Diet and Health FAQ

Tagged As: low carb diet lowering cholesterol

Question:
Someone at work has high cholesterol and is considering LC to lower it, but he doesn't need to lose weight. Can he follow a moderate plan with low carb diet like Atkins maintenance or The Zone and still lower his cholesterol? thanks .

Answer:
Absolutely. The determination of heart disease risk based on cholesterol levels is actually a measure of how much cholesterol is being transported to body cells for use in cell walls and hormone production, as opposed to how much cholesterol is being removed from body cells for disposal. This is where we get the definitions of good versus bad cholesterol. In simplified terms, TOTAL CHOLESTEROL as measured in the laboratory on a blood sample consists of LDL or bad cholesterol plus HDL or good cholesterol. (There are other subfractions which enter into the equation that are expained later). I have heard criticisms that a low carb diet causes an increase in cholesterol. This statement is meaningless if it means total cholesterol, because an increase in the good fraction will cause the total cholesterol to increase, but is a very beneficial effect. There is no way to know the significance of a high total cholesterol level without knowing the measures of HDL and LDL cholesterol. Criticisms about high fat intakes with low carb diets causing increased heart disease are typically based on the knowledge of studies showing exactly that effect in high carbohydrate diets (50% or more of total calories obtained from carbohydrate). It is a scientific error to ignore the difference in carbohydrate content of the diet. The evidence for this is clear. Scientific studies that considered both the carbohydrate and the fat content of the diet (dating as far back as 1977) demonstrated that increased fat in the diet caused an increase in HDL cholesterol. The mechanism for this is the production of a protein called Apo A-1, which is a major component at the surface of the HDL molecule as it makes contact with receptors on the cell wall, sending chemical messengers to the cell interior. These chemical messengers carry excess cholesterol to the HDL receptor, which then loads the cholesterol into HDL. As the flat HDL particle fills up with cholesterol, it swells and breaks contact with the HDL receptor. Thus, the role of HDL is to scavenge for excess and unwanted cholesterol and take it back to the liver so that the liver doesn't have to make so much cholesterol. In addition, saturated fat was shown to increase the production of Apo A-I more than polyunsaturated or monounsaturated fat. Add to this the evidence that the human body always uses dietary carbohydrates for energy before using fat, and we can see why a diet higher in carbohydrates should cause an increase in LDL cholesterol. If adequate calories are present in the carbohydrate content of a meal, then the fat in the same meal will be transported for storage. The molecules that ultimately transport the bulk of this fat is the LDL molecule. The fat itself is in the form of triglycerides, but a fairly constant amount of cholesterol is included in each LDL. It is therefore no surprise that a shift to a low carbohydrate diet that contains more saturated fat than recommended can lower LDL cholesterol and raise HDL cholesterol at the same time. Sometimes the increase in HDL is dramatic - in these instances, the total cholesterol may very well increase above normal levels - but it is a very desirable high cholesterol to have. It should be noted that there are persons who have various genetic conditions in which too much LDL cholesterol is manufactured, or is not cleared appropriately from the bloodstream. In these persons the same benefits in cholesterol measurements may not be obtained from a low carb diet, and they may require medications to lower cholesterol despite optimal dietary practices. This does not mean that the low carb diet does not work for them - it is still the healthiest way for them to eat, as long as the LDL cholesterol level is controlled. Now to get even more technical as to understanding the test results. Three major classes of lipoproteins are found in the blood of a fasting individual: low density lipoproteins (LDL), high density lipoproteins (HDL) and very low density lipoproteins (VDL or VLDL). The LDL typically contain 60-70 percent of the total serum cholesterol and both are directly correlated with risk for coronary heart disease (CHD). The HDL normally contains 20-30 percent of the total cholesterol, and HDL levels are inversely correlated with CHD risk. The VDL contains 0-15 percent of the total serum cholesterol along with most of the triglyceride in fasting serum; VDL are precursors of LDL, and some forms of VDL, particularly VDL remnants, appear to be atherogenic. The density of a lipoprotein refers to the relative amounts of lipid versus protein in the molecule. The greater the percentage of lipid, the lower the density. The total cholesterol consists of the amount of cholesterol attached in the high density lipoprotein fraction, the amount attached to the low density lipoprotein fraction, and the amount attached to the very low density lipoprotein fraction. The formula is: TC(Total Cholesterol)=HDL+LDL+VDL. Cholesterol is a fat-like substance (lipid) that is present in cell membranes and is a precursor of bile acids and steroid hormones. Cholesterol travels in the blood in distinct particles containing both lipid and proteins. These particles are called lipoproteins. The cholesterol level in the blood is determined partly by inheritance and partly by acquired factors such as diet, calorie balance, and level of physical activity. For both males and females, cohort studies within populations consistently show an association between blood cholesterol levels and CHD rates. Men with cholesterol levels near the top of the population distribution have CHD mortality rates that are five times those near the bottom. A large body of epidemiological evidence supports a direct relationship between the level of serum LDL cholesterol (or total cholesterol) and the rate of CHD. People with a high triglyceride level may have what is called hyperlipidemia, which tends to run in families. People with hyperlipidemia are more likely to have heart disease. They are the major components of the Very Low and Intermediate Density Lipoproteins, (VDL and LDL), the other lipid components found in the blood stream. The very low-density lipoprotein, or VLDL circulates through the bloodstream, dropping off the triglycerides to the muscle and fat cells to be used for energy or stored for later use. When VLDL drops off its triglycerides, it breaks up into smaller low-density lipoprotein, or LDL. LDL carries cholesterol throughout the system, dropping it off where it can be used for cell metabolism. Cholesterol carried by LDL that is not used, broken down by the liver, or excreted, is left to circulate in the bloodstream where it accumulates in the arterial walls, in the form of plaque nodules. Since VLDL is a precursor of the LDL, the bad cholesterol that causes the plaque accumulation, it is not as useful as a predictor of coronary heart disease risk. HDL is sometimes referred to as good cholesterol since high levels of HDL are a negative risk factor for coronary heart disease. This is because one of the main functions of HDL is to take excess cholesterol to the liver for excretion in the bile. Therefore, the best cholesterol-related parameter to measure as a risk factor for coronary heart disease is the LDL/HDL ratio. As I stated previously, the VLDL is included in the total cholesterol (VDL + LDL + HDL). So that's why we never hear much about VDL in test results, it really doesn't provide much for assessing risk. So, in my humble opinion, which is based on scientific fact, eating a low carbohydrate, high fat, moderate protein diet will result in positive and healthy cholesterol levels. I hope this helps.