Foods to avoid with kidney disease / Tomatoes
Yes. For most kidney diets a fresh tomato fits without drama: one medium tomato is about 292 mg potassium and 6 mg sodium. What deserves your attention is the processing. Cook the water out and every mineral climbs per gram, so paste and sun-dried tomatoes read several times higher than fresh, and canned sauce and juice carry salt the tomato never had. The plant is not the trap; the can is.
By the MedMenu Editorial Team · Published August 7, 2026
One plant, five different foods. Per USDA FoodData Central, in realistic portions:
| Form | Potassium | Sodium |
|---|---|---|
| Fresh tomato, 1 medium (123 g) | 292 mg | 6 mg |
| Tomato paste, 2 tbsp (32 g) | 324 mg | 19 mg |
| Tomato sauce, canned, 1/2 cup (122 g) | 362 mg | 578 mg |
| Sun-dried tomatoes, 1/4 cup (14 g) | 480 mg | 15 mg |
| Tomato juice, canned, 1 cup (243 g) | 527 mg | 615 mg |
Juice and sauce values are for the ordinary salted products; no-salt-added versions lower the sodium column, not the potassium one.
Two things happen on the way from the vine to the jar, and they stack.
This is why "are tomatoes high in potassium" has no single answer. Slices on a sandwich and a ladle of marinara are not the same food, even though they started as the same fruit.
No, portion does the work. A thin quarter-cup coating of canned sauce on pasta is about 181 mg potassium; the trouble arrives when sauce is eaten by the bowl, or when paste-heavy dishes stack on top of other potassium sources in the same meal. Three moves keep tomato flavor on the table:
Here the fresh tomato turns into a genuine ally. At about 5 g carbohydrate per medium tomato it barely moves blood sugar, which makes it one of the few flavor-carrying foods that both conditions welcome. The form to be careful with is juice: a cup packs the potassium of nearly two tomatoes with the fiber stripped out, so it lands faster on blood sugar than the fruit it came from. And sauce rarely travels alone; it usually arrives on a plate of pasta or rice, so the meal's carbohydrate comes from the starch underneath while the potassium and sodium come from the sauce. Portion both, not just one.
Every value on this page comes from USDA FoodData Central (Standard Reference legacy), read from the specific database entry for each preparation rather than a category average. For scale, many kidney diets use around 2,000 mg potassium a day as a common reference point, so a cup of tomato juice is roughly a quarter of such a day. There is no single potassium limit that fits everyone; your care team sets yours from your blood test results. Kidney nutrition guidelines put sodium under 2,300 mg a day for most adults; the full 2020 guideline is linked in Sources.
Sources
MedMenu is an information tool, not medical advice, and does not diagnose, treat, or manage any condition. Your nephrologist and renal dietitian set your personal targets from your labs and stage. Published August 7, 2026 · Last updated August 7, 2026.
This is a comprehensive website! Recipes look great and represent a variety of cuisines. You have emphasized the appropriate nutrients. Guidance tips are helpful. Science tab provides evidence-based references and are appropriate for the diseases addressed. Links to Drugs.com, WebMD & Medline are nice. As a registered dietitian, I feel comfortable recommending MedMenu.
Susan G. Rodder, MS, RDN, LD
Registered Dietitian
MedMenu offers all the data you need to plan meals based on specific dietary needs. There are lot of great recipes from a variety of cuisines to choose from, or you can test your own recipe to see how well it fits into your dietary guidelines.
Valerie B.
MedMenu user
Diabetically Speaking with SmartMove360
They sit in the middle: 237 mg per 100 g, or about 292 mg for a medium tomato. That is well below a banana and in the same range as many everyday vegetables, which is why fresh tomato in normal amounts fits most kidney diets.
Ketchup is made from paste, so it follows the same pattern as the other concentrated forms: more potassium and sodium per gram than fresh tomato. In tablespoon amounts it stays a small contributor; it becomes meaningful when it is used by the quarter cup or stacked with other sauces in the same meal.
It is the heaviest tomato form per serving on both counts that matter here: 527 mg potassium and 615 mg sodium per cup for the ordinary salted kind. If you love the flavor, a small glass of low-sodium tomato juice counted into your day is workable; as a daily habit by the tall glass it adds up quickly.
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