DrG's Medisense Feature Article
12121-Coconut_Oil
Coconut Oil (with a primer on fat structure)
by Ann Gerhardt
December 2012
Print Version
Bottom
Line at the Top: Coconut oil raises total and LDL-cholesterol
levels, but may not be as bad for the heart and blood vessels as we
thought previously. Is it a miracle food that should become
the predominate fat in your diet? No.
Fad nutritionists recently popularized coconut oil, turning it into a
purported health food and anti-aging body
emollient. Pro-coconut oil articles claim that,
when taken internally, it improves heart health, increases metabolism,
promotes lean bodies and supports the immune system.
I’ll address these issues in this article. Other,
cures-what-ails-you claims have so little supporting data that they
aren’t worth discussing here.
After years of hearing that coconut oil, rich in saturated fat, is bad
for your cholesterol, some people now claim that Pacific
Islanders’ good health is due to their diets rich in coconut
oil. Though there may be some validity to that conclusion, it
would be difficult to prove, because of other behavioral
variables. Pacific Islanders also eat a lot of nutrient-rich
plant foods and rely on their feet, not their cars, for
transportation. Exercise, fruits and vegetables can
compensate for a lot of dietary faults.
Coconut oil’s followers have donned cult-like
attributes: One site claims that “there was a
strong propaganda in 1970s spread by the corn oil and soy oil industry
against coconut oil.” That’s paranoia,
written in poor English and designed to inflame with absolutely no
justification.
The ‘propaganda’ mentioned was actually many good
scientific studies, which firmly established coconut oil as
consistently cholesterol-raising. This valid and
well-designed research was published in peer reviewed
journals. The only problem with their work was that they
studied short-term outcomes, like cholesterol levels, rather than
long-term end-points, such as illness and death.
Current studies reaffirm that coconut oil raises cholesterol levels,
but note that individuals do vary in their
response. Some people experience absolutely no
change, while others note markedly increased cholesterol levels.
On the plus side, HDL-cholesterol (the ‘good’ one)
bumps up, too. Or at least it doesn’t go down, as
happens with beef fat and lard. This might offset the bad
effects of higher LDL-cholesterol levels, with less consequent harm to
blood vessels and health.
So what sets coconut oil apart from lard in its effect on
cholesterol? Coconut oil contains mostly medium-chain fatty
acids which raise total, LDL-cholesterol (bad) and HDL-cholesterol
(good) levels. Lard is full of long-chain fatty acids, which
raise LDL-cholesterol, but not HDL-cholesterol.
To refresh your memory about fatty acids, chains and fats, the word
‘chain’ refers to the chain of carbons linked
together to form a fatty acid. Three fatty acids attached to
a glycerol molecule make a triglyceride. Mixtures of
triglycerides make up the bulk of fats and oils. They also
contain a few other minor fat-soluble substances.
Fatty acids come in short (4-6 carbons), medium (8-14 carbons) and long
(>16 carbons) -chain varieties. Short-chain fatty
acids appear in foodstuffs in only tiny quantities. Coconut,
palm and palm kernel are the major foods containing medium-chain fatty
acids. Fish oil, animal fat and most vegetable oils (soy,
corn, olive, etc) contain mostly long-chain fatty acids.
Fatty acids differ further according to how saturated (how many
possible sites of bonding to the carbons are
‘saturated’ with hydrogens) or unsaturated (missing
some hydrogens) they are. Saturated fats are solid at room
temperature. Regardless of chain length, they are used by the
body entirely for energy production. They promote higher
cholesterol levels and more clogged arteries. The body uses
unsaturated fats for a variety of purposes, including cell structure,
immune function and neurological signaling, in addition to providing
energy.
Every fat contains a mixture of fatty acid types. We tend to
characterize a fat by the fatty acid type that predominates, but that
doesn’t mean that it contains ONLY that fatty acid.
For example, olive oil is 82% oleic acid, therefore we call it a
long-chain, mono-unsaturated fatty acid fat, but it also contains 8
percent saturated fat and a variety of poly-unsaturated fatty
acids. Only half of the fatty acids in fish oil are the
extra-long chain types that quell inflammation, arrhythmias and
depression.
Coconut oil is 91.5% medium-chain fatty acids, all saturated.
Most of the remaining, long chain fatty acids are essential fatty acids
(a good thing), but the quantity is very small. Coconut oil
would have to supply over half your total calorie intake to meet your
daily requirement for essential fatty acids. Hydrogenation turns
essential fatty acids into saturated fatty acids, eliminating coconut
oil’s few healthful fatty acids.
If coconut oil does, in fact, induce less vascular disease than do
other medium-chain and saturated-fatty acid-containing fats, it may be
because of anti-oxidants dissolved in the oil.
In coconut oil, these
anti-oxidants are phenolic compounds, which are capable of reducing
inflammation in animals.
We need further research to see if this translates to humans.
Any claims about coconut oil being anti-bacterial are based on test
tube tests, not data from live people.
Some extraction methods eliminate coconut oil’s
anti-inflammatory and anti-oxidative benefits. Wet-extracted,
virgin coconut oil retains its beneficial anti-oxidant effects better.
Repeated
high heat during cooking generates carcinogens and
pro-oxidants. Rats
fed re-heated coconut oil grow abnormal liver cells and generate more
peroxidized fat and reactive oxygen species and less protective
anti-oxidant enzymes. Good reasons to not re-use cooking oil.
Some claim that coconut oil is slimming. A few studies seem
to suggest that there is something to this, but the evidence is far
from convincing. While equal calories from different fat
sources have equal effect on body weight,
people consuming coconut
oil tend to accumulate less abdominal fat and
have smaller waist-lines.
The science behind this probably relates to how the gut digests and
absorbs fatty acids of different chain length. Short- and
medium-chain fatty acids are absorbed directly into blood that flows
immediately to the liver. The liver can burn them for energy
or package them for transport into the blood stream for use elsewhere.
Long-chain fatty acids follow a different route: They pass
from the gut into the lymphatic system and are packaged in little fat
balls (chylomicrons) that raise blood triglyeride levels and can be
metabolized for energy or directly deposited into body fat.
Eventually they make it to the liver, but have lost much of the fatty
acid content by that time. This sounds good, but
doesn’t really explain the differential fat deposition or why
some people deposit more abdominal fat than do others.
Coconut oil is an effective skin and hair
moisturizer. Is the effect really
‘anti-aging’ and biochemical youth, as
claimed? – No, skin and hair just look
better, which may be enough to satisfy most people.
One ounce of coconut oil (6 teaspoons), like all other oils, provides
about 234 calories. Like other fats, it also contains various
fatty acid esters, alcohols and derivatives, fat soluble bioflavonoids
and vitamins E and K.
Should we shun coconut oil, as was recommended in the past?
No. Should we embrace it as our major food oil?
No. Should we eat Thai food now and then and include coconut
oil in our choices for cooking? Yes. Enjoy.