Is Your Heart Pumping Sludge?

by | Apr 15, 2012 | Articles, Conditions, Heart, Prevention

Blood thickness, or viscosity, may be the single unifying risk factor for heart disease.  The thicker and stickier the blood the more difficult it is for the heart to pump it through the arteries.  And, it leads to more mechanical stress inflicted upon the artery wall causing abrasive damage that “opens the door” for hardening of the arteries (arteriosclerosis) and artery plaque (atherosclerosis).  Knowing your blood viscosity may become more important than knowing your cholesterol.

The 1997 Edinburgh Artery Study showed that higher blood viscosity was the only marker that was associated with ALL the major cardiovascular disease (CVD) risk factors, including smoking, diabetes, high LDL cholesterol, low HDL cholesterol, high blood pressure, obesity and male gender.  In fact, high blood viscosity is an independent risk factor for CVD, just as predictive as high blood pressure and cholesterol, and even more predictive of CVD than smoking.

Louisiana State University pathologist, Dr Gregory Sloop, wrote a 1996 paper titled “A Unifying Theory of Atherogenesis” in which he opined that blood viscosity was able to predict the entire course of CVD.  High blood viscosity explains why plaque build-up occurs only in specific places in the artery system – that is, high pressure areas and turbulent artery junctions near the heart, such as the coronary arteries and the carotid arteries in the neck, as well as lower peripheral arteries where gravity impacts blood flow.  It also explains why artery plaque always develops in the same manner despite the many diverse risk factors.  Last, high blood viscosity provides a mechanism for blood platelets to activate and clot and includes an explanation of how the good HDL cholesterol protects against CVD, in part by lowering blood viscosity.

Blood Viscosity Physics

One of the really interesting things about blood is that the viscosity changes when the blood is moving.  The faster it moves the thinner the viscosity.  During systole, the part of the cardiac cycle when the heart is pumping, the blood is moving and the viscosity is at its lowest.  During diastole, the period between heart contractions, the blood is still and gets as much as 5 times thicker.  Part of the reason for this is that blood cells become more slippery and flexible when they are moving and as blood flow slows the cells tend to clump together causing an increased viscosity.

Other factors in the blood, such as infections or inflammation, will increase blood viscosity.  So does a diet containing inflammatory fats such as trans-fats or hydrogenated oils, cholesterol, refined high-glycemic carbohydrates, coffee, alcohol and high amounts of animal protein.  Excessive amounts of blood cells, including red cells, white cells or the blood clotting platelet cells will markedly increase blood viscosity.  Even stress is known to increase blood viscosity.

Athletes have the lowest blood viscosity and the highest flow of blood through the arteries, while at the other end of the spectrum those with chronic illness such as cancer, renal or heart disease have the highest blood viscosity and lowest blood flow.  This low blood flow means less oxygen and nutrient delivery to tissue, more tissue breakdown, more inflammation, and so on.

Testing and Treatment

We can easily test various markers that are known to increase blood viscosity, such as the erythrocyte sedimentation rate (ESR) which measures how fast red blood cells clump together.  C-reactive protein (CRP) is another simple blood test that measures inflammation.  But up until recently there has been no clinically available test for direct measurement of blood viscosity.  It is critical to measure viscosity at different flow rates since the it changes so much with different flow rates.  Testing involved a complicated preparation and manual procedures to determine blood viscosity.  This has thus far limited testing to research studies.

Now blood viscosity testing is available in the clinic with a simple blood draw and the technology allowing this is brilliant in its simplicity.  By putting blood into two tubes and filling them to different levels, with a tiny glass tube connecting the two tubes at the bottom, the flow rate of the blood and thus its viscosity can be analyzed.  As the two tubes equal out in the height of the blood columns the rate of blood flow through the tiny tube slows thus giving viscosity readings across a range of flow, simulating the high and low flow rates seen in the body.  Meridian Valley Labs has brought blood viscosity testing to the clinic by acquiring the world’s most advanced blood viscometer, the Hemathix Blood Analyzer.

Measures to lower blood viscosity start with diet.  Eliminate sugar and limit high-glycemic carbohydrates, trans-fats and hydrogenated oils.  Moderate caffeine and alcohol.  Increase the anti-inflammatory fats, EPA and DHA, found in fish and flax.  Include plenty of inflammation fighting raw fruits and veggies.

Next, get some regular exercise, which is well established as a way to lower blood viscosity.  Some studies reveal exercise will even overpower the effects of poor diet when it comes to blood viscosity, showing just how powerful modest exercise is for artery health.

Stress management is third on our list of blood viscosity lowering treatments.  We all have it, and we can’t avoid most of it, so let’s focus on management!  Wherever possible, make choices that lead to a healthy social environment, including work and home.  Seek healthy supportive relationships and be honest with yourself about relationships that are “toxic” and bring negative stress into your life.  Practice simple 5 minute deep breathing exercises throughout the day.  Consider activities such as yoga, tai chi or meditation, all of which are proven to lower the stress hormone cortisol.

Keeping the red blood cell count in check is another potent way to lower blood viscosity.  Many people have high red blood cells counts, sometimes caused by smoking or living at high altitude, other times caused by diseases that increase the cell count.  At any rate, simply donating blood periodically will keep the blood count in a normal range and will lower the blood viscosity.

Supplements that can be used to lower blood viscosity include the omega-3 oils EPA and DHA.  The best capsule form is fish oil.  Krill oil is arguably a bit better, but I’m not sure worth the extra cost.  Flaxseed oil is great but is not very efficient converting to the healthy EPA and DHA so I suggest just eating more of the delicious, nutty flavored flax and flaxseed products.

Nattokinase is an interesting supplement that we have used for many years to help thin the blood and lower the risk of CVD.  Invented and used as a prescription in Japan, nattokinase is made from fermented soy beans.  It is able to actually thin the blood and help prevent blood clots.  Our modern “clot-busting” drugs that are used to treat strokes and heart attacks started with spin-offs of nattokinase.

Blood viscosity testing is another important marker that can be used to help you improve you health.  It cost about $250 and is not covered by insurance.


Scott Rollins, MD, is Board Certified with the American Board of Family Practice and the American Board of Anti-Aging and Regenerative Medicine.  He specializes in bioidentical hormone replacement for men and women, thyroid and adrenal disorders, fibromyalgia and other complex medical conditions.  He is founder and medical director of the Integrative Medicine Center of Western Colorado ( and Bellezza Laser Aesthetics (   Call (970) 245-6911 for an appointment or more information.

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