Dietary Fats Explained!

While skimming through my alumni e-newsletter this weekend, I happened upon an interesting article about dietary fats.  While the main point of the article was to inform generally healthy people about the role of fats in their diet and which fats are healthy, there were some interesting facts in the article that helped me understand my son's MCADD a little bit more.

Some things that I learned:

First, I learned that fats have 4 main roles in our bodies...

1. Energy source and reserve–Fat provides 80-90 percent of the energy requirement at rest. One gram of pure lipid contains about 9 calories of energy, more than twice the energy available from carbohydrate or protein.
2. Protection of vital organs– The body’s internal fat (about 4 percent of the total) protects against trauma to vital organs like the heart, liver, kidneys, spleen, brain, and spinal cord.
3. Thermal insulation–Fat keeps us warm!
4. Vitamin carrier and hunger suppressor–Approximately 20g of daily dietary fat provides a sufficient source and transport medium for the four fat-soluble vitamins: A, D, E, and K. Severely reducing lipid intake depresses the body’s level of these vitamins and may lead to a deficiency.

Although we aren't on a low-fat diet, #4 on the list makes me wonder whether MCADD kids on the low-fat diet may have vitamin deficiencies as a result of not having enough fat to transport vitamins and fully reap their benefits?

Second, I learned that fatty acids have a chain length categorized as short to very long.  This becomes important since the different chain lengths undergo different metabolic fates.  Short-chain and medium-chain fatty acids are quickly available for use as energy. Long-chain fatty acids, in contrast, undergo more complex processes and are deposited as fat in the liver and other body fat cells. Thus, the short- and medium-chain fatty acids often are considered “good” fats since they are easily metabolized and don’t necessarily contribute to fatty livers.

The four different types of fatty acids include: 

1. Short-chain fatty acids = <6 carbons. These are typically found in butter and some tropical fats.
2. Medium-chain fatty acids = 6-12 carbons.  You’ll find these in coconut oil, palm kernel oil, and breast milk.
3. Long-chain fatty acids = 13-21 carbons. These are found in animal, fish, cocoa, seeds, nuts, and vegetable oils. (Chain lengths of 16-18 carbons are most common)
4. Very-long-chain fatty acids = >22 carbons. Examples include omega-3 and omega-6 fatty acids found in fatty fish (omega-3) and some processed vegetable oils

This explains the common information in the MCADD community about avoiding coconut oil and avocado, the only food regularly mentioned to be high in medium chain fats.

Anyway, if you're interested in a deeper dive into fats, I'd encourage you to read the article and, of course, GO BLUE!