Video for Fats, Oils and Your Diet:
Introduction
The implications of fats and oils can be categorized into the benefits and harms they might bring to our body.
Fats in the body play a crucial role. They function as an alternative form of energy storage, a cushion for vital organs and a transport system for fat-soluble vitamins. They also aid in the prevention of various diseases and facilitate healing. This explains why we cannot completely eliminate fats from our diet.
However, fats are concentrated sources of energy, in which they provide 9 kilocalories per gram as compared to 4 kilocalories per gram for carbohydrates and proteins. Therefore, overconsumption of fats can lead to detrimental effects on our health. The harms fats may bring to our body include increased risk of cardiovascular diseases, deposition of excessive amounts of saturated fats and cholesterol inside arterial walls.
There are four types of fats, namely saturated fats, monounsaturated fats, polyunsaturated fats and trans fats. They have different impacts on our health. The bad fats are saturated fats and trans fats as they raise low density lipoprotein (LDL) cholesterol levels and lower high density lipoprotein (HDL) cholesterol levels, increasing the risk of heart diseases. On the other hand, the good fats are monounsaturated fats and polyunsaturated fats as they tend to lower triglyceride levels, total and LDL cholesterol levels.
Explanation
1.1 Triglycerides in the Body
- Insoluble in aqueous medium as they aggregate into fat droplets within the aqueous environment of animal cells, also called adipocytes/adipose cells
- In animals, they serve as a major/efficient form of energy storage, due to high number of C-H bonds
- Fats therefore serve well as an alternative form of energy storage due to carbohydrates
- Besides storing and providing energy (9 kcal/g), lipids also provide insulation, help manufacture steroids and bile salts, transport fat soluble nutrients in the blood and is the key structure of cell membrane
1.2 Our Diet
To reduce the risk of cardiovascular disease, the American Heart Association (AHA) recommends that no more than 7% of total calories should come from saturated fat and no more than 1% from trans fat. Total fat intake should not exceed 20% to 35% of total kilocalories. Cholesterol should amount to a maximum of 300 milligrams per day.
1.3 Lipid Deficiency and our Health
- Children suffering from malnutrition and insufficient fats, cholesterol and sphingolipids are often stunted in physical and mental growth
- Essential fatty acid (linoleic/alpha-linoleic fatty acid) deficiency: scaly/dry skin, poor healing of wounds, impaired vision and healing
1.4 Excess Lipid Intake
- Maintaining balanced levels of saturated fats and cholesterol in your body is crucial to avoid deposition of excessive amounts of saturated fats and cholesterol inside arterial walls
- Over-consumption: imbalance in body resulting in diseases
- Diseases are associated with abnormal chemistry or metabolism of lipids such as obesity, atherosclerosis, diabetes mellitus, hypolipoproteinemia, fatty liver and lipid storage diseases
- Potential risks among dietary saturated fatty acids, LDL cholesterol and heart disease risk: 1% increase/decrease in dietary saturated fatty acids → 2% increase/decrease in LDL cholesterol → 2% increase/decrease in heart disease risk
1.5 Omega 3 and Omega 6 Fatty Acids
- Throughout life, Omega 3 fatty acids aid in the prevention and treatment of various diseases such as heart disease, diabetes, arthritis, inflammatory diseases and cancer. They also play a crucial role in protecting the health of brain, eyes and nervous system
- In Omega 3 fatty acids, the first double bond is between the third and fourth carbon from the omega end.
- Some examples of Omega 3 fatty acids are alpha linolenic acid, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).
- EPA and DHA protect heart health by lowering blood triglycerides and blood pressure, preventing blood clots, protecting against irregular heartbeats and defending against inflammation
- Food sources of Omega 3 fatty acids: canola, flaxseed, walnut, wheat germ oils
Figure 8. Molecular structure of alpha-linolenic acid
- In Omega 6 fatty acids, the first double bond is between the sixth and seventh carbon from the omega end
- Omega 6 fatty acids are abundant in nature and are partially responsible for the inflammatory immune response. They also lower total blood cholesterol and LDL cholesterol
- An example of Omega 6 fatty acid is linoleic acid
- Food sources of Omega 6 fatty acids: seeds, nuts, safflower, corn, sunflower oils
Figure 9. Molecular structure of linoleic acid
References:
- American Heart Association, 2014. Know Your Fats [online]. Available at: http://www.heart.org/HEARTORG/Conditions/Cholesterol/PreventionTreatmentofHighCholesterol/Know-Your-Fats_UCM_305628_Article.jsp#.WMv9YfJ67T8 [Accessed 8 March 2017].
- Christopher K. Mathews, Kensal E. van Holde, Dean R. Appling and Spencer J. Anthony-Cahill. Pearson, 2012. Biochemistry, 4th Edition (International Edition).
- David L. Nelson and Michael M. Cox. W.H.Freeman & Co Ltd, 2008. Lehninger Principles of Biochemistry (5th Edition)