Can a Low-Fat High Fiber Diet Raise LDL?

A low fat diet also tends to be a high carbohydrate diet. Carbohydrates that are high in fiber come from whole, natural sources such as fruit, vegetables and whole grains. These are thought to be much healthier than refined carbohydrates such as sugar and flour which have much more carbohydrates per serving than whole foods. But scientists are beginning to think that excessive carbohydrates might raise the risk of heart disease.

Cholesterol

• Cholesterol is one of several types of fat that circulate in the bloodstream. It is naturally occurring and is necessary for good health.

  It is actually composed of several types of compounds, known as High Density Lipoproteins (HDL), Low Density Lipoproteins (LDL) and Very Low Density Lipoproteins (VLDL).

  Generally speaking, the more HDL you have in your blood, the better your heart health. LDL cells are packed full of cholesterol, and VLDL cells are packed with triglycerides. While total cholesterol in your blood is not a very good predictor of heart disease--largely because HDL helps to clean your veins and prevent heart disease, while LDL tends to clog your system and cause heart problems--triglycerides levels are a good indication of potential heart health.

LDL and VLDL

• High LDL is a somewhat bad sign for your health, and high VLDL is very bad. The best predictor of heart disease is the amount of both VLDL and LDL combined in your blood. It's difficult to measure VLDL, so your doctor usually just measures HDL and LDL. If your LDL has gone up, it's likely that your VLDL has too. Low HDL levels put you at much higher risk for heart disease than normal HDL levels.

Fiber

• Researchers in the 1970s found that diets high in refined carbohydrates--which would include white sugars and flours--were strongly linked to heart disease, obesity and certain types of cancer. They speculated that it the link was caused by the removal of fiber from these carbohydrates, so they recommended that we increase our fiber intake. But in 2006, the Dietary Modification Trial of the Women's Health Initiative conducted on 49,000 women found no correlation between the amount of fiber in their diets and their rates of heart disease, colon cancer, breast cancer or obesity.

Carbohydrates

• The one thing that we know raises VLDL is carbohydrates. Because VLDL contains triglycerides, which are associated with heart disease, doing anything that raises this form of cholesterol will increase your risk of heart disease. Eating a high carbohydrate diet is therefore a strong risk factor.

Fat

• We need fat in our diets. Fat is responsible for regulating hormones, building cell walls, and keeping our brains healthy. It is estimated that these basic processes require that at least 15 percent of our calories come from fat. Researchers have also found that eating a high fat diet decreases triglycerides in some patients.

Conclusions

• A high fiber diet that is also high in carbohydrates can increase your triglycerides and LDL cholesterol, which means it is unlikely to lower your risk of heart disease.