Everything you ever wanted to know about fat – and more!
What is the difference between oils, fats, and lipids?
Fat = oil = lipid
“Lipid” is the general term for all fats and oils. Originally,
“fat” referred to lipids that are solid, and “oil” referred to lipids that are
liquid, at room temperature,[i]
but this is less important now that we know the chemical structure of the
molecules, so we just use them interchangeably. And to be clear, we are only
talking about life, NOT about the mineral oils that come from petroleum.
EFA – essential fatty acids, which are like vitamins, they
are required for life, and we must eat them because we can’t make them. This
includes omega 3 and omega 6 PUFA.
PUFA – polyunsaturated fatty acids are long-chain fatty
acids that have multiple double-bonds. They are made by plants and include
omega-3 and omega-6 EFA. These are also called: HUFA – highly unsaturated fatty
acids.
What are lipids?
Lipids are long chains of carbon atoms that have no polarity,
so they do not dissolve in water. In the
body, they generally have a molecule at one end that is water soluble, allowing
them to function. For example, our cell membranes are made out of fats called
phospholipids.
Because blood and body fluids are water-based, the
“hydrophobic tails” reject water
stick together, and their “hydrophilic heads” that are attracted to water stay
on the outside. These “heads” are phosphate, which attracts water. Thus, there
can be water-based fluid on both sides, creating a membrane barrier between the
inside and outside of cells.
What are fatty acids?
These are just lipids with long chains of carbons, that have
an acid (carboxyl) group on one end of the chain – where the phosphate would be
in the phospholipids. The fatty acid is the basic building block of oils in the
body and are converted for various uses, such as phospholipid membranes,
leukotrienes, or hormones.
What are saturated and unsaturated fats?
There are two main kinds of oils used in cell membranes and
in the body:
1.
Saturated
2.
Unsaturated
Saturated fats can be made by your body, or be eaten as
animal fats, butter, or coconut oil. They are generally solid at room
temperature. These have a long chain of carbons that are all filled with
hydrogen atoms, making them strait so they stick together easily, that’s why
they’re solid. Saturated fat is not the
enemy it has been made out to be. The problems that are seen with coronary
artery disease are not related to saturated fat.[ii]
Heart disease comes from inflammation, and clots in the arteries, caused, in
part, by omega-6 and partially-hydrogenated oils with trans-fats. Feel free to
eat saturated fat.
Unsaturated fats come from plants, such as corn, soy, or flaxseed
oil and are called PUFA’s (Poly-Unsaturated Fatty Acids). Olive oil and canola
oil are primarily “monounsaturated” having only one double-bond. Unsaturated
means there are places in the chain where there is only one hydrogen on the
carbon, making a double bond between the two carbon atoms. Plants make
unsaturated fats. We can get them from fish, but the fish get it from algae and
plankton. If chicken, pork, and beef have omega 3, or 6, they get it from
eating plants. The unsaturated fats are irregular, so they are more liquid.
What are triglycerides?
When these fatty acids are bound together in groups of three
by a three-carbon alcohol called glycerol, they are called triglycerides.[iii]
Triglycerides are the storage form of fat. This is the fat
that is in your fat cells. It contains both saturated and unsaturated fatty
acids, depending on the diet and genetic factors. If the fat is made in your
body, it is mostly saturated fatty acids, with a small amount of monounsaturated
fats. If you have a diet high in PUFA, these will be attached to a glycerol
molecule and stored in your fat cells as well.
What is rancid oil?
PUFA omega 3 and omega 6 oils can oxidize and become rancid.
This mostly affects the flavor of food, but the oxidized oils also act as
immune modulators, causing inflammation.
It is interesting to look at the PUFA content of foods to
see which are stable. For example, in the chart below, look at both safflower
oil and coconut oil. They are both stable because they have very little PUFA’s
and can be heated, whereas both soybean and flaxseed oil should not be used for
frying because they oxidize easily when heated. This is why scientists
developed hydrogenated oils. This is also the reason to make sure your oils are
“cold-pressed” and not heated during processing.
What are hydrogenated oils and “trans-fats?”
