Fats - biochemistry

Summary

This script explains the importance of fats in a healthy diet, detailing their structure and functions. It distinguishes between saturated and unsaturated fats, highlighting the health impacts of each. It also covers the digestion process of fats and the recommended dietary intake for different types of fats, emphasizing the benefits of unsaturated fats and the potential risks associated with saturated and trans fats.

Takeaways

• 🥑 Fats are crucial for a balanced diet, contributing to the taste, texture, and energy supply of foods.
• 🧬 Fats are composed of a glycerol backbone and fatty acid chains, which can link up to form monoglycerides, diglycerides, or triglycerides.
• 🔬 Fatty acids are categorized by their chain length and saturation level, distinguishing between short, medium, and long chains, as well as saturated and unsaturated fats.
• 🍗 Saturated fats have single bonds and are typically solid at room temperature, while unsaturated fats have double bonds, causing them to be liquid.
• 🐟 Omega-3 and omega-6 are essential polyunsaturated fatty acids found in marine sources and certain plant oils, respectively.
• 🌿 Omega-9 fatty acids are monounsaturated and can be synthesized by the human body; they are found in foods like olive oil and almonds.
• 🔄 The cis configuration of unsaturated fats causes a bend in the molecule, making them more fluid, while the trans configuration, resulting from partial hydrogenation, makes them more solid.
• 🚫 Trans fats, associated with coronary heart disease, have been largely removed from foods in North America and Europe due to health concerns.
• 🔄 The digestion of fats involves enzymes like lipases and bile salts, which break down triglycerides and increase their surface area for absorption.
• 🩸 Lipoproteins like chylomicrons transport dietary fats through the lymphatic system and into the bloodstream for distribution to tissues.
• 🏥 A diet rich in unsaturated fats, particularly omega-3 and omega-6, is linked to reduced cardiovascular disease risk and supports proper body functions like hormone production and brain development.

Q & A

What is the role of fats in a healthy diet?

Fats are essential in a healthy diet as they contribute to taste and texture of foods, provide a major source of energy, are critical components of cells and tissues, and help in absorbing essential vitamins.

What is the chemical structure of fats?

Fats have a three carbon backbone called glycerol and fatty acid chains, which are strings of carbon and hydrogen atoms. They can form monoglycerides, diglycerides, or triglycerides depending on the number of fatty acids attached.

How are fatty acid chains categorized by length?

Fatty acid chains are categorized by length as short chain (2 to 5 carbons), medium chain (6 to 12 carbons), and long chain (13 or more carbons).

What is the difference between saturated and unsaturated fatty acids?

Saturated fatty acids have only single bonds between carbon atoms and are typically solid at room temperature. Unsaturated fatty acids have one or more double bonds, causing a kink in the molecule, making them usually liquid at room temperature.

What are monounsaturated and polyunsaturated fatty acids?

Monounsaturated fatty acids have one double bond, while polyunsaturated fatty acids have two or more double bonds.

How are omega-3 and omega-6 fatty acids classified?

Omega-3 and omega-6 fatty acids are classified based on the position of the first double bond from the methyl end (omega end) of the fatty acid chain. Omega-3 has the first double bond three carbons from the end, and omega-6 has it six carbons from the end.

What are the sources of omega-3 fatty acids?

Omega-3 fatty acids come from marine sources like fish (anchovies, mackerel, salmon, sardines) and plant sources like flaxseed, walnuts, and canola and soybean oils.

Why is it recommended to consume foods with EPA and DHA rather than just ALA?

The body can convert ALA into EPA and DHA, but the process is inefficient. Therefore, dietary recommendations include foods rich in EPA and DHA for better absorption.

What is the difference between cis and trans configurations in fatty acids?

In cis configuration, the functional groups are on the same side of the double-bonded carbons, causing the fatty acid chain to bend and be more fluid. In trans configuration, the groups are on opposite sides, keeping the chain straight and easier to pack, which is typically more solid.

How are fats digested and absorbed in the body?

Triglycerides are broken down into free fatty acids and monoglycerides by lipases. Bile salts emulsify fats, increasing the surface area for lipases. The resulting monoglycerides and fatty acids form micelles, which are absorbed by enterocytes, reassembled into chylomicrons, and transported via the lymphatic system into the bloodstream.

What are the health benefits of polyunsaturated fats?

Polyunsaturated fats help lower total and LDL cholesterol, reduce the risk of cardiovascular diseases, and are precursors for prostaglandins that help lower blood pressure.

