digestion--resulting in satiety (a sense of fullness and satisfaction after eating).  In the absence of fats the food become non palatable.
    8. 8. Functions of Fats cont… 5. Fats provide essential fatty acids which the body can’t manufacture. 6. Fats are the constituents of cell membrane and regulates the membrane permeability. 7. Fats are also function as cellular metabolic regulators in the form of prostaglandins and steroid hormones.
    9. 9. Sources of dietary FATS Fats of animal origin : Ghee, butter, milk, cheese, eggs and fat of meat and fish Fats of plants origin: Groundnut oil, Coconut oil, Palm oil, Mustard oil, Canola oil, Sesame oil, Corn oil Other Sources: Cereals, Pulses, Oil seeds (Sunflower, Safflower, Soyabean, Cottonseeds), rice bran and Leafy green vegetables
    10. 10. Classification of Fats Mainly classified into two ways: A) Based on bio chemical composition B) Based on nutritional significance
    11. 11. Bio chemical classification of fats A. Simple Lipids: Simple lipids are defined as those which yield only one or more fatty acids and an alcohol on hydrolysis. Example: 1) Fats and Oils, also known as triglycerides 2) Waxes
    12. 12. Bio chemical classification of fats cont…. B. Compound Lipids: Compounds lipids are those lipids which contain in addition to fatty acids and glycerol, some other organic compounds such as phosphoric acid, nitrogenous base, sugars and Proteins. Example: Phospholipids, Sphingolipids, Glycolipids, Sulpholipids and lipoproteins
    13. 13. Bio chemical classification of fats cont…. C. Derived Lipids: These are the derivatives obtained on the hydrolysis of simple and compound lipids which possess the characteristics of lipids. Example: Fatty acids, mono and diacylglycerols, lipid soluble vitamins, steroid hormones and ketone bodies
    14. 14. Nutritional classification of Fats
    15. 15. Digestion of Fats Five different phases:  Hydrolysis of triglycerides (TG) to free fatty acids (FFA)     and monoacylglycerols Solubilization of FFA and monoacylglycerols by detergents (bile acids) and transportation from the intestinal lumen toward the cell surface Uptake of FFA and monoacylglycerols into the cell and resynthesis to triglyceride Packaging of TG’s into chylomicrons Exocytosis of chylomicrons into lymph
    16. 16. Enzymes Involved in Digestion of Lipids  lingual lipase: Hydrolyze short and medium chain fatty acids.  Gastric Lipase: Hydrolyze Long, medium and short chain fatty acids.  Pancreatic lipase: major enzyme affecting triglyceride hydrolysis  Colipase: protein anchoring lipase to the lipid  lipid esterase: secreted by pancreas, acts on cholestrol esters, activated by bile  phospholipases: cleave phospholipids, activated by trypsin
    17. 17. Digestion of Fats cont….
    18. 18. Metabolism of Fats cont…
    19. 19. Products of Fats Metabolism 1. 2. 3. 4. 5. Fatty Acids Triglycerides Phospholipids Sterols Lipoproteins
    20. 20. 1.Fatty Acids  Saturated Fatty Acids  Unsaturated Fatty Acids – Monounsaturated Fatty Acids - Polyunsaturated Fatty Acids
    21. 21. Saturated fatty acids • Saturated fatty contains no double bonds (having no points of Unsaturation).
    22. 22. Saturated fatty acids continues.. Saturated fats are considered as harmful fats because they increases total cholesterol level and TGs level. Sources : Animal foods such as meat, poultry and full-fat dairy products Tropical oils such as palm and coconut RDA: Less than 10% of total energy intake per day.
    23. 23. Unsaturated fatty acids Fatty acid with one or more points of Unsaturation. Unsaturated fats are found in foods from both plant and animal sources.