PUFA’s are cheap, but they are liquid and oxidize easily so
they don’t last long, causing food to spoil. Because saturated fats work better
for baking, cooking and preserving food, but animal fat is expensive, chemists
devised a way to “saturate” the unsaturated fats with hydrogen. This made saturated
fats plentiful, but also added the problem of “trans-fats.” During the chemical
reaction, some get a configuration called “trans-fat” that cannot be used by
the body and can become toxic, being stored in the fat cells, and used in the
membranes. This can lead to inflammation, heart disease, and cancer.[iv]
Why are the omega PUFA’s so important?
The “omega” oils are essential for life but cannot be made
in the body – we must eat them. What’s more, the relative amounts
of each that is eaten will determine to a great extent how the body functions. We
need them to make hormones and membranes. Without PUFA’s we cannot make a
single cell. For example, the DHA (omega 3) fat in the membranes of the brain
makes them more fluid and allows signals to get into the brain cells. Without
DHA the brain cannot function. Also, without the cell signaling of the omega 6
oils, we would not be able to activate the immune system and would die of
infection.
What is the difference between omega 3, 6 and 9?
Omega 3 and omega 6 are EFA, Essential Fatty Acids. They are
required for the body to function, and we cannot make them. On the other hand,
omega 9 is also needed, but we can make it, so it isn’t essential that we eat
it. The size and structure of each is similar, except for the first double-bond
from the “omega” end of the long chain. Each angle in the illustrations below[v]
represents a carbon and 2 hydrogens – unless there are two lines, then it is
only one hydrogen on each carbon, that’s why they are called “UN”-saturated.
Omega 9 fats are found in most food, but are high in safflower
oil, avocado oil, canola oil, olive oil, and macadamia nuts, as well as all
animal fats. Omega 9 oils are also called monounsaturated oil because they only
have one double bond at carbon number 9. These are not EFA, Essential Fatty
Acids, because they can be made by humans. But, eating these oils promotes the
use of fat for energy, which helps the metabolism in many ways, lowering blood
sugar, preventing heart disease, and increasing weight loss, for example. It is
good to replace omega 6 oils like corn oil with omega 9 such as olive oil.
How do EFA’s affect inflammation?
Omega 3 and omega 6 fats are required for immune function.
They balance inflammation – generally omega 6 is needed to cause inflammation
and help healing, and omega 3 suppresses inflammation and prevents damage to
cells. The balance between them is essential. The omega 3 and omega 6 oils use
the same enzymes to produce all the EFA needed in the body.[vi]
In the following illustration the various omega oils are on the outside, with
the enzymes in the middle.
In our food supply we have a large amount of omega-6 oils,
and few sources of omega-3. This causes excess pro-inflammatory hormones
causing inflammation. Inflammation is implicated in multiple diseases including
arthritis, autoimmune disease, Alzheimer's Disease, diabetes, heart disease,
and so forth. Trans fats and rancid PUFA also contribute to inflammation. Thus,
it is important to balance these EFA so you can have enough inflammation to
remove infections, but not too much to cause these diseases.
What foods contain EFA and in what amounts?
It is not so much the amount, as the percentage of oils that
make the difference. Too much omega 6 increases inflammation. The omega-6 to
omega-3 ratio should ideally be around 1:1, meaning you eat about the same
amount of omega-3 as omega-6. Different oils have very different compositions
of omega 6 and omega 3. The following is a graph of the composition of oils. Some
of the oils have no omega-3 at all.[vii]
Do I have to eat fat?
Besides oils used in cooking, the foods we eat all have some
fat content. We don’t think of broccoli as a good source of oil, but it has
about 100 milligrams of omega-3 oil in a cup of broccoli. All vegetables
contain some EFA. Vegetables are higher in omega 3 than omega 6 – between two
and ten times as much.[viii]
So, while the vegetables themselves have little oil, they have a great ratio so
over time there is great benefit. Some people spend a lot of money on
supplements such as krill oil, which has about 200 milligrams of omega-3 in a
capsule – 2 cups of broccoli would be about the same. Since they have
significantly more omega 3, vegetables are a good source of oil.
