By Dr. Mercola
Omega-3 fats are essential polyunsaturated fatty acids (PUFAs) your
body needs for digestion, muscle activity, blood clotting, visual
acuity, memory and much more. They're particularly important for proper
cell division and function of cell receptors.
These fats, although originally synthesized by microorganisms in the
oceans, are ideally obtained from the consumption of small fish that are
free of toxins.
Most omega-3s are
considered "essential fats" as your body cannot make them. You have to
get them from your diet. However, there's plenty of confusion when it
comes to which omega-3 fats are required for optimal health.
Can you substitute marine animal-based omega-3 for plant-based omega-3?
And is there really a difference between the omega-3 you get from fish,
versus that from krill? In this interview, Nils Hoem, Ph.D., a Norwegian
scientist specializing in omega-3 phospholipids, answers these and
other crucial questions.
The 2 Sources of Omega-3
You can obtain omega-3 fats from both plants and marine animals like
fish and krill. However, it's really important to realize that these
sources provide DIFFERENT TYPES of omega-3, and they are NOT
interchangeable.
If for whatever reason you choose to avoid all animal-based foods, you
simply cannot substitute with plant-based omega-3 and think you've
covered all your omega-3 needs.
Both plant- and animal-based omega-3 have their first double-bond in the
third position — hence the name "omega-3." However, the length of the
carbon chain of each omega-3 fat makes a significant difference when it
comes to bioavailability and biological effect.
Marine animal-based omega-3 (fatty fish, fish oil
and krill oil) primarily contain docosahexaenoic acid (DHA), a
long-chained PUFA consisting of 22 carbons and eicosapentaenoic acid
(EPA), which has 20 carbons.
Plant-based omega-3 (found in flaxseed, flaxseed
oil, chia seeds, walnuts and leafy greens, for example) contain
alpha-linolenic acid (ALA), a shorter-chained PUFA consisting of 18
carbons. They are completely devoid of DHA and EPA.
Why You Cannot Substitute Animal-Based Omega-3 With Plant-Based Omega-3
ALA is a precursor to EPA and DHA. However, an enzyme is required to
convert the shorter 18 carbon ALA into long-chained omega-3. In most
people, this enzyme doesn't work very well and hence the conversion rate
is exceptionally small.
Typically, less than 1 percent of the ALA is converted to EPA. Some
studies have found the conversion rate to be as 0.1 to 0.5 percent.1 Your conversion is also dependent on having adequate levels of other vitamins and minerals.
So, while a tiny amount of the ALA you consume can be converted by
your body into long-chain omega-3, it's a highly inefficient strategy
and nowhere near as helpful as supplying "straight" DHA and EPA from
marine sources. It pays to beware of misleading and confusing
advertising here. As noted by Hoem:
"Chemically you could name any fatty acid that has its first level
bond in the third position an omega-3 fatty acid. Increasingly we see
different players trying to use the label 'omega-3' as a general label
for healthy or a general label for having biological effects in line
with EPA and DHA.
That's simply not the case. It's a kind of mislabeling. [Ed. Note:
Omega-3 eggs are an example, as the hens were not actually fed marine
animal-based omega-3.]
We should be distinct in saying marine omega-3s, or we should say
long-chain omega-3s; that's correct. But the 18-carbon-chain omega-3s,
they do not have documentation about biological effects. In fact,
meta-studies ... come out with them being neither bad nor good.
We turn a very small amount of them into long-chain omega-3 fatty
acids, but it really doesn't help as much. There may be genetic
differences as told by a professor from Japan ...
But all in all, you cannot [attach] the same type of biological and
health effects on the shorter-chain omega-3s as you can with EPA and
DHA.
In Norway, for example ... we had a big headline in our main
newspaper telling us that reindeer meat contains as much omega-3s as
cod, which is technically correct, but it really confuses people.".
Additionally it is important to know that
you should NEVER take flax oi or use ground flax seed unless it is
freshly ground because the highly perishable ALA will be oxidized. If
you have any throw it away immediately. I take one tablespoon of organic
flax seeds a day but they are soaked overnight and blended into my
smoothie
How Different Lipids Affect Your Health
The short-chain or plant-based ALA does not provide the same health
benefits as EPA and DHA. And there's no evidence to show it can
significantly be converted by your body into the longer-chain EPA and
DHA fats.
