Onion

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Also indexed as: Allium cepa

Parts Used & Where Grown

Like its close cousins garlic, chives, scallions, and leeks, onion is a member of the lily family (Liliaceae). It is native to Eurasia but now grows all over the world, due mostly to people bringing it with them as a staple food wherever they migrated. The French explorer Pere Marquette was saved from starvation in 1624 by eating wild onions near the present site of Chicago—the name of the city is derived from a Native American word for the odor of onions. The bulb of the plant is used medicinally.

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Reliable and relatively consistent scientific data showing a substantial health benefit.

Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.

For an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support.

Our proprietary “Star-Rating” system was developed to help you easily understand the amount of scientific support behind each supplement in relation to a specific health condition. While there is no way to predict whether a vitamin, mineral, or herb will successfully treat or prevent associated health conditions, our unique ratings tell you how well these supplements are understood by the medical community, and whether studies have found them to be effective for other people.

For over a decade, our team has combed through thousands of research articles published in reputable journals. To help you make educated decisions, and to better understand controversial or confusing supplements, our medical experts have digested the science into these three easy-to-follow ratings. We hope this provides you with a helpful resource to make informed decisions towards your health and well-being.

Onion has been used in connection with the following health conditions:

Used for	Amount	Why
Type 1 Diabetes	20 grams fresh onion three times per day	[2 stars] Large amounts of onion have been shown to lower blood sugar levels in people with diabetes, possibly by blocking the breakdown of insulin in the liver. Learn More
Close Type 1 Diabetes 20 grams fresh onion three times per day Preliminary trials and at least one double-blind trial have shown that large amounts of onion can lower blood sugar levels in people with diabetes.⁵^{, 6}^{, 7} The mechanism of onion’s blood sugar-lowering action is not precisely known, though there is evidence that constituents in onions block the breakdown of insulin in the liver. This would lead to higher levels of insulin in the body.⁸ Learn More
Type 2 Diabetes	20 grams fresh onion three times per day	[2 stars] Large amounts of onion have been shown to lower blood sugar levels in people with diabetes, possibly by blocking the breakdown of insulin in the liver. Learn More
Close Type 2 Diabetes 20 grams fresh onion three times per day Preliminary trials and at least one double-blind trial have shown that large amounts of onion can lower blood sugar levels in people with diabetes.⁹^{, 10}^{, 11} The mechanism of onion’s blood sugar-lowering action is not precisely known, though there is evidence that constituents in onions block the breakdown of insulin in the liver. This would lead to higher levels of insulin in the body.¹² Learn More
Asthma	Refer to label instructions	[1 star] Onion may act as an anti-inflammatory in people with asthma. Learn More
Close Asthma Onion may act as an anti-inflammatory in people with asthma. Human studies have shown onion can be a strong anti-inflammatory.¹³ However, some people with asthma may experience an exacerbation of symptoms if they are allergic to onion and are exposed to it.¹⁴ Learn More
Cough	Refer to label instructions	[1 star] Onion has a long history of use for relieving coughs. Learn More
Close Cough The mucilage of slippery elm gives it a soothing effect for coughs. Usnea also contains mucilage, which may be helpful in easing irritating coughs. There is a long tradition of using wild cherry syrups to treat coughs. Other traditional remedies to relieve coughs include bloodroot, catnip, comfrey (the above-ground parts, not the root), horehound, elecampane, mullein, lobelia, hyssop, licorice, mallow, (Malvia sylvestris),red clover, ivy leaf, pennyroyal (Hedeoma pulegioides, Mentha pulegium),onion, (Allium cepa), and plantain (Plantago lanceolata, P. major). None of these has been investigated in human trials, so their true efficacy for relieving coughs is unknown. Learn More
Eczema	Refer to label instructions	[1 star] Onion injections into the skin and topical onion applications have been shown to inhibit skin inflammation in people with eczema, according to one trial. Learn More
Close Eczema Onion injections into the skin and topical onion applications have been shown to inhibit skin inflammation in people with eczema, according to one double-blind trial.¹⁵ The quantity or form of onion that might be most effective is unknown. Learn More
Hypertension	Refer to label instructions	[1 star] Onion may have a mild blood pressure-lowering effect, according to preliminary research. Learn More
Close Hypertension Garlic has a mild blood pressure-lowering effect, according to an analysis of ten double-blind trials.¹⁶ All of these trials administered garlic for at least four weeks, typically using 600–900 mg of garlic extract per day. Onion—closely related to garlic—may also have a mild blood pressure-lowering effect, according to preliminary research.¹⁷ Learn More
Infection	Refer to label instructions	[1 star] Onion is an herb that directly attack microbes. Learn More
Close Infection Herbs that directly attack microbes include the following: chaparral, eucalyptus, garlic, green tea, lemon balm (antiviral), lomatium, myrrh, olive leaf, onion, oregano, pau d’arco (antifungal), rosemary, sage, sandalwood, St. John’s wort, tea tree oil, thyme, and usnea. Learn More

Traditional Use (May Not Be Supported by Scientific Studies)

Onion has been used as food for many centuries. Onion was also a popular folk remedy, being applied to tumors, made into a syrup for relieving coughs, or prepared in a tincture (using gin) to relieve “dropsy” (heart failure–related edema). It was considered a weaker version of garlic by many herbal practitioners. Like garlic, onion has a longstanding but unsubstantiated reputation as an aphrodisiac.

References

1. Onstad D. Whole Foods Companion: A Guide for Adventurous Cooks, Curious Shoppers & Lovers of Natural Foods. White River Junction, VT: Chelsea Green Publishing Co, 1996:202–6.

