“My mom has been McDougalling for some time and her doctor is unhappy with her HDL being low, although her LDL is also low.” writes Monica on my discussion board (September 24, 2003).

There is a lot of confusion today about HDL-cholesterol, or high density lipoproteins, commonly referred to as "good" cholesterol.  HDL-cholesterol is one fraction of total cholesterol (other fractions are classified as VLDL (very low-density lipoprotein), LDL (low-density lipoprotein), and MDL (medium-density lipoprotein).  When total cholesterol is lowered, all fractions of cholesterol are reduced, including HDL-cholesterol. This is not bad, but expected, and actually of no harm.  One simple way to raise HDL-cholesterol is to eat more meat (cholesterol) – but that’s not good, because you also increase your risk of heart disease.

(If you are having trouble understanding this concept, then this analogy may help.  Imagine cutting a watermelon (representing the total cholesterol) in half – you now have half as much of all the parts of the melon, including half the number of seeds (HDL). Now double the size of your original watermelon and you now have twice as many seeds.)

Here is a classic experiment demonstrating how eating cholesterol raises cholesterol in the blood.  An "affluent" high-fat, high-cholesterol diet was substituted for five weeks for the traditional near-vegetarian diet of a group of 13 Tarahumara Indians – a Mexican people known to have virtually no coronary heart disease.  Cholesterol levels increased by 31 percent (121 to 159 mg/dl), LDL rose 39 percent (72 to 100 mg/dl) and their HDL-cholesterol, usually low in this population, increased by 31 percent (32 to 42 mg/dl).¹  If they had continued to eat this way they would soon have had heart disease, like their genetic relatives, the Pima Indians, living in Arizona on the Western diet – where 15 percent of males and 8 percent of females aged 40 years and over have had heart attacks, and approximately half of this population are diabetic and /or obese.²

HDL is associated with less heart disease when comparing people who all eat an unhealthy diet (like Americans).  This is because of differences in metabolism in people – some people more rapidly shift LDL (the form harmful to the artery walls) to HDL (the form that leaves the body).  This is fine to have it lower, but the level is dependent upon something you have virtually no control over – your metabolism.  Other than having the opportunity to pick out people with “better” metabolisms, knowing this number is largely irrelevant to achieving better health.

Worldwide (comparing people who eat different diets) those who have the lowest HDL levels (like people in rural Japan, China, and Africa) have the lowest rate of heart disease – and also the lowest total cholesterol.³  Those with the highest HDL levels (like people in the USA and Western Europe) have the highest rates of heart disease.  Looking at this comparison you realize that you can change your diet and change your risk of heart disease – such as is seen in various countries where people eat different diets.

One group of researchers summarized the preceding two paragraphs in one sentence, “In assessing coronary heart disease risk, it may be inappropriate to conclude that diet-induced decreases in HDL are equivalent to low HDL within a given diet.”⁴

So What if a Number – HDL – Is Lower or Higher?

Many people today rationalize their high total cholesterol levels by saying that they also have high HDL levels.  This rationalization occurs not just among lay people, but also among physicians.  I have met people with total cholesterol levels of 285 mg/dl who were told by their doctors not to worry because their "good" HDL cholesterol is also high – 75 mg/dl or higher.   Unfortunately, tens of thousands of people have heart attacks and eventually go to their graves each year with this false assurance ringing in their ears.

Just as HDL goes up as total cholesterol rises, so too do HDL levels fall as total cholesterol drops.  This is the case for anyone who adopts a low-fat, low-cholesterol regimen like ours.  In a study of over 2000 of my patients, we have found that, on average, people reduce their overall HDL levels by 19 percent (8 mg/dl – from 41 mg/dl to 33 mg/dl) in 11 days.⁵ (Total cholesterol also drops on average 29 mg/dl.)   People on healthy vegetarian diets are sometimes told to eat meat because their HDL is only 25 mg/dl.  Yet, their total cholesterol is only 125 mg/dl – a total cholesterol level that makes them virtually immune from heart disease.⁶

HDL cholesterol is a risk factor – not a disease.  No one dies of low HDL – they die of rotten arteries.  Focusing on risk factors, as the medical business does by treating blood pressure, cholesterol, sugar, triglycerides, and homocysteine with drugs, causes little or no improvement in health and longevity.  To get the health we deserve we need to correct the cause of the problem; an unhealthy diet and lifestyle (not the signs of disease – the risk factors).  Total cholesterol (as apposed to the cholesterol fractions, like HDL) is the number that matters most to me (an ideal level and your goal is 150 mg/dl or less⁶).  Don't be misled by partially-informed people.  When you adopt the McDougall Program, you will watch your total cholesterol fall dramatically.  As it does, both LDL and HDL levels will drop, as well.  And as they do, so too will your risk of heart disease.  And your health will improve dramatically. Unfortunately, because HDL doesn’t go up with a healthy diet some unenlightened physicians – acting like puppets for the pharmaceutical industry – give their patients a totally undeserved hard time.

References:

1)  McMurry MP.  Changes in lipid and lipoprotein levels and body weight in Tarahumara Indians after consumption of an affluent diet.  N Engl J Med. 1991 Dec 12;325(24):1704-8.

2)  Ingelfinger JA.  Coronary heart disease in the Pima Indians. Electrocardiographic findings and postmortem evidence of myocardial infarction in a population with a high prevalence of diabetes mellitus.  Diabetes. 1976 Jul;25(7):561-5.

3)  Knuiman JT.  HDL cholesterol in men from thirteen countries.  Lancet. 1981 Aug 15;2(8242):367-8.

4)  Brinton EA.  A low-fat diet decreases high density lipoprotein (HDL) cholesterol levels by decreasing HDL apolipoprotein transport rates.  J Clin Invest. 1990 Jan;85(1):144-51.

5)  McDougall J.  Rapid reduction of serum cholesterol and blood pressure by a twelve-day, very low fat, strictly vegetarian diet.  J Am Coll Nutr. 1995 Oct;14(5):491-6.  This report is on 500 of our people,  Report on 2000 is yet unpublished.

6)  Roberts WC.  Atherosclerotic risk factors--are there ten or is there only one? Am J Cardiol. 1989 Sep 1;64(8):552-4.