Tofu: Nutrients, What Research Shows and Safety

Tofu is a soft curd made from soybeans (Glycine max, a legume). The soybeans are turned into soy milk, which is then set with a setting agent such as calcium sulfate or nigari. [1] [2] People eat it as a plant protein, as a source of calcium when it is set with calcium, and because soy foods have been studied for cholesterol and heart health. This page keeps tofu apart from soy protein or isoflavone supplements, and apart from hype. For the wider soy picture, see Soy foods.

Read this first

• Soy is a major food allergen. The FDA names soybeans among the nine major allergens. For trouble breathing, swelling of the face, lips or throat, or any serious whole-body reaction, call 911 (or your local emergency number). [4] [5]
• MAOI antidepressants: NCCIH reports that soy foods high in tyramine, such as tofu and soy sauce, have been linked to dangerously high blood pressure in people taking MAOIs. Ask a pharmacist. [3]
• Evidence in one line: soy protein in place of other protein lowers LDL cholesterol a little in trials; people who eat tofu more often had a lower heart disease risk in large observational studies, which cannot prove cause. [6] [8]
• Pregnancy: NCCIH says soy in amounts greater than those commonly found in foods may be unsafe. [3]
• Thyroid tablets: evidence that soy affects levothyroxine is thin, mostly case reports. Ask your prescriber. [13]

What is in it (USDA values)

The values below are for raw, regular tofu prepared with calcium sulfate (USDA FoodData Central item 172476, SR Legacy). [1] The serving column is the USDA household portion of 0.5 cup, 124 g. [1] USDA also lists firm tofu prepared with calcium sulfate and magnesium chloride (nigari), item 172448, with a different profile: per 100 g it has 78 kcal, 9.04 g protein, 201 mg calcium and 1.61 mg iron, and its 0.5 cup portion is 126 g. [2]

% Daily Value uses the FDA 2016 Daily Values; values vary with the setting agent, firmness, brand and added ingredients. The serving figures are the 100 g values multiplied by 1.24. The calcium figure depends on the setting agent: the two USDA items above show 350 mg and 201 mg per 100 g, so read the label of your product. [1] [2] Tofu is not a fiber source (0.3 g per 100 g in this item). [1]

Plant compounds: soybeans contain isoflavones, which NCCIH describes as plant compounds similar in structure to estrogen. [3] A lab analysis of 30 soybean varieties found total isoflavones of 0.16% to 0.25% in types grown for tofu, higher than in edamame types. [15] That is laboratory chemistry, not a health result.

What research says

Eaten as food vs taken as a supplement. The cholesterol trials compared soy protein with other protein, so the result describes a swap, not an add-on. [6] NCCIH separates soy foods from soy protein and isoflavone supplements and says effects may differ by product. [3] Most heart disease evidence for tofu is observational. We did not check the funding of every review; the LDL analysis lists public research funding and one author at a soy nutrition institute. [6]

How much is a normal serving

The USDA household portions for the regular tofu item are 0.5 cup (124 g, about 94 kcal) or 0.25 block (116 g). [1] This is information from USDA data, not a prescription. USDA's firm tofu item lists 0.5 cup as 126 g and 0.2 block as 91 g, so block sizes differ by product. [2] Check the package for the serving size.

Safety, allergy and medicines

• Allergy. Soybeans are one of the major allergens US labels must name. [4] MedlinePlus lists soy among the most common food allergies, mostly in children, and says to call 911 or the local emergency number for serious or whole-body reactions, especially wheezing or trouble breathing. [5] See Food allergy basics and emergency signs.
• MAOIs. NCCIH names tofu and soy sauce as high-tyramine soy foods linked to dangerously high blood pressure with MAOI antidepressants. [3] The page does not give amounts. Ask a pharmacist.
• Thyroid tablets (levothyroxine). A 2023 review found mainly case reports, one randomized crossover study with no difference, and too little data on liquid forms. The authors thought any effect likely has little clinical impact. [13] Do not change a medicine on your own.
• Pregnancy and breastfeeding. NCCIH says soy in amounts greater than those commonly found in foods may be unsafe in pregnancy, and little is known about larger amounts while breastfeeding. [3] See Foods in pregnancy: what official bodies advise.
• Digestion. NCCIH lists bloating, constipation, diarrhea and nausea as possible side effects of soy. [3] NIDDK names legumes among foods that can cause gas. [14]
• Hormone-sensitive conditions. The sources we read do not tell an individual how much soy is right. Ask your clinician or cancer care team.
• Kidney disease and medicine timing. See Foods, kidney disease, potassium and oxalates and Foods and medicine interactions. We did not read a source that gives tofu-specific advice for either.

Choosing, storing and food safety

• Plain tofu has little sodium in the USDA data (7 mg per 100 g), but marinated, smoked or seasoned products can differ. [1] Read the label for sodium and allergens.
• If calcium is why you eat tofu, check whether the label says it is set with calcium. The two USDA items above differ by about 150 mg of calcium per 100 g. [1] [2]
• Follow the package directions for refrigeration and the use-by date.

Related pages

• Soy foods
• Edamame
• Tempeh
• Fermented tofu
• Foods for cholesterol and heart health
• Food allergy basics and emergency signs