But there's even more compelling evidence that you cannot replace
animal-based omega-3 with plant sources. Hoem's research shows that
after eating a meal of salmon or taking krill or fish oil, the fatty
acid level in your plasma (blood) will remain elevated for more than
three days afterward.
"Your body works on its distribution, redistribution and
re-redistribution for three days. That's hardly consistent with being
food," he says.
On the other hand, the short-chain omega-3s (ALA) are rapidly absorbed,
peaking a couple of hours after ingestion. Within 10 hours, they're
gone. This suggests your body is using long- and short-chain lipids
(fats) very differently.
According to Hoem, the short-chain fatty acids are simply food — they're
a source of energy — while the long-chain fatty acids, those with 20
and more carbons, especially EPA and DHA, are structural elements that
actually make up your cells. This is a MAJOR difference between plant-
and animal-based sources.
EPA and DHA have many biological effects, most notably anti-inflammatory
activity and communication within the cell and between cells.
Another tell-tale sign suggesting the importance of EPA and DHA is their
half-life, which may be as long as 60 days for DHA. Your body tends to
accumulate and hold on to it and not want to let it go.
EPA is used up much faster, in about 80 hours, in part because it's a
smaller molecule, but also because it behaves differently from DHA.
According to Hoem, EPA is "the mother" of docosapentaenoic acid (DPA), a
third member of the long-chained omega family that has gained a lot of
interest lately. The main difference is your body makes DPA. When you
eat EPA, a proportion of it becomes DPA.
EPA and DHA Are Crucial for Health
DHA is especially important, as it is a component of every cell in your
body, and it's particularly crucial for your brain. More than 90 percent
of the omega-3 fat found in brain tissue is DHA, and the development of
a normal brain in a fetus is dependent on the availability of DHA. All
other omega-3 fats are found only in trace amounts in your brain,
including ALA, regardless of how much ALA you consume.2
There are actually specific transporters for long-chained omega-3s in
your blood-brain barrier, the placenta (in pregnant women), and likely
also in your liver, which transport these molecules in a very precise
way into the cell membranes where they belong. No such transporters
exist for the short-chained omega-3s.
So please, don't make the mistake of confusing plant-based
(short-chained) and animal-based (long-chained) omega-3, as doing so
could have severe health consequences. You absolutely need animal-based
omega-3 (DHA and EPA), and you simply cannot obtain the same benefits from plant-based sources.
I'm not vilifying plant-based omega-3 fats. You do need ALA;
you just don't need an excess of it. And don't think you convert that
ALA to EPA and DHA, because you just can't. That said, ALA is a very
healthy fat that serves its own useful purpose.
Identifying Healthy Sources of Animal-Based Omega-3 Fat
The next practical question becomes: how do we identify healthy sources
of marine-based omega-3? Healthy, meaning, uncontaminated by toxins and
structurally intact with a high rate of absorption. Those are three big
issues. If you make a mistake on one of them, you're not going to be as
successful in integrating these important molecules into your cell
membranes.
Omega-3 fat bound to ethyl esters — a synthetic form of marine omega-3
fat used in some pharmaceutical-grade omega-3 supplements — appears to
have a particularly poor absorption rate. According to Hoem:
"If you have it together with a decent meal, ethyl esters will be
taken up. But I have seen experiments done where the ethyl esters simply
pass through without being absorbed whatsoever."
This synthetic form of marine omega-3 fat is a fatty acid that has been
sliced off from its triglyceride source, and then ethylated with
ethanol. The rationale for doing this is to have a safe way of purifying
it to meet pharmaceutical standards. This way it can also be
standardized and highly concentrated. One of the general principles for
healthy eating is that the less refinement a food goes through, the
better and this certainly appears to be true in the case of omega-3
supplements.
"I would maintain that the best way of getting your marine omega-3s
would be to eat safe, fresh fish. Whenever I'm asked, that is my
standard answer," Hoem says. "I lectured in physiology for
almost 20 years. I told my students about how fats are being taken up.
They get down into your gut.
