Tuesday, November 30, 2010

Lipid Lies: The Story of "High" Cholesterol

The above picture is the USDA's most recent food pyramid.  In case you can't read the writing, the orange represents how much of your diet grains should be.  The green represents vegetables, red for fruits, and teal for milk.  Conscious of how fat can destroy your heart health, the USDA included very small sections for oils (yellow) and meats (which is blue and also includes legumes).  The following are quotes from the text on that picture:
  • Most fat should be from fish, nuts, and vegetable oils.
  • Limit solid fats (note: saturated fats are solid at room temperature)...
  • Keep consumption of saturated fats, trans fats, and sodium low.
  • Eat lean meats...
Four comments saying basically the same thing in one picture.  The point is clear: avoid saturated fat.

The Lipid Hypothesis

To finish up with the USDA, here are two quotes from a page on their website:
  • When there is too much cholesterol (a fat-like substance) in your blood, it builds up in the walls of your arteries. Over time, this buildup causes "hardening of the arteries" so that arteries become narrowed and blood flow to the heart is slowed down or blocked. The blood carries oxygen to the heart, and if enough blood and oxygen cannot reach your heart, you may suffer chest pain. If the blood supply to a portion of the heart is completely cut off by a blockage, the result is a heart attack.  
  • Saturated fat and cholesterol in the food you eat make your blood cholesterol level go up. Saturated fat is the main culprit, but cholesterol in foods also matters. Reducing the amount of saturated fat and cholesterol in your diet helps lower your blood cholesterol level.

What you just read is called the lipid hypothesis: if you eat saturated fat and dietary cholesterol, your blood cholesterol will increase, become deposited in your arteries, and your chances of having a heart attack increase.

Should you be worried about your blood cholesterol level?  Is it high?  Should you avoid eating fat and cholesterol?  I'm going to dissect the lipid hypothesis, whether it's true or not, and the science behind it.  The name is a good place to start.

Lipid means fat.  It's called the lipid hypothesis and not the cholesterol hypothesis because it's not actually about cholesterol.  The so-called "bad cholesterol", low density lipoproteins (LDLs), are actually mostly fat with a little protein.  They carry cholesterol from the liver to other tissues of the body, but LDLs themselves are not composed of cholesterol whatsoever.  It's the same thing with high density lipoproteins (HDLs), which are also composed of protein and fat (HDLs are taxis for cholesterol from various tissues to the liver).  It's called a hypothesis because it's never been proven and validated by quality research (if it were absolutely proven to be true and verified by other professionals, I believe it would be a scientific fact).  According to Anatomy and Physiology, Fifth Edition, by Saladin, a hypothesis is "an educated speculation or possible answer to a question."  The question: what causes heart disease?  The speculation/possible answer: eating fat and/or dietary cholesterol might cause it.  Lets see what the original research said. 