What is the recommended daily intake of fats according to the National Academies of Medicine?

It is recommended to consume 20-35% of daily calories as fats, which for a 2000 calorie diet translates to 400-700 calories from fat, or about 44-78 grams.

How does the type of saturated fat affect cardiovascular health?

The impact of saturated fat on cardiovascular health is complex, with different types of saturated fatty acids potentially having different effects. It's recommended to keep saturated fat consumption low and replace it with healthier fats like polyunsaturated fats for better cardiovascular health.

Outlines

00:00

🥑 Fats: An Essential Component of a Healthy Diet

Fats are crucial for a balanced diet, enhancing food taste and texture, providing energy, and aiding in cell function and vitamin absorption. They consist of a glycerol backbone and fatty acid chains. Fatty acids vary in length and saturation, with short, medium, and long-chain types. Saturated fats have single bonds, are typically solid at room temperature, and longer chains tend to be more solid. Unsaturated fats contain double bonds, causing a kink in the molecule, making them usually liquid at room temperature. Unsaturated fats are further divided into monounsaturated with one double bond and polyunsaturated with multiple double bonds. Omega-3 and omega-6 are polyunsaturated, mainly found in marine sources and plant oils, respectively, while omega-9 is monounsaturated and can be synthesized by the body. The script also explains the digestion process of fats, their role in the body, and the importance of different types of fats for health.

05:02

🔬 The Chemistry and Health Impact of Fats

This section delves into the chemical structure of fats, focusing on the cis and trans configurations of unsaturated fatty acids. Cis fats are more fluid due to their bent shape, while trans fats, resulting from partial hydrogenation, are straighter and pack more tightly, often found in solid fats at room temperature. The script discusses the process of fat digestion, from enzymatic breakdown to absorption via chylomicrons, which transport fats through the lymphatic system into the bloodstream. It also addresses the health benefits of different fats, such as polyunsaturated fats reducing cholesterol and cardiovascular disease risk, and the importance of omega-3 fatty acids for brain and eye development in infants. The impact of saturated fats is more nuanced, with recommendations to keep intake low but also considering the type of saturated fat and what it is replaced with in the diet.

10:06

📊 Dietary Recommendations for Fats

The final paragraph summarizes the importance of fats in diet and health, emphasizing the distinction between saturated and unsaturated fats. It highlights that not all saturated fats are detrimental and that replacing them with polyunsaturated fats can benefit cardiovascular health. The National Academies of Medicine recommends a daily fat intake of 20-35% of total calories, with the WHO and US Dietary Guidelines suggesting less than 10% from saturated fats and minimal trans fat intake. The script concludes by advocating for a focus on the type of fat consumed rather than just the quantity, to reduce the risk of cardiovascular diseases.

Keywords

💡Fats

Fats are essential nutrients that provide energy, contribute to the taste and texture of foods, and are critical components of cells and tissues. They also help absorb essential vitamins and can be converted into other molecules like prostaglandins, which aid in cell communication. In the video, fats are discussed in the context of their role in a healthy diet and their various types, emphasizing their importance for overall health.

💡Glycerol

Glycerol is a three-carbon backbone that, along with fatty acid chains, forms the structure of fats. It plays a central role in the formation of triglycerides, which are the most common type of fat in the body. The script explains how glycerol binds with fatty acids to form different types of glycerides, such as monoglycerides, diglycerides, and triglycerides, which are crucial for energy storage and release.

💡Fatty Acid Chains

Fatty acid chains are composed of carbon and hydrogen atoms and are a key component of fats. They can be saturated, monounsaturated, or polyunsaturated, depending on the presence and arrangement of hydrogen atoms. The script describes how the saturation level of fatty acid chains affects the physical state of fats at room temperature and their health implications.

💡Saturated Fatty Acids

Saturated fatty acids have single bonds between all the carbon atoms in their chain, meaning they are 'saturated' with hydrogen atoms. These fats are typically solid at room temperature and are found in animal products and some plant-based sources. The video discusses how saturated fats, despite being a major energy source, are also linked to potential health concerns if consumed in excess.

💡Unsaturated Fatty Acids

Unsaturated fatty acids contain one or more double bonds, which means they have fewer hydrogen atoms than saturated fats. This causes a 'kink' in the molecule, preventing them from packing tightly together, and they are usually liquid at room temperature. The script explains that unsaturated fats are divided into monounsaturated and polyunsaturated fatty acids, which have different health benefits.

