Flaxseed lignan extract and cholesterol in people with high cholesterol
What it found
In 55 people with high cholesterol, an 8-week flaxseed lignan extract lowered total cholesterol, LDL cholesterol and fasting glucose, especially at the higher dose.
The authors say the effect was dose-dependent.
What they found
Studies in people
Total cholesterol
In the 600 mg SDG group, total cholesterol fell by about 22 to 24 percent at weeks 6 and 8 compared with placebo. The 300 mg group only showed a drop compared with its own starting level, not compared with placebo.
LDL cholesterol
LDL cholesterol fell by about 22 to 24 percent at weeks 6 and 8 in the 600 mg SDG group compared with placebo. The 300 mg group only showed a drop compared with its own starting level.
Fasting glucose
In the 600 mg SDG group, fasting glucose fell by about 25 percent at weeks 6 and 8 compared with placebo. The fall was larger in people whose starting glucose was 5.83 mmol/l or higher.
HDL cholesterol and triglycerides
There was no overall difference between groups in HDL cholesterol. Triglycerides fell mainly within the 600 mg SDG group. The ratio of total cholesterol to HDL cholesterol fell at weeks 6 and 8 in the 600 mg group compared with placebo.
Lignan levels in blood
Blood levels of secoisolariciresinol, enterodiol and enterolactone all rose significantly in the SDG groups. Cholesterol lowering was linked to blood levels of secoisolariciresinol and enterodiol.
Side effects
No adverse events were reported by the subjects. Kidney and liver blood tests stayed normal throughout the trial.
What the authors conclude
“In conclusion, dietary flaxseed lignan extract decreased plasma cholesterol and glucose concentrations in a dose-dependent manner.”
Also in their conclusions
- They conclude that dietary SDG lignan-rich flaxseed extract significantly lowered plasma cholesterol concentrations in these hypercholesterolaemic subjects.
- They say the cholesterol-lowering effect was more significantly observed for total cholesterol and LDL cholesterol in a dose-dependent manner.
- They suggest the flaxseed lignan extract should be further evaluated as another natural alternative for plasma cholesterol and glucose concentration management or intervention.
How it was done
Flaxseed lignans are being studied for health benefits, but earlier trials of flaxseed and flaxseed meal gave inconsistent results. The authors wanted to test a purified flaxseed lignan extract so the dose of the main lignan, SDG, was known exactly.
They gave 55 adults with high cholesterol either a placebo, 300 mg or 600 mg per day of secoisolariciresinol diglucoside (SDG) from flaxseed extract for 8 weeks. The study was randomised, double-blind and placebo-controlled. Blood was tested at the start and at weeks 2, 4, 6 and 8.
What it can’t tell you
- This was an 8-week study, so it cannot show what happens over longer periods.
- The study was done only in Chinese adults, so the results may not apply to other populations.
- The authors did not collect dietary intake data, so they could not fully explain the placebo effects seen.
Who paid
- Authors work at
- Tumor Hospital and Institute, China
The paper
- Title
- Dietary flaxseed lignan extract lowers plasma cholesterol and glucose concentrations in hypercholesterolaemic subjects
- Type
- Randomised controlled trial
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Zhang W, Wang X, Liu Y, et al (2008). Dietary flaxseed lignan extract lowers plasma cholesterol and glucose concentrations in hypercholesterolaemic subjects. The British journal of nutrition. doi:10.1017/S0007114507871649Free full textPubMed 18053310DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error