Low-density lipoprotein (LDL) cholesterol – commonly dubbed as the “bad” cholesterol – is the type of blood cholesterol that people tend to keep an eye on once they’ve been told that it’s time to keep their levels in check. In line with scientific evidence, doctors have always advised that the best way to do that is to limit intake of saturated fat and to include more unsaturated fats instead. But besides the knowledge that it’s better to sauté onions in cooking oil instead of butter, there has not been much information out there about the best oil substitutes for the job…until now.
Research published in the Journal of Lipid Research this month suggests that seed oils are the most effective in lowering LDL cholesterol and showcases the emerging technique researchers used to get this result.
The technique, known as network meta-analysis, was used to draw data from published studies analysing the effects of dietary fats on blood cholesterol. The team of researchers used this method to assess the results of 55 studies conducted in a period of over three decades.
The studies included examined the effects of consuming the same calories-worth of two or more different oils on the blood-lipid readings of participants. All the studies included in the meta-analysis had to either measure the effects of these oils on LDL cholesterol or measure their effects on other blood lipids such as total cholesterol, high-density lipoprotein cholesterol (HDL) (“good” cholesterol) or triglycerides over a minimum duration of three weeks.
Lukas Schwingshackl, a German Institute of Human Nutrition researcher involved in this study says that this method allows him and the rest of the research team to simultaneously compare data from the selected studies and create a ranking system for the different fats. So even if there has never been a study comparing the measurable effects of a specific fat with another, this method can still draw up comparative results.
And it did just that – the researchers found that seed oils such as rapeseed, flaxseed and sunflower came up on top as the best oils for lowering LDL.
Schwingshackl notes, however, that this data is limited when it comes to predicting clinical outcomes because it only measures the effects of certain fats on blood lipids. For instance, we can’t say for sure that eating these fats will definitely lead to or stave off an illness such as coronary heart disease that is more likely to happen with high LDL levels.
Another limitation of this method is that network meta-analyses can sometimes include low-confidence data and affect the resulting rankings. For this study, in particular, it was difficult to confidently choose the best seed oil. Additionally, the oils that best-lowered LDL were not found to be the most impactful when it came to positively affecting HDL and triglyceride levels.
But despite these challenges, Schwingshackl is optimistic about the potential of network meta-analyses in the world of research.
Maybe changing up your cooking oil of choice sometimes isn’t such a bad idea.
By Tesneem Ayoub