    24. 24. Monounsaturated fatty acids  Fatty acid containing one point of Unsaturation.  They are considered as beneficial for human health.  Replacing SFA with MUFA reduces LDL cholesterol concentration and total cholesterol / HDL cholesterol ratio.  Replacing carbohydrate with MUFAs increases HDL cholesterol concentration.  Sources: vegetable oils such as olive, canola, and peanut.  RDA: By difference
    25. 25. Classification of MUFAs Monounsaturated Fatty acids are of two type: 1) Cis- unsaturated fatty acids 2) Trans- unsaturated fatty acids
    26. 26. Cis- unsaturated fatty acids Natural unsaturated fatty acids have Cis- double bonds. The unsaturated fatty acids can’t bunch tightly together. The bend helps the fat stay liquid rather than solid. Significance –  Decreases total cholesterol and TGs level.  Increases HDL level.
    27. 27. Trans unsaturated fatty acids Unsaturated fatty acids (MUFAs and PUFAs) containing one or more double bonds in trans configuration are called trans fatty acids (TFAs). Hydrogen atoms are on the opposite sides of the molecule.
    28. 28. Trans fatty acids cont…. Produced during partial hydrogenation of vegetable oils. Partially hydrogenation of vegetable oil results in longer shelf life of a product. less rancidity and oxidation when exposed to heat and light. Also developed in vegetable oils during frying and heating. Sources: “Formation of trans fatty acids in edible oils during the frying and heating process” (Vol.123, No.4, 15Dec.2010, pp 976-982, doi: 10.1016/j.foodchem.2010.05.048)
    29. 29. Why trans fatty acids are harmful … Trans fatty acids are much more linear than cis fatty acids, so their melting points are higher and studies have shown that trans fats may act similarly to saturated fats. Increases the ratio of total cholesterol to HDL cholesterol, a powerful predictor of the risk of CHD A recent study suggests trans fats harm the cardiovascular system by triggering inflammation in blood vessels. In addition, trans fat may increase risk for cancers of the breast and prostate.
    30. 30. Trans fatty acids cont…. Sources: 1. Spreads: Butter, margarine 2. Package foods: Cake mixes, Biscuits 3. Soups: Plain soups, Noodle soups 4. Fast foods: Deep fried Fish and Chicken, Pancakes 5. Frozen foods: Frozen pies, pot pies, wafers 6. Backed foods: Cakes, doughnuts 7. Chips and Crackers: Potato chips 8. Cookies and Candy: Choc0late bars, Cream filled cookies
    31. 31. RDA for Trans fatty acid The American Heart Association recommends limiting total trans fat intake to less than 1 percent of our total daily calories, which means less than 2 grams per day for many people. Since most of us get that much from naturally occurring trans fat in red meat and dairy, we need to cut trans fat from other foods to zero. That means checking every ingredient list and bypassing foods that declare any hydrogenated oils or partially hydrogenated oils, even if it states "trans fat 0 g" on the nutrition panel.
    32. 32. Polyunsaturated fatty acids Polyunsaturated fatty acids are those fatty acids where Unsaturation occur more than two points. They possess protective role on human health. considered as beneficial for consumption.
    33. 33. Polyunsaturated fatty acids cont…  Increase esterification process of cholesterol & prevents its absorption.  By increasing the synthesis of eicosanoids, acts as an anti platelet aggregating factor, so decreases the chances of clot formation.  Decreases the synthesis of the precursor of VLDL AND TGs.  Increases clearance of LDL cholesterol.
    34. 34. Polyunsaturated fatty acids cont… Sources: Found in nuts and vegetable oils such as safflower, sunflower, and soybean, and in fatty fish. RDA: 6-10% of total energy intake per day.
    35. 35. Essential Fatty Acids: There are two PUFAs which cannot be synthesized in the body and required in the preformed state in diet for growth and maintenance of normal skin. These are called Essential fatty acids and include linoleic acid and linolenic acid. The term essential fatty acid was introduced by Burr and Burr.
