(CNN) Six supplements that people commonly take for heart health don't help lower "bad" cholesterol or improve cardiovascular health, according to a study published Sunday, but statins did.
Some people believe that common dietary supplements -- fish oil, garlic, cinnamon, turmeric, plant sterols and red yeast rice -- will lower their "bad" cholesterol. "Bad" cholesterol, known in the medical community as low-density lipoproteins or LDL, can cause the buildup of fatty deposits in the arteries. The fatty deposits can block the flow of oxygen and blood that the heart needs to work and the blockage can lead to a heart attack or stroke.
For this study, which was presented at the American Heart Association's Scientific Sessions 2022 and simultaneously published in the Journal of the American College of Cardiology, researchers compared the impact of these particular supplements to the impact of a low dose of a statin -- a cholesterol-lowering medication -- or a placebo, which does nothing.
Researchers made this comparison in a randomized, single-blind clinical trial that involved 190 adults with no prior history of cardiovascular disease. Study participants were ages 40 to 75, and different groups got a low-dose statin called rosuvastatin, a placebo, fish oil, cinnamon, garlic, turmeric, plant sterols or red yeast rice for 28 days.
The statin had the greatest impact and significantly lowered LDL compared with the supplements and placebo.
The average LDL reduction after 28 days on a statin was nearly 40%. The statin also had the added benefit on total cholesterol, which dropped on average by 24%, and on blood triglycerides, which dropped 19%.
None of the people who took the supplements saw any significant decrease in LDL cholesterol, total cholesterol or blood triglycerides, and their results were similar to those of people who took a placebo. While there were similar adverse events in all the groups, there were a numerically higher number of problems among those who took the plant sterols or red yeast rice.
"We designed this study because many of us have had the same experience of trying to recommend evidence-based therapies that reduce cardiovascular risks to patients and then having them say 'no thanks, I'll just try this supplement,' " said study co-author Dr. Karol Watson, professor of medicine/cardiology and co-director, UCLA Program in Preventive Cardiology. "We wanted to design a very rigid, randomized, controlled trial study to prove what we already knew and show it in a rigorous way."
Dr. Steven Nissen, a cardiologist and researcher at the Cleveland Clinic and a co-author on the study, said that patients often don't know that dietary supplements aren't tested in clinical trials. He calls these supplements "21st century snake oil."
In the United States, the Dietary Supplement and Health Education Act of 1994 sharply limited the US Food and Drug Administration's ability to regulate supplements. Unlike pharmaceutical products that have to be proven safe and effective for their intended use before a company can market them, the FDA doesn't have to approve dietary supplements before they can be sold. It is only after they are on the market and are proven to be unsafe that the FDA can step in to regulate them.
"Patients believe studies have been done and that they are as effective as statins and can save them because they're natural, but natural doesn't mean safe and it doesn't mean they're effective," Nissen said.
The study was funded via an unrestricted grant from AstraZeneca, which makes rosuvastatin. The company did not have any input on the methodology, data analysis and discussion of the clinical implications, according to the study.
The researchers acknowledged some limitations, including the study's small sample size, and that its 28-study period might not capture the effect of supplements when used for a longer duration.
In a statement on Sunday, the Council for Responsible Nutrition, a trade association for the dietary supplement industry, said "supplements are not intended to replace medications or other medical treatments."
"Dietary supplements are not intended to be quick fixes and their effects may not be revealed during the course of a study that only spans four weeks," Andrea Wong, the group's senior vice president for scientific and regulatory affairs, said in a statement.
Dr. James Cireddu, an invasive cardiologist University Hospitals Harrington Heart & Vascular Institute Cleveland, Ohio, said the work is going to be helpful.
"They did a nice job collecting data and looking at the outcomes," said Cireddu, who did not work on the study. "It will probably resonate with patients. I get asked about supplements all the time. I think this does a nice job of providing evidence."
Dr. Amit Khera, chair of the AHA Scientific Sessions programming committee, did not work on the research, but said he thought this was an important study to include in the presentations this year.
"I take care of patients every day with these exact questions. Patients always ask about the supplements in lieu of or in addition to statins," said Khera, who is a professor and director of preventive cardiology at UT Southwestern Medical Center. "I think if you have high quality evidence and a well done study it is really critical to help inform patients about the value, or in this case the lack of value, for some of these supplements for cholesterol lowering."
Statins have been around for more than 30 years and they've been studied in over 170,000 people, he said. Consistently, studies show that statins lower risk.
"The good news, we know statins work," Khera said. "That does not mean they're perfect. That doesn't mean everyone needs one, but for those at higher risk, we know they work and that's well proven. If you're going to do something different you have to make sure it works."
With supplements, he said he often sees misinformation online.
"I think that people are always looking for something 'natural' but you know there's a lot of issues with that terminology and most important we should ask do they work? That's what this study does," Khera adds. "It's important to ask, are you taking something that is proven, and if you're doing that and it's not, is that in lieu of proven treatment. It's a real concern."