There are lipases in your gut that will decompose them and they will
be re-synthesized in the erythrocyte. They will be taken up and they
will be re-synthesized. They will be made into other microns (small
emulsions). Then they will flow through your lymph ... Now, while that
is mostly right for the triglycerides, I never even considered what
happens with phospholipids.
With phospholipids, we've become aware of that it isn't exactly like
that. In phospholipids, at least part of the omega-3s is taken up as
lysophosphatidates. They are water-soluble enough to be taken directly
up into the blood. They're then passed into the liver and are
redistributed before they are sent into systemic circulation.
That explains part of why it takes so long to redistribute those
fatty acids. I think we've been grossly underestimating how complicated
this is. We've been underestimating the very fundamental problem our
bodies have with regards to the uptake of fat. Fats are not
water-soluble. Our bodies have to go through very radical techniques to
emulsify these fats after transporting [them] into different parts of
our body."
Lipid Groups
The two largest groups of lipids (fats) are both called glycerol lipids,
as the steroid hormone to which you add your fatty acids is glycerol, a
trivalent alcohol. Three fatty acids can be added to this little
glycerol molecule. This turns it into a triglyceride, which you find in
both fish and vegetable oil. This type of fat is an excellent energy
source, although high fasting triglyceride levels in your blood is also a
marker or risk factor for heart disease.
The other lipid molecule also starts out with glycerol. To this you add
two fatty acids, but instead of a third fatty acid, either a phosphate
or a choline is added. This seemingly small difference renders this
lipid into something "quite beautiful," to quote Hoem.
"If you take this molecule into water, it spontaneously forms
membranes or sheets. This molecule really is the molecule that forms the
sheets that every cell in our body is made of. If I were to select a
molecule of life, it would not be DNA; it would be phospholipids.
Phospholipids make us. It's impossible to think of life without this
membrane ... Everything that makes up a cell can be made from these
membranes.
[So] we have two glycerol lipids. One of them is not water-soluble
at all. It will not form any sheet because it's completely hydrophobic
and is basically used for energy. Then the other type makes us. We're
made of it."
Krill Oil Has a Unique Fat Profile
Indeed, fats are a complicated business, and minor differences can have a
big impact. For example, there are two key differences between the
phosphatidylcholine found in krill and that found in soybeans and
sunflowers. Hoem explains:
"Krill is quite unique with respect to the fact that almost all of
its phospholipid is phosphatidylcholine (PC). There is a little bit of
phosphatidylethanolamine, but otherwise there are two other types —
phosphatidylserine (PS) and phosphatidylinositol (PI) — that you really
don't find in krill at all.
For example, in lecithin from soybeans, you will find pretty much
equal amounts of the four different types. The other difference is the
fatty acid composition. Krill has very specific fatty acid composition.
Almost every PC molecule has one EPA or DHA. In the other possible
position, you will find either oleic acid or palmitic acid ... That
describes the phosphatidylcholine you find in krill oil, which is pretty
unique."
So krill oil contains all three types of fat: saturated, monounsaturated
and polyunsaturated. However, it bears noting that this only applies to
Antarctic krill (Euphausia superba). Krill is found in oceans around
the globe, but only krill from the cold waters of the Antarctic will
contain this unique lipid profile — likely because it allows the krill
to survive the cold.
How Krill Oil Is Extracted
Krill are plankton that feed on algae. However, it must be below
freezing in order for them to be able to digest it. In your stomach,
it's 98.6 degrees F (37 degrees C), and your lipases are really active
at that temperature. If you dropped the temperature down to freezing,
your lipases wouldn't work.
But krill lipases are able to digest at really low temperatures. This
means that if you leave a bucket of krill in a frozen state, it will
still decompose. To inactivate the enzymes you have to heat them. This
is done right on the krill boats, immediately after harvest. The krill
is heated for a very brief period of time to inactivate the enzymes and
kill off bacteria. After that the krill are dried to remove the water.
"That's the product that we bring onshore and from which we extract lipids," Hoem says. "We learned how to do that in a very gentle way. You keep a blanket of water vapor on top to displace air as we go.
When I entered Aker Biomarine, I thought ... we could do it the same
way as we do with fish oils. No way ... With fish oil, you can use
quite harsh extraction techniques ... None of that can be done with
krill oil. You would completely ruin your phospholipids.
