Soy Sauce: Sodium, Tamari, Gluten and USDA Nutrition

Soy sauce is a salty, savory liquid seasoning brewed from soybeans, salt and, in most bottles, wheat. Its calories are tiny, but its sodium is not: in USDA data, one tablespoon of regular soy sauce made from soy and wheat has about 879 milligrams of sodium, 38% of the FDA Daily Value. This guide covers soy sauce sodium by type, soy sauce vs tamari, whether soy sauce is gluten free, what reduced-sodium labels really promise, and the allergen facts that matter.

Peptide Labs does not sell soy sauce or any soy sauce product. This article is general nutrition information, not medical advice.

What is soy sauce and how is it made?

Traditional brewed soy sauce starts with soybeans, wheat and salt. A 2021 review in the Journal of Fungi describes the process: koji molds grow on the cooked soybeans and roasted wheat, and their enzymes break protein and starch into amino acids and sugars. The mash then ferments in salty brine with salt-tolerant yeasts and lactic acid bacteria for months, and the dark color comes from reactions between those amino acids and sugars. A 2020 review of soy sauce chemistry found its taste is dominated by umami and saltiness, driven by free amino acids, nucleotides and small peptides.

Not every bottle is brewed this way. USDA’s database has three main entries: soy sauce made from soy and wheat (shoyu), soy sauce made from soy (tamari), and soy sauce made from hydrolyzed vegetable protein, a faster industrial method. The ingredient list tells you which kind you have: look for “brewed” or “naturally brewed” and the grains named, or for “hydrolyzed” proteins, caramel color and corn syrup.

Soy sauce sodium by type

Sodium is the main nutrition story. FDA sets the Daily Value for sodium at less than 2,300 milligrams a day and notes that Americans average about 3,400, with more than 70% coming from packaged and prepared foods. FDA also says diets higher in sodium are associated with an increased risk of high blood pressure. The table uses USDA SR Legacy values for one tablespoon of each type.

Smaller amounts add up too. In USDA data, a teaspoon of shoyu has about 291 milligrams of sodium (13% of the Daily Value) and a single takeout packet has about 489 milligrams (21%). FDA’s rule of thumb is that 5% DV or less per serving is low and 20% DV or more is high, so even a packet lands in the high range. Soy sauce supplies very little else: about 1.3 grams of protein per tablespoon of shoyu in USDA data, and small amounts of minerals.

If you are watching sodium, our low-sodium foods guide shows where sodium hides across the diet, and the miso guide covers another salty fermented soy seasoning.

Low sodium soy sauce: what the label means

FDA rules in 21 CFR 101.61 define sodium claims. A food labeled “low sodium” must have 140 milligrams or less per reference serving, while “reduced sodium” or “less sodium” only means at least 25% less than a regular version. That is why the low sodium soy sauce entry in USDA’s database still lists about 511 milligrams per tablespoon, and the reduced-sodium hydrolyzed entry about 434. These bottles cut sodium compared with regular soy sauce, but they are not low-sodium foods in the label-claim sense.

One detail stands out in USDA data: the reduced-sodium hydrolyzed soy sauce entry lists about 465 milligrams of potassium per tablespoon, 10% of the Daily Value, far more than regular soy sauce. Check the ingredient list for potassium chloride or other potassium salts. If a clinician has told you to limit potassium, ask about these products; our salt substitutes guide explains why potassium-based swaps are not right for everyone. Diluting regular soy sauce with water or rice vinegar, or measuring it with a spoon rather than pouring, are simple kitchen ways to get the flavor with less of it.

Soy sauce vs tamari

Tamari is a style of soy sauce. USDA describes it as soy sauce made from soy, while shoyu is made from soy and wheat, which is why people avoiding wheat often look for tamari first.

• Sodium: per 100 g, USDA lists tamari at 5,586 milligrams and shoyu at 5,493, nearly the same. Tamari’s tablespoon weighs 18 g in USDA data versus 16 g for shoyu, so its tablespoon value is a little higher.
• Protein: tamari is slightly higher, about 1.9 grams per tablespoon versus 1.3 for shoyu in USDA data, which is still a small amount.
• Wheat: USDA defines its tamari entry as made from soy, but recipes vary by brand. Only the ingredient list and a gluten-free label settle the question.
• Soy: both contain soy, so neither works for a soy allergy.

Is soy sauce gluten free?

Usually not. NIDDK explains that gluten is a protein found naturally in wheat, barley and rye, and it lists condiments among foods that may contain it. The Celiac Disease Foundation names traditional soy sauce among sauces that contain gluten, because it is brewed with wheat. For people with celiac disease, the safe route is a product labeled gluten-free, which under FDA rules means less than 20 parts per million gluten. FDA also issued a 2020 rule that sets how it checks gluten-free claims on fermented and hydrolyzed foods, a group that includes hydrolyzed plant proteins used in sauces and seasonings.

Restaurant food is harder to judge, since sauces, marinades and glazes often contain regular soy sauce. NIDDK notes that a doctor or registered dietitian can help plan a gluten-free diet, and that cross-contact can make gluten-free foods unsafe for people with celiac disease.

Allergens and other cautions

• Soy and wheat: both are among the nine major food allergens under US law, so a packaged soy sauce must declare them on the label. Our elimination diet guide explains why suspected food allergies should be tested with an allergist.
• Sauces built on soy sauce: teriyaki, stir-fry sauces and many marinades carry the same allergens, which their labels must declare, and USDA lists ready-to-serve teriyaki at about 690 milligrams of sodium per tablespoon.
• Other soy foods: soy sauce is a seasoning, not a protein source. For soy foods with real protein, see our tofu, tempeh and natto guides, or the overview of fermented foods.
• Pairings: a dip such as hummus is a lower-sodium partner for vegetables than a soy-based dipping sauce, in USDA data.

Frequently Asked Questions

Questions about a label? Contact us or read our Buyer’s Guide. Food comes first; follow the label and ask a healthcare provider before starting a supplement, especially if you take medicines, are pregnant or have a food allergy. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

Last reviewed October 2026.

Related guides: Hummus: Nutrition, Calories, Ingredients and Safety Facts, Low Sodium Foods: USDA List, Foods High in Sodium and Label Terms, Miso: USDA Nutrition, Sodium per Tablespoon, Types and Miso Soup, Fish Sauce: USDA Nutrition, Sodium, Histamine and Allergen Facts.