The lemon is a hybrid, not a wild species. A study of 133 citrus accessions found that the citron contributed to all limes and lemons, and that the common yellow lemon is a cross of a citron with a bitter orange. Botanically it is a modified berry called a hesperidium.
The sour taste comes from citric acid, about 5 to 6% of the juice. That same acid is why lemon is studied for kidney stones, because citrate in urine helps stop stones forming. Lab measurements disagree on how much more citrate lemon juice has than orange juice, and in one metabolic trial orange juice, not lemonade, raised urine citrate.
Most human research is on lemon juice, lemonade or citrus flavonoid supplements, and much of it is small. A whole lemon without the peel gives about 34% of the daily vitamin C for 17 calories, and the nutrition facts on this page are for the fruit without peel.
Health benefits of lemons
The top findings from 28 studies, strongest evidence first
What the stars mean
- Strong. Several randomized trials, pooled in a meta-analysis, point the same way, or regulators (FDA or EFSA) have approved the claim.
- Moderate. Good randomized trials support it, but there are fewer of them, or their results vary.
- Limited. Small, short or single trials, or mixed results. Promising, but it needs confirmation.
Population and lab studies get no stars: they show a link or a mechanism, not proof.
How we rate evidence →- ★★Mixed results on cholesterol from hesperidin pillsHesperidin, a compound in citrus, lowered LDL, total cholesterol and triglycerides in 9 trials, but 10 earlier trials found no significant change. These were supplements, not lemons.
- ★★Slightly shorter colds with vitamin C pillsVitamin C pills of at least 0.2 g a day shortened colds by 8% in adults and 14% in children. They did not prevent colds in the general public, and the dose was well above one lemon.
- ★Mixed results on urine citrate for kidney stonesLemon juice (about 85 mL a day) for 3 months raised urinary citrate 2.5-fold in people with low citrate and calcium stones. It was a small trial of 30 people in three equal groups; in two other small trials, lemonade did not raise citrate.
- ★Smaller blood sugar rise after bread250 mL of lemon juice drunk with 100 g of bread lowered the blood sugar peak by 30% in healthy adults. In a second small study, blood sugar was 35% lower at 55 minutes.
- ★No extra fat loss from lemon juice dietAmong 84 overweight women in three groups, a 7-day lemon diet cut body fat, as did a placebo diet with the same food intake. It was a very low-calorie diet of lemon juice and syrups, not lemon water.
All 28 studies, strongest evidence first
Hesperidin, a flavonoid found in lemons and other citrus fruit, lowered LDL cholesterol, total cholesterol and triglycerides in 9 trials, but not blood pressure
Meta-analysis of 9 randomized trials (2,414 people) of hesperidin supplements. LDL, total cholesterol and triglycerides fell, while systolic and diastolic blood pressure and HDL did not change significantly. The trials disagreed a good deal (I2 of 70% for LDL). These were supplements, not lemons.
An earlier meta-analysis found that hesperidin supplements did not change cholesterol or blood pressure
Meta-analysis of 10 randomized trials (577 people). Hesperidin made no significant difference to total cholesterol, LDL, HDL or triglycerides, and systolic pressure changed by only 0.85 mmHg, which was not significant. It disagrees with the 2024 meta-analysis above, so the question is open. These were supplements, not lemons.
Vitamin C pills of at least 0.2 g a day shortened colds by 8% in adults and 14% in children, but did not prevent them in the general public
Cochrane review of placebo-controlled trials (29 comparisons, 11,306 people). Regular vitamin C did not lower the risk of catching a cold in the general community (risk ratio 0.97) but did in 598 marathon runners, skiers and soldiers (0.48). Treating a cold once it had started showed no consistent effect. These were supplements of at least 0.2 g a day, well above the dose in one lemon.
About 85 mL of fresh lemon juice a day for 3 months raised urinary citrate 2.5-fold in people with low citrate and calcium stones
Randomized study of 30 patients with low urinary citrate and calcium stones, split into three equal groups: lemon juice, potassium citrate (60 mEq a day) or diet advice only. Citrate rose 3.5-fold on potassium citrate and 0.8-fold with diet advice alone. Urinary calcium fell on lemon juice and potassium citrate, and oxalate did not change. It was small and measured urine, not new stones.
