LIPIDS Dr. Latifah Al-Oboudi 2012

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1 LIPIDS Dr. Latifah Al-Oboudi 2012

2 The Lipid Family Triglycerides Phospholipids Sterols

3 All types of lipids are: soluble in organic solvents such as chloroform, benzene, and ether, but not in water. Differ in their structure and functions extracted from cells using organic solvents.

4 1. TRIGLYCERIDES The most common type of lipid found in foods. The most common type of lipid found in the body. About 95% of the fats we eat and 95% of the fat stored in the body are in the form of triglycerides.

5 Structure of Triglycerides Dr. Latifah Al-Oboudi 2011

6 Dr. Latifah Al-Oboudi 2011

7 Dr. Latifah Al-Oboudi 2011 A triglyceride that loses a fatty acid is a diglyceride. A monoglyceride results when 2 fatty acids are lost.

8 The carbon chains of fatty acids can vary in 3 ways: The number of carbons in the chain. The extent to which the chain is saturated with hydrogen. The shape of the chain (straight or bent) Dr. Latifah Al-Oboudi 2012

9 Carbon Chain Length Usually have between 4 and 24 carbons Long chain fatty acids = 12 or more carbon atoms Fats from beef, pork, and lamb and most plant oils are long chain. Take the longest to digest. Transported via the lymphatic system.

10 Carbon Chain Length Medium chain fatty acids = 6 to 10 carbons in length Digested almost as rapidly as glucose. Transported via the circulatory system. Coconut and palm oil.

11 Carbon Chain Length Short chain fatty acids = Less than 6 carbons in length The fat in dairy products, such as butter and whole milk are short chain. Rapidly digested and transported via the circulatory system.

12 Fatty acids can be: Saturation Saturated Monounsaturated Polyunsaturated

13 A saturated fatty acid(sfa) Dr. Latifah Al-Oboudi 2012

14 A monounsaturated fatty acid(mufa) Dr. Latifah Al-Oboudi 2012

15 A polyunsaturated fatty acid(pufa) Dr. Latifah Al-Oboudi 2012

16 Shape The shape of carbon chain varies with saturation Saturated and trans fatty acids have straight carbon chain.

17 Hydrogenation Adds hydrogen to the carbon chain of unsaturated fats.

18 Naming Fatty Acids Two systems are commonly used to name fatty acids, omega and delta. Both are based on the number of carbon atoms and the location of double bonds in a fatty acid s carbon chain.

19 Essential fatty acids (Alfa-linolenic acid and linoleic acid)must be obtained from the diet because humans cannot synthesize them. Dr. Latifah Al-Oboudi 2012

20 Food Sources of Triglycerides Dr. Latifah Al-Oboudi 2012

21 Most triglyceride-rich foods contain a mixture of fatty acids Dr. Latifah Al-Oboudi 2012

22 Visible Fats In some foods fat is visible: butter on bread, mayonnaise in potato salad, and marbling in raw meat.

23 Hidden Fats In many foods fat is hidden: fat in whole milk, cheese, pastries, cookies, cake, crackers, french fries, hot dogs, and ice cream.

24 Function of Triglycerides Provide Energy. Provide Compact Energy Storage. Insulate and Protect the Body. Aid Fat-Soluble Vitamin Absorption and Transport. Essential Fatty Acid Functions

25 Essential Fatty Acid Functions Essential fatty acids, along with phospholipids and cholesterol, are important structural components of cell walls. They also keep the cell wall fluid and flexible, so that substances can flow into and out of the cell. Eicosanoids, which are made from essential fatty acids, have over 100 different actions, such as regulating blood pressure, blood clotting, sleep/wake cycles, body temperature.

26 2. Phospholipids The structure of phospholipids is very similar to that of triglycerides, except a fatty acid is replaced with a compound that contains the mineral phosphorus and often has nitrogen attached.

27 Phospholipids Functions In the body, phospholipids have 2 major roles: cell membrane component and emulsifier, phospholipids, along with fatty acids and cholesterol, are a primary component of cell membranes.

28 Phospholipids function in a watery environment without clumping together

29 Phospholipids Functions The hydrophilic head of phosphate is attached to water, and the fatty acid tail of phospholipids is attached to fats. When placed in water, phospholipids cluster together, with their hydrophilic phosphate heads facing outward in contact with water and their hydrophilic tails extending into the cluster away from the water.

30 Phospholipids Functions A cell membrane is the double- layered outer covering of a cell that corrals the cell s contents and regulates the movement of substances into and out of the cell.