💡Omega-3 Fatty Acids

Omega-3 fatty acids are a type of polyunsaturated fatty acid that plays a crucial role in brain function and cardiovascular health. The video mentions that omega-3s like EPA and DHA are found in marine sources, while ALA is found in plant sources. These fats are essential for the diet as the body cannot efficiently produce them from other sources.

💡Omega-6 Fatty Acids

Omega-6 fatty acids are another type of polyunsaturated fatty acid that the body can convert from linoleic acid found in plant oils. The script highlights that while omega-6 fatty acids are essential, they are often overconsumed in modern diets, and a balance with omega-3 fatty acids is important for health.

💡Omega-9 Fatty Acids

Omega-9 fatty acids are monounsaturated fats that the body can produce on its own, although they are also found in foods like canola and olive oil. The video notes that omega-9 fatty acids are typically not considered essential in the diet because the body can synthesize them.

💡Trans Fats

Trans fats are created through the process of partial hydrogenation, where hydrogen is added to unsaturated fats to make them more solid. The script explains that trans fats have been associated with coronary heart disease and have been largely removed from foods in many regions due to health concerns.

💡Digestion of Fats

The digestion of fats involves enzymes like lipases and bile salts that break down triglycerides into absorbable components. The video describes the process in detail, from the formation of micelles in the intestines to the assembly into chylomicrons, which are then transported via the lymphatic system into the bloodstream.

💡Cardiovascular Health

Cardiovascular health is a central theme in the video, as it relates to the types of fats consumed. The script discusses how different fats, particularly polyunsaturated and omega-3 fatty acids, can help reduce the risk of cardiovascular diseases by improving blood flow and cholesterol levels.

Highlights

Fats are essential for a healthy diet and contribute to taste and texture of foods.

Fats serve as a major source of energy and are critical for cell and tissue function.

Fats help in the absorption of essential vitamins and can be converted into molecules like prostaglandins.

Fats have a glycerol backbone and fatty acid chains made of carbon and hydrogen atoms.

Fatty acids can form monoglycerides, diglycerides, and triglycerides depending on the number of bonds with glycerol.

Fatty acid chains are categorized by length: short chain (2-5 carbons), medium chain (6-12 carbons), and long chain (13+ carbons).

Fatty acids are also categorized by the type of bonds: single bonds make saturated fatty acids, double bonds make unsaturated fatty acids.

Saturated fats are typically solid at room temperature due to their straight molecular structure.

Unsaturated fats usually have a kink due to double bonds, making them liquid at room temperature.

Unsaturated fatty acids are further classified as monounsaturated (one double bond) or polyunsaturated (two or more double bonds).

Omega-3 and omega-6 fatty acids are types of polyunsaturated fats, important for health, with sources like fish and plants.

Omega-9 fatty acids are typically monounsaturated and can be synthesized by the human body.

The cis configuration of unsaturated fats causes a bend in the molecule, making them more fluid.

Trans fats, with a trans configuration, are straighter and can be found in partially hydrogenated oils and some animal products.

Partial hydrogenation is a process that turns some double bonds into single bonds, creating trans fats.

Trans fats have been associated with coronary heart disease and are being removed from many foods.

Digestion of fats involves enzymes like lipases and bile salts to break down triglycerides into absorbable forms.

Fatty acids and monoglycerides are reassembled into chylomicrons in the enterocytes for transport via the lymphatic system.

Fats play various roles in the body, including hormone production and cardiovascular health.

Polyunsaturated fats can help reduce cholesterol and lower the risk of cardiovascular diseases.

DHA, an omega-3 fatty acid, is crucial for the development of eyes and brains in infants.

The impact of saturated fat on health is complex and depends on the type of saturated fat and what it replaces in the diet.

Dietary guidelines recommend a balance of fats with a focus on mono and polyunsaturated fats over saturated and trans fats.

Improving diet and health can be achieved by focusing on the type of fat consumed rather than just the quantity.

Transcripts

Fats are an essential part of a healthy diet.

They contribute to the taste and texture of foods, like the smoothness of guacamole and

the flakiness of a croissant.

Fats are also a major source of energy, a critical component of cells and tissues, and

they also absorb essential vitamins, and can be converted into other molecules like prostaglandins

which help cells communicate with one another.

Fats have a three carbon backbone called glycerol, as well as fatty acid chains.

The fatty acid chain is basically a string of carbon and hydrogen atoms.

