Let your food be your medicine, and your medicine be your food. ...Hippocrates

Fatty acids: saturated and unsaturated fatty acids

Fatty acids form part of triglycerides and hence are the basic blocks and the main nutritional components of fats. Chemically they consist of long chains of carbon atoms with methylene groups at one end and a carboxyl functional group. at the other end. Their length varies between four to more than 20 carbon atoms. The main fatty acids in foods, plasma triglycerides and body fats typically have 16 to 10 carbon atoms while those in fish oils are generally 20 to 22 carbon atoms long.

Type of Fatty acids
Fatty acids are classified based on the number of hydrogen attached to carbons and presence of double bonds. If each carbon atom is bound to as many hydrogen atoms as is chemically possible, it is saturated (no more hydrogen can be added). A monounsaturated fatty acid has one site where hydrogen atoms can be added. A polyunsaturated fatty acid has two or more sites for additional hydrogen atoms

1. Saturated fatty acids do not contain any double bonds or other functional groups along the acyl chain. Each carbon contain as many hydrogen’s as possible. Saturated fatty acids are non essential and can be made in adequate amounts to meet the body’s physiologic and structural functions. Saturated fatty acids form straight chains and, as a result, can be packed together very tightly, allowing living organisms to store chemical energy very densely. They are found primarily in animal products, including dairy items, such as whole milk, cream, and cheese, and fatty meats like beef, veal, lamb, pork, and ham. Some vegetable products such coconut oil, palm kernel oil, and vegetable shortening-are also high in saturates. The liver uses saturated fatty acids to manufacture cholesterol, therefore, excessive dietary intake of saturated fats can significantly raise the blood cholesterol level, especially the level of low-density lipoproteins (LDLs) and increase the risk of developing cardiovascular diseases (CVD). Further findings show that saturated fatty acids negatively influence the development of certain cancers. Education Program (NCEP), recommend that the daily intake of saturated fats be kept below 10 percent of total caloric intake. Examples of saturated fatty acids include stearic myristic and palmitic acids.

2. Monounsaturated fatty acids (MUFAS) contain one double-bonded carbon in the acyl chain, with all of the others single-bonded. Monounsaturated fatty acids are not essential to optimal body functioning since they can be synthesized in vivo. Examples of foods high in monounsaturated fat include avocados, nuts, and olive, peanut and canola oils. Scientists believe that increased consumption of monounsaturated fats (for example eating more nuts) is beneficial in lowering LDL cholesterol and lowering the risk of coronary heart disease, especially if monounsaturated fats are used to substitute for saturated fats and refined sugars. Since  they lower the levels of LDL without affecting( High Density Lipoproteins (HDL)  this results in an overall decrease in LDL/ HDL quotient. Dietary intake of MUFAS lowers serum triglycerides in persons with hyperperglyceridemia.

A high-MUFA diet is recommended in patients with Non Insulin Dependant Diabetes Mellitus who present with a distinct metabolic profile and do not need to loose weight, because it might positively influence serum lipid and glucose profiles and slightly increase HDL. Limited data suggest that MUFAs decrease platelet aggregation, increase bleeding time, and increase fibrinolysis, thereby protecting against thrombogenesis. MUFAS also provide a protective effect  against LDL oxidation this is because they lower susceptibility  of LDL particles to oxidative modification in vitro..

Based on the numerous favorable effects, it is recommended that up to 15% of total  daily energy should be supplied in form of monounsaturated fatty acids preferably in plant form. United States National Education Program of the year 2001 further recommends that monounsaturated fatty acids should  comprise  20 %  of  total energy as  an upper limit.

 

 

The following links also have dietary information related to lowering cholesterol:
Cholesterol: good or bad for health?
Cholesterol: benefits and how to raise HDL cholesterol level
More food stuffs high/low in cholesterol
Foods of animal origin high in cholesterol- USDA
Foods low in cholesterol content - USDA
Plant food that help lower cholesterol
List of food totally free of cholesterol
Cholesterol content in seafoods (tuna, salmon, shrimp)
Cookbooks for low cholesterol diet


Related links

Fruits and vegetables moderate lipid cardiovascular risk factor in hypertensive patients


References

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