We use only ethanol and water. That's the magic medium by which you
can extract both triglycerides and phospholipids. We manage to take out
quantitatively the lipids out of the krill meat. Of course, when that
has been done, you have to remove some of what you do not want ...
We have a separation technique, again, using only water and ethanol,
that takes out all polar constituents like salts, trimethylamine oxide
and so forth. Remove that and you're left with a lipid that is clean,
but in many respects extracted almost like virgin olive oil. It's very
gentle."
Not all companies use these gentle methods however. Some will use more
dangerous solvents like hexane. Aker Biomarine uses no toxic solvents at
all, and that's a really important consideration when choosing a krill
oil product.
Hoem also provides details on the harvesting and sustainability
standards for krill oil. Overall, it's a far more sustainable source
than fish. If this is a concern for you, please listen to the full
interview, or read through my previous article, "Why Krill is your Best and Most Sustainable Source of Omega-3 Fat."
Phospholipids Make Krill Oil a Superior Source of Omega-3 Fat
Total Video Length: 05:40
Just as there are two different types of omega-3 sources, plants and
marine animals, there are two primary types of marine animal-based
omega-3 supplements: fish oil and krill oil. While both are marine
animals, krill oil is everything that fish oil is and more. As Hoem
says, "Fish oil has its place, but krill oil is a much more complete
lipid package. It's a more complete nutrient."
Both fish and krill oil contain EPA and DHA. However, there are
important differences between these two marine sources. One of the most
important differences is the fact that krill oil is bound to
phospholipids.
Fatty acids are water soluble, but they cannot be transported in their
free form in your blood — they require "packaging" into lipoprotein
vehicles. Most fatty acids are typically bound to esters, which do not
travel efficiently in your bloodstream. As indicated earlier, krill oil
is an exception in this regard.
• Fish oil is bound to triglycerides and methyl esters:
which must be broken down in your gut to its base fatty acids of DHA
and EPA. About 80 to 85 percent is simply eliminated in your intestine. • Krill oil is bound to triglycerides and phospholipids:
which allows the omega-3 fats to travel efficiently into your hepatic
system; hence they're more bioavailable. Your body can readily absorb
it. Studies have shown that krill oil may be 48 times more potent than fish oil.
This means you need far less of it than fish oil, as confirmed by a 2011 study published in the journal Lipids.3
Researchers gave subjects less than 63 percent as much krill-based
EPA/DHA as the fish oil group, yet both groups showed equivalent blood
levels, meaning the krill was more potent.
Phospholipids are also a principal compound in high-density lipoproteins
(HDL), which you want more of, and by allowing your cells to maintain
structural integrity, phospholipids help your cells function properly.
(You can learn more about this in the video above.) • Krill oil also has natural astaxanthin:This
is important as the omega-3 fats in marine oils are polyunsaturated
meaning that they are highly susceptible to oxidation and going rancid.
Astaxanthin is a potent antioxidant that protects these perishable fats and is not naturally present in fish oil.
Tests reveal that krill oil remains undamaged after being exposed to a steady flow of oxygen for 190 hours. Fish
oil goes rancid after a single hour. That makes krill oil nearly 200
times more resistant to oxidative damage compared to fish oil.
Other Advantages of Krill Oil Over Fish Oil
Research also shows krill oil has a number of other advantages over fish oil, including the following:
• Contains phosphatidylcholine: when
you consume fish oil, your liver has to attach it to
phosphatidylcholine in order for it to be utilized by your body. Krill
oil already contains phosphatidylcholine, which is another reason for
its superior bioavailability. Phosphatidylcholine is composed partly of
choline, the precursor for the vital neurotransmitter acetylcholine,
which sends nerve signals to your brain, and for trimethylglycine, which
protects your liver.
Choline is important to brain development, learning and memory. In fact,
choline plays a vital role in fetal and infant brain development and is
particularly important if you are pregnant or nursing. According to
Hoem, krill oil is about 90 percent phosphatidylcholine, so it's an
excellent source of this important phospholipid.
"Remember, we're talking about a basic building block," he says.
"You need it for your membranes. You need it as a methyl donor in a
number of fundamental and biochemical transformations. It's a basic
building block for your body ...