    36. 36. Essential Fatty Acids cont…..  Sources of linoleic acid:  Leafy vegetables, nuts, vegetable oils (seasame, corn oil, sunflower, soybean), poultry fat  Sources o f linolenic acid:  Nuts, seeds (soybean, walnuts, flaxseed) and oils (soybean, canola)  RDA: Minimum intake levels for essential fatty acids estimated to be 2.5% E LA and 0.5% E ALA
    37. 37. Omega 6 Fatty Acid- Linoleic acid RDA: 5-8% of total energy intake per day Sources: Safflower oil Sunflower oil Corn oil Soybean oil Pros: - helps lower LDL cholesterol; thereby lowering our risk of heart disease - helps make our blood "sticky" so it is able to clot - support skin health
    38. 38. Omega 6 Fatty Acid (continued) But when omega-6s aren't balanced with sufficient amounts of omega-3s… Cons: - Excessive amounts increase the inflammatory response in our bodies - Can exacerbate conditions like arthritis, lupus and perhaps some cancers - When blood is too 'sticky,' it promotes clot formation― increasing the risk of heart attack and stroke
    39. 39. Omega 3 Family of Fatty Acids ALA (alpha linolenic acid) RDA: 1-2 % of total energy intake per day Sources: Flaxseed Walnuts Canola oil Soybean oil Dark green vegetables (Mint,Watercress,Parsley)
    40. 40. Omega 3 Family of Fatty Acids (continued) ALA can convert to other omega 3 fatty acids—DHA and EPA (at a very low percentage) DHA = Docosahexaenoic acid EPA = Eicosapentaenoic acid Sources: Fish Mother’s milk
    41. 41. Specific Functions of Each  DHA: - important for maintaining neurotransmitter function and a calming effect on the nervous system - anti-inflammatory effect in the joints, blood stream and tissues - support retinal and brain development in fetus and infants  EPA: - fights inflammation by bolstering the immune system - prevents clotting thus helping to prevent cardiovascular events - prevents some heart arrhythmias
    42. 42. Health Benefits of Omega 3 Fatty acids  Reduces the risk of coronary heart disease: -  Stimulates blood circulation Increases the breakdown of fibrin-thus lowering the clot formation Lower triglycerides Acts as an anti-inflammatory agent Lowers blood pressures (a little) Promotes nervous system’s health and development
    43. 43. 2.Triglycerides  Structure  Glycerol + 3 fatty acids  Functions  Energy source  9 kcals per gram  Form of stored energy in adipose tissue  Insulation and protection  Carrier of fat-soluble vitamins  Sensory properties in food
    44. 44. 3.Phospholipids  Structure  Glycerol + 2 fatty acids + phosphate group  Functions  Component of cell membranes  Provides lipid transport, as part of lipoproteins  Emulsifiers  Food Sources: Most abundant in egg yolks, liver, soybeans, and peanuts
    45. 45. 4.Sterols: Cholesterol  Functions  Component of cell membranes  Precursor to other substances  Sterol hormones  Vitamin D  Bile acids  Synthesis  Made mainly in the liver  Food Sources: Highest in organ meats like beef kidney, beef liver, and beef brain, egg yolks, and breast milk
    46. 46. Total Cholesterol  Direct, positive association between TC and CHD risk  Diets high in saturated fats raise total cholesterol and CHD incidence and mortality  ATP-III Guidelines: lowering total cholesterol and LDL-C reduces CHD risk  10% reduction in TC decreases CHD risk by about 30%
    47. 47. 5.Eicosanoids These compounds are derived from long chain poly unsaturated fatty acids  Prostaglandins. They have roles in:  Prostacyclines, Inflammation Fever Regulation of blood pressure Blood viscosity Blood clotting Tissue growth Bronchocostriction Asthma.  Thromboxanes  Leukotrienes
    48. 48. 6.Lipoproteins  Lipoproteins serve as a transport vehicle for lipids in the blood and lymph  Major classes  Chylomicrons  VLDL  LDL  HDL
