Tomato vs Onion: Which Is Better for Kidneys?

Q: Which has more potassium, tomato or onion?

Per 100 g, tomato contains 3427 mg and onion contains 146 mg of potassium.

Q: Is tomato or onion better for kidney disease?

Based on CKD stage 3-4 daily limits, tomato is rated higher risk and onion is rated kidney-friendly. Ratings reflect mineral load per 100 g only — individual advice should come from your healthcare team.

Q: What is the main difference for a CKD diet?

The largest difference is potassium: onion sits at 7% of the daily limit versus 171% for tomato. See each food page for the full mineral profile.

Comparing Tomato and Onion per 100 g: Tomato rates Higher risk, while Onion rates Kidney-friendly under CKD stage 3-4 daily limits. Onion carries the lighter mineral load overall, driven mainly by Potassium (7% vs 171% of the limit).

Tomato
Higher risk Onion
Kidney-friendly

Phosphorus

356 mg

36%

29 mg

Sodium

107 mg

4 mg

<1%

Potassium

3427 mg

171%

146 mg

See Tomato details See Onion details

Frequently asked questions

Which has more potassium, tomato or onion?

Per 100 g, tomato contains 3427 mg and onion contains 146 mg of potassium.

Is tomato or onion better for kidney disease?

Based on CKD stage 3-4 daily limits, tomato is rated higher risk and onion is rated kidney-friendly. Ratings reflect mineral load per 100 g only — individual advice should come from your healthcare team.

What is the main difference for a CKD diet?

The largest difference is potassium: onion sits at 7% of the daily limit versus 171% for tomato. See each food page for the full mineral profile.