Fish is a good source of omega-3 with low levels of omega-6.
Farmed fish has about three times as much fat as wild fish, and about four
times as much omega-3 as omega-6, but wild salmon has about twelve times more
omega-3.[ix]
Thus, although wild-caught has a better profile, farmed salmon has more fat,
and ounce-for-ounce has more omega-3.
Grass-fed animal fats have a better EFA ratio than grain-fed
because grass has about 1:8 omega-6 to omega-3. In beef, for example, the
omega-6 to omega-3 ratio is about 2:1 in grass fed cattle, and about 5:1 in
those that are grain-fed.[x]
Since butter is mostly saturated and monounsaturated fat, the grass-fed variety
may be less important. Even if you eat grass-fed beef, consider that it still
has more omega-6 than omega-3. Lamb and pork are also about 4:1 omega-6 to 3
ratio.
What is the right amount of EFA?
Even though both types of EFA are essential for life, there
is a big difference in their effect, as noted above. Omega-6 causes
inflammation, leading to disease. The following graph[xi]
illustrates the percentage of omega-6 in the tissues (blood) of various areas
of the world. Notice that as the relative amount of omega-6 PUFA goes up, the
death rate from heart disease goes up in that area.
In Greenland, where they live on fish, and have no
significant source of omega-6 oils, they have the lowest death rate from
cardiovascular disease. Their ratio of omega-6 to omega-3 is around 1:3. Wherever
the ratio is 3:1, as recommended by the U.S. government, the cardiovascular
death rate is six times higher. It seems that when it comes to omega-6 EFA,
lower is better. However, there is no way to completely avoid omega-6 fats in
your diet. Look at the chart above with the list of oils – none of them are devoid
of omega-6 – however, there are many that are missing omega-3.
How do I keep my omega EFA balanced?
Supplement marketing tells us to take in more omega-3 oil –
by buying pills. It seems the better way may be to lower the omega-6. It is not
so much the amount, but rather the percentage of the various PUFA’s that are in
our food. The balance between fatty acids determines whether we make more
inflammation, or less. The great thing about this is that it’s easy to balance
your EFA. The graph above indicates that less omega-6 is better. The take-home
message is: Avoid omega-6 fats. That is really easy – read the chart of different
oils above, and don’t eat anything with:
·
Sunflower oil
·
Cottonseed oil
·
Corn oil
·
Soy oil
·
Peanut oil
·
Sesame oil
But avoiding omega-6 is only part of the story, the other
half is to increase omega-3.
·
Eat fruit and vegetables.
·
Eat grass-fed meat, eggs, and dairy in small
amounts.
·
Eat fish (wild-caught is better)
·
Use flaxseeds and chia seeds in your food.
·
Use olive oil, grass-fed butter, or coconut oil
for cooking.
What about taking omega-3 supplements?
It is ideal to get your oils from fresh and natural foods,
but it seems that most Americans need supplements. Consider the amount of
omega-3 that is in the following supplements:
·
Fish oil capsule 1 gram
·
Flaxseed (1 TBS) 2
grams
·
Krill oil: 0.24 grams (Contains multiple EFA)
·
Cod Liver Oil (1 tsp) 0.9 grams (Also has vitamin A and Vitamin D)
·
ALA (from flaxseeds) 0.6 grams
·
Algal oil 0.25
– 0.9 grams (Vegan DHA)
When you consider
the large amount of fat that is eaten every day, about 100 grams,[xii]
the amounts of omega-3 oils in the supplements is small, mostly less than 1%. This
is why it might be wise to avoid foods that are high in omega-6 oils and still
take supplements with omega-3. Above all, don’t take any supplements that
contain omega 6.
What is the
bottom-line recommendation?
·
Avoid omega 6 oils (vegetable oils)
·
Avoid hydrogenated oils, especially “partially
hydrogenated oil”
·
Eat whole foods with omega 3 oils (fish, flaxseed,
chia seeds)
·
Take an omega-3 supplement – fish oil – 1-2 grams
per day.