In a crossover trial in 13 people, lemonade did not raise urine pH or citrate, but orange juice did
Randomized crossover trial of 13 volunteers (nine healthy people and four stone formers) who received water, orange juice and lemonade in turn on a controlled diet. Orange juice, but not lemonade, supplied alkali and raised urine pH and citrate, despite similar citrate content, and orange juice also lowered the calculated calcium oxalate supersaturation. It was short-term and cannot show whether either drink prevents stones.
In 21 stone formers, lemonade did not improve urinary citrate or pH, while potassium citrate did
Prospective crossover trial in which 21 people who form kidney stones took lemonade and potassium citrate, with 24-hour urine collections for each. People kept a higher urine volume on lemonade than on potassium citrate. Neither treatment changed uric acid levels significantly.
Lemonade made from 4 ounces of lemon juice in 2 liters of water more than doubled urinary citrate in 12 people with low citrate
Twelve patients who could not tolerate or keep up citrate pills drank the lemonade through the day for 6 days. Citrate rose from 142 to 346 mg a day, and 7 of the 12 reached normal levels. Urinary calcium fell by 39 mg a day and oxalate did not change. There was no comparison group and the test lasted only 6 days.
A sugar-free lemonade drink (1 L a day for a week) raised urinary citrate about as much as potassium citrate
Randomized crossover trial in 8 people with low urinary citrate, who took potassium citrate, the lemonade drink or both for a week each. Citrate rose with all three (by 172, 68 and 173), and none of the differences reached statistical significance. This was a commercial lemonade drink, not fresh lemons, and the trial was very small.
Lemon-tomato juice drunk with milk cut crystal formation in urine in 22 people with calcium oxalate stones
Randomized crossover trial. After an overnight fast, 22 patients drank milk alone or milk with lemon-tomato juice, and their urine was tested. Urine optical density, a measure of crystal formation, was 0.053 after the juice and 0.131 after milk alone. It was a one-time urine test, not a test of stone recurrence.
250 mL of lemon juice drunk with 100 g of bread lowered the blood sugar peak by 30% in healthy adults
Randomized crossover trial comparing water, black tea and lemon juice with the same bread. The peak also came later (78 minutes against 41 with water), black tea had no effect, and none of the drinks changed how much people ate 3 hours later. The authors link it to the acid slowing starch digestion. Healthy volunteers only.
Bread eaten with lemon juice gave 35% lower blood sugar at 55 minutes than bread with water in a stomach imaging study
Randomized crossover trial in 10 people who ate 100 g of bread with water, diluted lemon juice or black tea, with MRI scans of the stomach. Lemon juice also made the stomach empty 1.5 times faster, and tea changed nothing. The authors suggest the acid stops salivary amylase from breaking down starch. It was a small study of healthy people.
Tomato juice with 10 g of lemon juice and 5 g of perilla oil, drunk before a rice meal, lowered blood sugar at 30 minutes to 103.1 vs 127.8 mg/dL with water
Randomized crossover trial in 21 young healthy women who drank the preload 10 minutes before 200 g of boiled white rice. Lemon and oil were added together, so lemon’s own share is unknown, and the mix only tended to beat plain tomato juice (113.9 mg/dL, p = 0.078). Insulin at 30 minutes was lower than with plain tomato juice.
A lemon flavonoid capsule (200 mg a day) for 12 weeks lowered blood sugar by 6% and raised the gut hormone GLP-1 by 22% in people with prediabetes
Double-blind randomized trial of Eriomin, a supplement of 70% eriocitrin (a flavonoid from lemon juice and peel), 5% hesperidin and 4% naringin, against placebo. Gut bacteria shifted too. This was a supplement, not fruit, and the abstract does not give the number of people.
A 7-day lemon detox diet of lemon juice and syrups cut body fat, but so did a placebo diet with the same food intake, and only the lemon group had lower CRP
Randomized trial in 84 overweight women in three groups: no diet change, a pair-fed placebo juice diet, or lemon juice with maple and palm syrups for 7 days (11 days with transition food). Weight, body fat and insulin resistance fell in both diet groups, while the inflammation marker hs-CRP fell only in the lemon group. The authors credit calorie restriction. It was a very low-calorie diet, not lemon water.
Women who ate more lemon, and women who walked more, had a bigger drop in systolic blood pressure over five months
Observational study of 101 middle-aged women on an island near Hiroshima, Japan, who recorded lemon eaten and steps walked for five months. Both lemon intake and steps correlated with a fall in systolic pressure, but the link is not proof of cause, because health-conscious people may do both. The authors think the two work by different routes: lemon through blood citric acid, steps through blood pressure.
