Six popular heart supplements didn’t beat a placebo, and berberine is a closer call

Key takeaways

• In a 2022 Cleveland Clinic trial of 190 adults, fish oil, cinnamon, garlic, turmeric, plant sterols and red yeast rice didn’t lower LDL cholesterol more than a placebo in 28 days, while a 5 mg statin cut it by more than a third¹².
• Berberine has real but modest effects: in pooled placebo-controlled trials, mostly from China, it lowered fasting blood sugar about 9 mg/dL and LDL about 19 mg/dL, by our math⁵.
• Berberine isn’t a natural Ozempic; Poison Control says it works differently and shouldn’t be used in the drug’s place, and it can change how several common medicines act in the body³⁶.
• Red yeast rice lowers cholesterol only when it contains monacolin K, the same molecule as the statin lovastatin, and the FDA says such products can’t legally be sold as supplements⁹.
• In 2023 the FDA found two prescription diabetes drugs hidden in a “glucose support” supplement sold online, so tell your clinician about every product you take¹⁴.

In November 2022, cardiologists at the Cleveland Clinic reported a blunt experiment¹. They gave 190 adults a low-dose statin, a placebo or one of six supplements that people buy for heart health. Four weeks later, they checked everyone’s cholesterol¹.

The statin, rosuvastatin at 5 mg a day, lowered LDL cholesterol by 37.9%². Fish oil, cinnamon, garlic, turmeric, plant sterols and red yeast rice did no better than the placebo¹.

The study had a sponsor worth knowing about. AstraZeneca, which makes rosuvastatin, paid for it with an unrestricted grant, and the Cleveland Clinic said its own team ran the design and analysis¹.

The blood sugar side of the aisle soon got its own star. In 2023, social media began calling berberine, a plant compound, “Nature’s Ozempic”³.

If you’d rather manage cholesterol or blood sugar with plants than prescriptions, these products are aimed at you. Below, we look at how each rates, at the doses tested, and how to avoid getting hurt.

A month-long trial put six heart supplements up against a placebo

The trial is called SPORT, short for the Supplements, Placebo or Rosuvastatin Study. It was randomized and single-blind, meaning one side of the study, rather than both, was kept from knowing who took what¹.

Volunteers were 40 to 75 years old and had no history of heart disease¹. Their LDL ran from 70 to 189 mg/dL, and their estimated 10-year risk of a heart attack or stroke was 5% to 20%². Their average age was 64, and 59% were women².

Each group had about 25 people². These were the daily doses:

• Fish oil, 2,400 mg
• Cinnamon, 2,400 mg
• Garlic, measured as 5,000 mcg of allicin
• Turmeric curcumin, 4,500 mg
• Plant sterols, 1,600 mg
• Red yeast rice, 2,400 mg²

After 28 days, none of the six had lowered LDL significantly compared with placebo¹. Against placebo, the statin cut LDL by 35.2%². The statin group’s total cholesterol fell an average of 24%, and its triglycerides fell 19% compared with placebo¹.

Two supplements moved numbers the wrong way. Garlic raised LDL by 7.8% compared with placebo, and plant sterols lowered HDL, the “good” cholesterol, by 7.1%². Side effects were similar across groups, though slightly more common with plant sterols and red yeast rice¹.

What does 35% look like on a lab report? The reports we read didn’t give the volunteers’ average starting LDL, but for someone at 130 mg/dL, it’s a drop of about 46 mg/dL, by our math.

Now the limits. Lead researcher Luke Laffin said 28 days may not have captured the supplements’ full effect, and he reported research funding from AstraZeneca². The groups were small, and SPORT measured lab numbers, not heart attacks².

So SPORT’s lesson is narrow: at common label doses, these six products didn’t move LDL like a starter-dose statin. The 2026 U.S. cholesterol guideline, issued by the American College of Cardiology, the American Heart Association and partner groups, recommends against dietary supplements for lowering LDL or triglycerides, citing limited and inconsistent data¹³.

Berberine lowers blood sugar a little, but it isn’t Ozempic

Berberine is found in goldenseal, barberry and Oregon grape, in their roots, bark and fruit³. Traditional Chinese medicine has long used it for dysentery and diarrhea³.

Modern trials are numerous, and most come from China⁴⁵. The National Center for Complementary and Integrative Health (NCCIH) describes a 2021 review of 46 studies with 4,158 people⁴. It found possible benefits for blood sugar, insulin resistance and blood fats, but the studies varied and some were poor quality⁴.

A stricter 2025 analysis in Frontiers in Pharmacology pooled only placebo-controlled trials: 12 of them, with 889 people⁵. Nine were in China, two in Mexico and one in India⁵. People took 300 to 1,500 mg of berberine a day for 12 to 20 weeks⁵.

