Soy Sauce & Tamari: Nutrients, What Research Shows and Safety
Soy sauce and tamari as foods: USDA sodium values, wheat and gluten, soy allergy, MAOI medicines and histamine, plus what research does and does not show.
Content last updated . This page has not been medically reviewed.
Soy sauce is a dark, salty liquid made by fermenting soybeans, usually with wheat. Tamari is a similar sauce that USDA lists as made from soy alone. This page is about the sauce as a seasoning, used by the spoonful. It keeps the food apart from soy foods in general, and apart from hype. It is information only, not personal advice. [1] [2]
Read this first
- Salt is the main point. USDA lists about 5,493 mg of sodium in 100 g of soy sauce with wheat (shoyu) and 5,586 mg in tamari. One tablespoon (16 g or 18 g) holds roughly 880 to 1,000 mg, which is about 38% to 44% of the 2,300 mg Daily Value. [1] [2] [3]
- Wheat and gluten: USDA's regular soy sauce item is "made from soy and wheat." People with celiac disease or a wheat allergy need to read the label, and "tamari" on a label does not by itself mean wheat-free. [1] [7] [8]
- Allergy: soybeans and wheat are both major US food allergens. For trouble breathing or swelling of the face or throat, call 911 (or your local emergency number). [7]
- MAOI antidepressants: people taking these medicines are often told to ask about fermented soy foods. Ask the prescriber or pharmacist before using soy sauce. [11]
- Evidence in one line: we found no trial of soy sauce for a health outcome. Evidence about fermented soy in general is mixed. [15] [16]
What is in it (USDA values)
The values are from USDA FoodData Central, SR Legacy: soy sauce made from soy and wheat (shoyu, FDC 174277) and soy sauce made from soy (tamari, FDC 174278). [1] [2] The serving is the USDA household portion of 1 tablespoon: 16 g for shoyu and 18 g for tamari. We multiplied the 100 g values by the serving weight.
Soy sauce made from soy and wheat (shoyu)
| Nutrient | Per 100 g | Per 1 tbsp (16 g) | % Daily Value per serving |
|---|---|---|---|
| Energy | 53 kcal | 8.5 kcal | not set |
| Protein | 8.14 g | 1.3 g | 3% |
| Total fat | 0.57 g | 0.09 g | 0% |
| Carbohydrate | 4.93 g | 0.79 g | 0% |
| Sodium | 5,493 mg | 879 mg | 38% |
| Potassium | 435 mg | 70 mg | 1% |
| Magnesium | 74 mg | 11.8 mg | 3% |
| Manganese | 1.018 mg | 0.16 mg | 7% |
| Phosphorus | 166 mg | 26.6 mg | 2% |
| Niacin (B3) | 2.196 mg | 0.35 mg | 2% |
Soy sauce made from soy (tamari)
| Nutrient | Per 100 g | Per 1 tbsp (18 g) | % Daily Value per serving |
|---|---|---|---|
| Energy | 60 kcal | 10.8 kcal | not set |
| Protein | 10.51 g | 1.9 g | 4% |
| Total fat | 0.1 g | 0.02 g | 0% |
| Carbohydrate | 5.57 g | 1.0 g | 0% |
| Sodium | 5,586 mg | 1,005 mg | 44% |
| Potassium | 212 mg | 38 mg | 1% |
| Magnesium | 40 mg | 7.2 mg | 2% |
| Manganese | 0.499 mg | 0.09 mg | 4% |
| Phosphorus | 130 mg | 23.4 mg | 2% |
| Niacin (B3) | 3.951 mg | 0.71 mg | 4% |
% Daily Value uses the FDA 2016 Daily Values (sodium: 2,300 mg). Real products vary by brand, recipe and type; one study of 102 soy sauces sold in Malaysia found sodium from about 3,370 to 5,710 mg per 100 g depending on the type. [17] A tablespoon gives very little of any vitamin or mineral except sodium. [1] [2]
Plant compounds: a laboratory study of seven commercial soy sauces found two naturally formed compounds, harman and norharman, that blocked the enzyme MAO in test tubes. This is lab chemistry, not a result in people. [12]
What research says
| Health goal or question | What the sources found | Strength of evidence | What was studied |
|---|---|---|---|
| Salt intake and blood pressure | Pooled randomized trials (34 trials, 3,230 people) found that a modest cut in salt lowered blood pressure by about 4.2 mmHg (top number) and 2.1 mmHg (bottom number). [5] WHO says high sodium raises blood pressure and the risk of heart disease and stomach cancer, and names soy sauce as a condiment that often has a lot of sodium. [4] | Established for salt in the diet. This is not a trial of soy sauce itself. | Adults, salt reduction |
| Soy sauce eaten for a health outcome | Proper evidence not found in the sources we read. We did not find a trial or cohort study of soy sauce alone for heart, blood sugar, weight or cancer outcomes. | None | Not applicable |
