Six dietary supplements often promoted to improve heart health do not lower LDL-C levels when compared with placebo, a study finds.

People with raised lipid levels often turned to dietary supplements, the study authors said, but there was a lack of evidence to show they could reduce LDL-C levels, particularly when compared with statins.

For the study, which was published in the Journal of the American College of Cardiology and presented at this month’s American Heart Association’s Scientific Sessions in Chicago, researchers recruited 199 adults aged 40-75 years with LDL-C levels of 70-189 mg/dL and an increased 10-year risk of atherosclerotic cardiovascular disease, but no history of cardiovascular disease.

Patients were randomized to either a daily low-dose statin (5 mg rosuvastatin), placebo, fish oil, cinnamon, garlic, turmeric, plant sterols or red yeast rice.

The primary endpoint was the percentage change in LDL-C from baseline for rosuvastatin 5 mg daily compared with placebo and each supplement after 28 days.

'The difference in LDL-C reduction with rosuvastatin compared with placebo was -35.2%,' the researchers reported.

None of the dietary supplements demonstrated a significant decrease in LDL-C compared with placebo. However, the garlic dietary supplement increased LDL-C compared with placebo (7.5%).

Rates of adverse events were similar across all the groups, the authors said, and they noted no significant adverse changes in liver function testing, estimated glomerular filtration, or blood glucose in patients randomised to rosuvastatin.

Those in the statin group also had an average 24% decrease in total cholesterol and a 19% decrease in blood triglycerides.

However, there was no difference in total cholesterol measures or triglycerides for participants taking any of the dietary supplements compared with placebo.

Looking at HDL-C, there was no significant change among the group taking the statin, but people taking the plant sterols had lower levels of HDL-C compared with placebo.

Lead author Dr Luke Laffin, co-director of the Center for Blood Pressure Disorders at the Cleveland Clinic in Ohio, said health professionals should consider using the study results to have evidence-based discussions with patients.

'Although there are prior studies demonstrating that red yeast rice and plant sterol supplements may reduce LDL cholesterol, the findings of our study underscore that the contents of these dietary supplements may vary. Therefore, they do not produce consistent reductions in cholesterol,' he said in a statement.

'This study sends an important public health message that dietary supplements commonly taken for ‘cholesterol health’ or ‘heart health’ are unlikely to offer meaningful impact on cholesterol levels. The results also indicate that a low-dose statin offers important beneficial effects on one’s cholesterol profile.'

Dr Laffin said a limitation of the study was the 28-day timeframe, which was long enough to demonstrate a reduction in LDL-C with the statin medication, but it was unknown if some of the supplements might require a longer time to work.

The authors declared that the study was funded with a grant from AstraZeneca, the makers of rosuvastatin.