    49. 49. Chylomicrons:- TG rich. Synthesized in intestine. Transports exogenous TGs. Hydrophobic Core Triglyceride (93%) Cholesteryl Esters (1%)
    50. 50. Chylomicrons  Largest particles  Transport dietary fat and cholesterol from the small intestine to the liver  In the bloodstream, triglycerides are hydrolyzed by lipoprotein lipase (LPL) in muscle and adipose tissue  When 90% of triglyceride is hydrolyzed, released into blood as a remnant  Liver metabolizes remnants, but some deliver cholesterol to the arterial wall
    51. 51. VLDL:- rich in CE and TGsSurface Monolayer Phospholipids (12%) Free Cholesterol (14%) Protein (4%) Transport endogenous cholesterol Hydrophobic Core Triglyceride (65%) Cholesterol Esters (8%)
    52. 52. Very-Low-Density-Lipoproteins  Manufactured in the liver to transport     endogenous triglyceride and cholesterol 60% is triglyceride Large VLDL may be non atherogenic VLDL remnants or IDL appear to be atherogenic Not routinely measured, but TG in them is measured in total triglyceride
    53. 53. LDL:- cholesterol rich. Surface Monolayer Phospholipids (25%) Free Cholesterol (15%) Protein (22%) Synthesized from VLDL in blood circulation. Transports cholesterol from liver and delivers to other tissues.
    54. 54. Intermediate-Density Lipoprotein  Formed with catabolism of VLDL, a precursor of LDL  Rich in cholesterol and apo E  High concentrations of IDL and VLDL remnants directly related to lesion progression and coronary events  Not routinely measured, though components can be
    55. 55. Low-Density Lipoprotein  Primary cholesterol carrier in blood  Total cholesterol and LDL-cholesterol are strongly correlat  LDL is formed in VLDL catabolism, 60% is taken up by LDL receptors in liver, adrenals, other tissues; rest is metabolized via alternative pathways  Number and activity of receptors determines LDL cholesterol levels in the blood
    56. 56. LDL-Cholesterol  Particles heterogeneous in size, density, lipid components  Phenotype A: large particles, not associated with disease risk  Phenotype B typified by small, dense LDL particles; triglyceride rich, cholesterol depleted; predictive of CHD risk in men and women
    57. 57. High density lipoproteinSurface Monolayer Phospholipids (25%) Free Cholesterol (7%) Protein (45%) Promotes reesterification process of cholesterol. Reverse cholesterol transport
    58. 58. High Density Lipoproteins (HDL)  Contain more protein than the other lipoproteins  Apo A-1 is involved in tissue cholesterol removal  High HDL is associated with low levels of Chylomicrons, VLDL remnants, and small, dense LDL
    59. 59. Lipoprotein Summary
    60. 60. Lipids and Health  Obesity  Cardiovascular diseases
    61. 61. 1.Cardiovascular disease  The Prevalence of Coronary Heart Disease (CHD) “ HEART ATTACK” is rapidly increasing in India  It has become an “ EPIDEMIC”.  It is a major contributor for mortality and morbidity.
    62. 62. Cardiovascular disease cont…  Cardiovascular disease will account for 33.5% of total deaths by the year 2015, would replace infectious diseases, as the number one killer in the Indian Population.  It is expected that deaths due to HEART ATTACK will double in the next 10 years  The death rate due to heart attack will be 295 per 1,00,000 population in the year 2015.
    63. 63. Unchangeable Risk Factors  Age- the older you get, the greater the chance.  Sex- males have a greater rate even after women pass menopause.  Family history- if family members have had CHD, there is a greater chance.  Personal Medical History- other diseases such as Diabetes Mellitus can increase chances.
