How Fats Are Digested and What You Can Do About It

By Kathi Fentress, CLT, CHT

According to the American Heart Association, LDL (known as bad cholesterol) produced naturally by your body, as well as your consumption of saturated fat, trans-fatty acids and dietary cholesterol can seriously affect your health by raising your blood cholesterol level. Lets see how they get into your tissues.

What happens to these
saturated fats when we eat them?

Dietary fats, contained in meat, butter and cooking oils, belong to a class of substances called lipids. They are the most highly concentrated source of energy in your daily diet. Being insoluble in water, lipids are not readily broken down by water-based lipase, the fat-digesting gastrointestinal enzyme.

To overcome this problem, bile, produced in the liver and stored in the gallbladder, emulsifies these fats. Like soap, it disperses them into small droplets suspended in the watery contents of the small intestine. Emulsification allows lipase to accelerate their breakdown and digestion.

Lipase enters the duodenum (transition from the stomach to the small intestine) from the pancreas, the main source of enzymes for digesting fats and proteins. Lipase chops up the complex lipid molecules into 95% fatty acid and 5% glycerol molecules.

How fat is digested and
absorbed into the bloodstream?

In the small intestine, absorption of the fatty acid and glycerol is accomplished by millions of villi, finger-like projections covering the inside wall. Inside each villus is a series of lymph vessels (lacteals) and blood vessels (capillaries). The lacteals absorb the fatty acids and glycerol into the lymphatic system, which, eventually drains into the bloodstream.

The fatty acids are transported through the bloodstream to adipose (fat) cells, where they are stored. The glycerols are absorbed by the liver and converted into glucose (gluconeogenesis), and/or used to help breakdown glucose into energy (glycolysis).

What can you do
about your fat intake?

One approach is to consciously reduce your intake of saturated fat. Saturated fat is the main dietary cause of high blood cholesterol. Saturated fat is found mostly in foods from animals and some plants.

Foods from animals include beef, beef fat, veal, lamb, pork, lard, poultry fat, butter, cream, milk, cheeses and other dairy products made from whole and 2 percent milk. All of these foods also contain dietary cholesterol.

Foods from plants that contain saturated fat include coconut, coconut oil, palm oil and palm kernel oil (often called tropical oils), and cocoa butter. However, unless you read the food labels, it is difficult to tell the saturated fat content of processed foods.

A recent development
that can help

One recently developed product is a naturally occurring, soluble fiber that forms a very stable complex or emulsion with fat. Scientific research shows this stable complex appears to prevent the digestive enzyme lipase from breaking down dietary fat in the small intestine, thus preventing it from being absorbed into the blood stream. This, in turn, reduces the number of calories that are absorbed from foods and lowers blood lipid (fat) levels.