Hey friends!! Hope everyone is enjoying the holiday season! Finding ways to de-stress, stay centered and grounded. I thought this time of year would be the perfect time to get cozy with a nutrient that has a BIG reputation, FAT! Today I’m going to get deep in the science of nutrition, talking about what fat is, the function it has in our body, how we digest fat and ways to eat more healthy fats to reap all the goodness. For all my nutrition nerds this is a special gift for you 😉
What are dietary fats?
Fats are super interesting! My favorite macronutrient to talk about (nerd alert)! Dietary fat is one of the three energy containing macronutrients, the other two being carbohydrates and proteins. Although carbohydrates are our bodies preferred energy source, fats have a vital role. They are a little more needy so it takes longer for our bodies to use them for fuel. Fats are the most energy dense of the three macronutrients, containing about 9 kcal per 1gram of food. Fat for long-term energy reserve versus quick energy from carbohydrates.
Functions of Fats.
Fats are needed for many important processes in the body. They can be a source of energy, function as membranes for cells and tissues in our body, blood clotting, muscle movement, regulating hormones, nerve signaling, gene expression (DNA and RNA) and utilization of fat soluble vitamins A, D, E, & K keeping our, skin glowing, hair and nails strong.
Science tells us the biological effects/health impacts of fatty acids according to their fatty acid class (like: saturated, unsaturated and trans fatty acids). But we now know individual fatty acids can have different actions and effects on our body. A good current example of this is coconut oil. Although coconut oil is a saturated fat, its health effects may be more favorable due to its unique chemical structure, medium chain triglycerides (MCT’s). MCT’s are metabolized in a different pathway than most saturated fats, making it easier for our bodies to utilize. ****However, coconut oil is not a magical cure. Overall fat intake,the types and amounts you have on a daily basis, should always be considered. Need more specific help with this? Consider nutrition coaching, I’d love to personalize it for you!
Bottom Line: Not all fat affects our body the same way. We should be mindful of the overall fat and quality of the fats we eat.
Let’s introduce you to the key players. Dietary Lipids include triacylglycerol, cholesterol, cholesterol esters and phospholipids.Triglycerols make up 95% of dietary fat, the fat we eat.
Triglycerols = Glycerol+ 3 Fatty Acids
The fatty acids in glycerol can be all saturated, all monounsaturated, all poly-unsaturated or occur in combination. Triacylglycerols exist as solids or liquids at room temperature depending on the position of the carbon bonds of fatty acids to the glycerol.
Fat Digestion & Absorption
First a little primer. Digestion is the process of breaking down chemicals into smaller chemicals within the digestive tract. This happens two ways: 1) Mechanically- with physical motions like peristalsis and 2) Chemically- by actions of enzymes breaking down chemical bonds. Absorption is when our body uses those broken down chemicals for natural everyday cellular purposes. Want to read more about basic digestion read this post.
Fat is a super important energy source, just as carbohydrates and protein. They all have their own responsibility for making sure our body stays in good working condition. Fat digestion begins in the mouth, although minimal, with lingual lipase released from the salivary glands breaking down triglycerides to fatty acids. Fat travels down the esophagus into the stomach where gastric lipase, the stomachs fat digesting enzyme, breaks down the triglyceride (TAG).
**Fat takes a bit more time to leave your stomach, which increases the satiety factor, so when you eat fat you feel fuller longer.
TAG’s leaves the stomach, enters the small intestine where most of the digestion will occur, where they go through Phase I: Emulsification- the TAG combines with bile salts from the liver to form smaller fat particles. The short chain fatty acids are able to directly enter the blood for circulation. BUT long chain fatty acids are not able to directly enter the blood circulation.
** Long chain fatty acids would be any fatty acid that has between 13-21 carbons, like omega- 6 and 3 fatty acids, linoleic acid and alpha linolenic acid respectively. Some examples are hemp seed and chia seeds.
Instead long chain fatty acids enter into the cells of the intestines, called enterocytes, where they can be converted back to TAG’s. Re-converted TAG’s are packed up into bubbles called chylomicrons lipoproteins inside the enterocytes, so the fat can travel from enterocytes into the lymphatic circulation via chylomicron bubble.
Once in the lymphatic system, the chylomicrons slowly enter the blood stream; this can take up to 14 hours after consumption of a high fat meal. Blood carries chylomicrons to tissue sites (like muscle and fat tissues) where lipoprotein lipase, found on capillaries, allows for easy absorption of fats into the muscle and fat cells. Fats are either stored by fat tissues for later use or absorbed by muscle tissue for energy depending on what your body needs. After the chylomicron delivers the fat to where it needs to go it shrinks and is taken up by the liver, where it is recycled for reuse.
You got through it, you rock! There is so much more to learn about fats but I hope that you now have a better understanding of the digestion and absorption of fats.
I hope you enjoyed digging into the science of nutrition metabolism. Look forward to going more in-depth about fat storage and the effects of different kinds of fatty acids on our body. It is just too much for one post! But for now here are some examples of healthful fats and ways you can boost your good fat intake.
How to Eat Healthy Fats.
As we have seen fats are not the most efficient source of energy for our body. But that’s okay because carbohydrates can fill the role of energy source, while fats work to keep the process running smoothly. It is best to combine carbohydrate, protein and fat at each meal/snack.
Avocados>>
Blend in a smoothie
Spread on Toast
Pureed Avocado Mousse
On top of a Nourish Bowl – with lots of greens!
Nuts>>
Snack on them raw or in a trail mix
Soak for cashew cheese or pecan milk
Grind for almond butter
Crushed on Thai style noodles
Sliced on oats or pudding or ice cream
Seeds>>
Sprinkle on cereals, smoothies, or soup
Soak chia seeds and top with berries
Baked goods- Flax seed or chia “egg”
Thanks to my fellow nutrition nerds for reading I hope you enjoyed digging into the science of nutrition metabolism. Look forward to sharing about other macronutrients like protein, fiber and carbohydrates. Would love to hear from you. Leave questions in comment section below. Have an awesome week!
Be Well,
J
Resources:
Leave a Reply