Compared with placebo, berberine lowered (our conversions from metric units):

• fasting blood sugar by about 9 mg/dL
• LDL cholesterol by about 19 mg/dL
• triglycerides by about 33 mg/dL⁵

Only two trials were judged at low risk of bias, two at high risk, and the other eight raised some concerns⁵. Blood sugar results varied widely from trial to trial⁵. The authors work at Chinese medicine universities, and the text we read didn’t list the study’s funding⁵.

An earlier review of 28 studies, summarized in the MSD Manual, found berberine’s blood sugar effect was weaker in trials longer than 90 days and in people over 60⁶.

The Ozempic comparison falls apart. Poison Control says berberine isn’t a plant version of semaglutide; it acts through different routes and shouldn’t stand in for the drug³. For weight, NCCIH describes a 2022 review where losses showed up mainly at more than 1 gram a day for more than 8 weeks⁷. Many of those studies had a high risk of bias, and NCCIH called the evidence not conclusive⁷.

Most people in those studies had diabetes or fatty liver, and very few of the studies came from North America⁷. In the 2025 analysis, body mass index fell 0.435 points⁵. For someone 5 feet 6 inches tall, that’s about 1.2 kilograms, under 3 pounds, by our math.

Berberine’s interaction list is longer than its label

Stomach trouble is the usual complaint: an upset stomach, nausea, constipation or diarrhea³. In the 2025 analysis, stomach complaints were mostly mild and not significantly more frequent than with placebo⁵.

The bigger issue is other medicines. Berberine slows liver enzymes that clear many drugs, the MSD Manual explains, so it may raise blood levels of midazolam, omeprazole, dextromethorphan, losartan, tacrolimus and caffeine⁶.

Berberine may also add to the sugar-lowering effect of diabetes medicines and strengthen the blood thinner heparin⁶. Goldenseal, a common berberine source, may lower metformin levels, raise levels of the transplant drug cyclosporine and interact with warfarin⁶.

Poison Control describes a published 2022 case of a 68-year-old man on the blood thinner rivaroxaban³. After three weeks of berberine, his rivaroxaban level was high and he developed jaundice and liver damage, which improved after he quit the supplement³.

Who should avoid it. NCCIH says berberine may be unsafe in pregnancy and breastfeeding and is likely unsafe for infants, because it can let bilirubin build up and damage a baby’s brain⁷. The MSD Manual adds that people with seizure disorders or clotting problems shouldn’t take goldenseal⁶.

In a January 2026 warning letter to Supersmart USA, the FDA cited the company’s claims that berberine lowers blood sugar and blood fats, and said products meant to treat disease are unapproved new drugs⁸.

Diabetes trials have often used 500 mg doses taken two or three times daily, but there’s no standard dose³.

Red yeast rice works when it’s quietly a statin

Red yeast rice is made by fermenting rice with Monascus purpureus¹⁰. The kind sold as a food ingredient has little or no monacolin K¹⁰. Some supplements have a lot, and monacolin K is the same molecule as lovastatin, a prescription statin⁹.

That creates a paradox. Products with real amounts of monacolin K may lower cholesterol, but they also carry lovastatin’s risks, from side effects to drug interactions⁹. Products with little or none haven’t been studied, so nobody knows whether they help⁹.

The FDA decided in 1998 that red yeast rice with substantial monacolin K was an unapproved new drug¹⁰. It still says such products can’t legally be sold as supplements⁹.

Reported side effects include muscle damage, including a severe breakdown called rhabdomyolysis, and liver toxicity¹⁰. NCCIH advises against combining red yeast rice with a prescription statin and against using it during pregnancy, while trying to get pregnant or while breastfeeding¹⁰. Our article on factory contamination covers the 2024 red yeast rice crisis in Japan and the kidney toxin citrinin.

Cinnamon and chromium: decades of small, mixed results

Cinnamon. NCCIH describes a 2019 review of 16 studies with 1,098 people that found lower fasting blood sugar and insulin resistance⁴. Two 2020 reviews in type 2 diabetes found drops in blood pressure, triglycerides and LDL, but the effects shrank in Western countries and in better or longer studies⁴. In SPORT, 2,400 mg a day didn’t lower LDL¹².

Studies found no apparent risk under 6 grams a day, NCCIH says, but cassia cinnamon contains coumarin, and large amounts may worsen liver disease⁴. Cinnamon supplements can also cause side effects alongside diabetes medicines⁴. Our spice article covers coumarin limits and lead in cinnamon.

Chromium. This trace mineral may make the body more sensitive to insulin¹¹. Adults need only an Adequate Intake of 35 mcg a day for men 19 to 50 and 25 mcg for women, falling to 30 and 20 mcg after 50¹¹.