| Fermented soy products and blood markers | A pooled analysis of 15 randomized trials of fermented soy products found small drops in fasting glucose and total cholesterol and in waist size, but most other measures did not change. [15] | Mixed; not specific to soy sauce | Trials of fermented soy foods, various |
| Fermented soy foods overall | An umbrella review of meta-analyses concluded that benefits of fermented soy were inconclusive, and some studies hinted at possible harm. [16] | Insufficient evidence | Reviews of observational studies |
| Blocking the MAO enzyme | Diluted soy sauce blocked human MAO-A and MAO-B in the lab. The author says more study is needed and that other substances may contribute. [12] | Lab or animal only | Test-tube enzymes, 7 commercial sauces |
| Fermentation and food allergy | A review of 10 studies found that fermentation sometimes lowered the allergenicity of gluten or soy proteins, but one study found a worse reaction and most studies had weaknesses. [18] | Insufficient evidence; do not assume fermented means safe for allergy | Mixed study types |
Eaten as food vs other forms. Everything above is about soy sauce as a seasoning. Soy protein trials, isoflavone supplements and whole soy foods are different questions; see soy foods. Fermented foods are also not the same as probiotic supplements; see fermented foods vs probiotic supplements. [19]
How much is a normal serving
The USDA household portion is 1 tablespoon (16 g shoyu; 18 g tamari), about 9 to 11 kcal. [1] [2] That is information from the USDA data, not a prescription. Most of the "cost" of a serving is salt: the Dietary Guidelines for Americans advise adults to keep sodium under 2,300 mg a day, and WHO recommends less than 2,000 mg a day (under 5 g of salt). [3] [4] FDA says most dietary sodium comes from packaged and prepared foods, and that 20% Daily Value or more per serving is high. [3]Safety, allergy and medicines
- Sodium and blood pressure: see the table above. Americans average about 3,400 mg of sodium a day, according to FDA. [3] A single tablespoon of soy sauce is a large share of a day's limit. [1] [3]
- Kidney disease: NIDDK names soy sauce among high-sodium sauces and says many people with chronic kidney disease need a sodium limit lower than 2,300 mg, set by their care team. It also warns that salt substitutes can be high in potassium. [6]
- Soy allergy: soybeans are one of the nine major food allergens under US law (milk, eggs, fish, crustacean shellfish, tree nuts, peanuts, wheat, soybeans, sesame). Symptoms can include hives, swelling of the face, lips or tongue, wheezing and throat swelling. Severe reactions (anaphylaxis) need emergency care: call 911. [7] See food allergy basics and emergency signs.
- Wheat, gluten and celiac disease: USDA's regular soy sauce is made with wheat. [1] FDA's "gluten-free" label rule covers fermented and hydrolyzed foods, and a "gluten-free" claim is voluntary. [8] A 2026 lab study that tested 15 soy sauces by the standard test found gluten below its detection limit, yet it still found small amounts of celiac-active protein pieces in them. [9] A StatPearls review notes gluten is common in processed foods such as soy sauce. [10] Take-away: read the label, look for a gluten-free claim, and ask your clinician if you have celiac disease. Wheat allergy is a different condition from celiac disease, and a low gluten test does not prove a sauce is safe for a wheat-allergic person.
- MAOI antidepressants and tyramine: a 1999 lab study measured tyramine in soy products and found wide differences; one soy sauce was high, and the authors advised people on MAOIs to avoid soy sauce. [11] That study is old, and brands differ. Another review says fermented foods can carry histamine and tyramine, with effects such as migraine and higher blood pressure, and that medicines can raise the risk. [14] Ask the prescriber or pharmacist. See histamine, tyramine and fermented foods.
- Histamine sensitivity: a 2025 study isolated histamine- and tyramine-making microbes from soy sauce and soybean paste ferments. [13] We did not read a source with a typical histamine amount per tablespoon, so we give none.
- Pregnancy, breastfeeding and children: we did not read an official statement on soy sauce itself. FDA says sodium limits are lower for children under 14. [3] For official advice in pregnancy see foods in pregnancy.
