Tag Archives: LDL

Twilight Zone of Diet Studies

Imagine if you will a diet study, a seemingly ordinary diet study. One that compares low carb and low fat diets. Now imagine that you are reading the results, and find the unequivocal superiority of the low carb diet.

Results:

Both the Low and Moderate Carbohydrate groups lost significantly more weight as well as inches from their waists and thighs than the Control group, while the Low Carbohydrate group lost a greater percentage of body fat. Although the Moderate Carbohydrate group showed significant reductions in serum cholesterol, the Low Carbohydrate group showed the greatest improvements in serum cholesterol, triglycerides, high-density lipoprotein, low-density lipoprotein, and very-low-density lipoprotein.

Consider, if you will, how you would write the conclusion to these findings. That all-important snippet of text that will be read by those too busy to read the full synopsis, the snippet that will be picked up in articles and future studies.

Perhaps you will write something that bears some resemblance to the words and phrases in the Conclusion. Something that recognizes the low carb diet as being at least equal in your test for weight loss, yet reducing more body fat than the low fat diet. Consider how you will sum up the findings, that the low carb diet provided significantly better results for cholesterol and triglycerides. But before you put your pen to paper, read the actual conclusion:

Moderate approaches to weight loss such as a moderate-carbohydrate low-fat diet may be prudent.

There is nothing wrong with your eyes. Those are the words the study authors penned. An example, perhaps of cognitive dissonance.

You are traveling through another dimension –a dimension not only of sight and sound but of mind. A journey into a wondrous land whose boundaries are that of imagination. That’s a signpost up ahead: your next stop: the Twilight Zone of Diet Studies!

How Carbs Influence LDL

One of the fears some have in adopting a low carb diet is the possibility that LDL cholesterol will increase. And indeed, in the typical blood test we take, there is sometimes an increase in this so-called bad cholesterol. But what is the real relationship between carb consumption and LDL particles in the bloodstream?

Dr. William Davis of the Heart Scan Blog has some clarification for us:

Carbohydrates:
1) Increase triglycerides and very low-density lipoprotein particles (VLDL)
2) Triglyceride-rich VLDL interact with LDL particles, making them smaller. (A process mediated by several enzymes, such as cholesteryl-ester transfer protein.)
3) Smaller LDL particles are more oxidizable–Oxidized LDL particles are the sort that are taken up by inflammatory white blood cells residing in the artery wall and atherosclerotic plaque.
4) Smaller LDL particles are more glycatable–Glycation of LDL is an important phenomenon that makes the LDL particle more atherogenic (plaque-causing). Glycated LDLs are not recognized by the LDL receptor, causing them to persist in the bloodstream longer than non-glcyated LDL. Glycated LDL is therefore taken up by inflammatory white blood cells in plaque.

Of course, carbohydrates also make you fat, further fueling the fire of this sequence.

Dr. Davis’ main concern is the impact eating carbs has on your cardiovascular health … not fat, but carbs. He focuses on the most recent scientific evidence and techniques to shepherd his patients past heart disease and toward longer, healthier lives. Is he concerned that the standard blood test may show a rise in LDL cholesterol? Not at all.

The standard blood test uses the Friedewald calculation rather than measuring the blood lipids directly. We have several articles on LDL and the Friedewald calculation for your edification.

Dieting for Risk Factors

With the usual caveat that I am not a medical professional, I want to propose an idea for your consideration. I would encourage you to discuss this idea with your doctor before embarking on any diet plan.

I think it makes sense to first identify your individual risk factors for the things that kill us. The Centers for Disease Control (CDC) publishes charts showing the leading causes of death for men and for women. Looking at the charts you see that heart disease is the leading cause of death at about 27% of all deaths. We tend to focus on those stats and work to minimize our chances of dying from heart disease. That’s certainly the approach taken on a society-wide level with the low-fat diet recommendations (the low fat diet is thought to reduce serum cholesterol levels leading to less heart disease, although many of us find that it increases cholesterol instead.) What I think we are ignoring is that our individual risk factors may be for something entirely different. Remember, that heart disease is not the cause of death for a majority of the people … 73% of them, in fact. Are we increasing our risk of dying early by trying to reduce our risk for heart disease?

The American Heart Association (AHA) identifies the risk factors for heart disease in two categories, those you can change and those you cannot. The categories are a mistake, in my view. It is the risk factors you cannot change that may be the most susceptible to changes in diet: age, sex and heredity. 83% of the deaths due to heart disease happen after age 65, so time is on your side if you are younger than that. Males are more susceptible to heart disease, and have a higher incidence of dying younger than that age 65 statistic. And family history, including race, plays a factor.

The factors you “can change”, according to the AHA, are things like tobacco use, obesity, high blood pressure, serum cholesterol levels, activity levels, and diabetes.

