Broccoli packs a surprising amount of nutrition into very few calories. A single chopped cup (about 91 grams) contains just 31 calories but delivers 3 grams of protein, 6 grams of carbohydrates, and 2 grams of fiber. Beyond those basics, broccoli is loaded with vitamins, minerals, and a set of plant compounds you won’t find in most other vegetables.
Vitamins and Minerals per Cup
Broccoli is one of the richest vegetable sources of vitamin C. One raw cup provides more than 80% of the daily value, putting it in the same league as oranges. It’s also high in vitamin K, which plays a central role in blood clotting and bone health, delivering well over 100% of what most adults need in a day.
On the mineral side, a cup of raw chopped broccoli contains roughly 288 mg of potassium, 43 mg of calcium, and small amounts of iron. The potassium alone covers about 6% of a typical adult’s daily needs. Broccoli also supplies folate (a B vitamin important for cell growth), vitamin A from beta-carotene, and smaller amounts of B6, manganese, and phosphorus.
The Compound That Makes Broccoli Unique
Broccoli belongs to the cruciferous family alongside cauliflower, kale, and Brussels sprouts. What sets this whole family apart is a group of sulfur-containing compounds called glucosinolates. In broccoli, the standout is glucoraphanin. When you chew or chop raw broccoli, an enzyme called myrosinase breaks glucoraphanin down into sulforaphane, a compound that has attracted serious research attention.
Sulforaphane triggers your body’s own antioxidant and detoxification defenses. It essentially switches on genes that produce protective molecules, including glutathione, one of the body’s most important internal antioxidants. About 90% of the glutathione circulating in your blood is made in the liver, and sulforaphane appears to support that process. It also helps dial down inflammation by blocking one of the key molecular pathways that drives it. These combined effects have made sulforaphane one of the most studied plant-derived compounds in nutrition research, with particular interest in liver protection, cancer prevention, and cardiovascular health.
Other Antioxidants in Broccoli
Sulforaphane gets the headlines, but broccoli contains several other antioxidants worth knowing about. Kaempferol and quercetin are flavonoids found in the florets that help reduce oxidative stress and inflammation in cells. Broccoli also contains lutein and zeaxanthin, two carotenoids best known for protecting eye health. Cooked broccoli provides about 2,226 micrograms of lutein and zeaxanthin per 100 grams, making it a meaningful source alongside leafy greens like spinach and kale. These two compounds accumulate in the retina and filter harmful blue light, which is why they’re often linked to lower risk of age-related macular degeneration.
Beta-carotene, the precursor your body converts to vitamin A, rounds out the antioxidant profile. Together, these compounds make broccoli one of the more nutrient-dense vegetables you can eat on a per-calorie basis.
How Much Broccoli Actually Matters
You don’t need to eat enormous amounts to see benefits. A pooled analysis of 17 studies involving more than 97,000 people found that those who ate the most cruciferous vegetables (20 to 40 grams per day, roughly a quarter cup) had a 17% lower risk of colon cancer compared to people who ate the least. The protective effect leveled off after about 40 grams, meaning a small daily portion is enough. That’s roughly a handful tossed into a stir-fry, mixed into a salad, or added to a pasta dish.
How Cooking Changes What You Get
The way you prepare broccoli has a real impact on its nutritional value. Vitamin C is the most vulnerable nutrient. Boiling broccoli in a large pot of water draws vitamin C out into the cooking liquid, and much of it never makes it to your plate. Stir-frying has also been shown to significantly reduce vitamin C content in broccoli. Steaming, microwaving, and roasting all preserve more of it.
Cooking method also affects sulforaphane. The myrosinase enzyme that converts glucoraphanin into sulforaphane is sensitive to heat. Boiling for more than a few minutes destroys most of it, which means cooked broccoli can produce far less sulforaphane than raw. One practical workaround: chop your broccoli and let it sit for about 30 to 40 minutes before cooking. This gives myrosinase time to do its work before heat deactivates it. Another option is to add a pinch of mustard seed powder (which contains its own myrosinase) to cooked broccoli dishes.
If you do cook broccoli, use as little water as possible and eat it within a day or two. Vitamin C content continues to decline when cooked vegetables sit exposed to air. Steaming for three to five minutes is a good middle ground: it softens the texture, makes some nutrients like beta-carotene easier to absorb, and keeps vitamin C and sulforaphane losses relatively low.
Fiber and Digestive Benefits
The 2 grams of fiber in a cup of broccoli is a mix of soluble and insoluble types. The soluble fiber feeds beneficial gut bacteria, while the insoluble fiber adds bulk and helps keep things moving through the digestive tract. Broccoli’s fiber content is modest compared to beans or lentils, but it adds up when eaten regularly alongside other vegetables. Some people experience gas or bloating from broccoli, which is caused by the same sulfur compounds that produce sulforaphane. Cooking broccoli rather than eating it raw tends to reduce this effect.
Protein for a Vegetable
At 3 grams of protein per cup, broccoli is higher in protein than most vegetables. It won’t replace meat or legumes as a primary protein source, but for people building meals around plants, broccoli contributes meaningfully. About a third of its calories come from protein, which is an unusually high ratio for a vegetable. Combined with its fiber, this helps explain why broccoli tends to be more filling than its calorie count would suggest.