Food covers that. A cup of grape juice has about 7.5 mcg, and a whole-wheat English muffin has about 3.6 mcg¹¹. There’s no upper limit, though people with kidney or liver disease may be more vulnerable to high intakes¹¹. Deficiency hasn’t been reported in healthy people¹¹.

Chromium-only supplements often hold 200 to 500 mcg¹¹. In a 1997 trial of 180 adults with type 2 diabetes, 1,000 mcg a day of chromium picolinate brought A1C to 6.6% after four months, versus 8.5% on placebo¹¹. Later trials disagreed: a 24-week trial of the same form and dose in 137 people found no benefit¹¹.

A 2019 review of eight meta-analyses covering 58 trials found slight drops in fasting blood sugar and A1C in people with diabetes, of unclear clinical importance¹¹. In 2005, the FDA allowed a “qualified” claim for chromium picolinate and insulin resistance, but called the link “highly uncertain”¹¹.

Chromium can push blood sugar too low alongside insulin or other diabetes drugs, and it can reduce absorption of the thyroid drug levothyroxine when taken at the same time¹¹. Rare case reports describe kidney failure, liver problems and muscle breakdown¹¹.

What the diabetes guideline says. The American Diabetes Association’s 2026 Standards of Care don’t recommend chromium, magnesium, cinnamon or aloe vera supplements to improve blood sugar¹². The guideline adds that people with diabetes who aren’t deficient gain nothing from herbal, vitamin or mineral supplements¹².

The rest of the aisle, in brief

• Bergamot. NCCIH says the evidence that this citrus fruit and its extracts lower blood fats is limited⁹.
• Turmeric. At 4,500 mg a day, it didn’t lower LDL in SPORT². The ADA names curcumin, turmeric’s main compound, among the herbs without enough evidence for blood sugar¹².
• Garlic, fish oil and plant sterols. Our separate articles on each cover their longer trials and doses.
• Niacin and vinegar. Our vitamin field guide covers niacin’s heart trials, and our carbohydrate article rates vinegar promising but early for fasting blood sugar.

The supplement aisle scorecard

This scorecard is our own, built from the sources above. Ratings use our four-level scale: Strong evidence, Promising but early, Not enough evidence, and Evidence says no, or unsafe.

Product	Best human evidence	Typical effect	Safety and interactions	Rating
Berberine	12 placebo trials, mostly in China, 300 to 1,500 mg a day5	Fasting sugar down about 9 mg/dL, LDL about 19 mg/dL, by our math5	Many drug interactions; avoid in pregnancy, nursing and infancy67	Promising but early
Berberine for weight	Reviews with high risk of bias7	Under 3 pounds in our example5	Same as above	Not enough evidence
Red yeast rice	Works when it contains lovastatin’s twin, monacolin K9	Unknown for any given bottle9	Statin side effects; not with a statin10	Evidence says no, or unsafe as a statin swap
Cinnamon	Mixed reviews; no LDL drop at 2,400 mg in SPORT24	Small fasting sugar drop in some reviews4	Liver risk from cassia’s coumarin4	Promising but early for fasting sugar; the ADA doesn’t recommend it12
Chromium	58 trials, mixed; big 1997 result not repeated11	Slight A1C and sugar drops11	Lows with diabetes drugs; levothyroxine11	Promising but early for blood sugar; the ADA doesn’t recommend it12
Fish oil, garlic, turmeric for LDL	SPORT, 28 days12	No LDL drop; garlic raised it2	See our garlic and fish oil articles	Evidence says no, or unsafe for LDL in this test

Hidden drugs: the riskiest “blood sugar” pill may not be herbal at all

In November 2023, the FDA warned shoppers about Dr. Ergin’s SugarMD Advanced Glucose Support, sold online for blood sugar¹⁴. FDA lab tests found glyburide and metformin, the active ingredients in prescription diabetes drugs, and neither was on the label¹⁴.

Glyburide can drive blood sugar dangerously low, the agency said, which in severe cases can cause seizures, coma or death¹⁴. Metformin can cause lactic acidosis, a buildup of acid in the blood¹⁴. People with chronic kidney disease face the greatest risk¹⁴. One lot was voluntarily recalled later that month¹⁴.

NCCIH warns against replacing medical treatment with an unproven product and notes the FDA’s alerts about pills that promise to replace your diabetes medicine⁴. That matters because diabetes is the leading cause of kidney disease, and some supplements have been linked to kidney damage⁴.

