Fennel vs Onion – Which is Healthier?

Our Verdict

When comparing fennel to onion, we picked the fennel.

Why?

First note, in case you didn’t see the picture: we are talking about white onions here (also called brown onions, by virtue of their attire).

Looking at the macros, fennel has nearly 2x the fiber and a little more protein, while onion has more carbs. An easy win in this category for the fennel.

In the category of vitamins, fennel has more of vitamins A, B2, B3, B5, B9, C, E, K, and choline (most of them by generous margins and some by especially large margins, we are talking, for example, 480x the vitamin A, 29x the vitamin E, and 157x the vitamin K), while onions have more of vitmains B1 and B6. Another clear win for fennel.

When it comes to minerals, fennel has more calcium, copper, iron, magnesium, manganese, phosphorus, potassium, selenium, and zinc, while onion is not higher in any minerals. No prizes for guessing: fennel wins this category too.

You may be curious as to how they add up on the polyphenol front, and the answer is, they don’t, much. Wonderful as these two vegetables are, an abundance of polyphenols is not amongst their strengths; fennel has some lignans and onion has some flavonols, but we’re talking tiny numbers here (in contrast, red onion would have aced it with 120mg/100g quercetin, amongst others, but red onion wasn’t on trial today).

Adding up the sections makes a clear win for fennel today.

Want to learn more?

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Take care!