Digestion
- Fat digestion begins in the mouth where food is mixed with saliva that contains a small amount of lipase, a digestive enzyme that breaks fat apart. Your stomach also makes a small amount of lipase, but most fat digestion occurs in the small intestine. Fat is mixed with bile, which helps break large globs of fat into smaller bits of fat. Pancreatic lipase continues digestion by breaking the fat down into individual fatty acids, which can be absorbed into your bloodstream.
Absorption and Transportation
- The fatty acids are absorbed across the small intestine walls and into the circulatory system. Some fatty acids enter the bloodstream and are carried to the liver to be processed, while other fatty acids go into the lymphatic system and are formed into chylomicrons that move into the bloodstream. The chylomicrons are broken down in the bloodstream and the fatty acids are absorbed into muscle, liver or fat cells.
Storage and Metabolism
- As long as you're getting plenty of food to eat, adipocytes, also known as fat cells, absorb fatty acids from the blood and store them as fats. Adipocytes can also convert extra carbohydrates to fat. When you're not getting enough food or your energy needs increase due to physical activity or illness, the stored fats are broken back down into individual fatty acids. The fatty acids travel to the liver where they are processed and used as energy or converted to glucose.
Dietary Fats and Health
- Fats are found in foods from both plant and animal origins. Common sources include vegetable oils, margarine, whole milk, cream, meat and poultry products, fish and seafood, nuts and seeds. According to the Centers for Disease Control and Prevention, about 20 to 35 percent of your calories should come from fats. Less than 10 percent should come from saturated fat, and trans fats should be avoided whenever possible.
