Red Cabbage: USDA Data, Raw vs Cooked and the pH Color Trick

Red cabbage, sold in many stores as purple cabbage, is the deep violet form of the same head cabbage that most people know in green. In USDA FoodData Central, a cup of chopped raw red cabbage has about 28 calories and more than half the Daily Value for vitamin C. Its color comes from anthocyanins, pigments that shift with acidity, which is why red cabbage turns blue in some pots and pink in others and why it doubles as a kitchen pH test. This guide covers USDA values raw and cooked, the red cabbage indicator, what research on its pigments does and does not show, and the vitamin K and iodine facts worth knowing.

Peptide Labs does not sell red cabbage or red cabbage products. This article is general nutrition information, not medical advice.

What is red cabbage?

Red cabbage is a head cabbage, Brassica oleracea, in the red-leaved form that researchers name Brassica oleracea var. capitata f. rubra. It is the same species as green cabbage, broccoli, cauliflower and kale. Purple cabbage is simply another name for the same vegetable.

For green, savoy and napa heads, and for how red and green heads compare side by side, see our main cabbage guide. This guide stays with the red head and the questions that only it raises. Our sibling guide covers another striking brassica, romanesco.

Is red cabbage healthy? What USDA data shows

USDA FoodData Central (SR Legacy) has separate entries for raw red cabbage and for red cabbage boiled and drained without salt. The table shows both per USDA serving and per 100 grams, with percent Daily Values based on FDA reference values.

So is red cabbage healthy? In USDA terms it is a low-calorie vegetable with a large share of the Daily Value for vitamin C, a useful amount of vitamin K and a little fiber. It is not a meaningful source of protein or fat. The USDA numbers describe nutrients, not a promised health effect, and they vary with the head, storage time and cooking method. For other foods ranked by single nutrients, see our guides to vitamin C in foods and vitamin K in foods.

Raw vs cooked red cabbage

Comparing the two USDA entries per 100 grams shows a few clear shifts:

• Vitamin C drops: boiled red cabbage lists 34.4 milligrams of vitamin C per 100 grams versus 57 milligrams raw in USDA data. The NIH Office of Dietary Supplements explains that vitamin C dissolves in water and is destroyed by heat, and that steaming or microwaving may lessen cooking losses.
• Vitamin K and fiber look higher: the boiled USDA entry lists more vitamin K and fiber per 100 grams, so the cooked portion is not poorer on every line.
• Vitamin A nearly disappears: the boiled entry lists almost no vitamin A, compared with 56 micrograms RAE per 100 grams raw in USDA data.

In practice, raw shredded red cabbage in slaws keeps the most vitamin C, while a short braise or steam gives a softer texture. Both are reasonable; the choice comes down to the dish you want.

Why purple cabbage changes color

The pigment family behind red cabbage is the anthocyanins, the same group that colors blueberries. Anthocyanins change shape with acidity, and the shape changes the color. A 2026 lab study in the journal Molecules found that red cabbage anthocyanin extracts ranged from red under acidic conditions to blue-green under alkaline conditions, and that heat, then light and oxygen, broke the pigment down over time.

That chemistry explains several kitchen puzzles:

• Blue cabbage: cooking red cabbage in hard water or with baking soda pushes the pigment toward the alkaline side, so it can turn blue or green-blue.
• Bright red cabbage: a splash of vinegar or a few apple slices keeps the cooking liquid acidic, so the color stays red to magenta.
• Fading: long cooking and light exposure dull the color, in line with the lab finding that heat, light and oxygen degrade the pigment.

How to make a red cabbage indicator

Because the color tracks acidity, a red cabbage indicator is a classic kitchen science project. Food researchers use the same idea: a 2026 study in the journal Foods built red cabbage films that shifted visibly from red to yellow-green across a wide pH range and tested them as freshness indicators for fish. At home, the steps are simple:

1. Chop a few red cabbage leaves and cover them with hot water.
2. Let them steep until the water turns deep purple, then strain out the leaves.
3. Pour the purple liquid into clear glasses.
4. Add lemon juice or vinegar to one glass and watch it turn pink to red; add a pinch of baking soda to another and watch it shift toward blue-green.

Keep the experiment to food-safe kitchen ingredients, and have an adult supervise children, especially with hot water. The liquid is a color test, not a drink.

What research says about red cabbage pigments

Red cabbage anthocyanins attract a lot of research, but most of it is about color rather than nutrition. A 2026 paper in Ultrasonics Sonochemistry tested ways to extract and stabilize the pigment as a natural colorant for yogurt, and other recent studies use it in smart packaging that changes color as food spoils. Lab tests on extracts cannot show what eating red cabbage does in people, and this guide makes no such claim. Studies of anthocyanins in human diets are a separate and still developing research field.

Vitamin K, iodine and other cautions

• Vitamin K: a cup of raw red cabbage has about 28% of the Daily Value for vitamin K in USDA data. The NIH Office of Dietary Supplements describes a serious interaction between vitamin K and warfarin and advises people taking it to keep vitamin K intake consistent, and MedlinePlus says to eat consistent amounts of vitamin K foods week to week and talk to your doctor before changing your diet.
• Iodine and goitrogens: the Office of Dietary Supplements iodine fact sheet lists cruciferous vegetables such as cabbage among foods high in goitrogens, which interfere with iodine uptake in the thyroid, and says that for most people in the United States who get enough iodine and eat a variety of foods, reasonable amounts are not a concern. If you have a thyroid condition, ask your clinician, and see our iodine guide.
• Gas: NIDDK lists cruciferous vegetables among foods that may lead to extra gas; our gas and bloating guide covers other common causes.
• Allergies: red cabbage is not among the nine major food allergens under US law, but any food can cause a reaction in some people.

Choosing, storing and cooking red cabbage

• Choosing: look for a heavy, tight head with crisp, glossy outer leaves and no soft spots.
• Storing: keep the whole head unwashed in the refrigerator crisper; wrap a cut half tightly and cook it soon.
• Slaw: shred thinly and dress with a vinegar or citrus dressing, which also keeps the color bright.
• Braised: cook slowly with onion, apple and vinegar for a classic sweet-sour side.
• Pickled or fermented: red cabbage pickles quickly, and it can also be fermented like green cabbage; our sauerkraut guide covers fermentation.
• Stains: the pigment colors wooden boards and hands, so rinse spills quickly.

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: Romanesco: Nutrition, Romanesco vs Cauliflower and Its Spirals, Cabbage Benefits and Nutrition: Red vs Green Cabbage, Foods High in Vitamin C: USDA List of Fruits and Vegetables.