The recipe is simple: when you wake up in the morning, squeeze the juice of half a lemon into a glass of warm water and drink it; repeat every morning. This habit is widely considered to provide a number of benefits1 – boosting your immune system, helping with digestion, detoxifying your liver, lowering your blood pressure, cleaning your skin and helping you stay slim. But are these proven facts or just old wives’ tales?
Lemon juice is a good source of vitamin C.2 In 1795, the Royal Navy added a daily serving of lemon to its sailors’ diets to make sure they had enough vitamin C to avoid contracting scurvy.3 Even today, people who don’t eat enough fresh fruits and vegetables can develop the disease.4
A glass of water with lemon does have vitamin C, but it’s only a small amount. According to Muriel Jaquet, a dietician at the Swiss Nutrition Society: “The amount of vitamin C in the juice of half a lemon is much lower than that in a glass of orange juice or a serving (120 g) of strawberries, bell peppers, broccoli, and many other fruits and vegetables.”
Many studies, including several carried out in vitro with citrus fruit concentrates, have shown that flavonoids and limonoids have a number of beneficial properties. For instance, they can slow the proliferation of cancer cells.9, 10 Research has shown that citrus juices in general – and orange and grapefruit juice in particular – can help fight tumors.11 Regularly consuming certain types of flavonoids can reduce the risk of cardiovascular disease9 since they improve coronary vasodilatation, decrease blood platelet clotting and prevent the oxidation of “bad” cholesterol (LDL). The flavonoids in citrus fruits also have proven anti-inflammatory properties – they inhibit the synthesis and biological activity of pro-inflammatory mediators.9 And studies carried out on animals have demonstrated that some flavonoids, such as quercetin, can be effective in treating obesity and diabetes12 by reducing blood pressure13 and body mass.14 However, that doesn’t necessarily mean the same results can be obtained in humans.
In most of the research mentioned above, the subjects drank citrus concentrates rather than citrus juice. But we generally drink lemon juice in small portions, so we actually consume only a tiny amount of the beneficial compounds it contains. That said, flavonoids and limonoids can be found in many other fruits and vegetables as well.
Lemons are a natural source of citric acid. Its concentration can be particularly high – up to 8% of the fruit’s dry weight.15 This acid stimulates the secretion of bile by the liver, thereby helping digestion.
Not a panacea
While lemons do contain substances that are proven to be good for us, the amount we get by drinking the juice of half a lemon a day is in fact quite small. So the health benefits of this habit shouldn’t be exaggerated. Especially since the main ingredients of lemon juice are water (92.5 g/100 mL) and sugar (6.1 g/ 100 mL).16
- 1. “Boire du jus de citron avec de l’eau chaude à jeun : 15 bienfaits,” com, March 10, 2014.
- 2. Kozlowska, A. and Szostak-Wegierek, D. (2014). “Flavonoids–food sources and health benefits.” Panstw. Zakl. Hig.
- “Le Traitement anti-scorbutique du docteur Mac Bride de Dublin à bord des vaisseaux de la Navy, (1766-1767),” Patrick Grellier, dissertation for PhD in medicine, Nantes, 1978.
- 4. “Vitamine C,” PasseportSanté.net, updated April 2015.
- 5. Tounsi, M. S., Wannes, W. A., Ouerghemmi, I., Jegham, S., Ben Njima, Y., Hamdaoui, G., et al. (2011). “Juice components and antioxidant capacity of four Tunisian Citrus varieties.” Sci. Food Agric.
- 6. “Le citron et ses bienfaits sur la santé,” PasseportSanté.net, updated July 2017.
- 7. Lam L.K.T., Hasegawa S.,et al. (2000). “Limonin and nomilin inhibitory effects on chemical-induced tumorigenesis.” In: Berhow M.A., Hasegawa S., Manners G.D., editors. Citrus Limonoids FunctionalChemicals in Agriculture and Foods.
- 8. Yu J., Wang L.,et al. (2005). “Antioxidant activity of citrus limonoids, flavonoids, and coumarins.” Agric. Food Chem.
- 9. Benavente-Garcia O., Castillo J. (2008). “Update on uses and properties of citrus flavonoids: new findings in anticancer, cardiovascular, and anti-inflammatory activity.” Agric. Food. Chem.
- 10. Poulose S.M., Harris E.D., Patil B.S. (2005). “Citrus limonoids induce apoptosis in human neuroblastoma cells and have radical scavenging activity.” Nutr.
- 11. Cirmi S., Maugeri A., Ferlazzo N., et al. (2017). “Anticancer Potential of CitrusJuices and Their Extracts: A Systematic Review of Both Preclinical and Clinical Studies.” Pharmacol.
- 12. Kawser Hossain M., Abdal Dayem A, et al. (2016). “Molecular Mechanisms of the Anti-Obesity and Anti-Diabetic Properties of Flavonoids.” Int J Mol Sci.
- 13. Edwards R.L., Lyon T., Litwin S.E., et al. (2007). “Quercetin reduces blood pressure in hypertensive subjects.” Nutr.
- 14. Yamamoto Y., Oue E. (2006). “Antihypertensive effect of quercetin in rats fed with a high-fat high-sucrose diet.” Biotechnol. Biochem.
- 15. Penniston K.L., Nakada S.Y., Holmes R.P. and Assimos D.G. (2008). “Quantitative Assessment of Citric Acid in Lemon Juice, Lime Juice, and Commercially-Available Fruit Juice Products.”Journal of Endourology.
- 16. Swiss database of nutritional values, values for lemon juice, Swiss Federal Food Safety and Veterinary Office (OSAV).