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Kale benefits come from a lot of nutrition packed into very few calories: a cup of raw chopped kale has about 7 calories yet supplies around two thirds of the Daily Value for vitamin K and about a fifth for vitamin C, and a cup of cooked kale adds fiber, vitamin A, manganese and calcium that the body absorbs about as well as the calcium in milk, according to USDA and NIH data. Below are the USDA kale nutrition facts for raw and cooked kale, what the vitamin K content means for people on blood thinners, what is true about kale and the thyroid, and how to get the most from it in the kitchen.
Peptide Labs does not sell kale as a food. This article is general nutrition information, not medical advice.
Key Takeaways
- A cup of raw kale has about 7 calories, 68% of the Daily Value for vitamin K and 22% for vitamin C in USDA data.
- A cup of cooked kale packs far more leaves: about 42 calories, 17% of the Daily Value for fiber and over four times the Daily Value for vitamin K.
- NIH says the calcium in kale is absorbed about as well as the calcium in milk.
- People who take warfarin can usually eat kale but should keep their vitamin K intake consistent and talk to their doctor before big diet changes.
- Kale is a cruciferous vegetable; NIH says goitrogens in these foods matter mainly when iodine intake is low.
Kale nutrition: raw vs cooked
The table compares two USDA FoodData Central SR Legacy entries: raw chopped kale (FDC 168421, 1 cup = 21 grams) and kale boiled and drained without salt (FDC 169238, 1 cup = 118 grams). When comparing raw vs cooked kale by the cup, remember that the cooked cup weighs more than five times as much because heat shrinks the leaves, so cooked numbers look larger. Percent Daily Value (%DV) uses the FDA Daily Values printed on Nutrition Facts labels.
| Nutrient | Raw kale, 1 cup (21 g) | %DV | Cooked kale, 1 cup (118 g) | %DV |
|---|---|---|---|---|
| Calories | 7 | Not applicable | 42 | Not applicable |
| Protein | 0.6 g | 1% | 3.5 g | 7% |
| Fiber | 0.9 g | 3% | 4.7 g | 17% |
| Vitamin K | 82 micrograms | 68% | 494 micrograms | 412% |
| Vitamin C | 19.6 milligrams | 22% | 21 milligrams | 23% |
| Vitamin A (RAE) | 51 micrograms | 6% | 172 micrograms | 19% |
| Calcium | 53 milligrams | 4% | 177 milligrams | 14% |
| Manganese | 0.19 milligrams | 8% | 0.64 milligrams | 28% |
| Folate (DFE) | 13 micrograms | 3% | 77 micrograms | 19% |
| Vitamin E | 0.14 milligrams | 1% | 1.9 milligrams | 13% |
| Potassium | 73 milligrams | 2% | 170 milligrams | 4% |
Two patterns stand out. Kale is one of the richest everyday sources of vitamin K, the vitamin the body needs to make clotting proteins. And kale is a good source of vitamin C even raw. Gram for gram, USDA lists about 93 milligrams of vitamin C per 100 grams of raw kale and about 18 milligrams per 100 grams of boiled kale, so boiling loses a large share of the vitamin C, while vitamin K holds up well. Kale is also rich in the carotenoids beta-carotene, lutein and zeaxanthin; see our beta-carotene guide for how carotenoids relate to vitamin A.
Kale benefits backed by data
Here is what the numbers and the reference sources support, without overselling a single vegetable:
- Low energy density: 35 calories per 100 grams raw and about 90% water, so kale adds volume and fiber to a plate for very few calories.
- Vitamin K: one raw cup covers about two thirds of the Daily Value. Our vitamin K food list compares kale with other sources.
- Vitamin C: about a fifth of the Daily Value per raw cup. More options are in foods high in vitamin C.
- Calcium that absorbs well: the NIH Office of Dietary Supplements (ODS) notes that the calcium in kale, broccoli and bok choy is absorbed about as well as the calcium in milk, unlike spinach, whose oxalic acid binds most of its calcium. See foods high in calcium.
- Fiber: a cooked cup provides about 17% of the Daily Value. Our high fiber foods list puts that in context.
- Lower oxalate than spinach: the University of Chicago Kidney Stone Program lists kale among lower-oxalate vegetables. Our oxalates guide explains when that matters.
What the data do not show is that kale on its own protects against a specific disease. Kale is a cruciferous vegetable, and the National Cancer Institute notes that human studies of cruciferous vegetables and cancer have shown mixed results. The fair summary is that kale is a nutrient-dense vegetable that helps you reach Daily Values for several vitamins and minerals.