When an “OH” from the glycerol molecule binds to an “H” from the fatty acid, an

“H20” - a water molecule - gets released, and the two molecules link up.

If this happens once, the result is a monoglyceride, if it happens twice it’s a diglyceride,

and three times makes a triglyceride.

Now, there are various types of fatty acid chains, and one way to categorize them is

by their length, in other words, how many carbons they have.

Short chain fatty acids have 2 to 5 carbons, medium chain fatty acids have 6 to 12 carbons,

and long chain fatty acids have 13 or more carbons.

Fatty acid chains are also categorized by the bonds connecting the carbons in the chain.

A single bond is just one bond between the carbon atoms, and when a fatty acid chain

has only single bonds, it’s called a saturated fatty acid - because it has as many hydrogen

atoms as possible - it’s saturated with them.

Triglycerides with saturated fatty acids are nice and straight so they pack together really

well, and as a result they’re usually solid at room temperature.

And the longer the saturated fatty acid chain, the more likely it will be solid at room temperature.

Carbons can also have double bonds between them, and when a fatty acid has one or more

double bonds, it’s called an unsaturated fatty acid because it’s not saturated with

hydrogen atoms - for every double bond there are two fewer hydrogen atoms.

Also a double bond causes a kink in the molecule so the triglycerides don’t pack together

as nicely as saturated fats.

As a result, unsaturated fats are usually liquid at room temperature.

Unsaturated fatty acids can be further classified, according to the number of their double bonds.

Monounsaturated Fatty acids are fatty acids with only a single double bond.

Polyunsaturated fatty acids have two or more double bonds.

Also, they can be classified according to their location as well, since these hydrogens

can get kinda crazy, we’ll take them away for now.

So, we also call the methyl end the omega end, and and then we count the number of carbons

until the first double bond.

Since this one’s three, it would be an omega-3 fatty acid.

If the double bond is 6 carbons from the end, it’s omega-6, and if it’s 9 carbons from

the end, it’s called omega-9.

Now, to make things even easier, I’m just going to show the bonds.

Alright, so omega 3’s are usually polyunsaturated fatty acids, and include alpha-linolenic acid,

or ALA eicosapentaenoic acid, or EPA, docosahexaenoic acid, or DHA.

EPA and DHA are marine sources of omega-3’s.

They’re produced by microalgae, and end up in the tissues of fish like anchovies,

mackerel, salmon, and sardines.

ALA is found in plants like flaxseed, walnuts, and canola and soybean oils.

Our bodies can convert ALA into EPA and DHA, but it’s an inefficient process that yields

only small quantities, and that’s why dietary recommendations include foods that have EPA

and DHA.

Omega-6 polyunsaturated fatty acids are also usually polyunsaturated, and include and linoleic

acid and arachidonic.

Linoleic acid is found in oils like safflower, corn, and soybean oils.

Arachidonic acid is found in animal sources like fish, meat, and eggs.

Our bodies can convert linoleic acid into arachidonic acid, but once again the process

is inefficient.

Because ALA and linoleic acid can only be obtained in the diet, they are considered

essential fatty acids.

Omega-9 fatty acids are typically monounsaturated fatty acids, and an example would be Oleic

acid, these can be made by the human body.

Foods like canola and olive oil, as well as almonds contain omega-9s.

Now, looking at the double bond of this unsaturated fatty acid, like most unsaturated fats, it’s

got a cis configuration.

In a cis configuration, the two functional groups are on the same side of the double-bonded

carbons.

Now when this happens, the fatty acid chain naturally bends.

A molecule that bends doesn’t pack tightly together, so it’s a lot more fluid - think

about cooking oils, which are liquid at room temperature.

Some fats are in a trans configuration, though.

In a trans configuration, the functional groups are on opposite sides of the double-bonded

carbons.

This keeps the chain more straight and easier to pack.

Trans fats result from a process called partial hydrogenation.

In just hydrogenation, hydrogens are added to cis-fats to get rid all the double bonds

double bond, so let’s say you’ve got this triglyceride, it has a total of two double

bonds, so we’d add 4 hydrogens, 2 for each double bond.

That turns the unsaturated fatty acids with cis double bonds into saturated fatty acids!

Partial hydrogenation, on the other hand, refers to adding hydrogens to most but not

all double bonds.

Let’s say now we just add 2 hydrogens.

When this happens, some double bonds can be turned into single bonds by the hydrogens,

but then reform, and what you end up with is an unsaturated fat but some that have trans

double bonds.

