Combination of onion and garlic keeps flu and colds at bay

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09.08.2025

Combination of onion and garlic keeps flu and colds at bay

A combination of garlic and onion extracts protects people over 65 against flu and colds, according to a 2023 Spanish human study. The researchers used a supplement, but regular onions and garlic likely offer just as much protection.

Combination of onion and garlic keeps flu and colds at bay

Study

Spanish pharmacologists from the University of Granada conducted a 36-week experiment with approximately sixty people aged 65 and over, living in a nursing home. The researchers divided their subjects into two groups: one group that took a placebo every day with lunch and one group that took a supplement with lunch.

The supplement was called AlioCare, a product of the Spanish company Domca. Domca did not fund the study.

Each AlioCare capsule contains 180 milligrams of vitamin C and 7 milligrams of zinc, along with 100 milligrams of extract. This extract consists of 86 milligrams of onion extract and 14 milligrams of garlic extract. The onion extract in AlioCare is standardized for propiin - full name: S-allyl-L-cysteine-sulfoxide - and its analogues.

The structure of propiin is shown below.

Combination of onion and garlic keeps flu and colds at bay

The main active ingredient in the garlic extract was allicin - or at least its precursors. You can see the structural formula of allicin here.

According to Domca, one capsule contains as much active ingredient from onion and garlic as you can get from two garlic cloves and a regular onion. [aliocare.es]

Results
Supplementation with the combined garlic and onion extract protected the subjects against colds and flu. The risk of these viral infections decreased by a factor of four, according to the table below. Click on it for a larger version.

Supplementation reduced the number of times the over-65s experienced coughs, bone pain, or fatigue, as shown above. This isn't surprising. These are classic symptoms of colds and the flu.

Finally, the combination of garlic and onion reduced the number of days the subjects experienced these symptoms after becoming ill. On average, supplementation reduced the duration of symptoms by a factor of three.

Conclusion
"In conclusion, regular consumption of an Allium extract improves the immunity of elderly volunteers and can be used prophylactically against the most common infectious respiratory diseases," the researchers summarize.

More coming soon.

Source:
Nutrients. 2023 May 15;15(10):2308.

More:
Garlic's antiviral effect thwarts coronavirus 17.06.2025
Fighting colds with garlic 26.03.2020

Archives:
Immune System
Onions
Garlic



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