CHOLESTEROL AND ITS IMPORTANCE

Cholesterol is an important lipid found in the cell membrane. It is a sterol, which means that cholesterol is a combination of a steroid and an alcohol .

It is an important component of cell membranes and is also the basis for the synthesis of other steroids, including the sex hormones estradiol and testosterone, as well as other steroids such as cortisone and vitamin D.

In the cell membrane, the steroid ring structure of cholesterol provides a rigid hydrophobic structure that helps boost the rigidity of the cell membrane.

Without cholesterol the cell membrane would be too fluid. In the human body, cholesterol is synthesized in the liver.

Cholesterol is insoluble in the blood, so when it is released into the blood stream it forms complexes with lipoproteins.

Cholesterol can bind to two types of lipoprotein, called high-density lipoprotein (HDL) and low-density lipoprotein (LDL).

A lipoprotein is a spherical molecule with water soluble proteins on the exterior. Therefore, when cholesterol is bound to a lipoprotein, it becomes blood soluble and can be transported throughout the body.

HDL cholesterol is transported back to the liver. If HDL levels are low, then the blood level of cholesterol will increase.

High levels of blood cholesterol are associated with plaque formation in the arteries, which can lead to heart disease and stroke.

VITAMINS

Based on solubility Vitamins are classified as either fat-soluble (lipid soluble) or water-soluble. Vitamins A, D, E and K are fat-soluble

Vitamin C and B is water soluble.

B-COMPLEX VITAMINS

Eight of the water-soluble vitamins are known as the vitamin B-complex group: thiamin (vitamin B1), riboflavin (vitamin B2), niacin (vitamin B3), vitamin B6 (pyridoxine), folate (folic acid), vitamin B12, biotin and pantothenic acid.

Functions of  lipids

1. They are the concentrated fuel reserve of the body  (triacylglycerols).

2. Lipids are the constituents of membrane structure and regulate the membrane permeability (phospholipids  and cholesterol).

3. They serve as a source of fat soluble vitamins (A, D, E and K).

4. Lipids are important as cellular metabolic regulators (steroid  hormones and prostaglandins).

5. Lipids protect the internal organs, serve as insulating materials and give shape and smooth appearance to the body.

Biotin

 Biotin helps release energy from carbohydrates and aids in the metabolism of fats, proteins and carbohydrates from food.

RDA The Adequate Intake (AI) for Biotin is 30 mcg/day for adult males and females

Biotin Deficiency Biotin deficiency is uncommon under normal circumstances, but symptoms include fatigue, loss of appetite, nausea, vomiting, depression, muscle pains, heart abnormalities and anemia.

BIOLOGICAL ROLES OF LIPID

Lipids have the common property of being relatively insoluble in water and soluble in nonpolar solvents such as ether and chloroform. They are important dietary constituents not only because of their high energy value but also because of the fat-soluble vitamins and the essential fatty acids contained in the fat of natural foods

Nonpolar lipids act as electrical insulators, allowing rapid propagation of depolarization waves along myelinated nerves

Combinations of lipid and protein (lipoproteins) are important cellular constituents, occurring both in the cell membrane and in the mitochondria, and serving also as the means of transporting lipids in the blood.

FAT-SOLUBLE VITAMINS

The fat-soluble vitamins, A, D, E, and K, are stored in the body for long periods of time and generally pose a greater risk for toxicity when consumed in excess than water-soluble vitamins.

VITAMIN A: RETINOL

 Vitamin A, also called retinol, has many functions in the body. In addition to helping the eyes adjust to light changes, vitamin A plays an important role in bone growth, tooth development, reproduction, cell division, gene expression, and regulation of the immune system.

The skin, eyes, and mucous membranes of the mouth, nose, throat and lungs depend on vitamin A to remain moist. Vitamin A is also an important antioxidant that may play a role in the prevention of certain cancers.

One RAE equals 1 mcg of retinol or 12 mcg of beta-carotene. The Recommended Dietary Allowance (RDA) for vitamin A is 900 mcg/ day for adult males and 700 mcg/ day for adult females.

Vitamin A Deficiency

Vitamin A deficiency is rare, but the disease that results is known as xerophthalmia.

Other signs of possible vitamin A deficiency include decreased resistance to infections, faulty tooth development, and slower bone growth.

Vitamin A toxicity The Tolerable Upper Intake Level (UL) for adults is 3,000 mcg RAE.

VITAMIN D

Vitamin D plays a critical role in the body’s use of calcium and phosphorous. It works by increasing the amount of calcium absorbed from the small intestine, helping to form and maintain bones.

Vitamin D benefits the body by playing a role in immunity and controlling cell growth. Children especially need adequate amounts of vitamin D to develop strong bones and healthy teeth.

RDA  From 12 months to age fifty, the RDA is set at 15 mcg.

20 mcg of cholecalciferol equals 800 International Units (IU), which is the recommendation for maintenance of healthy bone for adults over fifty.

Vitamin D Deficiency

Symptoms of vitamin D deficiency in growing children include rickets (long, soft bowed legs) and flattening of the back of the skull. Vitamin D deficiency in adults may result in osteomalacia (muscle and bone weakness), and osteoporosis (loss of bone mass).

Vitamin D toxicity

The Tolerable Upper Intake Level (UL) for vitamin D is set at 100 mcg for people 9 years of age and older. High doses of vitamin D supplements coupled with large amounts of fortified foods may cause accumulations in the liver and produce signs of poisoning.

VITAMIN E: TOCOPHEROL

Vitamin E benefits the body by acting as an antioxidant, and protecting vitamins A and C, red blood cells, and essential fatty acids from destruction.

RDA  One milligram of alpha-tocopherol equals to 1.5 International Units (IU). RDA guidelines state that males and females over the age of 14 should receive 15 mcg of alpha-tocopherol per day.

Vitamin E Deficiency Vitamin E deficiency is rare. Cases of vitamin E deficiency usually only occur in premature infants and in those unable to absorb fats.

VITAMIN K

Vitamin K is naturally produced by the bacteria in the intestines, and plays an essential role in normal blood clotting, promoting bone health, and helping to produce proteins for blood, bones, and kidneys.

RDA

Males and females age 14 - 18: 75 mcg/day; Males and females age 19 and older: 90 mcg/day

Vitamin K Deficiency

Hemorrhage can occur due to sufficient amounts of vitamin K.

Vitamin K deficiency may appear in infants or in people who take anticoagulants, such as Coumadin (warfarin), or antibiotic drugs.

Newborn babies lack the intestinal bacteria to produce vitamin K and need a supplement for the first week.