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GREEN ONION

Also known as: Allium cepa, Onion, Green Onion

Overview

Allium cepa, commonly known as onion or green onion, is a vegetable belonging to the Allium genus, widely used for both culinary and medicinal purposes. As a supplement, it is utilized for its potential health benefits, particularly in improving metabolic parameters and cardiovascular health. Onions are rich in flavonoids, especially quercetin, and contain sulfur-containing amino acids, contributing to their bioactive properties. Research on onion supplementation is growing, supported by randomized controlled trials (RCTs) and meta-analyses. These studies suggest that onion supplementation can positively influence body fat percentage, lipid profiles, and blood pressure. The quality of available evidence is considered high, making it a promising area of nutritional research. Onions can be consumed raw, cooked, or as supplements, offering versatile options for incorporating them into one's diet.

Benefits

Onion supplementation has shown significant benefits in improving various metabolic parameters. A systematic review and meta-analysis indicated that it significantly improved body fat percentage (BFP), low-density lipoprotein-cholesterol (LDL-c), total cholesterol (TC), high-density lipoprotein-cholesterol (HDL-c), systolic blood pressure, adiponectin, and aspartate aminotransferase (AST). Interventions lasting more than 12 weeks and dosages exceeding 300 mg/day demonstrated significant improvements in weight, waist circumference (WC), body mass index (BMI), BFP, LDL-c, TC, HDL-c, AST, alanine aminotransferase (ALT), systolic blood pressure (SBP), and diastolic blood pressure (DBP). Quercetin derived from onion skin extract has also been suggested to decrease blood pressure in hypertensive individuals. These benefits appear to be generalizable across various populations, with longer follow-up periods and higher dosages potentially yielding more pronounced effects.

How it works

Onions exert their beneficial effects through several mechanisms. They contain flavonoids like quercetin, which possess antioxidant and anti-inflammatory properties, influencing lipid metabolism, blood pressure regulation, and insulin sensitivity. The sulfur-containing amino acids in onions also contribute to cardiovascular health by affecting blood lipid profiles and blood pressure. These compounds interact with the cardiovascular system by improving lipid profiles and reducing blood pressure, and they affect the metabolic system by influencing glucose and insulin levels. The antioxidant properties of onions protect against oxidative stress, benefiting overall health. Quercetin from onions can target various molecular pathways involved in inflammation and oxidative stress, and it may interact with enzymes involved in lipid metabolism. The bioavailability of these compounds can vary depending on the form of consumption, with enhanced bioavailability when consumed with fatty meals.

Side effects

Onions are generally considered safe for consumption, but potential side effects should be considered. Gastrointestinal discomfort can occur with high consumption. Allergic reactions or intolerance to onions can occur in some individuals, though severe allergic reactions are rare. While there is limited evidence of drug interactions, it is advisable to consult with a healthcare provider, especially for individuals on anticoagulant medications, due to the potential antiplatelet effects of quercetin. Individuals with known allergies to onions or other Allium species should avoid onion supplementation. Pregnant or breastfeeding women should consult their healthcare provider before starting any new supplement regimen, including onion supplementation. Monitoring for any adverse reactions and consulting with a healthcare professional can help ensure safe usage.

Dosage

The minimum effective dose for metabolic benefits appears to be >300 mg/day of onion supplementation. Dosages exceeding 300 mg/day have been associated with significant improvements in metabolic parameters. There is no established maximum safe dose, but high consumption should be approached with caution due to potential gastrointestinal side effects. There is no specific timing recommendation, but consumption with meals may enhance bioavailability. Both raw and cooked forms of onions can be beneficial, but supplements may offer a more consistent and concentrated dose of active compounds. Bioavailability can be enhanced when consumed with fatty meals. A balanced diet can support the overall efficacy of the supplement.

FAQs

How often should I take onion supplements?

It is recommended to take them daily, preferably with meals, to enhance bioavailability and ensure consistent intake of active compounds.

Are there any potential interactions with medications?

While there is no significant evidence, it is always best to consult with a healthcare provider, especially if you are on anticoagulant medications.

Are onions safe for everyone?

Generally, yes, but individuals with allergies or intolerances should avoid them to prevent adverse reactions.

What can I expect from taking onion supplements?

You may experience improvements in metabolic parameters such as lipid profiles and blood pressure with consistent supplementation.

Can I take onion supplements at any time of the day?

Yes, but taking them with meals may enhance bioavailability, optimizing the absorption of beneficial compounds.

Research Sources

https://pubmed.ncbi.nlm.nih.gov/38056991/ – This systematic review and meta-analysis of 14 RCTs found that onion supplementation significantly improved body fat percentage, LDL-c, total cholesterol, HDL-c, systolic blood pressure, adiponectin, and AST. Higher dosages (>300 mg/day) and longer follow-up periods enhanced these benefits, suggesting a dose-response relationship and the importance of long-term intervention.
https://journal.medtigo.com/a-comprehensive-review-of-allium-cepa-in-metabolic-syndrome-management/ – This comprehensive review suggests that quercetin from onion skin extract can decrease blood pressure in hypertensive individuals, highlighting the potential of onion-derived compounds in managing metabolic syndrome. The review consolidates findings from various studies, emphasizing the role of Allium cepa in improving cardiovascular health.
https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2021.746944/full – This meta-analysis of prospective studies indicates that high consumption of allium vegetables might have a protective effect against cancer. While not specifically focused on onion supplementation, the study supports the broader health benefits of allium vegetables, including potential anti-cancer properties.
https://www.researchgate.net/publication/227672875_The_Green_Onion_A_Corporate_Environmental_Strategy_Framework – This source is not relevant to the health benefits or properties of green onions as a supplement. It discusses a corporate environmental strategy framework and is unrelated to the nutritional or medicinal aspects of Allium cepa.
https://academic.oup.com/jid/article-abstract/183/8/1273/907946?redirectedFrom=fulltext&login=false – This source is not directly relevant to the health benefits of onion supplementation. It discusses the effects of quercetin on HIV-1 replication in vitro, which is a specific antiviral application and not a general health benefit of onion consumption.