Lipids are fatty substances that do not dissolve in water but do dissolve in organic compounds such as ether.
Lipids can be broadly classified into two categories -- fats and oils.
By definition, fats are lipids that are solid at room temperature, while oils are lipids that are liquid at room temperature.
Many people use the terms fats and lipids interchangeably.
To avoid any confusion, we will refer to lipids that are consumed in the diet as fats.
Like carbohydrates, lipids are composed of carbons, hydrogens and oxygens.
Depending on the arrangement of these elements, the lipids can take many different forms such as triglycerides, phospholipids, lipoproteins or cholesterol.
Triglycerides are the most abundant and these lipids are composed of three fat acids and a three-carbon glycerol molecule.
The fatty acid chains of the triglyceride can range in length from 4 to 20 carbon atoms.
Short chain fatty acids are primarily found in healthy foods.
Medium chain acids like coconut and palm oil contain 812 carbon, while long chain fatty acids, typically from animal fat, contain 16 to 20 carbon atoms.
The short chain acids are usually oils, but the longer chain fatty acids are often fats.
If a fatty acid has its full complement of hydrogen atoms, it is called saturated.
On the other hand, if an acid has one or more double bonds between carbon atoms, it is said to be unsaturated -- that is, not saturated with hydrogen atoms.
When a fat acid has one double bond it is monounsaturated, while it is called polyunsaturated when it has more than one double bond.
Saturated fat acids, mainly from animal products are usually solid at room temperature; but saturated fat acids can also come from some plants and be liquid.
Olive oil and nuts have a large percentage of monounsaturated fat acids while safflower and corn oil are examples of polyunsaturated fat acids.
As a general rule, the more saturated the fatty acid, the harder it is.
With this in mind, manufacturers have developed a way to change the consistency of a fat acid by hydrogenating it.
Hydrogenation places hydrogens on unsaturated fatty acids, thus making the fat acid more saturated and harder.
Margarines have been hydrogenated with the degree of firmness determined by the degree of hydrogenation of the product.
Another type of lipid is the phospholipid.
Phospholipids are structurally similar to triglycerides, except that a phosphorous containing unit replaces one of the fat acids.
Phospholipids are important in the structure of cell membranes and thus in the transport of substances into and out of the cell.
Lipoproteins are lipids encased by proteins that make them soluble and have an essential role, particularly by the small intestine.
Microns, formed in the small intestine, are the smallest of the proteins.
The other proteins are classed according to their density: high density lipoproteins, low density lipoproteins and very low density lipoproteins.
Cholesterol is a lipid very different from triglycerides because the carbon units are organized in rings and short chains.
Cholesterol is found only in animal sources and is not found in plant sources.
Cholesterol is also produced by the liver of the human body.
Therefore, cholesterol can be obtained either exogenously or endogenously.
Lipids can be broadly classified into two categories -- fats and oils.
By definition, fats are lipids that are solid at room temperature, while oils are lipids that are liquid at room temperature.
Many people use the terms fats and lipids interchangeably.
To avoid any confusion, we will refer to lipids that are consumed in the diet as fats.
Like carbohydrates, lipids are composed of carbons, hydrogens and oxygens.
Depending on the arrangement of these elements, the lipids can take many different forms such as triglycerides, phospholipids, lipoproteins or cholesterol.
Triglycerides are the most abundant and these lipids are composed of three fat acids and a three-carbon glycerol molecule.
The fatty acid chains of the triglyceride can range in length from 4 to 20 carbon atoms.
Short chain fatty acids are primarily found in healthy foods.
Medium chain acids like coconut and palm oil contain 812 carbon, while long chain fatty acids, typically from animal fat, contain 16 to 20 carbon atoms.
The short chain acids are usually oils, but the longer chain fatty acids are often fats.
If a fatty acid has its full complement of hydrogen atoms, it is called saturated.
On the other hand, if an acid has one or more double bonds between carbon atoms, it is said to be unsaturated -- that is, not saturated with hydrogen atoms.
When a fat acid has one double bond it is monounsaturated, while it is called polyunsaturated when it has more than one double bond.
Saturated fat acids, mainly from animal products are usually solid at room temperature; but saturated fat acids can also come from some plants and be liquid.
Olive oil and nuts have a large percentage of monounsaturated fat acids while safflower and corn oil are examples of polyunsaturated fat acids.
As a general rule, the more saturated the fatty acid, the harder it is.
With this in mind, manufacturers have developed a way to change the consistency of a fat acid by hydrogenating it.
Hydrogenation places hydrogens on unsaturated fatty acids, thus making the fat acid more saturated and harder.
Margarines have been hydrogenated with the degree of firmness determined by the degree of hydrogenation of the product.
Another type of lipid is the phospholipid.
Phospholipids are structurally similar to triglycerides, except that a phosphorous containing unit replaces one of the fat acids.
Phospholipids are important in the structure of cell membranes and thus in the transport of substances into and out of the cell.
Lipoproteins are lipids encased by proteins that make them soluble and have an essential role, particularly by the small intestine.
Microns, formed in the small intestine, are the smallest of the proteins.
The other proteins are classed according to their density: high density lipoproteins, low density lipoproteins and very low density lipoproteins.
Cholesterol is a lipid very different from triglycerides because the carbon units are organized in rings and short chains.
Cholesterol is found only in animal sources and is not found in plant sources.
Cholesterol is also produced by the liver of the human body.
Therefore, cholesterol can be obtained either exogenously or endogenously.