In the first of its kind, a comprehensive review of literature on onion supplementation has found significant cardio-metabolic benefits.
The systematic review and meta-analysis, published in Clinical Nutrition, included the review of 14 randomised controlled trials (RCTs), published between years 2007 and 2020.
The RCTs involved onion supplementation as onion extract, onion peel extract, onion juice, onion peel extract powder or steamed onion. Quercetin was the bioactive ingredient in the supplementation.
The results showed onion supplementation significantly improved cardio-metabolic parameters including improved body fat percentage, HDL, LDL and total cholesterol and systolic blood pressure.
Subgroup analysis revealed that prolonged interventions (lasting more than 12 weeks) significantly altered weight, waist circumference, body mass index and both systolic and diastolic blood pressure.
While higher intakes of onion supplementation (more than 300mg/day) were found to significantly improve anthropometric measurements/indices of obesity and hepatic health. Specifically, weight, waist circumference, BMI, body fat percentage, HDL, LDL and total cholesterol, aspartate and alanine aminotransferases, systolic and diastolic blood pressures.
The SLR has some limitations due to the differences in the administration of onion, such as method, dosage, and the part of the vegetable used (e.g. peel, stem, juice).
This research continues to build on the growing evidence supporting the weight management and heart health benefits associated with onion consumption.
Practice tips
- Provide practical advice to enjoy onions across a variety of meal occasions. Try adding onion in an omelette at breakfast, sliced onion on a sandwich at lunch and add quartered onions to your pan of vegetables for a roast dinner. Need more inspiration? Try our free meal plan patient resource.
- A serving of onion is 75g (half an onion) and can count as a serve of vegetables.
- Half an onion (75g) has approximately 30mg of quercetin.
Reference
Hejazi N, Ghalandari H, Nouri M, Askarpour M. Onion supplementation and health metabolic parameters: A systematic review and meta-analysis of randomized controlled trials. Clin Nutr ESPEN. 2023 Dec;58:1-13. doi: 10.1016/j.clnesp.2023.08.032. Epub 2023 Aug 30. PMID: 38056991. https://pubmed.ncbi.nlm.nih.gov/38056991/