    64. 64. Changeable Risk Factors  Hypertension  Serum cholesterol  Obesity  Diabetes Mellitus  Physical Inactivity  Cigarette Smoking  Alcohol Intake
    65. 65. Primary Prevention of CHD  Know your risk factors  Make dietary changes  Start/continue exercise  Stop smoking  Stress reduction  Use medication if necessary
    66. 66. Risk Factors for CHD cont..  High Total Blood Cholesterol  >200 mg/dl: borderline high risk  >240 mg/dl: high risk  High LDL-C  >130 mg/dl: borderline high  >160 mg/dl: high risk
    67. 67. Lowering your LDL-C  Decrease dietary saturated fat  < 10% calories (Step 1)  < 7% calories (Step 2)  Decrease dietary cholesterol  < 300 mg/day (Step 1)  < 200 mg/day (Step 2)
    68. 68. Lowering your LDL-C  Replacing dietary SFA with MUFA  Canola oil, olive oil  Increase dietary fiber  Whole grains, oats, fruits, vegetables  Decrease dietary Trans-FA  Medication  “Statin” drugs
    69. 69. Risk Factors for CHD cont.. Low HDL-C  < 40mg/dl : high risk  > 60mg/dl : protective
    70. 70. Increasing your HDL-C  Aerobic exercise for 30 min a day  Loosing weight  Restrict trans fats in the diet  By taking diet rich in whole grains, Nuts, legumes, fruits, vegetables and fish
    71. 71. 2.Obesity It is defined as abnormal increase in the body weight due to excessive fat deposition Obesity is a state of excess adipose tissue mass Man & Women are consider obese if their weight due to fat (in adipose tissue) respectively, exceeds more than 20% and 25% of body weight.
    72. 72. Nutritional basis for Obesity Obesity is basically a disorder of excess calorie intake, in simple language –overeating. Every 7 calorie of excess consumption leads to 1 gm fat deposit and increase in bodyweight. Over eating coupled with lack of physical exercise further contribute to obesity.
    73. 73. Indices for Obesity measurement clinicaly A) Body Mass Index-BMI Clinicaly obesity is represented by BMI BMI is calculated as the weight in kg divided by the Height in meter square
    74. 74. Body mass index cont…… Classification of weight status and risk of disease Category Obesity Class Risk of disease < 18.5 Nil --------- 18.5 to 24.9 Nil --------- Over weight 25 to 29.9 Nil Increased Obesity 30 to 34.9 Class I obesity High Obesity 35 to 39.9 Class II obesity Very high Extreme Obesity 40 or >40 Class III obesity Extremely high Under weight Healthy weight BMI (Kg/M sq.)
    75. 75. Indices for Obesity measurement clinicaly cont… B) Ratio between waist and hip size:The distribution of adipose tissue in different anatomic depots has substandard implication for morbidity. Intra abdominal and abdominal subcutaneous fat have more significance than subcutaneous fat present in the buttocks and lower extremities
    76. 76. Indices for Obesity measurement clinicaly cont… This distribution is measured clinically by determining the waist to hip ratio. With a ratio More than 0.9 in women and more than 1.0 in Men is considered abnormal. Many of the most important complication of obesity , such as insulin resistance, diabetes, hypertension and hyperlipidemia are linked more strongly to intra abdominal and/or upper body fat than over all adiposity.
    77. 77. Genetical aspect of obesity One gene namely Ob gene, expressed in adipocytes (of white adipose tissues) producing a protein called leptin is closely associated with obesity. Leptin is regarded as body weight regulatory hormone. It binds to a specific receptor in brain and function as a lipostat.
    78. 78. Genetical aspect of obesity cont… When the fat store in the adipose tissue are adequate, leptin levels are high. This signals to restrict the feeding behaviour and limit fat deposition. Any genetic defect in leptin or its receptor will lead to extreme overeating and massive Obesity.
    79. 79. Pathologic consequences of obesity Obesity is associated with an increase in mortality , with a 50-100% increased risk of death from all causes compared to normal weight individuals, mostly due to cardiovascular causes. Life expectancy of a moderately obese individual could be shorted by 2 to 5 years. A 20 to 30 year old male with a BMI >45 may lose 13 years of life.