In a companion analysis of 101 women, lemon intake had no direct effect on muscle, blood fats or blood pressure markers
Observational analysis, written in Japanese, by the same research group, of 101 female lemon farmers on islands in the Seto Inland Sea who recorded lemon eaten and steps walked from September 2011 to March 2012. Lemon showed only an indirect link, through blood citric acid, to factors tied to artery stiffness, while walking affected cholesterol, including HDL. It is a correlation study.
Lemonade therapy for about 44 months raised urinary citrate in 10 of 11 patients with low citrate
Retrospective comparison of 11 patients on lemonade (average rise 383 mg a day) with 11 matched patients on slow-release potassium citrate (rise of 482 mg a day). Stone formation fell from 1.00 to 0.13 stones per patient per year on lemonade, but that change was not statistically significant. It was not randomized, and the authors call for a prospective randomized trial.
In a case-control study, eating citrus fruit more than twice a day went with 37 times the odds of dental erosion
Study of 106 people with tooth erosion and 100 controls. Daily soft drinks (adjusted odds ratio 4), weekly apple vinegar (10), vomiting (31) and low saliva flow (5) were also linked to erosion. The groups were small, and citrus fruit was not split into lemons and other kinds.
Eating fruit between meals, but not with meals, went with erosive tooth wear, while acidic drinks did either way
Case-control study of 300 people with erosive tooth wear and 300 matched controls at London dental clinics. Prolonged fruit eating (odds ratio 12.82) was as strongly linked as three or more acid intakes a day (10.92), and brushing within 10 minutes of acid was not linked after adjustment. The fruit was not split into lemons and other kinds.
Pooling 71 observational studies, eating acidic foods went with 2.4 times the odds of erosive tooth wear
Systematic review of 87 publications reporting 71 studies of adults, with random-effects meta-analyses. Acidic foods (odds ratio 2.40) and carbonated drinks (1.43) were linked to erosion, as were regurgitation and digestive disorders. Lemons were not singled out.
Two people who sucked lemons developed eroded front teeth that needed repair
Case report of 2 patients whose tooth erosion was attributed to lemon sucking, treated with direct composite resin fillings that remove little tooth. Two cases show it can happen, not how often.
Lemon juice took 32.0 mg of enamel from cow teeth in 7 days, the largest loss of 10 fluids tested
Lab study on bovine tooth enamel and dentine soaked at 37 °C in drinks including cola, orange juice (24.3 mg lost), apple juice (27.1 mg), tap water (no loss) and lemon juice. Lemon juice was significantly more erosive than all except Sprite and apple juice. Constant soaking is far harsher than drinking, so this shows relative acidity, not real-life damage.
Canned lemon juice visibly eroded the enamel of baby teeth in the lab, as cola and guaraná drinks did
Lab study on human deciduous (baby) teeth, examined by microscope. The erosion grew with soaking time for every product tested. It says nothing about how often lemon juice harms teeth in real drinking.
Lemon juice completely stopped starch breakdown by salivary amylase in the stomach in a lab digestion model
Lab study of 21 drinks and condiments, which blocked digestive enzymes by 10% to 100%. In a model of digestion of bread, black tea cut released sugars by about 20% in the intestinal phase, while lemon juice interrupted stomach amylase by acidifying the contents. It gave the reason for the blood sugar trials above.
Fresh lemon juice contains about 1.44 g of citric acid per ounce, more than orange juice squeezed from the fruit
Lab measurement of 21 commercial juices and concentrates and the juice of three fruits. Lime juice had 1.38 g per ounce and lemon concentrate 1.10 g. Ready-made lemonades varied widely, from 0.03 to 0.22 g per ounce. This is a measurement of the drink, not an effect in people.
Lemon juice contained about as much citrate as orange juice (47.66 vs 47.36 mmol/L), and homemade lemonade far less
Lab measurement by NMR of citrate in a squeezed lemon and common drinks. Grapefruit juice was highest at 64.7 mmol/L, and homemade lemonade was 17.42 mmol/L. The amount in a glass depends on how much juice goes in, which matters for the kidney stone studies above.
Lemon juice had the biggest positive effect on iron availability in a lab model of hummus
Lab study using simulated digestion and human gut-like cells. Lemon juice raised iron bioaccessibility by 15.9, while tahini lowered it by 8.9, and hummus gave more usable iron than cooked chickpeas alone (30.4 against 7.23 ng ferritin per mg of protein). No people were tested.