If you take choline chloride, for example, most of that is not taken
up at all. It actually ends up as food for bacteria, which makes it
into trimethylamine, which is taken up and then excreted as
trimethylamine oxide. The phosphatidylcholine form is taken up [well]
because it's not being broken down. We know now that a substantial part
of it is taken up directly and delivered to the liver."
The importance of choline has been known for a long time. This is one of
the reasons why decades ago many health food enthusiasts were
recommending lecithin as a source of phosphatidylcholine. Again, the
primary difference between soybean or sunflower lecithin and the
phosphatidylcholine you get from krill is the fatty acids.
Rather than getting an omega-6 based fat, which most get too much of
already from their diet, you're getting long-chain fatty acids, EPA and
DHA, omega-3s. • Superior metabolic influence: researchers
have found that krill oil is vastly superior to fish oil when it comes
to having a beneficial influence on your genetic expression and
metabolism. Genes have "switches" that can be flipped on and off, which
control virtually every biochemical process in your body, and nutrients
like omega-3 fats control those switches.
Fatty acids help to direct metabolic processes such as glucose
production, lipid synthesis, cellular energy, oxidation and dozens of
others. We now know that various types and sources of omega-3 fat affect
liver tissue differently, which is what a 2011 study4 in Frontiers in Genetics was designed to examine.
It compared the livers of mice fed krill oil to those fed fish
oil by looking at the gene expression triggered by each. Although both
fish oil and krill oil contain omega-3s, they differ greatly in how they
affect the genes controlling your metabolism. Krill oil:
◦ Enhances glucose metabolism in your liver, whereas fish oil does not ◦ Promotes lipid metabolism; fish oil does not ◦ Helps regulate the mitochondrial respiratory chain; fish oil does not ◦ Decreases cholesterol synthesis, whereas fish oil increases it
So, krill oil will help lower your triglyceride and cholesterol
levels and increase your energy production, whereas fish oil does
neither. Last year, an Italian study5,6
confirmed that krill oil helps improve lipid and glucose metabolism and
mitochondrial function, which may help protect against hepatic
steatosis (fatty liver disease) caused by an unhealthy diet (such as
diets high in unhealthy fats).
By stimulating certain mitochondrial metabolic pathways, including fatty
acid oxidation, respiratory chain complexes and the Krebs cycle, krill
oil helps restore healthy mitochondrial energy metabolism. • Contaminant-free: fish
are very prone to mercury and other heavy metal contamination, courtesy
of widespread water pollution. Antarctic krill is not prone to this
contamination. Not only are they harvested from cleaner waters, but
since krill is at the bottom of the food chain, it feeds on
phytoplankton and not over other contaminated fish.
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The Importance of Maintaining a Healthy Omega-3 to Omega-6 Balance
As you increase your intake of animal-based omega-3 fats, the EPA and
DHA content in your red blood cells increase. As your omega-3 ratio
increases in the cell, it "pushes out" omega-6 at a ratio of about 1 to
1. While you need some omega-6 fats, most people get FAR too much of it
in their diet these days. Consumption of soybean oil (which is almost
exclusively omega-6) rose 1,000-fold between 1900 and 2000.
Modern processing and refinement add to the problem as it damages the
omega-6 fats, not to mention most soybeans are genetically engineered
and heavily treated with Roundup. In my view, it's reasonable to assume
this massive increase in damaged omega-6 oils has significantly
contributed to our current epidemics of diabetes, heart disease, cancer and neurodegenerative diseases.
"I think only recently have we started to realize that we need a balance between these two [omega-3 and omega-6]," Hoem says.
"Of course, you need inflammation, but when inflammation overshoots or
it becomes too keen, then it may do more harm than good ... You need
your omega-3s in the right proportion to modify or modulate inflammatory
response.
By now we also know that the omega-3s have important actions
downstream. You have the inflammation started, for example, by
arachidonic acid. To start it all, what our bodies need to do at the
same time is to limit excessive inflammation with the proper fats."
The Omega-3 Index — An Important Health Test
In terms of how much omega-3 fat you need, there's been a lack of
reliable ways of measuring them. Hoem cites a recent paper that looked
at omega-3 intakes on a global scale, identifying countries with high
and low intakes.
"It really puts a lot of numbers behind things that we need to know with regards to the global consumption," he says. "They also compared different ways of measuring omega-3s — in your blood, plasma and erythrocyte.
