A previous post described the general results from the PREDIMED Study, a study that reported on the healthy benefits of a Mediterranean-type diet. See the previous post HERE. Now new results from a subset of volunteers from the same study gives us further insight into the way the Mediterranean diet may be heart healthy.
Researchers randomly chose 296 volunteers with a high risk of heart disease who had previously participated the PREDIMED STUDY. Each was assigned to one of the following three diets for one year:
- A traditional Mediterranean diet with added 4 tablespoons of virgin olive oil per day
- A traditional Mediterranean diet with an added handful of nuts per day
- A healthy control that basically was a low fat diet (decreased red meat, sweets, processed food and high-fat dairy products)
Blood tests to measure high density lipoproteins (HDL) and low density lipoprotein (LDL) were conducted at the beginning and end of the study. For a more detailed discussion of the role of HDL and LDL as heart disease risks, see the information at the end of this post.
High levels of LDL or “bad” are linked to an increased risk of plaque formation in coronary arteries while high levels of HDL are linked to a decreased risk. LDL promotes atherosclerosis in arteries and HDL absorbs cholesterol and returns it to the liver for removal from the body. Therefore, its role helps to keep the blood vessels open.
Researchers think that it is not just the number of HDL particles that allegedly reduces the risk of heart disease, but its functional ability to do so, i e., how well does HDL work?
The results of this study showed only the control diet lowered total and LDL cholesterol as found in other studies. None of the diets improved HDL levels significantly; however, the Mediterranean diets both improved the functionality of the HDL significantly. Additionally, this benefit was much larger among those who given the diet with the extra amount of olive oil.
The Med Diets enhanced the functional ability of HDL by:
- HDL removal of cholesterol from plaque in the arteries
- Protected the process from LDL action on plaque development
- Increased blood vessel relaxation to open blood flow.
One author concluded: “Following a Mediterranean diet rich in virgin olive oil could protect our cardiovascular health in several ways, including making our “good” cholesterol work in a more complete way.” The study was published in Circulation 135:633-643, 2017, a journal of the American Heart Association
Risk Factors for Heart Disease include: High blood pressure, diabetes, obesity, and abnormal blood lipid levels as well as genetics, smoking activity, gender and age. Some of these risk factors are modifiable by diet.
How are Lipids Transported in the Body?
The liver is the major lipid-producing organ. The liver uses excess protein and carbohydrate to make triglycerides or cholesterol. Triglycerides and cholesterol are carried to the cells by low-density lipoproteins (LDLs), the primary cholesterol delivery system for cells.
LDL’a must be taken up by cells by binding to an LDL receptor on the cell membrane surface or membrane. This binding allows LDLs to be removed from the blood and enter cells where they are broken apart to releases fats and cholesterol for the cell to use. If the amount of LDL cholesterol in the blood exceeds the amount that can be taken up by cells due to either too much LDL or too few receptors, the result is a high level of LDL cholesterol and high levels are associated with an increased risk of heart disease
How is Cholesterol Eliminated?
Cholesterol cannot be broken down by the body so it must be returned to the liver to be eliminated. This is accomplished by lipoproteins called high-density lipoproteins (HDLs.) HDLs are particles that originate in the intestinal tract and liver and pick up cholesterol and takes it to the liver for disposal if not needed. A high level of HDL decreases the risk of cardiovascular disease.
So the bottom line:
When you have blood work, the doctor may order blood tests that measures your total cholesterol, your LDL and HDL cholesterol to determine your individual risks of having heart disease in the future.
- Total Cholesterol: Low risk <200; High risk >240
- LDL Cholesterol: Low risk <100; High risk >160
- HDL Cholesterol: Low risk: > 60; High risk <40
- Triglycerides: Low risk; <150; High risk >200
So you ideally want your LDL-C to be low and your HDL-C values to be as high as possible (more than likely dependent on diet and genetics. So think L means “lousy” and H means “healthy.”