Adding lemon juice to green tea extract raised blood catechin levels in pigs, but did not improve cholesterol or antioxidant markers
Study in 16 pigs on low-fat or high-fat diets given a single dose, not people. The juice added no clear benefit to the tea within 24 hours, apart from lower triglycerides in the low-fat group.
Who should be careful with lemons
Most people can eat lemons freely. Take a little care if one of these applies:
- Tooth enamel. In a 7-day lab test, lemon juice took 32.0 mg of enamel from cow teeth, the most of 10 fluids. In a case-control study, eating citrus more than twice a day went with 37 times the odds of erosion. Researchers advise taking acids with meals, not between them, and avoiding habits that keep acid on the teeth, such as sipping slowly or sucking lemons.
- Heartburn or reflux. The US National Institute of Diabetes and Digestive and Kidney Diseases lists acidic foods such as citrus fruits among those commonly linked to reflux symptoms. Not everyone reacts, so skip lemon only if it sets yours off.
- Kidney stones. Lemonade is not a proven stand-in for prescribed potassium citrate: in a 21-person trial only the tablets raised urinary citrate and pH. Ask your clinician before swapping one for the other.
How to choose, store and eat lemons
- With starchy food: 250 mL of lemon juice with 100 g of bread lowered the blood sugar peak by 30% in healthy adults.
- Fresh juice or lemonade: fresh juice holds about 1.44 g of citric acid per ounce, while ready-made lemonades hold 0.03 to 0.22 g.
- In the kitchen: the acid in the juice slows browning of cut apples, bananas and avocados, and the colored outer rind, the zest, holds the aromatic oils.
Choose lemons that are firm, bright yellow, shiny and heavy for their size, and avoid soft, spongy or wrinkled ones. They keep about 2 weeks at room temperature and about 6 weeks in a plastic bag in the fridge. Residues are no reason to skip lemons, but if you use the zest, wash the peel first: the EU’s 2024 pesticide residue report named lemons, pomegranates and tomatoes from Türkiye for the highest rate of samples over the legal limit.
Sources
- Järvinen VK, Rytömaa II, Heinonen OP. Risk factors in dental erosion. J Dent Res. 1991.
- O’Toole S, Bernabé E, Moazzez R, Bartlett D. Timing of dietary acid intake and erosive tooth wear: a case-control study. J Dent. 2017.
- Zimmer S, Kirchner G, Bizhang M, Benedix M. Influence of various acidic beverages on tooth erosion. Evaluation by a new method. PLoS One. 2015.
- Marschner F, Kanzow P, Wiegand A. Anamnestic risk factors for erosive tooth wear: systematic review, mapping, and meta-analysis. J Dent. 2024.
- Eating, diet, & nutrition for GER & GERD. National Institute of Diabetes and Digestive and Kidney Diseases.
- Koff SG, Paquette EL, Cullen J, et al. Comparison between lemonade and potassium citrate and impact on urine pH and 24-hour urine parameters in patients with kidney stone formation. Urology. 2007.
- Freitas D, Boué F, Benallaoua M, et al. Lemon juice, but not tea, reduces the glycemic response to bread in healthy volunteers: a randomized crossover trial. Eur J Nutr. 2021.
- Penniston KL, Nakada SY, Holmes RP, Assimos DG. Quantitative assessment of citric acid in lemon juice, lime juice, and commercially-available fruit juice products. J Endourol. 2008.
- Fruit and vegetable guide series: lemons. Utah State University Extension. 2023.
- Lemon. Wikipedia.
- The 2024 European Union report on pesticide residues in food. European Food Safety Authority. EFSA Journal. 2026.
History of lemons
Nobody knows exactly where the lemon began. Northwest India has been proposed, and some evidence points to the first millennium BC. Genetic work shows that yellow lemons came from a cross between a citron and a bitter orange, and that lemons and limes arose from many separate crossing events.
Lemons reached Europe near southern Italy no later than the 2nd century AD. They arrived in Persia, Iraq and Egypt around 700 AD, and a 10th-century Arabic farming treatise is the first written record. Between 1000 and 1150 they spread across the Arab world and the Mediterranean. Columbus brought lemon seeds to Hispaniola in 1493.