31 Source of phospholipids Phospholipids can be synthesized by the body or supplied by the diet.

32 The last class of lipids. 3. Sterols The structure of sterols is very different from that of the long carbon chains seen in fatty acids and phospholipids. The carbons in the structure of sterol are mostly arranged in many rings

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34 Sterol Functions Cholesterol, The most well-known sterol, is used in the body to make bile and steroid hormones, such as testosterone, estrogens, the active form of vitamin D hormone, and corticosteroids.

35 Source of Sterol(Cholesterol) Cholesterol is found in foods of animal origin, such as meat, fish, poultry, eggs, and diary products. Food of plant origin do not contain cholesterol.

36 Recommended Fat Intake(1) The adequate macronutrient distribution range for total fat is 20 to 35% of calories for most age groups. Saturated fat intake, including trans fats, and cholesterol of should be kept as low as possible while still consuming a nutritionally adequate diet.

37 Recommended Fat Intake(2) Cholesterol intake should be limited to about 300mg daily. Fat intake recommendation are lower for those at risk of heart disease. Adequate intakes for essential fatty acids equal less than 120 calories daily for women and 170 calories for men- that s about 2 to 4 tablespoons daily of oil rich in these fatty acids

38 Recommended Fat Intake)3( Omega-6 fatty acid intake is usually plentiful, but omega-3 intakes often are lower than optimal.

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40 Fat Digestion and Absorption)1( Digestion Fat digestion occurs mostly in the small intestine. The presence of fat in the small intestine triggers the release of cholecystokinin from intestinal cells. Cholecystokinin stimulates the release of bile and pancreatic enzymes.

41 Fat Digestion and Absorption(2) Digestion Bile emulsifies fats and allows enzymes to efficiently break triglycerides into monoglycerides and free fatty acids. Phospholipids and cholesterol are digested mostly in the small intestine.

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43 Fat Digestion and Absorption)3( Absorption The lipid portion of the micelles is absorbed by the brush border of the absorptive cells lining the duodenum and jejunum sections of the small intestine. After absorption, short and medium chain fatty acids mostly enter the circulatory system. Long chain fatty acids enter the lymphatic circulation.

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45 Transporting Fat in the Blood Fats are transported in the blood as lipoproteins called chylomicrons, very-low-density lipoproteins(vldls), low-density lipoproteins(ldls), and high-density lipoproteins(hdls). Lipoproteins have a core, made of lipids, that is covered with a shell composed of protein, phospholipid, and cholesterol. The shell lets the lipoprotein circulate in the blood.

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48 Pathways for Cholesterol Uptake The receptor pathway for cholesterol uptake removes LDL from the blood, breaks it down, and uses the component parts for maintaining the cell membrane or synthesizing compounds.

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51 Pathways for Cholesterol Uptake Oxidized LDL is removed from the blood by the scavenger pathway for cholesterol uptake. Over time cholesterol builds up in the scavenger cell. When scavenger cells have collected and deposited cholesterol for many years at a heavy pace, cholesterol builds up on the inner blood vessel walls and plaque develops.

52 Pathways for Cholesterol Uptake HDL roams the blood stream, picking up cholesterol from dying cells and other sources, and donates the cholesterol to other lipoproteins for transport back to the liver to be excreted. Dr. Latifah Al-Oboudi 2012

53 Health Concerns Related to Fat Intake High Polyunsaturated Fat Intake Intakes of polyunsaturated fats greater than 10% of total calorie intake seem to increase the amount of cholesterol deposited in arteries, which raises the chances of developing cardiovascular disease. High intakes also may impair the immune system s ability to fight disease

54 Health Concerns Related to Fat Intake Excessive Omega-3 Fatty Acid Intake Diets that include fish rich in omega-3 twice a week can reduce blood clotting abilities and may favorably affect heart rhythm.

55 Intake of Rancid Fats Rancid fats contain compounds that can damage cells.

56 Diet High in Trans Fat Trans fatty acids raise blood cholesterol levels, lower HDL cholesterol levels, and increase inflammation in the body.

57 Diet High in Total Fat Diets high in total fat increase the risk of obesity; colon, prostate, and breast cancer; and cardiovascular disease(cvd).

58 Cardiovascular Disease(CVD) Atherosclerotic plaque is probably first deposited to repair injuries in the lining in any artery. As atherosclerosis progresses, plaque thickens over time, causing arteries to harden, narrow, and become less elastic.

59 Risk Factors for CVD Age, gender, genetics, race, blood cholesterol levels, blood triglyceride levels, hypertension, smoking, physical inactivity, obesity, and diabetes. All adults age 20 years or older should have a blood lipoprotein profile done every 5 years. Lifestyle changes can lower blood LDL cholesterol levels and reduce health risks.