    80. 80. Pathologic consequences of obesity cont.. Obesity causes insulin resistance which leads to type 2 DM Obesity causes cardiovascular diseases:“ The Framingham study revealed that obesity was an independent risk factor for the 26 year incidence of cardiovascular diseases in man and women.”
    81. 81. Diet therapy for obesity The primary focus of diet therapy is to reduce overall calorie consumption The NHLBI recommended initiating treatment with a calorie deficit of 500-1000 Kcal/day compared to patients habitual diet. This reduction is consist with a goal of loosing approximately 1-2 Ib per week.
    82. 82. Diet therapy for obesity cont.. This calorie deficit can be accomplished by suggesting substitutions or alternatives to diet. Example:Choosing small portion sizes of meal Eating more fruit and vegetables Consuming more whole grain cereals Selecting skimmed dairy products Reducing fried foods and other added fats and oils Drinking water instead of calorie beverages
    83. 83. Recommendations for dietary Fats (FAO/WHO expert consultation on fats in human nutrition, Geneva,2008) Recommendations for dietary fats are directed towards: Meeting the requirement of optimal foetal and infant growth and development  Maternal health  For combating chronic energy deficiency in children and adults  Diet related non-communicable diseases in adults
    84. 84. Recommendations for dietary Fat intake for Indians (ICMR-2010) Age/Gender/Ph ysiological groups Physical activity Adult Man Sedentary Moderate Heavy Adult Women Minimum level of Total fat (%E) 20 Fats from foods other than visible fats (%E) 10 Visible Fat (%E) gm/day 10 25 30 40 20 10 10 25 30 40 Pregnant 20 10 10 30 Lactating Infants Sedentary Moderate Heavy 20 10 10 30 0-6 months 07-24 months Children 10-12 years 13-15 years 16-17 years Girls 10-12 years 13-15 years 35 Fat present in Human Milk 10 25 3-6 years 7-9 years Boys 40-60 25 25 30 25 10 15 35 45 50 35 40
    85. 85. Recommendations for visible fats  The quantity and fatty acid composition of both visible fat and fat from all other foods (invisible fats) contribute to the intake of various fatty acids in the total diet.  The data on fatty acid intake in Indian adults determined by taking into account the contribution of various fatty acids from all foods (invisible fat) & visible fats ( in diets of either rural or urban population respectively) shows that a complete dependence on just one vegetable oil does not ensure the recommended intake of fatty acids for optimal health and prevention of DR-NCD
    86. 86. Recommendations for visible fats cont.. A long term(in home) study with oil combinations (which increase ALA) showed improvement of LC n-3 PUFA nutritional status in adults Therefore, to ensure optimal fat quality, the use of correct combination of vegetable oils is recommended
    87. 87. Recommendations for visible fats cont.. 1) Use correct combination / blend of 2 or more vegetable oils (1:1) (a) Oil containing LA + oil containing both LA and ALA Example: Groundnut / Sesame / Rice bran / Cottonseed + Mustard/ Rapeseed Groundnut /Sesame / Rice bran / Cottonseed + Canola Groundnut / Sesame / Rice bran/ Cottonseed + Soyabean Palmolein+ Soyabean Safflower / Sunflower + Palm oil/ Palmolein + Mustard/ Rapeseed
    88. 88. Recommendations for visible fats cont.. (b) Oil containing high LA + oil containing moderate or low LA Example: Sunflower / Safflower + Palmolein / Palm oil / Olive oil Safflower / Sunflower + Groundnut / Sesame / Rice bran / cottonseed
    89. 89. Recommendations for visible fats cont.. 2) Re Limit use of butter/ghee 3) Avoid use of PHVO as medium for cooking / frying 4) Replacements for PHVO Frying : Use oils which have higher thermal stability Ex:- palm, sesame, rice bran, cottonseed oil (single / blends) ( home /commercial) Food applications which require solid fats: (Bakery food/ Indian sweets) Use coconut oil/ palm oil / Palmolein
    90. 90. Thank you