Q. not sure if this is important:
chylomicron has 4% phospholipid, 90% triacylglycerol, 5% cholesterol, 1% protein.
low-density lipoprotein has 20% phospholipid, 10% triacylglycerol, 45% cholesterol, 25% protein.
high-density lipoprotein has 30% phospholipid, 5% triacylglycerol, 20% cholesterol, 45% protein.
chylomicron has 4% phospholipid, 90% triacylglycerol, 5% cholesterol, 1% protein.
low-density lipoprotein has 20% phospholipid, 10% triacylglycerol, 45% cholesterol, 25% protein.
high-density lipoprotein has 30% phospholipid, 5% triacylglycerol, 20% cholesterol, 45% protein.
A. Particles (and systems in general) always follow the "principal of least energy" which reduces the free energy of a system to minimum.
Phospholipids are polar compounds based upon a glycerol backbone. Two fatty acids are attached to the phospholipid at the sn-1, and sn-2 position (end and middle respectively). Both fatty acids are non-polar and hydrophobic (water-hating). The third spot is taken by a polar group at the sn-3 position (e.g. the other end) which is hydrophilic (water loving). In addition to polar amino acids and proteins, the outer side of the lipoprotein particles face the water while the hydrophobic portions point inward, where triglycerides, cholesterol and cholesterol esters are.
The hydrophilic outer portion allows lipoprotein particles to stay suspended in serum and blood. The inner lipid and sterol portion attract each other and form a stable system.
The shape that reduces free energy to a minimum is a sphere so lipoprotein particles assume that shape.
Without the phospholipids and proteins surrounding the water-insoluble portions, the lipid and sterol molecules would simply coalesce, which would result in blobs of fat accumulating in the circulatory system.
Phospholipids are polar compounds based upon a glycerol backbone. Two fatty acids are attached to the phospholipid at the sn-1, and sn-2 position (end and middle respectively). Both fatty acids are non-polar and hydrophobic (water-hating). The third spot is taken by a polar group at the sn-3 position (e.g. the other end) which is hydrophilic (water loving). In addition to polar amino acids and proteins, the outer side of the lipoprotein particles face the water while the hydrophobic portions point inward, where triglycerides, cholesterol and cholesterol esters are.
The hydrophilic outer portion allows lipoprotein particles to stay suspended in serum and blood. The inner lipid and sterol portion attract each other and form a stable system.
The shape that reduces free energy to a minimum is a sphere so lipoprotein particles assume that shape.
Without the phospholipids and proteins surrounding the water-insoluble portions, the lipid and sterol molecules would simply coalesce, which would result in blobs of fat accumulating in the circulatory system.
what foods contain high density lipoproteins (HDL's)?
Q. I heard that cholesterol isnt bad if it is packed with hdl's. So I want my diet to have more HDL's since its high in cholesterol.
A. Egg whites are a great source of HDLs. But only about 10% of your cholesterol comes from diet, the other 90% comes from synthesis by the liver, controlled by genetics. The best way to increase your HDL's is to exercise.
Do we need both HDL (High-density lipoprotein) and LDL (Low-density lipoprotein)?
Q. If so, then how do vegans exist?
A. The liver and the intestines both form lipoproteins such as HDL, LDL, IDL and VLDL. Levels of each are determined by multiple factors. For example, the fats that are carried by the lipoprotein particles come from food and from fat synthesized by the liver.
Eating foods high in cholesterol actually has little effect of serum cholesterol levels(1). The body has a sensitive feedback mechanism that tightly regulates the production of cholesterol (2). When dietary consumption of cholesterol increases, less is produced by the liver. High levels of insulin increase the synthesis of cholesterol by the liver and also by individual cells in the body.
Fats do have an effect on the levels of HDL, LDL and VLDL. Saturated fats strongly increase HDL and to a lesser estent, LDL. Polyunsaturated fats tend to lower both HDL and LDL. A higher refined carbohydrate intake can strongly increase the serum levels of triglycerides, which can also increase LDL. The liver produces primarily palmitic and palmitoeic acid from carbohydrates. Palmitic acid is also the predominant fatty acid in animal.
Since production of HDL, LDL and triglycerides is mediated by many factors, it is impossible to make many generalizations about the association of dietary fats and carbohydrates and serum cholesterol. Very low carbohydrate diets can result in a more favorable lipid profile than a low fat diet (3). Strict meat eaters can have a fairly low serum choleserol while vegans can have a higher serum cholesterol. People eating a paleolithic diet and a vegan diet can have similarities, in so much that both ways of eating discourage the consumption of vegetable seed oils, refined carbohydrates and favor eating whole foods.
Eating foods high in cholesterol actually has little effect of serum cholesterol levels(1). The body has a sensitive feedback mechanism that tightly regulates the production of cholesterol (2). When dietary consumption of cholesterol increases, less is produced by the liver. High levels of insulin increase the synthesis of cholesterol by the liver and also by individual cells in the body.
Fats do have an effect on the levels of HDL, LDL and VLDL. Saturated fats strongly increase HDL and to a lesser estent, LDL. Polyunsaturated fats tend to lower both HDL and LDL. A higher refined carbohydrate intake can strongly increase the serum levels of triglycerides, which can also increase LDL. The liver produces primarily palmitic and palmitoeic acid from carbohydrates. Palmitic acid is also the predominant fatty acid in animal.
Since production of HDL, LDL and triglycerides is mediated by many factors, it is impossible to make many generalizations about the association of dietary fats and carbohydrates and serum cholesterol. Very low carbohydrate diets can result in a more favorable lipid profile than a low fat diet (3). Strict meat eaters can have a fairly low serum choleserol while vegans can have a higher serum cholesterol. People eating a paleolithic diet and a vegan diet can have similarities, in so much that both ways of eating discourage the consumption of vegetable seed oils, refined carbohydrates and favor eating whole foods.
Powered by Yahoo! Answers
Tidak ada komentar:
Posting Komentar