Turnips: Nutrients, What Research Shows and Safety

The turnip (Brassica rapa subsp. rapa) is a root vegetable in the cabbage family (Brassicaceae). The round root is the part usually eaten, and the leaves (turnip greens) are eaten too. People eat turnips for vitamin C, fiber and the sulfur plant compounds called glucosinolates. This page keeps the whole food apart from supplements and extracts, and it does not use hype. It is information, 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: the turnip root has almost no vitamin K (USDA: 0.1 micrograms per 100 g). Turnip greens are a different food, and we could not read a source giving their vitamin K amount, so we make no number claim. MedlinePlus advises people on warfarin to keep vitamin K foods steady from week to week and to talk with the doctor before diet changes. [2]
• Thyroid: a 2024 systematic review found eating brassica vegetables with enough iodine poses no adverse effect on thyroid function, and a review of goitrin found turnip tops contain little. [6][7]
• Evidence in one line: turnips count as a vegetable in official advice, and vegetables in general are linked to better health in observational studies. We found no human trial testing turnips themselves for a disease.

What is in it (USDA values)

Source: USDA FoodData Central, raw turnips (SR Legacy, item 170465). [1] % Daily Value uses the FDA 2016 Daily Values; values vary with variety, ripeness and storage. Per-serving figures are our arithmetic from the USDA per-100 g values.

Turnips contain glucosinolates, sulfur compounds that break down into isothiocyanates when the raw vegetable is chopped or chewed. A Linus Pauling Institute table lists 60 mg of total glucosinolates in half a cup (65 g) of cubed turnip. [3] A systematic review of turnip greens found 19 glucosinolates and many phenolic compounds, mostly measured in the lab. [4] Flavonoids and other compounds are described in turnip, but the bioactivity work reviewed is in cells and animals, not people. [5]

What research says

Eaten as food vs taken as a supplement or extract. The human findings above are about vegetables eaten as food. The turnip results that point to health effects come from extracts, isolated compounds, cells and animals. A mouse result for an extract does not tell us what a bowl of turnips does. We do not cover turnip supplements.

How much is a normal serving

• NHS: 80 g of fresh, canned or frozen vegetables is one portion of the 5 A DAY, and turnips count (unlike potatoes). [11] That is a bit more than half a cup of cubes (the USDA household portion of 0.5 cup is 65 g; 1 cup is 130 g). [1]
• WHO: at least 400 g of fruits and vegetables a day for people older than 10 (fact sheet date 26 January 2026). [12]
• These are official figures, information only, not a prescription.
• Cooking: the Linus Pauling Institute says cooking destroys myrosinase, the enzyme that makes isothiocyanates, though light steaming for under 5 minutes may keep some. [3] We did not find a source on how boiling changes turnip vitamin C: Proper evidence not found.

Safety, allergy and medicines

• Allergy: we did not find a source describing a turnip-specific allergy rate. Any food can cause one. For trouble breathing or swelling of the face or throat, call 911.
• Warfarin and turnip greens: MedlinePlus says people on warfarin should not eat large amounts of leafy green vegetables, should keep intake consistent week to week, and should ask the doctor or pharmacist before diet changes. [2] A hospital patient guide frames the goal as steady intake, not avoidance. [13] The guide does not name turnip greens, and we found no source with their vitamin K amount. Ask your anticoagulation clinic. See foods and medicine interactions.
• Thyroid (goitrogens): some glucosinolates break down into goitrin, which in high amounts can reduce thyroid iodine uptake. A review found turnip tops contain under 10 micromoles of goitrin per 100 g, considered minimal risk, unlike collards or Brussels sprouts. [7] The 2024 review of 123 articles found brassica vegetables with adequate iodine pose no adverse effects on thyroid function. [6] If you have a thyroid condition, ask your clinician; see thyroid conditions and iodine.
• Kidney disease and potassium: turnip has 191 mg potassium per 100 g (4% Daily Value). [1] We did not read a source on turnips and kidney disease, so we make no claim. People on a potassium-limited diet should ask their kidney team; see foods, kidney disease, potassium and oxalates.
• Digestive effects such as gas, and pregnancy: Proper evidence not found in the sources we read.
• Pesticide residues: we did not read a source on turnip residues, so we make no claim.

Choosing, storing and food safety

• Choose produce that is not bruised or damaged; cut away damaged areas. [14]
• Wash all produce under running water, even if you will peel it. Do not use soap or produce wash. Washing reduces bacteria but does not eliminate them. [14]
• Keep perishable produce refrigerated at 40°F or below and keep raw produce away from raw meat. [14]
• Fresh, canned and frozen vegetables all count toward 5 A DAY; NHS suggests canned vegetables without added salt. [11] See fresh, frozen and canned produce.

Related pages

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