Is standard cornstarch actually high in sodium?

No. Plain cornstarch contains 0mg sodium per tablespoon. It is compatible with a low-sodium diet. The concern is with flavored or blended products (e.g., seasoned gravy thickeners) that may contain added salt — check the label of your specific product.

Which substitute works best for thickening fruit pie filling on a low-sodium diet?

Tapioca starch is the most commonly recommended option for fruit fillings. Use 1 tbsp tapioca starch per 1 tbsp cornstarch called for. It handles the acidity of fruit well and produces a clear, glossy set. Arrowroot is a close second but can become slimy if the filling is baked at very high heat for a long time.

Can I use these substitutes in a slow cooker or for dishes that will be frozen?

All-purpose flour holds up best in slow cooker applications and through freezing. Arrowroot, tapioca starch, and potato starch all degrade in texture when frozen or cooked for extended periods at high heat — sauces thickened with them tend to separate or become watery after freezing and reheating.

Low sodium cornstarch substitutes

Plain cornstarch is naturally sodium-free, so it is not the ingredient itself that creates a sodium problem — but many commercial thickening blends and modified food starches contain added salt. If your recipe calls for a thickener and you need to stay under 1500mg sodium per day, the safest approach is to verify the label of whatever starch you reach for. All substitutes below are either sodium-free or contain only trace amounts naturally occurring in the ingredient.

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Rank	Substitute	Ratio (replaces 1 cup cornstarch)	Notes
#1	Arrowroot powder	1 tbsp arrowroot powder per 1 tbsp cornstarch	Arrowroot is sodium-free and thickens at a lower temperature than cornstarch, making it reliable for sauces and glazes that should not be boiled hard. It produces a clearer gel than cornstarch. Does not hold well in dishes that will be frozen or reheated — the gel breaks down and becomes slimy. Widely recommended by King Arthur Baking and Serious Eats as a 1:1 swap in most applications.
#2	Tapioca starch	1 tbsp tapioca starch per 1 tbsp cornstarch	Sodium-free and produces a glossy, slightly stretchy gel well suited to fruit pie fillings and Asian-style sauces. Sets firmer than arrowroot and holds better through moderate reheating. Can turn gummy if overcooked; remove from heat as soon as the sauce clears. America's Test Kitchen uses it as a direct swap in fruit fillings.
#3	All-purpose flour	2 tbsp all-purpose flour per 1 tbsp cornstarch	Plain all-purpose flour contains only trace amounts of naturally occurring sodium (around 1–2mg per tbsp) with no added salt — check the label of your specific brand. It produces a more opaque, matte sauce and requires cooking for at least 1–2 minutes to eliminate raw-flour taste. Results are noticeably heavier than cornstarch-thickened sauces. Works in a pinch for gravies and pan sauces but is not a good choice for delicate glazes or clear soups.
#4	Potato starch	1 tbsp potato starch per 1 tbsp cornstarch	Sodium-free and thickens at lower temperatures than cornstarch, yielding a light, clear sauce. Breaks down if held at high heat for more than a few minutes, so stir it in at the end of cooking and do not boil hard afterward. Works well for soups and pan sauces. Less commonly stocked than arrowroot but increasingly available and well-regarded by food writers at Food52 and Bon Appétit.

Why standard cornstarch isn't low sodium

Plain, unflavored cornstarch sold in mainstream grocery stores (Argo, Bob's Red Mill, store brands) contains zero sodium and is already low-sodium compliant. The issue arises with seasoned thickening blends, gravies mixes, or modified food starches that include salt — always read the nutrition label before using any packaged starch product on a sodium-restricted diet.

Plain cornstarch is already a zero-sodium ingredient, so swapping it is only necessary if the product you have on hand contains added salt — a label check solves the problem most of the time. When a genuine substitute is needed (due to availability, texture preference, or a labeled product with sodium), arrowroot and tapioca starch are the most reliable 1:1 alternatives with comparable thickening power and no sodium.

The right choice among these substitutes depends on the dish. Arrowroot gives the clearest result and the most neutral flavor, making it the default for sauces and gravies. Tapioca starch is better for baked fruit fillings. Potato starch works for quick pan sauces finished off heat. All-purpose flour is the fallback when nothing else is available, but it produces a heavier, starchier result that experienced cooks will notice.

Frequently asked questions

Is standard cornstarch actually high in sodium?: No. Plain cornstarch contains 0mg sodium per tablespoon. It is compatible with a low-sodium diet. The concern is with flavored or blended products (e.g., seasoned gravy thickeners) that may contain added salt — check the label of your specific product.
Which substitute works best for thickening fruit pie filling on a low-sodium diet?: Tapioca starch is the most commonly recommended option for fruit fillings. Use 1 tbsp tapioca starch per 1 tbsp cornstarch called for. It handles the acidity of fruit well and produces a clear, glossy set. Arrowroot is a close second but can become slimy if the filling is baked at very high heat for a long time.
Can I use these substitutes in a slow cooker or for dishes that will be frozen?: All-purpose flour holds up best in slow cooker applications and through freezing. Arrowroot, tapioca starch, and potato starch all degrade in texture when frozen or cooked for extended periods at high heat — sauces thickened with them tend to separate or become watery after freezing and reheating.

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