Is kale good for you? How it compares
Is kale good for you? For most people, yes, as one of many vegetables. It is not a superfood that outranks everything else. Spinach has more iron, folate and magnesium on paper, while kale’s calcium is easier to absorb; our guide to dark greens compares spinach, kale, collards and lettuces side by side. Kale is also far denser in nutrients than a watery vegetable such as cucumber:
| Per 100 g raw (USDA) | Kale (168421) | Cucumber with peel (168409) |
|---|---|---|
| Calories | 35 | 15 |
| Water | 89.6 g | 95.2 g |
| Fiber | 4.1 g | 0.5 g |
| Vitamin K | 390 micrograms (325% DV) | 16 micrograms (14% DV) |
| Vitamin C | 93 milligrams (104% DV) | 2.8 milligrams (3% DV) |
| Calcium | 254 milligrams (20% DV) | 16 milligrams (1% DV) |
Kale and blood thinners: keep it consistent
Warfarin (Coumadin) works against vitamin K, and the ODS vitamin K fact sheet calls the interaction serious and potentially dangerous. The advice is consistency, not avoidance: people taking warfarin need to keep their vitamin K intake from food and supplements steady, because sudden changes can increase or decrease the drug’s effect. MedlinePlus says to eat consistent amounts of vitamin K foods from week to week and to talk to your doctor before making changes to your diet. That matters for kale in particular, because a single cooked cup holds several times the Daily Value. Starting a daily kale smoothie, or stopping one, is exactly the kind of change to discuss first. Newer blood thinners work differently, so ask your clinician or pharmacist which advice applies to your medicine.
Kale and the thyroid
Kale belongs to the Brassica genus with broccoli and cabbage. These vegetables contain glucosinolates, sulfur compounds that NCI says give them their pungent aroma and bitter taste. Some of their breakdown products act as goitrogens, which can interfere with iodine uptake by the thyroid. The ODS iodine fact sheet says this matters mainly for people with marginal iodine status, and that for most people in the US, eating reasonable amounts of these foods is not a concern. If you have a thyroid condition, ask your clinician whether your diet needs adjusting; our iodine guide covers who may fall short on iodine.
Other cautions
- Kidney disease: kale has moderate potassium per cooked cup. People told to limit potassium should follow their care team’s advice; see foods high in potassium.
- Gas and bloating: fiber and sulfur compounds can cause gas when intake rises fast. Increase gradually; our bloating guide has more.
- Juices and powders: kale juice loses most of the fiber, and powders vary by brand. Read the Nutrition or Supplement Facts panel.
How to eat kale
- Massage raw kale: rubbing chopped leaves with a little oil and lemon softens them for salads. Some fat with the meal also helps the body absorb vitamin K and carotenoids, per ODS.
- Cook it briefly: sauteing or steaming keeps more vitamin C than long boiling in lots of water.
- Strip the stems: tough center ribs can be chopped fine or added to soups.
- Frozen counts: plain frozen kale is convenient and has nothing added; check the label for sauces or salt.
Supplements are not a swap for vegetables. One greens product we carry, Bloom Nutrition Super Greens Gummies, lists kale as one of more than a dozen fruit and vegetable powders in its greens blend, according to its label. A small amount of powder spread across many ingredients is not the same as a serving of kale, and the label, not a marketing claim, tells you what is inside.
Frequently Asked Questions
What are the main kale benefits?
USDA data show kale is very low in calories and high in vitamin K, vitamin C, vitamin A, manganese and fiber, and NIH says its calcium is absorbed about as well as milk’s.
Is kale better raw or cooked?
Both work. Raw kale keeps more vitamin C, while a cooked cup packs more leaves and so more fiber, calcium and vitamin K per cup.
Is kale good for you every day?
For most people kale can be part of a varied diet. People on warfarin should keep intake consistent and talk to their doctor before big changes.
Does kale affect the thyroid?
Kale contains glucosinolates, but NIH says goitrogens in food are mainly a concern when iodine intake is low. Ask your clinician if you have a thyroid condition.
Is kale high in oxalate?
No. The University of Chicago Kidney Stone Program lists kale among lower-oxalate vegetables, unlike spinach.
How many calories are in kale?
USDA lists about 7 calories in a cup of raw chopped kale and about 42 in a cup of boiled kale.
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 such as blood thinners, are pregnant or have a kidney or thyroid condition. 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: Cucumber Benefits: USDA Cucumber Nutrition, Calories and Safety, Leafy Greens: USDA List of Dark Greens, Spinach vs Kale and Tips, Foods High in Vitamin K: USDA List, K1 vs K2 and Warfarin Notes, Types of Kale: Curly, Lacinato and Red Russian Compared.