Sailors knew lemons as a cure for scurvy long before anyone knew why. In 1579 a Spanish friar, Agustín Farfán, recommended oranges and lemons, and in 1601 Captain James Lancaster gave one of four East India Company ships a routine dose of lemon juice. The crews on the other three ships fell ill with scurvy, and many died.
In 1747 the Scottish naval surgeon James Lind tested six remedies on twelve sick sailors aboard HMS Salisbury. The pair given two oranges and one lemon did best, although the fruit ran out after six days. Lind published the trial in 1753, but it had little effect at first, and he never promoted lemon juice as a single cure.
The Royal Navy changed course in 1795, after HMS Suffolk reached India on a four-month voyage with no scurvy. The Admiralty ordered a daily ration of lemon juice and sugar for all warships, and by 1800 the system was working. Scurvy had been virtually eliminated from the Royal Navy.
Lemons did not last in the navy, though. Spain’s alliance with France made Mediterranean lemons hard to get, so Britain switched to limes from its Caribbean colonies, which were believed to work better because they were more acidic. Those limes held less vitamin C than lemons, and the juice was stored and piped through copper, which cut it further. Britain’s 1867 Merchant Shipping Act required a daily lime or lemon juice ration on merchant ships, and British sailors became known as “limeys”.
Sources
- Curk F, Ollitrault F, Garcia-Lor A, et al. Phylogenetic origin of limes and lemons revealed by cytoplasmic and nuclear markers. Ann Bot. 2016.
- Cook GC. Scurvy in the British Mercantile Marine in the 19th century, and the contribution of the Seamen’s Hospital Society. Postgrad Med J. 2004.
- Lemon. Wikipedia.
- Scurvy. Wikipedia.
- James Lind. Wikipedia.
Frequently asked questions about lemons
Are lemons good for you?
For most people, yes, as a low-calorie way to add vitamin C and flavor. One lemon without peel (58 g) has 17 calories and 31 mg of vitamin C, 34% of the daily value, and 100 g has 29 calories and 2.8 g of fiber. Evidence for specific health effects is limited: none of the studies here reaches strong evidence, and most trials were small.
Does lemon water detox your body?
No study here shows it does, and a PubMed search found no trial showing lemon water removes toxins. In an 84-woman trial of a 7-day lemon detox diet, body fat fell, but a placebo juice diet worked as well, and the authors credit calorie restriction. That is a very low-calorie diet, not a glass of lemon water.
Is lemon water alkaline, and does it alkalize your body?
Not in the studies that measured it. In a crossover trial of 13 people, orange juice raised urine pH and citrate but lemonade did not, and in a 21-person trial lemonade did not raise urine pH either, while potassium citrate did. Lemon juice itself is acidic, with about 5 to 6% citric acid.
Does lemon juice help prevent kidney stones?
Possibly, but the evidence is small and mixed. Urinary citrate rose in several small studies, 2.5-fold with about 85 mL of juice a day for 3 months, and in 10 of 11 patients on lemonade for about 44 months, while two crossover trials of 13 and 21 people saw no rise. No randomized trial here measured new stones, so ask your clinician before changing treatment.
Does lemon juice lower blood sugar?
It lowered the blood sugar peak after bread in two small trials of healthy people: by 30% with 250 mL of juice and 100 g of bread, and by 35% at 55 minutes in a 10-person MRI study. No trial here tested people with diabetes, and the effect was seen with starchy food, so it is not a treatment. Ask your care team about your own plan.
Does lemon lower blood pressure?
Not proven. In a five-month observational study of 101 women, more lemon and more walking each went with a bigger fall in systolic pressure, but that shows a link, not a cause, and a companion analysis found no direct effect of lemon. Hesperidin supplements changed systolic pressure by only 0.85 mmHg in a meta-analysis of 10 trials, which was not significant.
How much vitamin C is in a lemon, and does it help colds?
One lemon without peel (58 g) has about 31 mg of vitamin C, 34% of the daily value, and 100 g has 53 mg, or 59%. No trial here tested lemons for colds. In a Cochrane review, vitamin C pills of at least 0.2 g a day did not lower the chance of catching a cold in the general public (risk ratio 0.97) but shortened colds by 8% in adults, a dose well above one lemon.
Is lemon water bad for your teeth?
It can be, mostly when sipped slowly or often between meals. Lemon juice took 32.0 mg of enamel from cow teeth in a 7-day lab soak, and eating citrus more than twice a day went with 37 times the odds of erosion in a case-control study. Diluted lemon water was not tested here, so the risk of one glass with a meal is not known.