One characteristic all the many different compounds classifed as lipids share is
they do not easily dissolve in water
Examples of lipds....
Fatty acids, triglycerides, phospholipids and sterols- each of their structures are unique. Fatty acids are the simplest lipids.
Fatty acids can be categorized as ........
Saturated Monounsaturated polyunsaturated Trans-fatty acid - all dependent on the bonds that link the carbon units together
Saturated fatty acids ...
contain only single bonds. They are saturated with hydrogen
Monounsaturated fatty acid .
contains one double bond that prevents the maximum number of hydrogens from bonding with the carbon
Polyunsaturated fatty acid
has tow or more carbon- carbon double bonds
How are foods classified as a specific type of fatty acid?
Foods can contain any combination of the three types of fatty acids. They are classified as a specific type based on which fatty acid is present in the highest concentration.
Saturated fats found primarily in ___________ and are ________ at room temperature.........
found in animal foods and are solid at room temperature
Unsaturated fats are _________ at room temperature.
liquid at room temperature
Examples of monounsaturated fats and polyunsaturated fatty acids
Canola and olive oils are monunsaturated fatty acids Corn, soybean and sunflower oils are polyunsaturated fatty acids
What is hydrogenation ?
Unsaturated fatty acids naturally occur in the cis formation. The structure is comprised of double bonds and the fatty acid chain is bent. During food processing, the double bonds are broken as hydrogen is added to the unsaturated fatty acid. This results in a straighter chain which is more saturated. Simply stated, hydrogenation, the process of adding hydrogen, changes an unsaturated fatty acid into a saturated fatty acid. The product changes from a liquid to a semi liquid or a solid.
Trans fatty acids are found in partilally hydrogenated food products such as margarine and deep fried foods.
What is an omega 3 fatty acid?
Refers to the placement of the carbon-carbon double bond in the fatty acid.
This bond is located at the third carbon from the methyl end (-CH3).
What is the essential omega 3 fatty acid ?
Alpha-linolenic acid is the essential Omega 3 acid. Essential because they must come from food as our body cannot make them.
Sources of Omega 3 fatty acids include: soybean, canola oil, walnuts, flaxseed oil, salmon, tuna and mackerel.
What is an omega 6 fatty acid and what is the essential omega 6 acid that our body needs?
The first carbon carbon double bond is located at the sixth carbon from the methyl -CH3 end
linoleic acid is the essential Omega 6 acid
Vegetable oils are good sources of Omega 6 fatty acids.
Three fatty acids that bond together with a glycerol molecule make a
Triglycerides are the major form of fats in our body and in our diet.
Functions of triglycerides aside from an energy source include a stored form of energy in the adipose tissue, insulation and protection, carrier of fat soluble vitamins, and they make food taste good.
A type of lipid -
Phospholipids are comprised of a glycerol+ two fatty acids+ a phosphate group. They are an important part of cell membranes, they are used to transport lipoproteins and act as emulsifiers. We will discuss this later in the module. Good food sources are egg yolks, peanuts, liver and soybeans.
Last class of lipids .........
Cholesterol is the most common sterol. Sterols have a different structure than triglycerides or phospholipids. There is no glycerol backbone.
Cholesterol is part of cells, is necessary in the production of some hormones and bile acids. It is only found in animal foods, but we do not need any in our diet. Our liver makes all the cholesterol our body requires.
How do food manufacturers use fat ?
They use fat for taste, flavor, satiety as emulsifiers and to prevent fats from becoming rancid.
Lecithin, a phospholipid, is used as an emulsifier in salad dressing to keep the fats and water from separating. Rancidity occurs when the double bonds in unsaturated fats begins to break down due to exposure to light and oxygen. Foods then take on an unpleasant flavor and odor. To prevent this, manufacturers often add partially hydrogenated plant oils to products. Crackers, cookies, pastries, fried foods, cakes and pies often contain trans fats to prevent rancidity. As you can see, fats can be hidden in almost any product
How much digestion of triglycerides occurs in the mouth and stomach ?
Where is the primary site of fat digestion\?
Minimal - the initial digestion of fat is done by the enzympe lipase produced by the salivary glands and the stomach.
The primary site of fat digestion and absorption is the small intestine. Bile secreted by the gallbladder, digests fat and emulsifies it for absorption. At the same time, the pancreas secrets lipase to aid in digestion. During this process the triglycerides are broken down into monoglycerides and fatty acids which are suspended in watery juices. These byproducts are then absorbed through the intestinal wall.
What happens to fats after absorption ?
After absorption they are often reformed into triglycerides. For fats to travel through blood and lymph to get to the various cells in the body, lipoproteins are required.
Discuss the importance of lipoproteins........
Lipoproteins are lipids surrounded by a shell of protein, phospholipids and cholesterol.
This coating allows the fats to be transported in watery substances such as blood to tissue and cells.
What are the four types of lipoproteins ?
1. Chylomicrons - which transport the triglycerides from the intestine to the cells and the liver
2. Very Low Density Lipoproteins - deliver triglycerides to the cell
3. Low Density Lipoproteins (LDL) - deliver cholesterol to cells
4. High Density Lipoproteins (HDL) - pick up the cholesterol for removal via the liver
HDL and LDL are often referred to as ..............
Good cholesterol and bad cholesterol respectively
What risk potential is associated with high levels of LDL and low levels of HDL?
High levels of LDL or low levels of HDL are linked to an increased risk of cardiovascular disease. High levels of LDL can lead to plaque formation in the arteries, this is called atherosclerosis.
The plaque inhibits the blood flow through the arteries resulting in high blood pressure, a stroke or heart attack.
How can you lower your LDL levels ? And help prevent cardiovascular disease ?
By consuming a diet low in saturated fat, trans fat and cholesterol and high in fiber and Omega 3 fatty acids, you can lower your LDL levels.
Smoking cessation, exercise, weight management and blood pressure control can also lower your risk for cardiovascular disease. High levels of HDL are also desirable in preventing heart disease.
What syndrome has been linked to high fat diets ?
Metabolic Syndrome - this is a cluster of symptoms that include
excess abdominal fat, high blood glucose levels, high triglycerides, low HDL cholesterol and hypertension. If a person has three or more of these symptoms, they are diagnosed with Metabolic Syndrome which is sometimes called Syndrome X. Their risk of mortality increases related to diabetes, obesity and cardiovascular disease.
How much of our daily caloric intake should come from fats according to the American Heart Association ?
The American Heart Association recommends that Americans consume no more than 30% of their calories from fat, no more than 7% of total calories from saturated fats, less than 1% from trans fats and cholesterol intake should be less than 300 mg per day.
What are some healthy steps that can be taken to prevent cardiovascular disease ?
The following lifestyle recommendations are also provided to prevent Cardiovascular Disease.
1. Maintain a healthy weight
2. Eat a diet high in fruits and vegetables
3. Increase intake of whole grains and high fiber foods
4. Limit foods and drinks with added sugars
5. Prepare foods with little or no salt
6. If you consume alcohol, do so in moderation