- Thyroid medicine and soy: we did not read an official source on soy sauce and thyroid tablets, so we make no claim.
- Contaminants: we did not read a source for 3-MCPD or other processing contaminants in soy sauce, so we make no claim. See heavy metals and contaminants in foods.
Choosing, storing and food safety
- Compare the Nutrition Facts panel: 5% Daily Value or less sodium per serving is low and 20% or more is high. [3]
- If gluten matters, look for a "gluten-free" claim and read the ingredient list for wheat. [8]
- We did not read a source on how long an opened bottle keeps or on home-made soy sauce, so we give no storage advice. For home fermenting in general see fermented foods safety and home fermentation risks.
Related pages
Health connections for Soy Sauce & Tamari
What research links to eating or drinking this food, and how strong the evidence is. Many studies are observational or use juice, powder, oil or extracts rather than the food as eaten; each card says which.
Fermented soy products and blood sugar and cholesterol markers
Preliminary or mixedPooled trials of fermented soy foods found small drops in fasting glucose, total cholesterol and waist size; an umbrella review called benefits inconclusive. Not specific to soy sauce.
Supplements: Trials used various fermented soy foods, not soy sauce by the spoon.
MAO enzyme inhibition by compounds in soy sauce (lab)
Lab or animal research onlyDiluted soy sauce blocked human MAO enzymes in the test tube; the author says more study is needed.
Supplements: Lab study only; no human result.
Is soy sauce a probiotic food?
Not enough evidenceFermented foods are defined by microbial growth during making; that is different from a probiotic. We read no source on live microbes in finished soy sauce.
Supplements: Probiotic supplements are a separate question.
Connected topics
Open a group to see how each topic connects and how strong the evidence is.
Health goals (2)
- Blood Pressure SupportDocumented risk
Soy sauce is high in sodium (about 880 to 1,000 mg per tablespoon by USDA), and high sodium raises blood pressure. This is a caution, not a benefit.
- Heart HealthDocumented risk
WHO links high sodium intake to heart disease risk; soy sauce is a high-sodium condiment.
Body systems (2)
- Cardiovascular SystemDocumented risk
High sodium intake raises blood pressure and cardiovascular risk (WHO).
- Kidney & UrinaryDocumented risk
People with chronic kidney disease are often given a lower sodium limit; NIDDK names soy sauce as a high-sodium sauce.
Body parts (1)
- KidneysDocumented risk
NIDDK names soy sauce among high-sodium foods for people with chronic kidney disease.
Root causes (2)
- Autoimmune DysfunctionDocumented risk
Regular soy sauce is made with wheat; people with celiac disease (an autoimmune reaction to gluten) must check labels.
- Medication Side EffectsDocumented risk
Fermented foods can contain tyramine; people on MAOI antidepressants are told to ask. One older lab study found high tyramine in a soy sauce.
Conditions & symptoms (5)
- Essential HypertensionDocumented risk
High sodium raises blood pressure; soy sauce is a high-sodium condiment. A caution, not a treatment.
- Food AllergyDocumented risk
Soy and wheat are major US allergens; call 911 for trouble breathing or throat swelling.
- Celiac DiseaseDocumented risk
Regular soy sauce is made with wheat; check for a gluten-free claim.
- Chronic Kidney InsufficiencyDocumented risk
NIDDK names soy sauce among high-sodium sauces for people with chronic kidney disease.
- Wheat HypersensitivityDocumented risk
Regular soy sauce is made with wheat; a low gluten test does not prove safety for wheat allergy.
Documented risks and interactions (6)
- Sodium from soy sauce and blood pressure. USDA lists about 5,500 mg of sodium per 100 g, roughly 880 to 1,000 mg in a tablespoon. Pooled trials show that cutting salt lowers blood pressure.
- Wheat, gluten and celiac disease. USDA lists regular soy sauce as made from soy and wheat. A lab study found gluten below the test limit in 15 soy sauces but still found small celiac-active peptide amounts.
- Soy and wheat allergy. Soybeans and wheat are major US food allergens. Fermentation does not reliably remove allergens: one reviewed study found a worse reaction.
- MAOI antidepressants and tyramine. A 1999 lab study found high tyramine in one soy sauce and advised avoiding soy sauce on MAOIs; product values differ.
- Histamine and biogenic amines in fermented soy sauce. Microbes that make histamine and tyramine were isolated from soy sauce ferments. We read no typical amount per tablespoon.
