Lemon juice is mostly water, citric acid, and vitamin C, with smaller amounts of potassium, magnesium, and plant compounds called flavonoids. One cup of raw lemon juice contains about 94 mg of vitamin C, which exceeds the full daily requirement for most adults. But vitamin C is only part of the picture.
Citric Acid: The Dominant Ingredient
Fresh lemon juice is about 5% to 6% citric acid by weight, roughly 1.44 grams per ounce. That’s what gives it the sour punch and makes it useful for everything from salad dressings to cleaning. Citric acid is also the compound behind one of lemon juice’s most studied health effects: it can bind to calcium in the urinary tract and reduce the formation of kidney stones. In clinical studies, patients who drank lemonade regularly saw their urinary citrate levels rise by 200 to 350 mg per day, which helps prevent calcium oxalate crystals from forming.
The high citric acid content also makes lemon juice strongly acidic. This is worth knowing if you have acid reflux or sensitive tooth enamel, since frequent contact with undiluted lemon juice can erode enamel over time. Diluting it in water reduces that risk considerably.
Vitamin C Content
A full cup of raw lemon juice delivers about 94 mg of vitamin C. For context, the recommended daily intake is 90 mg for adult men and 75 mg for adult women (smokers need an extra 35 mg). So a single cup gets most people to 100% or more of their daily target. Of course, most people use far less than a cup at a time. The juice of one lemon yields roughly two tablespoons, which works out to about 12 mg of vitamin C, or around 13% to 16% of your daily needs.
Vitamin C acts as an antioxidant, supports immune function, and helps your body absorb iron from plant-based foods. Squeezing lemon juice over spinach or lentils actually increases how much iron you take in from those foods.
Minerals in Lemon Juice
Lemon juice isn’t a major mineral source, but it does contribute modest amounts. Per cup, raw lemon juice contains approximately 303 mg of potassium, 15 mg of magnesium, and 17 mg of calcium. The potassium is the most notable of these. While a cup of lemon juice has far less potassium than a banana (which has about 420 mg), it adds up if you’re regularly drinking lemon water throughout the day. Potassium plays a role in blood pressure regulation and muscle function.
Flavonoids and Other Plant Compounds
Beyond the basics, lemon juice contains a range of flavonoids, which are plant-based compounds with antioxidant properties. The two most concentrated are hesperidin and eriocitrin, which together make up the vast majority of the flavanone content in lemons. Hesperidin alone accounts for about 59% of the flavanone total, with eriocitrin at roughly 36%. Smaller amounts of other flavonoids like naringin, rutin, and quercetin are also present.
These compounds are more concentrated in the peel and the white pith than in the juice itself. If you zest a lemon into your food or use whole-lemon preparations, you get significantly more of them. The peel also contains volatile oils, with d-limonene being the most abundant. Limonene gives lemons their characteristic aroma and has been studied for its anti-inflammatory properties, though the amounts in juice alone are small.
Fresh Versus Bottled Lemon Juice
What’s in your lemon juice depends partly on whether it came from a fresh lemon or a bottle. Bottled lemon juice goes through pasteurization, a heating process that extends shelf life but destroys heat-sensitive nutrients. Vitamin C takes the biggest hit. Some analyses suggest bottled juice retains only a fraction of the vitamin C found in fresh-squeezed.
Bottled versions also commonly contain sulfites, chemical preservatives added to prevent discoloration and bacterial growth. If you’re sensitive to sulfites (some people with asthma are), this is worth checking on the label. Fresh lemon juice has none of these additives. For cooking and cleaning, bottled juice works fine. For nutritional purposes, fresh is meaningfully better.
Calorie and Sugar Profile
Lemon juice is remarkably low in calories and sugar compared to other fruit juices. A full cup contains roughly 60 calories and about 6 grams of sugar. Compare that to orange juice at around 110 calories and 21 grams of sugar per cup. This makes lemon juice one of the few fruit juices you can use liberally without worrying about added sugar intake. Most of the carbohydrate content is split between small amounts of natural sugars and the organic acids that dominate its flavor.