Rice is mostly starch, with smaller amounts of protein, trace minerals, and B vitamins. A single cup of cooked white rice delivers about 242 calories, nearly all of them from carbohydrates. But the full picture depends on whether you’re eating white, brown, black, or red rice, because each type keeps or loses different layers of the grain, and those layers carry very different nutrients.
The Three Layers of a Rice Grain
Every rice grain starts with three distinct parts: the bran, the germ, and the endosperm. What you eat depends on how much processing the grain has undergone.
The bran is the fiber-rich outer shell. It contains B vitamins, iron, copper, zinc, magnesium, and protective plant compounds that act as antioxidants. The germ is the tiny core where a new plant would sprout. It’s packed with healthy fats, vitamin E, and more B vitamins. The endosperm, the large starchy interior, holds nearly all the carbohydrates plus a modest amount of protein and a few minerals.
Brown rice keeps all three layers intact. White rice has been milled to strip away the bran and germ entirely, leaving only the endosperm. That single processing step removes most of the fiber, a large share of the vitamins, and nearly all the healthy fats.
Calories and Macronutrients
A cup of cooked medium-grain brown rice has about 218 calories. The same amount of white rice has roughly 242 calories. The difference is small, but the nutritional quality of those calories varies considerably.
Both types are roughly 80% carbohydrate by calorie. Protein makes up a smaller share, around 4 to 5 grams per cooked cup. Fat is nearly absent in white rice and only slightly present in brown rice, where the germ contributes a small amount of unsaturated fat. Fiber is where the gap widens most: brown rice delivers about 3 to 4 grams per cup, while white rice provides less than 1 gram.
Vitamins and Minerals
Brown rice is a genuinely good source of certain B vitamins. Based on a typical daily intake, brown rice can supply over 60% of your recommended thiamin (B1) and niacin (B3). White rice, with the bran removed, delivers only about 10 to 12% of the same thiamin requirement and 17% of niacin.
Rice also contains manganese, selenium, and magnesium, particularly in brown varieties. These minerals play roles in bone health, thyroid function, and energy metabolism. Folate content is low across the board, with both white and brown rice contributing only 3 to 8% of recommended intake per serving.
What Enriched White Rice Adds Back
Most white rice sold in the United States is labeled “enriched,” meaning nutrients lost during milling have been partially replaced. Federal standards require that each pound of enriched rice contain 2 to 4 milligrams of thiamin, 1.2 to 2.4 milligrams of riboflavin, 16 to 32 milligrams of niacin, 0.7 to 1.4 milligrams of folic acid, and 13 to 26 milligrams of iron.
Enrichment closes the gap on a few specific nutrients, especially folic acid (which barely exists in natural brown rice either). But it doesn’t replace the fiber, magnesium, zinc, vitamin E, or antioxidants found in the intact bran and germ. Think of enriched white rice as a partial fix, not a nutritional equivalent of whole grain rice.
Rice Protein and Its Limits
Rice protein is about 36% essential amino acids and 18% branched-chain amino acids, which puts it in a reasonable range for a plant protein. However, rice is notably low in lysine, one of the amino acids your body can’t make on its own. Lysine is the limiting amino acid in most grains, meaning it’s the one that runs out first and caps how much of the protein your body can fully use.
This is why pairing rice with beans, lentils, or other legumes (which are high in lysine but low in the sulfur-containing amino acids that rice provides) creates a more complete protein profile. You don’t need to eat them in the same meal, just over the course of the day.
What’s in Black and Red Rice
Pigmented rice varieties contain compounds that white and brown rice essentially lack. Black rice gets its deep purple-black color from anthocyanins, the same antioxidant pigments found in blueberries and blackberries. Concentrations can reach over 5,000 micrograms per gram in some cultivars. Red rice owes its color to a different group of compounds called proanthocyanidins, which can reach about 3,000 micrograms per gram.
These pigments are tightly linked to antioxidant capacity. The higher the pigment content, the higher the total polyphenol and antioxidant levels in the grain. White rice, with no pigment layer, contains essentially none of these compounds.
Phytic Acid and Mineral Absorption
Rice contains phytic acid, a compound that binds to minerals like iron and zinc in the grain and reduces how much your body can absorb. Brown rice has more phytic acid than white rice because it’s concentrated in the bran layer, with levels ranging from about 4 to 7 milligrams per gram depending on the variety.
The practical effect: even though brown rice contains more iron and zinc on paper, your body may not absorb all of it. Zinc absorption drops significantly when the ratio of phytic acid to zinc exceeds 15:1. For iron, a ratio of 1:1 or lower is ideal for good absorption from grains. Soaking rice before cooking, or eating it alongside vitamin C-rich foods, can help reduce phytic acid’s impact and improve mineral uptake.
Arsenic in Rice
Rice absorbs more arsenic from soil and water than most other grains. Testing has found average inorganic arsenic concentrations of 92 parts per billion in white rice and 154 parts per billion in brown rice. Brown rice contains more because arsenic, like many minerals, accumulates in the outer bran layer.
These levels are low enough that occasional rice consumption isn’t a concern for most adults, but they matter for people who eat rice multiple times a day or for infants fed rice cereal regularly. Rinsing rice thoroughly and cooking it in extra water (then draining) can reduce arsenic content by roughly 40 to 60%.
Resistant Starch in Cooked and Cooled Rice
Freshly cooked white rice contains about 0.64 grams of resistant starch per 100 grams. Resistant starch behaves more like fiber than like regular starch: it passes through your small intestine undigested and feeds beneficial bacteria in your colon. If you cook rice and then cool it for 10 hours at room temperature, resistant starch roughly doubles to 1.30 grams per 100 grams. Cooling it in the refrigerator for 24 hours and then reheating it pushes the level even higher, to about 1.65 grams per 100 grams.
This happens because cooling causes some of the starch molecules to rearrange into a crystalline structure that resists digestion, even after reheating. It’s a small effect in absolute terms, but for people managing blood sugar, eating leftover rice may produce a slightly lower glucose spike than eating it fresh off the stove.