The standard treatment to reduce risk factors for heart disease is a low fat, relatively high carbohydrate diet and prescription drugs to lower cholesterol. The prescription drugs are necessary because many people find a low fat, high carbohydrate diet raises cholesterol (especially triglycerides). Low carb diet advocates challenge this view, and note that many people find a low carb diet improves their lipid profile without the use of prescription drugs (as well as improving weight, high blood pressure and other factors).

The problem is that there is no easy way to score these factors. Do you check off each factor, and if you have more than three, start to worry? Or is family history such an important factor that it, by itself, compels you to work to reduce your risk? Certainly, if your parents and all your siblings died of heart attacks, you probably realize it “runs in your family.” But for most of us, even getting the full list of risk factors isn’t enough to tell us if we, personally, are at risk.

The place to start is a doctor who knows your medical history. Ask him point blank: what do you think I’m going to die from? The answer will be about risk factors for the diseases on those CDC charts, and which one your history indicates the greatest risk for you. Heart disease and cancer are at the top, by a large margin. But as you read down the list, you see stroke, respiratory disease, and diabetes.

Its interesting that diabetes is a risk factor for heart disease, and diabetes itself is the 6th leading cause of death.

My largest risk factor, given my family history and age, sex and physical condition is diabetes. Several people in my family, a brother and my mother, have adult-onset diabetes. I’m male, over 50, and have more than two of the markers for “metabolic syndrome” (pdf file from CDC on metabolic syndrome). In contrast to that, I have very little heart disease in my immediate family.

My doctor recommended a low carb diet to reduce my high triglyceride level; success is shown by lowering triglycerides from 462 to 113 on my last blood test. I’m staying on it to lower my weight and blood glucose level, as well as meet the other cholesterol goals (HDL, LDL, etc., as shown on the About Page).

The term “diet” is often associated with a reduced calorie, temporary eating regimen that you abandon after reaching a weight goal. The problem with this approach is that it ignores the very real impact your diet has on your health. The real goal should be to live longer, not simply to lose weight and “look good”. A pretty corpse is still dead.

Your diet should reflect the best bet to protect against your individual risk factors, and not to fulfill a broad societal goal.

Low Carb Better than Low Fat

Another article has been posted to our Research pages, this time recapping a study that compared a standard LCD (low carb diet) to the American Heart Association diet that emphasizes low fat. The study was published in the Nutrition, Metabolism and Cardiovascular Diseases journal, and is posted here.

The study selected 39 individuals and divided them into two groups. One group ate a carb-restricted diet for 12 weeks. The other group ate a carb-restricted diet for 6 weeks, and then switched to the AHA diet for the remaining 6 weeks.

In this study, the low carbohydrate diet followed the recommendations of most of the low carb diets: 20 to 25% of calories from carbs. The AHA diet, by comparison, doubles that amount with 50 to 55% of the calories from carbs.

One concern often expressed about eating low carb and increasing saturated fat in the diet is that LDL can rise using the normal calculated value. This study looks specifically at the type of LDL that each of the diets produces, using direct measurements rather than an inaccurate calculation.

The short version of the results is that the low carb diet “had a better effect on atherogenic VLDL and HDL than the low fat diet recommended by AHA.” Atherogenic VLDL and HDL are particles that lead to the formation of atheromas on the walls of the arteries, or what we commonly call atherosclerosis.

This is just one study, and won’t immediately change the dietary recommendations of nutritionists, doctors and the American Heart Association. But the “Low Fat Age” is seeing its reign come to an end, and the Low Carb Age is upon us.

LDL – Measure it Directly

My medical history includes a high triglyceride level over 400, and my doctor asked for a direct measurement of my LDL. Usually, the labs calculate the LDL by using a formula rather than measuring it directly. As Dr. Michael Eades says in his blog:

… Friedewald substituted triglycerides (TGL) divided by 5 for VLDL in the above equations, giving us the so-called Friedewald equation for calculating LDL.

LDL = Total cholesterol – HDL – TGL/5

And this is how it is still done in labs all over the world 27 years after Friedewald’s paper. If you’ve had a lab report showing an LDL figure, I can guarantee it was calculated by the Freidewald equation and not measured directly.

It has long been recognized that if the triglycerides are over 400, the calculation does not work. So you have to measure the level directly. In that same blog post, Dr. Eades explains his experience that LDL calculations are inaccurate when the triglycerides are low as well. I have linked two articles Dr. Eades identifies as supporting that position in our new LDL Research Page.

Many studies show marked improvement in patients HDL, triglycerides and glucose levels with low carb diets. Often, the low carb dieter has a rise in total cholesterol and LDL. Researchers are not concerned with the higher total cholesterol number, but the LDL level increase does concern them. But most studies use the Friedewald calculation that may not give an accurate picture of the true LDL level.

If my LDL gets too high, I’ll be certain to ask for a direct measurement of it, rather than a calculation. The extra cost for the test is probably cheaper than taking statins.