Lemons: Nutrients, What Research Shows and Safety

The lemon (Citrus limon) is the sour fruit of a small tree in the citrus family (Rutaceae). The juicy pulp and juice are used in drinks and cooking, and the peel (zest) is used for flavor. People eat and drink lemon mostly for its vitamin C. This page separates lemon as a food from supplements and from hype, and says plainly where the evidence is thin.

Read this first

• Lemons are an everyday food, but any food can cause an allergic reaction. For trouble breathing or swelling of the face or throat, call 911. See food allergy basics and emergency signs. We did not find a source we could read on how common true lemon allergy is.
• Lemon juice on the skin followed by sunlight can cause a painful rash and dark marks (phytophotodermatitis). Case reports describe this mainly for lime, and lime and lemon are both citrus. [8]
• Lemon juice is acidic. A laboratory study found undiluted lemon juice strongly roughened tooth enamel; this was in extracted teeth, not in people. [9]
• Honest summary: vitamin C from foods such as lemon prevents scurvy (established). Claims that lemon water "detoxes", cures colds or dissolves kidney stones are not supported by the trials we read.

What is in it (USDA values)

USDA data for raw lemon without peel. One lemon (2-1/8 inch diameter) is 58 g edible portion. [1]

Source: USDA FoodData Central item 167746 (SR Legacy). [1] The per-lemon column is the USDA per-100 g value scaled to 58 g. % Daily Value uses the FDA 2016 Daily Values (vitamin C: 90 mg); values vary with variety, ripeness and storage.

Lemon is mainly a vitamin C food. Its other nutrients are small per fruit. The USDA also lists tiny amounts of carotenoids (for example 20 µg of beta-cryptoxanthin per 100 g). [1] We did not read a source that measured or tested lemon's plant compounds (such as flavonoids) in people, so we make no claim about them.

What research says

Eaten as food vs taken as a supplement or extract. The cold trials above used vitamin C tablets, at least 0.2 g (200 mg) a day, which is far more than one lemon contains. A result for tablets does not tell us what lemon juice or fruit does, and the lemonade trial used a commercial drink. A lemon has about 31 mg of vitamin C, according to USDA. [1] Observational studies of fruit intake are not proof that lemons prevent any disease, and we did not find any lemon-specific long-term study.

How much is a normal serving

For vitamin C, US adult recommended daily intakes listed by MedlinePlus are 90 mg for men and 75 mg for women, with more advised for smokers, and pregnant or breastfeeding women. [2] The UK NHS says adults aged 19 to 64 need 40 mg a day (page reviewed August 2020). [3] Different bodies set different figures.

Cooking, long storage, microwaving and steaming can reduce vitamin C, and light can too, according to MedlinePlus. [2] Raw fruit and fresh juice are therefore better sources than long-stored products; we did not find lemon-specific figures. Bottled juice and drinks vary; check the label for added sugar. See fruit juice vs whole fruit.

Safety, allergy and medicines

• Allergy. True lemon allergy is possible, as with any food. For trouble breathing or swelling of the face or throat, call 911. Proper evidence on how common it is, or on cross-reactivity, was not found in the sources we read.
• Medicines. The FDA grapefruit page names grapefruit, Seville oranges, pomelos and tangelos as fruits that may affect some medicines. It does not mention lemons or limes. [10] That is the absence of a warning on that page, not proof of safety. Ask a pharmacist about your own medicines. See foods and medicine interactions.
• Skin and sun (phytophotodermatitis). Citrus juice or peel on skin followed by ultraviolet light can cause a streaky, painful, darkening skin reaction caused by furocoumarins in lime juice or peel. It is described in case reports and is often mistaken for burns or allergy. [8] Rinse juice from skin before sun exposure; the reports do not give a threshold.
• Teeth. In a laboratory study on extracted human teeth, lemon juice caused severe surface erosion of enamel, similar to cola. The authors say this should not be read as a clinical result. [9] We did not find a human trial we read on lemon water and teeth. Ask a dentist if you have sensitive teeth or enamel wear.
• Kidney stones and kidney disease. One systematic review graded lemon juice or lime powder as possibly causing at least a small harm in stone prevention trials (low certainty). [7] A small trial of lemonade in people with low urine citrate found no significant differences. [6] Because the evidence is unclear, people with stones or kidney disease should ask a clinician. See foods, kidney disease, potassium and oxalates.
• High-dose vitamin C supplements are a different product. MedlinePlus says over 2,000 mg a day is not recommended and can cause stomach upset, diarrhea and rarely kidney stones; the NHS says over 1,000 mg a day can cause stomach pain, diarrhoea and wind. [2][3] A lemon itself does not contain amounts like this.
• Pregnancy. MedlinePlus says large supplemental doses of vitamin C are not recommended during pregnancy. [2] We did not find a source we read that warns about normal amounts of lemon as a food.
• Reflux and sensitive stomach. Proper evidence not found in the sources we read for lemon and reflux; if citrus triggers your symptoms, ask a clinician.
• Pesticide residues. Not assessed: we did not read a USDA or EWG source on lemons.

Choosing, storing and food safety

• Pick fruit that is not bruised or damaged; keep cut fruit refrigerated at 40°F (4°C) or lower. [11]
• Rinse whole fruit under running water before cutting, even if you will not eat the peel, so dirt and bacteria are not carried into the flesh. Do not use soap or produce wash. [11]
• If you use zest, wash the fruit first and scrub firm skins with a clean brush. [11]
• Washing reduces bacteria but does not remove them entirely. [11]

Related pages

• Citrus fruits: oranges, grapefruit and others
• Fruit juice vs whole fruit
• Foods and medicine interactions: vitamin K, grapefruit and others
• Foods, kidney disease, potassium and oxalates
• Food allergy basics and emergency signs
• Fresh, frozen and canned produce