Partial hydrogenation is a process that occurs naturally in the digestive tract of some animals

like cows and pigs, which is why trans fats can be found naturally in meat and dairy products.

Trans fats are also created through the partial hydrogenation of liquid oils a process that

makes them solid..

Partially hydrogenated oils have been largely removed from foods in North America and Europe

because trans fats have been associated with coronary heart disease.

Although some foods may have more of one type of fat than another, the truth is that all

foods are made up of a blend of fatty acids.

When you eat a food like peanut butter, which has about 75% of its calories from fat, the

body goes through a set of steps to digest and absorb the fatty acids.

First of all, triglycerides are hydrophobic.

So they form large globules of fat - like what you see when you pour oil into water.

Enzymes called lipases in the saliva, stomach, and secreted by the pancreas can break down

triglycerides into free fatty acids and monoglycerides.

But working on the surface of a globule is inefficient, so to speed things up, bile salts

produced by the liver, break the large fat droplet into smaller droplets which increases

the surface area for the lipases to work.

Once the triglycerides are broken down into monoglycerides and free fatty acids, these

self-assemble into mixed micelles which have and a hydrophobic interior.

and hydrophilic or water loving exterior.

The micelles glide through the watery environment of the intestinal lumen, and reach the enterocytes

in the intestinal wall.

When they get to the enterocytes, the micelles release the fatty acids and monoglycerides,

which diffuse into the enterocyte.

Inside the enterocyte, the fatty acids and monoglycerides reassemble into triglycerides,

and these get packed into a larger structure called a chylomicron.

The chylomicron has lipids and proteins - so it’s a lipoprotein.

It has an outer membrane with phospholipids and proteins, and a hydrophobic core that

contains triglycerides, cholesterol, and fat-soluble vitamins A, D, E and K.

The chylomicron then leaves the enterocyte.

It’s too large to get into the endothelial cells, so instead it enters a nearby lymphatic

capillary called a lacteal.

From there, the chylomicron floats in the lymph and flows into the thoracic duct, and

then gets dumped into the blood - essentially bypassing the portal vein.

Once in the blood, the chylomicron releases fatty acids and monoglycerides in peripheral

tissues like muscle which use them for energy, as well as adipose tissue which can store

them.

After delivering the triglycerides, the chylomicron shrinks in size and eventually gets engulfed

by the liver.

Now fats play a very important role throughout the body.

They have a great number of health benefits and those benefits can vary by the type of

fat we eat.

For example, polyunsaturated fats are precursors for hormone-like molecules called prostaglandins

that stimulate endothelial cells that line blood vessels to release nitric oxide.

Nitric oxide is a vasodilator, so that decreases resistance to blood flow and, in turn, lower

blood pressure.

Polyunsaturated fatty acids also help reduce the total and LDL cholesterol - and that’s

linked to lower rates of cardiovascular diseases like heart attacks and strokes.

Long-chain omega-3 fatty acids like DHA and EPA both help to lower plasma triglyceride

levels which also protects against cardiovascular disease.

Finally, DHA is important in the development of eyes and brains of young infants.

The impact of saturated fat on cardiovascular health is more complex.

Generally speaking, it’s recommended to keep consumption of saturated fat low, but

just like with unsaturated fats there are different types of saturated fats.

Evidence suggests that different types of saturated fatty acids may have different effects

on our cardiovascular health.

Evidence also suggests that the health impact of reducing or replacing saturated fat in

the diet depends on the nutrient that replaces it.

For example, replacing saturated fat with polyunsaturated fat has been shown to benefit

cardiovascular health, whereas replacing saturated fat with refined carbohydrate has not.

Based on this, the National Academies of Medicine recommends consuming 20-35% of our daily calories

as fats - for a 2000 daily calorie intake, that’s between 400 and 700 calories from

fat, or about 44 to 78 grams.

And it’s not just about the amount of fat we eat, the type also matters.

The World Health Organization and the US Dietary Guidelines recommend that less than 10% of

daily calories come from saturated fats and that trans fat consumption should be kept

as low as possible.

All right, as a quick recap: Fats are an essential part of our diet and health.

Fatty acids are either saturated or unsaturated, and foods with fat always contain a mixture

of fatty acid types.

Healthy diets that emphasize mono and polyunsaturated fats over saturated and trans fats are associated

with lower cardiovascular disease risk.

Improvements to your diet and health can be achieved by focusing more on the type of fat

we eat and less on the amount.