Fats have the highest caloric density of all the nutrients we consume. They are essential for healthy cells, are required for a wide range of normal bodily function and also go by the name of lipids.
During the digestion process, fats are required to be broken down into single free fatty acids. Without this breakdown, the fats simply pass through our digestive system intact and end up in our feces. This section will examine the crucial importance of proper assimilation of lipids.
Two Main Types of Lipids
The two main groups of lipids are saturated fatty acids and polyunsaturated fatty acids.
Saturated fatty acids are the type of lipids that are solid at room temperature. They typically have a higher melting point and are more stable. The main source of saturated fats typically comes from animals and animal products. However, certain plant oils, such as coconut oil, are also rich in saturated fats.
Polyunsaturated fatty acids are liquid at room temperature and have lower melting points. These fatty acids come both from animal products and plants. Some of them are considered essential, because our bodies are unable to create them. Polyunsaturated fatty acids are discussed in further detail in the omegas chapter.
Why We Need Lipids
Lipids are a major source of energy for our bodies and have a high caloric density. A single gram of fat contains 9 calories, while a gram of carbohydrates or proteins only contain 4 calories. As a result, they become an effective method of obtaining substantially more calories for the same amount of consumed food.
Meeting energy requirements is not the only thing we need fats for. In addition to helping us meet our caloric requirements, fat also:
- Act as the structural component of the cells in our bodies. This means that every single cell in our body depends on fat for meeting energy requirements and providing insulation.
- Required in the absorption of fat soluble nutrients, such as certain vitamins (specifically A, D, E, and K) and sterols.
- Serve as key components of many hormones and are required for the production of hormone-like fatty acid compounds called prostaglandins.
The Process of Lipids Digestion and Absorbtion
The digestion of fat starts at the mouth. Here an enzyme by the name of lipase is secreted and starts its work on breaking down large fat globules.
As the food hits the stomach, the gastric juices further breakdown fat globules into even smaller components. The stomach is not very good at breaking down the majority of fats, but it does do a good job with medium chain fatty acids. And the more fat content present in the food, the more time it spends in the stomach.
Once the fat is passed from the stomach to the small intestine, the biggest part of the fat digestion process takes place. Here, the fat globules are broken down into tiny droplets by the bile salts. Because of fats strong surface tension, this breakdown is essential for better interaction with the lipase and eventual absorption of individual fatty acids by the microvilli. And at this stage, a stable supply of bile is essential for the breakdown of fat. Without adequate bile, the lipase wouldn’t have be as capable at doing it’s job and the fat would simply pass through our system.
The Potential for Malabsorption of Lipids
Due to the high surface tension (ability to hold together) of fat, the malabsorption of lipids can be quite common if the digestive system is failing to perform at full capacity.
If more than 6-7% of the lipids you consume make it through the digestive system, this is considered abnormal and referred to as steatorrhea (basically means malabsorption of fat). Some possible causes of malabsorption include nutrient insufficiencies, shortened bowel, various diseases, or bile duct obstruction. However, the amount of total potential causes is much larger, and this can make the issues difficult to diagnose. The best approach to determining the source is to consult with a gastroenterologist, as they are the most qualified for this job.
In recent years, oils high in medium chain fatty acids (coconut oil, palm oil) have been gaining lots of popularity. Part of this can be attributed to the fact that medium chain fatty acids are extremely easy for our bodies to digest and absorb. This allows for quick energy extraction and may be of benefit individuals having issues with more difficult fats.
This section provided an overview of the types of lipids, why wee need them, how our bodies process them and potential issues that may arise. Key points include:
- Fats (lipids) are calorie dense micronutrients which need to be broken down to single free fatty acids for usage within the body
- There are two main types of lipids, saturated and polyunsaturated, the first come mainly from animal sources while the second from plants
- Lipids are essential for a variety of bodily functions including cellular structure, absorption of fat soluble nutrients and hormone production
- The small intestine is responsible for the majority of fat digestion and adequate bile production is essential to the process
- Because of their high surface tension, lipids have the highest probability of malabsorption and it can be difficult to pin-point the underlying reason
- Medium chain fatty acids are easier to breakdown and may be of benefit to individuals who have difficulties digesting fats