They consistently found that the best way of doing it, the way that
correlates best with tissue levels on your whole body level, is the
omega-3 index [which measures the omega-3 in your red blood cells or
erythrocyte]. Doing that, you will know [whether you're getting enough].
Your index ideally should be above eight.
In experimental animals, I've seen levels up to 20. I've heard that
dolphins have levels way above 20. They're really loaded with omega-3.
Their diet will secure that. They're pretty intelligent animals too.
Their brains will be well supplied. I think the best way ... is to have
people measure their levels. They would have to adjust their dosage
until they reach [the optimal] level."
I believe the omega-3 index test can be an enormously important health screen, and it's commercially available. As with vitamin D,
getting your level tested is really the best way to customize your
dosage to ensure sufficiency, because requirements for omega-3 will vary
depending on your lifestyle; your intake of fatty fish, for example,
and your level of physical activity.
Athletes tend to burn off their omega-3 quite rapidly, as the DHA gets
burned as fuel rather than being used as a structural component of their
cell membranes. Hence they will need higher dosages. Interestingly,
when this index is done on vegans, the results are typically half of
what is found in those who are eating some marine fats.7
Speculative Suggestions That May Improve Omega-3 Uptake
While speculative, I also believe it may be advantageous to take your
DHA/EPA with some form of short-chained fat like MCT oil or coconut oil,
which is a medium-chain triglyceride that burns quickly. It's possible
this fat could be used to discourage your body from burning up the
omega-3 fat, which is more important for maintaining structural
integrity. Hoem weighs in on this hypothesis saying:
"That's an interesting speculation. I think you're onto exactly why
the uptake of long-chain omega-3s is so slow. I think they're so slow to
get below the radar, not to be eaten. They kind of hide themselves.
Yes, that might be one strategy; take them together with other fats ... I
would [also] probably advise athletes to take their krill oil in the
afternoon after they've had their exercise ... "
Dosage Recommendations
According to Hoem, fatty fish is your best source of long-chained
omega-3 fats. However, remember that all fish do NOT contain these fats.
Tilapia, for example, contains no EPA or DHA. Ideally, the fish needs
to be harvested from cold water, as this is what triggers the production
of these fats in the fish.
"There are particular types of fish that are fatty and fish that
live in cold waters. You need to inform yourself with regards if your
particular type of fish contains enough of the long-chain omega-3s or
not. But I would guess in a fatty fish, typically I would say two to
three servings a week would be enough.
With regards to krill oil, again depending on who you are and what
you do, I certainly would not recommend less than 1 gram. I take 2 grams
a day. By that I am well supplemented. I'm between eight and 10 in my
omega-3 index. Also, I would say ... I wouldn't be afraid of taking too
much. I hardly think, within the normal ranges we're seeing, that we
would be able to do that. I have still not yet seen an overdose of
fish."
Setting the Record Straight on Plant- and Marine-Based Omega-3s
To recap, it's really important to realize that you cannot trade
animal-based omega-3 for plant-based omega-3. Even if you take large
amounts of plant-based omega-3, it simply will not provide you with the
raw materials you need for a healthy body and brain.
This strategy doesn't work because your body cannot convert enough ALA
into DHA and EPA. Unfortunately, there are a lot of people who believe
that. Even many health professionals have fallen for this misconception.
If you're in this camp, I strongly urge you to reconsider.
"I think it is pretty clear. All research point in that direction," Hoem
says. So please remember, while plant-based omega-3s are quite healthy,
and you do need them, without marine based omega-3s you're unlikely to
achieve optimal health. If you're an unwavering vegetarian and refuse to
eat either fish or krill, you could potentially obtain some EPA and DHA
from eating algae, although there are open questions about algae as a
clean, healthy source.
"I think you're still left with some lipid extract from algae. I do not know much about it," Hoem says.
"I know that the products used for baby formula is technically speaking
very high-quality with respect to control of the extraction and, for
example, any residual solvents.
But you're simply left with that. I would still maintain that the
best way of doing it would be to eat some sort of seafood. I don't know
if any larger algae from marine sources would ever be available. And
there would always be concerns with algae from marine sources as they
may contain natural toxins."
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