Plants made statins possible, and that’s why dose and honesty matter

There’s a deeper lesson in red yeast rice. Monacolin K, made naturally as the rice ferments, is the same molecule as a prescription statin⁹¹⁰. Natural compounds can be powerful. That power is exactly why the amount in each pill, and what else is in it, matters so much.

Apply the same scrutiny to every sponsor. A statin maker paid for SPORT¹. Most trials in the 2025 berberine analysis were done in one country, and that analysis didn’t name its funder⁵. Neither fact makes a result wrong, but both are worth weighing.

Food still has the better record for your numbers, as our articles on fiber and dietary patterns show. Before adding a supplement, the FDA advises telling your health care providers about everything you take, including nonprescription products¹⁴.

Questions readers ask

The bottom line

In a head-to-head test, six popular heart supplements didn’t lower LDL in a month, while a low-dose statin cut it by more than a third. Berberine has modest, real effects on blood sugar and cholesterol in mostly Chinese trials, but it isn’t a weight-loss drug and it interacts with many medicines. Red yeast rice works only when it’s effectively an unlabeled statin.

If you want to try one of these products, bring the bottle to your clinician or pharmacist first¹⁴. Keep taking your prescribed medicines, and watch for the warning signs above.

Related reading

• Plant sterols reliably lower LDL, yet no trial has shown they prevent heart attacks
• Some of the Worst Supplement Contamination Began Inside the Factory
• Garlic pills nudge blood pressure down, but a Stanford trial found no cholesterol benefit
• One workout raises insulin sensitivity for about a day, and habits make it last
• What happens when you don’t tell your doctor about supplements

Sources

1. Cleveland Clinic Newsroom. “Cleveland Clinic Trial Finds Six Widely Used Dietary Supplements Do Not Lower Cholesterol Compared With Either a Low-Dose Statin or Placebo” (on Laffin LJ, et al., Journal of the American College of Cardiology, 2022). November 6, 2022. newsroom.clevelandclinic.org
2. MDedge (Clinical Endocrinology News). “Dietary Supplements Hyped for LDL-Cholesterol Lowering Are a Bust: SPORT.” November 8, 2022. mdedge.com
3. Johnson-Arbor K. “Berberine: Benefits, Side Effects, and Safety.” Poison Control, National Capital Poison Center, accessed October 2026. poison.org
4. National Center for Complementary and Integrative Health. “Diabetes and Dietary Supplements: What You Need To Know.” NIH, last updated November 2023. nccih.nih.gov
5. Liu D, Zhao H, Zhang Y, Hu J, Xu H. “Efficacy and Safety of Berberine on the Components of Metabolic Syndrome: A Systematic Review and Meta-Analysis of Randomized Placebo-Controlled Trials.” Frontiers in Pharmacology, 2025;16:1572197. frontiersin.org
6. Shane-McWhorter L. “Goldenseal.” MSD Manual Professional Version, reviewed July 2025. msdmanuals.com
7. National Center for Complementary and Integrative Health. “Berberine and Weight Loss: What You Need To Know.” NIH, last updated November 2023. nccih.nih.gov
8. U.S. Food and Drug Administration. Warning letter to Supersmart USA, LLC (CMS 706566). January 21, 2026, posted May 5, 2026. fda.gov
9. National Center for Complementary and Integrative Health. “High Cholesterol and Natural Products: What the Science Says.” NCCIH Clinical Digest, February 2024. nccih.nih.gov
10. National Center for Complementary and Integrative Health. “Red Yeast Rice.” Fact sheet D475, updated July 2013 (archived PDF). files.nccih.nih.gov
11. NIH Office of Dietary Supplements. “Chromium: Fact Sheet for Health Professionals.” Updated June 2, 2022. ods.od.nih.gov
12. American Diabetes Association Professional Practice Committee. “5. Facilitating Positive Health Behaviors and Well-being to Improve Health Outcomes: Standards of Care in Diabetes—2026.” Diabetes Care, 2026;49(Suppl 1) (course copy hosted by the Weitzman Institute). education.weitzmaninstitute.org
13. Blumenthal RS, Morris PB, et al. “2026 ACC/AHA/AACVPR/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA Guideline on the Management of Dyslipidemia.” Circulation, 2026; doi:10.1161/CIR.0000000000001423 (copy posted on a Universidad Nacional de Córdoba course site). fcm.aulavirtual.unc.edu.ar
14. U.S. Food and Drug Administration. “FDA Warns Consumers of Hidden Drug Ingredients in Dr. Ergin’s SugarMD Advanced Glucose Support.” Alert November 3, 2023; updated November 29, 2023. fda.gov
15. National Institute of Diabetes and Digestive and Kidney Diseases. “Low Blood Glucose (Hypoglycemia).” NIH, last reviewed July 2021. niddk.nih.gov