High levels of cholesterol can be harmful, and they can increase a person's risk of serious cardiovascular events, such as heart attack or stroke. A high-fat diet can contribute to raised cholesterol levels, but some researchers say that ingesting a specific type of oil may prevent this negative effect.
Generally speaking, there are two types of cholesterol: high-density lipoprotein (HDL) cholesterol, also known as "good" cholesterol, and low-density lipoprotein (LDL) cholesterol, which people describe as "bad" cholesterol.
Healthcare professionals often refer to LDL cholesterol as "bad" because the overaccumulation of this fatty substance can interfere with blood circulation and increase a person's risk of heart attack or stroke.
Conversely, they tend to say that HDL cholesterol is "good" because it helps remove LDL cholesterol from the body. It does this by taking the LDL cholesterol to the liver, which will break it down and process the resulting waste.
In order to prevent LDL cholesterol from reaching high levels in the blood, specialists advise people to adhere to diets that promote high HDL and low LDL cholesterol.
However, researchers from the University of Georgia in Athens have found that adding cottonseed oil to a high-fat diet can actually decrease a person's LDL cholesterol levels.
The study paper reporting these results appears in the journal Nutrition Research.
Pitting cottonseed oil against olive oil
The researchers worked with a group of 15 male participants aged 18–45 who were within healthy weight ranges. They asked the participants to follow one of two versions of a high-fat diet, each of which included a particular component.
In one version of the diet, the researchers used olive oil to enrich the meals. In the other, they used cottonseed oil instead. All of the participants adhered to their assigned diet for a period of 5 days.
After comparing the effects of the two diet regimens on the participants, the investigators found that those who had followed the cottonseed oil-enriched diet had lower LDL cholesterol and triglyceride levels.
Conversely, the participants who had followed the olive oil-enriched diet saw no significant changes.
"One of the reasons these results were so surprising is because of the magnitude of change observed with the cottonseed oil diet," says study author Jamie Cooper, an associate professor at the University of Georgia.
"To see this amount of change in such a short period of time is exciting," she adds.
Effects on LDL vs. HDL cholesterol levels
The individuals on the cottonseed oil-enriched diet saw, on average, a decrease of approximately 8 percent in total cholesterol levels. Their LDL cholesterol levels decreased by 15 percent on average, and their triglyceride levels decreased by 30 percent.
As for the levels of HDL cholesterol, these actually increased by about 8 percent for individuals on the cottonseed oil-enriched diet.
The researchers speculate that a specific type of fatty acid called dihydrosterculic acid, which is present in cottonseed oil but not in olive oil, may prevent triglyceride accumulation.
"By doing that," Cooper explains, "it pushes the body to burn more of that fat because it can't store it properly, so you have less lipid and cholesterol accumulation."
Cooper also suggests that the polyunsatured fats and omega-6 that are abundant in cottonseed oil may have beneficial effects.
The authors explain that several sponsors — including the nonprofit company Cotton Incorporated, the University of Georgia Clinical and Translational Research Unit, and the Augusta University and University of Georgia Medical Partnership — financially supported the recent study.
In the future, the investigators aim to learn more about the effects of cottonseed oil on health by recruiting older participants who already have high cholesterol levels and extending the dietary intervention period.