Lipid Hypothesis Origin and Founding Research

The lipid hypothesis was originally suggested by a cardiologist named Ancel Keys.  In 1954, Keys and other well-known individuals in the medical field met at a World Health Organization meeting.  Keys then proposed this hypothesis, although the original studies on this matter weren't even finished (and some weren't even started).  What were these studies that eventually served as the backing for Keys hypothesis to spread?
  1. Seven Countries Study: Keys original study.  From 1958 to 1970, Keys and assistants surveyed 40-59 year old men in seven countries.  He found a linear relationship: as saturated fat consumption and total cholesterol increased, so did heart disease.  HOWEVER, the problem with this study was that it was originally 22 countries and Keys dropped the other 15 because they didn't support his hypothesis!  To his dismay, several countries had low total cholesterol and low fat consumption but high levels of heart disease, and vise versa.
  2. Framingham Study: This study is an ongoing survey in Framingham, Massachusetts.  The first generation of subjects (5,209 residents of the town, between ages 30 and 62) began in 1948.  A big claim of the Framingham study is that it identified high blood cholesterol as a heart disease risk factor.  However, a 30 year follow-up analysis concluded, "After age 50 years, there is no increased overall mortality with either high or low serum cholesterol levels.  There is a direct association between falling cholesterol levels over the first 14 years and mortality over the following 18 years...After age 50 years the association of mortality with cholesterol values is confounding by people whose cholesterol levels are falling."  In other words, the Framingham Study found high or low blood cholesterol to have no effect on death rates for people over 50.  The only thing that did affect the overall death rate, especially from heart disease, was lowering one's cholesterol rate.
  3. Anti-Coronary Club: In 1957, a group of businessmen, aged 40-59, decided to take matters into their own hands by putting together this study.  The experimental group ate what was called a "prudent diet," eating meat a maximum of four times per week, generally replacing their butter with margarine, steak with chicken/fish, and eggs with cereal.  The majority of their fat intake came from polyunsaturated fat.  The control group continued to eat butter, eggs, and meat daily.  The experimental group lowered their total cholesterol level average from 260 to the 220s, while the control group started at 250 and finished at 251, with little change in the middle.  Eight people died in the experimental group, while none died in the control group (you can see a brief discussion of the study in the fifth and sixth paragraphs of this article).
  4. MRFIT: In the 1970s, 362,000 men, aged 35-57 years, were measured over a period of six years.  The author of this study, Jeremiah Stamler (who was a friend of Ancel Keys), mentions several times that total cholesterol levels of 180 or greater are associated with increased cardiovascular disease rates in middle-aged men.  In summarizing the results of this study while supporting the US Department of Health's then recently established nutrition goal of getting total blood cholesterol under 200 mg/dL, Stamler concluded that, "the massive data set reported herein is yet another scientific underpinning for these goals and endeavors." Oh, really? Fortunately, the results are charted below.  As you see, those who had a cholesterol level of about 240 or greater did have the highest level of death due to heart disease, but the author's ignored the more important issue: overall mortality.  I don't know about you, but I'm not trying to avoid death via heart disease, I'm trying to avoid death period.  As far as overall mortality goes, the results showed that total cholesterol levels of about 170-230 had the lowest rates.  Blood cholesterol levels of under 150 or over 280 had the highest death rates.

What does this all mean?

The results are all conflicting.  If anything, they show that a cholesterol level over 200 mg/dL might be healthy or that total cholesterol has no effect on health.  However, these studies (mostly just epidemiological studies that can't prove causation due to an excess of uncontrolled variables) and the individuals who twisted the data for the results they wanted are the basis for why the USDA and other organizations tell you not to eat saturated fat, cholesterol, and red meat.  The media increases the strength of these lies by reporting the occasional study that finds even a slight association (like Meat Intake and Mortality in 2009), however it skips over other studies of similar or better quality that doesn't support its biases (such as a recent meta analysis of 23 studies that found meat to have no association to heart disease).

Here are the truths when it comes to heart disease, cholesterol, and fat:
  1. Having a lipid ("cholesterol") total over 200 mg/dL is not a sign of poor cardiovascular health. 
  2. Most of our blood cholesterol doesn't come from diet. 
  3. Eating saturated fat and/or dietary cholesterol does not negatively impact cardiovascular health at all!
  4. Cholesterol makes up part of your cell membranes.  Cholesterol is made by almost every cell in the body and is critical to brain and nervous system function.  In other words, cholesterol is very important to have.
  5. LDL total is a very poor indicator of heart disease.  It is not black and white.  LDLs vary in size.  If the LDLs are large, they generally perform their desired physiological tasks without any sticking to artery walls.  If LDLs are small, they are much more likely to lead to get stuck in the arteries.  Getting the total LDL number means nothing.  Find our your LDL particle size or just pay attention to other risk factors.
  6. Accurate negative markers of heart disease are high blood pressure, high triglycerides, high blood sugar, and inflammation (C-reactive protein test), to name a few.   A positive marker is having a high HDL total.  Again, LDL total basically means nothing.
  7. Statins lead to muscle pain and atrophy.  They also may increase rates of cancer, heart failure, and cognitive impairment.  Considering that high cholesterol is not a sign of heart disease, why would you take them?  
For more information, check out the following articles and sites:
  1. The International Network of Cholesterol Skeptics (ThINCS)
  2. Does High Cholesterol Cause Heart Disease? by Dr. Bill Davis
  3. The Benefits of High Cholesterol by Dr. Uffe Ravnvskov
  4. Myth and Truths about Cholesterol by Dr. Uffe Ravnvskov
  5. Saturated Fat and Heart Disease: Studies New and Old by Dr. Michael Eades
  6. It's the Beef by Dr. Mary Enig
For a more thorough breakdown of the discussed issues, try the following books:
  1. The Great Cholesterol Con by Dr. Malcolm Kendrick
  2. Good Calories Bad Calories by Gary Taubes


Fred Hahn said...

Excellent post!

Dr. Sean Preuss said...

Thank you Fred. Hopefully the message about cholesterol will get out through your site, mine, and all of the others who are informed.