Flaxseed lignan extract lowered cholesterol and blood sugar in people with high cholesterol
What it found
Taking a flaxseed lignan extract for 8 weeks lowered total cholesterol, LDL cholesterol and fasting blood sugar in people who already had high cholesterol.
The effect was stronger at the higher dose tested.
What they found
Studies in people
Total and LDL cholesterol
People taking 600 mg of SDG daily saw their total cholesterol fall by about 24% and their LDL cholesterol fall by about 22% to 24% after 6 to 8 weeks compared with placebo. Those taking 300 mg also saw drops from their starting levels, but the difference from the placebo group was not clear.
Fasting blood sugar
The 600 mg dose lowered fasting blood sugar after 6 and 8 weeks compared with placebo. The drop was largest in people whose starting blood sugar was 5.83 mmol/l or higher, falling by about 25%.
Lignans in the blood
Blood levels of three lignan compounds rose in both groups taking the extract and stayed steady within 2 weeks. The size of the cholesterol drop tracked with how much of two of these compounds appeared in the blood.
Body weight unchanged
Average body mass index stayed around 26 to 27 kg/m2 across all groups over the 8 weeks. No side effects were reported, and kidney and liver markers stayed normal.
What the authors conclude
- They conclude that the flaxseed lignan extract lowered blood cholesterol and fasting glucose in a way that depended on the dose taken.
- Their data suggest that two specific lignan compounds found in the blood may be the key active parts behind the cholesterol-lowering effect.
- They advise further testing of this extract as a natural option for managing cholesterol and blood sugar.
How it was done
Earlier studies using whole flaxseed gave mixed results, partly because flaxseed also contains fats and fibre that can change cholesterol on their own. The authors wanted to test just the main lignan compound from flaxseed, called SDG, to see its effects on blood fats and blood sugar without those other parts.
They ran an 8-week trial with 55 people who had high cholesterol. Participants took four tablets a day providing either 0 mg, 300 mg or 600 mg of the flaxseed lignan SDG, split between breakfast and dinner. Blood tests were taken every 2 weeks.
What it can’t tell you
- All participants were Chinese nationals, so the results might differ in populations with wider genetic diversity.
- The study lasted only 8 weeks, so it cannot show whether these changes last over a longer period or affect heart disease risk.
- Participants ate their normal diets without food records being kept, so unknown dietary differences could have played a role.
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 1 Oct 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error