Onion supplements and metabolic health in 14 trials
What it found
In people, onion supplements improved body fat percentage, cholesterol, blood pressure, adiponectin and one liver enzyme.
Longer use or higher doses were linked to more improvements.
What they found
Studies in people
Body fat and cholesterol
Onion supplementation significantly improved body fat percentage, LDL cholesterol, total cholesterol and HDL cholesterol.
Blood pressure and hormones
Onion supplementation significantly improved systolic blood pressure and adiponectin.
Liver enzyme
Onion supplementation significantly improved aspartate aminotransferase, a liver enzyme.
Longer than 12 weeks
When interventions lasted more than 12 weeks, they significantly altered weight, waist circumference, body mass index, body fat percentage, LDL cholesterol, total cholesterol, systolic blood pressure and diastolic blood pressure.
More than 300 mg a day
Taking more than 300 mg a day of onion supplementation significantly improved weight, waist circumference, body mass index, body fat percentage, LDL cholesterol, HDL cholesterol, total cholesterol, aspartate aminotransferase, alanine aminotransferase, systolic blood pressure and diastolic blood pressure.
What the authors conclude
“It seems that the intake of onion supplementation can improve health metabolic parameters.”
Also in their conclusions
- They conclude that the intake of onion supplementation can improve health metabolic parameters.
- They observed that with either longer follow-up periods or higher dosages of onion supplementation, improvements in cardio-metabolic parameters could be expected.
How it was done
Onions are a functional food that has been the centre of many recent investigations, so the authors gathered the existing information on how onion supplementation affects metabolic health.
They searched major online databases up to October 2022 and found 14 randomised controlled trials that met their criteria. They combined the results of those trials.
What it can’t tell you
- We summarised it from the abstract only.
- The trials used onion supplements, so the results may not apply to onions eaten as food.
- The review combined trials that varied in dose, length and the people studied, so it cannot show what would happen in any one person.
Who paid
- Conflicts
- Declaration of competing interest The authors declared no conflicts of interest.
- Authors work at
- Shiraz University of Medical Sciences, Iran
The paper
- Title
- Onion supplementation and health metabolic parameters: A systematic review and meta-analysis of randomized controlled trials
- Type
- Systematic review and meta-analysisThe authors follow a set, published method to find every relevant study, then combine the numbers from them into one result.
- Evidence
- Studies in people
- Summarised from
- Abstract only
- Cite
- Hejazi N, Ghalandari H, Nouri M, Askarpour M (2023). Onion supplementation and health metabolic parameters: A systematic review and meta-analysis of randomized controlled trials. Clinical nutrition ESPEN. doi:10.1016/j.clnesp.2023.08.032PubMed 38056991DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error