Wednesday, July 11, 2012

STPM Biology - chapter 1: Revision essay question 7


7. State and explain two effect of trans fat on human.
 Answer:
Effect of trans fats on the heart. Dietary trans fats raise the level of low-density lipoproteins (LDL or "bad cholesterol") increasing the risk of coronary heart disease. Trans fats also reduce high-density lipoproteins (HDL or "good cholesterol"), and raise levels of triglycerides in the blood. Both of these conditions are associated with insulin resistance which is linked to diabetes, hypertension, and cardiovascular disease. Researchers have reported thatpeople who ate partially hydrogenated oils, which are high in Trans fats, worsened their blood lipid profiles and had nearly twice the risk of heart attacks compared with those who did not consume hydrogenated oils. Because of the overwhelming scientific evidence linking trans fats to cardiovascular diseases, the Food and Drug Administration started requiring all food labels to disclose the amount of trans fat per serving in 2006.
Effect of trans fats on the brain. Trans fats also have a detrimental effect on the brain and nervous system. Neural tissue consists mainly of lipids and fats. Myelin, the protective sheath that covers communicating neurons, is composed of 30% protein and 70% fat. Oleic acid and DHA are two of the principal fatty acids in myelin. Studies show that trans fatty acids in the diet get incorporated into brain cell membranes, including the myelin sheath that insulates neurons. These synthetic fats replace the natural DHA in the membrane, which affects the electrical activity of the neuron. Trans fatty acid molecules alter the ability of neurons to communicate and may cause neural degeneration and diminished mental performance. Neurodegenerative disorders such as multiple sclerosis (MS), Parkinson's Disease, and Alzheimer's Disease appear to exhibit membrane loss of fatty acids. Unfortunately, our ingestion oftrans fatty acids starts in infancy. A Canadian study showed that an average of 7.2% of the total fatty acids of human breast milk consisted of trans fatty acids which originated from the consumption by the mothers of partially hydrogenated vegetable oils.

  Assignment submitted by L.Y., Kong,  S. H., Lim, S. C., Soo, C. W. Tan and C.C.,Teh 2011/2012 (IBM)

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