Bok Choy: Nutrients, What Research Shows and Safety

Bok choy (also spelled pak choi) is Brassica rapa subsp. chinensis, a leafy vegetable in the cabbage family (Brassicaceae). The pale stalks and the green leaves are eaten, raw or cooked. People eat it for its vitamins and as part of a vegetable-rich diet. This page keeps the whole food apart from supplements and from hype. Information only, not a plan for what to eat.

Read this first

• Allergy: any food can cause an allergic reaction. For trouble breathing or swelling of the face or throat, call 911. See food allergy basics and emergency signs.
• Warfarin (a blood thinner): bok choy contains vitamin K, which affects how warfarin works. MedlinePlus advises eating consistent amounts of vitamin K foods from week to week and talking to your doctor before changing your diet. [2] It does not say to avoid vegetables.
• Thyroid: one published case report links very large amounts of raw bok choy to a life-threatening thyroid problem. It is one person; see the safety section. [6]
• Evidence in one line: we found no trials of bok choy itself. What exists is general evidence on vegetable intake (observational) and nutrient facts from USDA.

What is in it (USDA values)

USDA FoodData Central lists "Cabbage, chinese (pak-choi), raw" (SR Legacy). [1] The household portion is 1 cup shredded, 70 g.

% Daily Value uses the FDA 2016 Daily Values; values vary with variety, ripeness and storage. Per-serving figures are the per-100 g values scaled to 70 g. [1]

USDA lists beta-carotene (2,681 mcg per 100 g) and lutein plus zeaxanthin (40 mcg per 100 g), plant pigments the body can use to make vitamin A or that are studied for eye health. [1] Like other cabbage-family vegetables, bok choy contains glucosinolates, sulfur compounds that break down into biologically active isothiocyanates when the leaf is chopped or chewed; the Linus Pauling Institute says human research on these compounds is limited and that observational links to lower cancer risk do not show the isothiocyanates are the cause. [3] We did not find a source measuring glucosinolates in bok choy specifically, so we give no amounts.

What research says

Eaten as food vs taken as a supplement or extract. Everything above is about the vegetable as food. We did not find a trial of bok choy powder, juice or extract, and results for other products would not carry over. Eating a vegetable that is rich in a nutrient is not proof that it treats a disease.

How much is a normal serving

• The USDA household portion is 1 cup of shredded raw bok choy, 70 g. [1]
• The NHS counts 80 g of fresh, canned or frozen vegetables as one portion of its "5 A DAY". [9] The WHO recommends at least 400 g of fruit and vegetables a day for people older than 10. [10] These are official population figures, information and not a prescription.
• Cooking effects on bok choy's nutrients: Proper evidence not found in the sources we read. The Linus Pauling Institute notes that cooking inactivates myrosinase, the plant enzyme that turns glucosinolates into isothiocyanates, though light steaming keeps some. [3]

Safety, allergy and medicines

• Warfarin and vitamin K: warfarin is counteracted by vitamin K, and sudden changes in intake can alter its effect. Keep vitamin K intake steady and ask your provider. [2][4] See foods and medicine interactions.
• Thyroid and raw bok choy: a case report in the New England Journal of Medicine is titled "Myxedema coma induced by ingestion of raw bok choy." [6] We could read only the title and citation record (no abstract is available), so we cannot describe the amounts or details ourselves. Outside the journal, news coverage says it involved an older woman eating very large daily amounts for months; we have not verified that from the report. A single case report cannot show how common this is. The 2024 review above found no adverse thyroid effect from eating brassica vegetables, particularly with enough iodine. [8] If you have a thyroid condition or take thyroid medicine, ask your clinician. NHS notes an underactive thyroid is usually treated with levothyroxine tablets. [11]
• Kidney stones and oxalate: NIDDK lists spinach, rhubarb, nuts and wheat bran as foods to limit for calcium oxalate stones; bok choy is not on that list. [12] We did not find a source stating bok choy's oxalate content, so we make no claim. Ask a health professional if you have had stones. See foods, kidney disease, potassium and oxalates.
• Allergy: bok choy allergy is not described in the sources we read; any food can still cause a reaction.
• Pregnancy: no special caution for eating vegetables appears in the sources we read. See foods in pregnancy.

Choosing, storing and food safety

• Choose produce that is not bruised or damaged; keep perishable produce at 40 degrees F or below and refrigerate pre-cut or packaged produce. [13]
• Rinse under running water; the FDA says not to use soap, detergent or commercial produce wash. Cut away damaged areas. [13]
• Keep raw produce and its cutting boards away from raw meat, poultry and seafood. [13]

Related pages

• Cruciferous vegetables
• Sulforaphane and glucosinolates in cruciferous vegetables
• Leafy greens
• Foods and medicine interactions: vitamin K, grapefruit and others
• Fresh, frozen and canned produce
• Foods, kidney disease, potassium and oxalates