- Soy sauce and kidney disease sodium limits. NIDDK names soy sauce among high-sodium sauces and says many people with chronic kidney disease need a lower sodium limit set by their care team.
Frequently asked questions
Is soy sauce gluten-free?
Not usually. USDA's regular soy sauce item is made from soy and wheat. [1] Some products carry a "gluten-free" label, which FDA regulates. [8] Read the label.
Is tamari the same as soy sauce?
Tamari is a kind of soy sauce. USDA lists a tamari item made from soy alone, with about the same sodium. [2] Individual products can differ, so check the ingredient list for wheat.
How much sodium is in a tablespoon of soy sauce?
USDA data give about 879 mg for 1 tablespoon of soy and wheat soy sauce and about 1,005 mg for tamari, around 38% to 44% of the 2,300 mg Daily Value. [1] [2] [3]
Can I use soy sauce if I take an MAOI antidepressant?
Ask your prescriber or pharmacist. An older lab study found high tyramine in one soy sauce, and the authors advised avoiding soy sauce on MAOIs. [11]
Does soy sauce help health?
We did not find a trial of soy sauce for a health outcome. Studies of fermented soy as a group are mixed. [15] [16]
References
- U.S. Department of Agriculture. FoodData Central: Soy sauce made from soy and wheat (shoyu), SR Legacy, FDC 174277. April 2018 release. Read 2026-10-24.
- U.S. Department of Agriculture. FoodData Central: Soy sauce made from soy (tamari), SR Legacy, FDC 174278. April 2018 release. Read 2026-10-24.
- U.S. Food and Drug Administration. Sodium in Your Diet. Content current as of 2024-03-05. Read 2026-10-24.
- World Health Organization. Salt reduction fact sheet. Page dated 2026-05-11. Read 2026-10-24.
- He FJ et al. Effect of longer-term modest salt reduction on blood pressure. Cochrane Database Syst Rev 2013 (abstract read via Europe PMC). Read 2026-10-24.
- NIDDK. Healthy eating for adults with chronic kidney disease. Last reviewed January 2025. Read 2026-10-24.
- U.S. Food and Drug Administration. Food allergies. Content current as of 2026-03-11. Read 2026-10-24.
- U.S. Food and Drug Administration. Gluten-free labeling of foods. Content current as of 2026-03-17. Read 2026-10-24.
- Tissen E et al. Proteomics analysis of celiac disease-active peptides in food products with partially hydrolyzed gluten. J Agric Food Chem 2026 (abstract read via Europe PMC). Read 2026-10-24.
- Akhondi H et al. Gluten-associated medical problems. StatPearls 2025 (abstract read via Europe PMC). Read 2026-10-24.
- Shulman KI, Walker SE. Refining the MAOI diet: tyramine content of pizzas and soy products. J Clin Psychiatry 1999 (abstract read via Europe PMC). Read 2026-10-24.
- Herraiz T. beta-Carboline alkaloids in soy sauce and inhibition of monoamine oxidase (MAO). Molecules 2023. Read 2026-10-24.
- Zhang X et al. Isolation and characterizations of histamine- and tyramine-producing strains isolated from fermented soybean food: soy sauce and soybean paste. Foods 2025 (abstract read via Europe PMC). Read 2026-10-24.
- Saha Turna N et al. A review of biogenic amines in fermented foods: occurrence and health effects. Heliyon 2024 (abstract read via Europe PMC). Read 2026-10-24.
- Maleki Sedgi F et al. Effect of fermented soybean on metabolic outcomes, anthropometric indices, and body composition: a systematic review and meta-analysis of clinical trials. Food Funct 2025 (abstract read via Europe PMC). Read 2026-10-24.
- Li W et al. Soy foods consumption and multiple health outcomes: an umbrella review of meta-analyses. Mol Nutr Food Res 2026 (abstract read via Europe PMC). Read 2026-10-24.
- Harun Z et al. Reformulation of soy sauce to reduce sodium content and assessment of manufacturer readiness, consumer acceptance, and shelf life. Sci Rep 2025 (abstract read via Europe PMC). Read 2026-10-24.
- Hyseni B et al. The role of fermented foods in managing food allergies in children and adults: a systematic review. Front Nutr 2025 (abstract read via Europe PMC). Read 2026-10-24.
- Marco ML et al. The ISAPP consensus statement on fermented foods. Nat Rev Gastroenterol Hepatol 2021 (abstract read via Europe PMC). Read 2026-10-24.