Rapeseed oil and cholesterol metabolism in men with metabolic syndrome
What it found
In 37 men with metabolic syndrome, swapping butter for cold-pressed turnip rapeseed oil for 6 to 8 weeks lowered total cholesterol by 7.2%, but the drop was not explained by changes in how the body made or absorbed cholesterol.
The authors say the mechanism remains unknown.
What they found
Studies in people
Cholesterol drop
Serum cholesterol was 7.2% lower after the rapeseed oil period than after the butter period.
Synthesis markers
Markers of cholesterol synthesis in the blood did not differ between the rapeseed oil and butter periods.
Absorption markers
The absorption marker cholestanol did not differ between periods. Campesterol and sitosterol ratios were 39% and 16% higher after rapeseed oil, but the authors say this reflects the extra plant sterols in the oil, not absorption efficiency.
PCSK9
Blood levels of PCSK9 did not differ between the rapeseed oil and butter periods.
Plant sterol intake
The rapeseed oil provided 217 mg of plant sterols a day, compared with 0.6 mg from butter. This explained the higher campesterol and sitosterol levels.
What the authors conclude
“In conclusion, modifying the diet with CPTRO instead of butter in men with MetS significantly lowered LDL cholesterol concentration, but the reduction could not be explained by changes in whole-body cholesterol or PCSK9 metabolism.”
Also in their conclusions
- They conclude that modifying the diet with cold-pressed turnip rapeseed oil instead of butter in men with metabolic syndrome significantly lowered LDL cholesterol concentration.
- They state that the reduction could not be explained by changes in whole-body cholesterol or PCSK9 metabolism.
- They say further studies are necessary to determine the mechanisms.
How it was done
The authors had already found that cold-pressed turnip rapeseed oil lowered total and LDL cholesterol compared with butter. They wanted to find out whether this came from changes in cholesterol metabolism.
37 men with metabolic syndrome, aged 35 to 65, took part in a randomised crossover study. They added either 35 mL of cold-pressed turnip rapeseed oil or 37.5 g of butter to their usual diet for 6 to 8 weeks each, with an 8-week washout in between. Blood markers of cholesterol synthesis, absorption and PCSK9 were measured at the end of each period.
What it can’t tell you
- The study included only men with metabolic syndrome, so the findings cannot be generalised to the whole population.
- The participants were not blinded to which fat they were eating, which could affect the results.
- This was an analysis of secondary outcomes from a trial designed for a different main endpoint.
Who paid
- Conflicts
- Competing interests: None declared.
- Authors work at
- Kanta-Häme Central Hospital, Finland; University of Helsinki and Helsinki University Central Hospital, Finland; Mahasarakham University, Thailand
The paper
- Title
- Determining the mechanisms of dietary turnip rapeseed oil on cholesterol metabolism in men with metabolic syndrome
- Type
- Randomised controlled trial
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Saarinen HJ, Sittiwet C, Simonen P, et al (2018). Determining the mechanisms of dietary turnip rapeseed oil on cholesterol metabolism in men with metabolic syndrome. Journal of investigative medicine. doi:10.1136/jim-2017-000495Free full textPubMed 28801309DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error