Fundamentals of Human Nutrition/Lipid storage
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6.2 Lipid Storage
Lipids, which include steroids, like cholesterol, fatty acids, and triglycerides, are either synthesized by the body or derived from the foods that one consumes in their diet. They are stored in adipocytes, which unlike other cells, have a fairly unlimited amount of storage capacity, making consuming excess fat dangerous to one’s health. Overconsumption can impair the function of these cells and other bodily processes.
Looking first at dietary lipids, or lipids that come from the foods we consume, these macronutrients begin to be digested first in the mouth. As they move throughout the digestive system, they eventually reach the small intestine where they are mixed with a secretion of bile acids and broken down into cholesterol, fatty acids, and glycerides. The cholesteryl esters and triglycerides are then prepared for transport through the body by being packed into chylomicrons along with phospholipids, cholesterol, and protein. These lipoproteins, known as chylomicrons, can then be transported through the lymph, thoracic duct, and ultimately into the bloodstream. The triglyceride portions of the chylomicrons are absorbed by different organs and tissues, such as the heart and muscle, and stored in the cells as lipid droplets.
As discussed previously, lipids can also be synthesized by your body from the remnants of other macronutrients like carbohydrates and proteins. This process occurs in the liver where either amino acids from proteins or glucose from carbohydrates can be used to form lipids. These synthesized lipids can either be stored or used in the liver, or shipped via VLDL (very low density lipoproteins) to other tissues to be stored as lipid droplets.
Disorders and diseases
As with all bodily processes, disorders can appear along different parts of the path and for a variety of reasons in lipid storage. For the most part however, these diseases involve either mutated enzymes that do not properly break down lipids or their bodies simply don’t produce enough of the needed enzyme to be effective. These disorders can be genetically passed down as autosomal recessive or sex-linked recessive. If the disorder is autosomal recessive, in order for the offspring to inherit the trait, both parents have to be carriers and there is still only a 25% chance they will express the disorder. If the disorder is sex-linked recessive, the offspring will have a higher chance of inheriting it if it is a male than female. As a male, if the mom is a carrier, the offspring as a male will have a 50% chance of inheriting the disease.
One of the most common lipid storage disorders is Gaucher disease which is caused when the body cannot produce enough of the enzyme glucocerebrosidase. This disorder is marked by extra fatty accumulation in the brain, liver, bone marrow, and other organs. There are three different types of it which range in symptoms and severity. Typically, the disorder can be diagnosed through biopsies, genetic testing, or looking for common symptoms which include liver enlargement, liver malfunction, swollen lymph nodes, anemia, and yellow eye spots.
Birsoy, K., Festuccia, W., & Laplante, M. (n.d.). A comparative perspective on lipid storage in animals. Retrieved August 16, 2015, from http://jcs.biologists.org/content/126/7/1541.full (Links to an external site.)
Lipid Storage Diseases Fact Sheet. (n.d.). Retrieved August 16, 2015, from http://www.ninds.nih.gov/disorders/lipid_storage_diseases/detail_lipid_storage_diseases.htm (Links to an external site.)
Peluso, M. (n.d.). How Are Lipids Stored in the Body. Retrieved August 16, 2015, from http://healthyeating.sfgate.com/lipids-stored-body-5236.html (Links to an external site.)
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