High cholesterol is one of the major controllable risk factors for coronary heart disease, heart attack and stroke.
The American Heart Association explains that if you have other risk factors — such as smoking, high blood pressure or diabetes — your risk increases even more. That's why getting your annual physical checkup is so important, especially the older you get.
LDL is the "bad" kind. It's produced naturally by the body, but many people inherit genes from their parents or grandparents that cause them to make too much. To make matters worse, eating foods with saturated fat or trans fats also increases the amount of LDL cholesterol in your blood. If high blood cholesterol runs in your family, lifestyle modifications may not be enough to help lower your LDL blood cholesterol and you'll have to take medication to keep it in check. In the United States, 28% of adults who are 40 and older use lipid-lowering drugs to manage their cholesterol levels.
Just because you require medication to manage your cholesterol, doesn't mean you shouldn't also make those lifestyle modifications. In fact, a recent study from the University of California, San Diego School of Medicine has found that cholesterol levels improve with weight loss and a healthy fat-rich diet.
Whether your cholesterol is borderline high, already too high or requires you to take medication to keep it under control, eating healthy fats, such as olive oil in the Mediterranean diet, or a low-fat, high-carbohydrate diet can help you lose weight and, therefore, help lower LDL levels.
More specifically, the researchers report that a meal plan rich in walnuts, which are high in polyunsaturated fats, has a significant effect on lipid levels for women, especially those who are insulin-resistant.
So about those lifestyle changes… Weight loss and reducing consumption of saturated fat have always been associated with reducing levels of "bad" cholesterol, but a question remained.
Should consumers reduce fat intake by replacing carbohydrates or substituting unsaturated fats for saturated fats?
"Many diets have said it is okay to eat healthy fats and emphasize olive and canola oils," said Cheryl Rock, PhD, principal investigator of the study, published in the Journal of the American Heart Association. "What we found is that a diet high in healthy oils did lower lipids, but it also lowered both good and bad cholesterol."
You don't want to lower the good cholesterol, HDL. When it comes to HDL, higher levels are better. When HDL cholesterol gets too low — and this seems like a cruel twist of fate — it puts you at higher risk for heart disease, same as occurs if your LDL gets too high. People with high blood triglycerides, genetic factors, Type 2 diabetes, smoking, being overweight and being sedentary can all result in lower HDL cholesterol.
With that in mind, the study enrolled a group overweight and obese adult women in a one-year behavioral weight-loss program and randomly assigned them to one of three diets:
The findings showed that all three dietary plans promoted similar weight loss. Insulin-sensitive women lost the most weight with a low-fat diet but that strategy did not result in the most benefit for lipid levels.
The walnut-rich diet had the greatest effect on cholesterol levels by decreasing LDL and increasing beneficial HDL. The high-fat, low-carb group, which consumed monounsaturated fats, did not experience the same beneficial effects as the walnut-rich diet, which featured polyunsaturated fatty acids.
At six months, the average weight loss was almost 8% among all groups.
"This weight loss may not put these women at their ideal weight, but it made a significant reduction in their risk of cardiovascular and other diseases," said Rock. "This level of weight loss is achievable and can have a dramatic impact on their quality of life."
Insulin sensitivity was assessed in the study because people who are overweight usually have some degree of insulin resistance. Higher amounts of insulin are more likely to cause cells to lose their ability to regulate growth, a precursor to cancer.
"Diet composition impacts lipid levels, but the critical factor to lose weight continues to be to burn more calories than you consume," said Rock.