After last week’s blog entry about lowering cholesterol through diet and exercise, a fellow naturopathic physician, Dr. Melanie Trowbridge, emailed me asking about the supplement side of lowering cholesterol.
I mentioned it last week, but it really warrants a longer discussion. So long,
in fact, that I’m going to have to split it up into two entries to cover
everything!
There are a number of supplements out there that claim to
lower cholesterol, and it can be hard for consumers and practitioners to assess
what does and doesn’t work. I’ve searched the medical literature to try to
generate an accurate picture of what’s effective, and what to expect from these
supplements.
At the risk of sounding like a lawyer, I’m going to state
here that by no means is this meant to constitute medical advice or otherwise
take the place of a consult with a healthcare provider. Unlike, say, seasonal allergies, you can’t tell if your cholesterol is improving unless you have it
tested by a healthcare provider – this is part of the importance of working
with someone. Additionally, high cholesterol is a chronic condition that
requires long-term work. Don’t go it alone. Get some assistance along the way,
someone who can assess your current situation, help you set goals, figure out a
plan to reach those goals, and help you weather the inevitable challenges. I'd be remiss if I didn't mention the AANP's Find a Naturopathic Doctor Service here.
One last thing before we dive in – here’s an entry I wrote on understanding cholesterol/lipid lab tests, just in case you need a
refresher as we go.
Plant
sterols (including beta-sitosterol) – I’m including this first
because plant sterols are actually recommended by the ATP III as a way to lower
cholesterol. So what are they? Plant sterols are molecules found in fruits and
vegetables that resemble cholesterol, but are not used by the human body in the
same way as cholesterol, and don’t appear to have the same harmful effects.
They act by competing with cholesterol for absorption in the small intestine,
thus reducing the amount of dietary cholesterol absorbed into the blood. They
have been documented to reduce cholesterol, LDL cholesterol and triglycerides,
in a manner that appears to be dose-dependent; moderate doses produce a 10-14% reduction in LDL cholesterol, whereas higher doses can generate larger reductions in LDL cholesterol. In addition to lowering cholesterol in
therapeutic doses, amounts of sterols that occur naturally in food appear to have a protective effect, helping to keep cholesterol in a healthy range. Plant
sterols generally appear to be safe, though at least one study I read suggests potential side effects, which have yet to be fully described and documented –
all that much more reason to work with a professional.
Green
tea – Regular readers of this blog will know how much I love tea –
it’s healthy, it’s delicious, and it’s endlessly varied. So what about
cholesterol and green tea? A few studies I found demonstrated that either green
tea or a green tea extract lead to a mild decrease in total cholesterol and LDL
cholesterol (1, 2, 3), though at least one other found no benefit. The decrease is mild,
less than 10% change in total cholesterol or LDL cholesterol. For some, this
might be enough to bring their cholesterol into a healthy range, though for
many, this change is too little to control cholesterol adequately. What sets
green tea apart from the other supplements I’m discussing today is that it has
been demonstrated to reduce LDL oxidation (1, 2). Here’s why this is important: While
doctors generally test total LDL to assess a patient’s cardiovascular risk
factors, it’s becoming more and more clear that it’s oxidized (damaged) LDL
that accumulates in artery walls, forming plaques and obstructing blood flow –
this is part of the reason that smoking is so bad for you. Thus, while green
tea’s ability to lower cholesterol is only moderate, it has the ability to
prevent that cholesterol from becoming a potently harmful form of cholesterol.
Fish oil – Omega-3
fatty acids, like those found in fish oil, have received a lot of attention
recently for their cardiovascular benefits. So what does the data say? Well, my
research into the topic is by no means exhaustive, but clear trends started to
emerge fairly quickly. According to the studies and reviews available, fish
oils either have no effect on cholesterol levels, or slightly raise them –
across the board, including total cholesterol, LDL cholesterol and HDL
cholesterol (1, 2, 3). So how do we reconcile this? Isn’t fish oil supposed to be good
for your heart?
The answer is yes, fish oil is good for your heart, and
without going into a full discussion of fatty acid metabolism and transport, I
should point out that there is good news buried in this elevation of
cholesterol. Firstly, HDL cholesterol is ‘good cholesterol’, and the fact that
it fish oil increases it is good news. Secondly, though fish oils apparently
raise blood levels of LDL cholesterol, it has been observed in some studies that the size and shape of LDL is modified towards less disease-causing forms, (1, 2) though this was not universally observed (1, 2). Additionally, there is reason to believe that the slight increase in LDL levels is linked to a significant decrease in VLDL levels (1, 2). Like with green tea, the emphasis is not on the change in the
LDL levels, but rather on the health of those LDL molecules – green tea makes
the LDL less oxidized/damaged, and fish oil makes the LDL larger, more buoyant,
and less likely to cause damage to arteries.
In assessing fish oil, we should also remember that
cardiovascular disease isn’t all about cholesterol. Several studies have
demonstrated that fish oil has a significant protective effect when it comes to
cardiovascular disease itself, including angina, stroke, heart attacks and
other disease. A large Italian study in the 1990s showed that fish oil given
to heart attack survivors significantly reduced their chance of having another
heart attack, having a stroke, or dying from other causes. A similarly large Japanese study found that patients with high cholesterol taking EPA (an omega-3
fatty acid found in fish oil) in addition to statin medications had a
significant reduction in non-fatal heart problems compared to patients on
statins alone, though LDL levels did not significantly differ between the
groups.
The take-home message is this: fish oil may not lower
cholesterol, but it is clearly good for your heart. Fish oil is one of the few
supplements I recommend to nearly all of my patients. But for those of you out
there who have taken it and not seen a lowering of cholesterol levels, this may
go some of the way to explanation. Even so, it’s still good for you!
Phew! I think that’s enough for the day. Tune in again next
time for Part 2, which will feature discussion of garlic, niacin and red yeast
rice.