2. Onstad D. Whole Foods Companion: A Guide for Adventurous Cooks, Curious Shoppers & Lovers of Natural Foods. White River Junction, VT: Chelsea Green Publishing Co, 1996:202–6.

3. Felter HW, Lloyd JU. King’s American Dispensatory, 18th ed, vol 1. Portland, OR: Eclectic Medical Publications, 1898, 1983:146.

4. Onstad D. Whole Foods Companion: A Guide for Adventurous Cooks, Curious Shoppers & Lovers of Natural Foods. White River Junction, VT: Chelsea Green Publishing Co, 1996:202–6.

5. Jain RC, Sachdev KN. A note on hypoglycemic action of onion in diabetes. Curr Med Pract 1971;15:901–2.

6. Mathew PT, Augusti KT. Hypoglycaemic effect of onion, Allium cepa Linn, on diabetes mellitus, a preliminary report. Ind J Physiol Pharmacol 1975;19:231–7.

7. Tjokroprawiro A, Pikir BS, Budhiarta AA, et al. Metabolic effects of onion and green beans on diabetic patients. Tohoku J Exp Med 1983;141(suppl):671–6.

8. Sharma KK, Gupta RK, Gupta S, Samuel KC. Antihyperglycemic effect of onion: Effect on fasting blood sugar and induced hyperglycemia in man. Ind J Med Res 1977;65:422–9.

9. Jain RC, Sachdev KN. A note on hypoglycemic action of onion in diabetes. Curr Med Pract 1971;15:901–2.

10. Mathew PT, Augusti KT. Hypoglycaemic effect of onion, Allium cepa Linn, on diabetes mellitus, a preliminary report. Ind J Physiol Pharmacol 1975;19:231–7.

11. Tjokroprawiro A, Pikir BS, Budhiarta AA, et al. Metabolic effects of onion and green beans on diabetic patients. Tohoku J Exp Med 1983;141(suppl):671–6.

12. Sharma KK, Gupta RK, Gupta S, Samuel KC. Antihyperglycemic effect of onion: Effect on fasting blood sugar and induced hyperglycemia in man. Ind J Med Res 1977;65:422–9.

13. Dorsch W, Ettl M, Hein G, et al. Anti-asthmatic effects of onions: inhibition of platelet-activating factor-induced bronchial construction by onion oils. Int Arch Allergy Appl Immunol 1987;82:535–6.

14. Valdivieso R, Subiza J, Varela-Losada S, et al. Bronchial asthma, rhinoconjunctivitis, and contact dermatitis caused by onion. J Allergy Clin Immunol 1994;94:928–30.

15. Dorsch W, Ring J. Suppression of immediate and late anti-IgE-induced skin reactions by topically applied alcohol/onion extract. Allergy 1984;39:43–9.

16. Silagy C, Neil AW. A meta-analysis of the effect of garlic on blood pressure. J Hypertension 1994;12:463–8.

17. Louria DB, McAnally JF, Lasser N, et al. Onion extract in treatment of hypertension and hyperlipidemia: A preliminary communication. Curr Ther Res 1985;37:127–31.

18. Brodnitz MH, Pascale JV. Thiopropanal S-oxide: A lachrymatory [sic] factor in onions. J Agric Food Chem 1971;19:269–72.

19. Zohri AN, Abdel-Gawad K, Saber S. Antibacterial, antidermatophytic and antitoxigenic activities of onion (Allium cepa L.) oil. Microbiol Res 1995;150:167–72.

20. Kim JH. Anti-bacterial action of onion (Allium cepa L.) extracts against oral pathogenic bacteria. J Nihon Univ Sch Dent 1997;39:136–41.

21. Sharma KK, Gupta RK, Gupta S, Samuel KC. Antihyperglycemic effect of onion: Effect on fasting blood sugar and induced hyperglycemia in man. Indian J Med Res 1977;65:422–9.

22. Jain RC, Sachdev KN. A note on hypoglycemic action of onion in diabetes. Curr Med Pract 1971;15:901–2.

23. Mathew PT, Augusti KT. Hypoglycaemic effect of onion, Allium cepa Linn, on diabetes mellitus, a preliminary report. Indian J Physiol Pharmacol 1975;19:231–7.

24. Tjokroprawiro A, Pikir BS, Budhiarta AA, et al. Metabolic effects of onion and green beans on diabetic patients. Tohoku J Exp Med 1983;141(suppl):671–6.

25. Sharma KK, Gupta RK, Gupta S, Samuel KC. Antihyperglycemic effect of onion: Effect on fasting blood sugar and induced hyperglycemia in man. Indian J Med Res 1977;65:422–9.

26. Dorsch W, Ettl M, Hein G, et al. Anti-asthmatic effects of onions: Inhibition of platelet-activating factor-induced bronchial construction by onion oils. Int Arch Allergy Appl Immunol 1987;82:535–6.

27. Dorsch W, Wagner H, Bayer T, et al. Antiasthmatic effects of onions: Alk(en)ylsulfinothic acid alk(en)ylesters inhibit histamine release, leukotriene and thromboxane biosynthesis in vitro and counteract PAF- and allergen-induced bronchial obstruction in vivo. Biochem Pharmacol 1988;37:4479–85.

28. Srivastava KC. Effect of onion and ginger consumption on platelet thromboxane production in humans. Prostaglandins Leukot Essent Fatty Acids 1989;35:183–5.

29. Dorsch W, Ring J. Suppression of immediate and late anti-IgE-induced skin reactions by topically applied alcohol/onion extract. Allergy 1984;39:43–9.

30. Chen JH, Chen HI, Tsai SJ, Jen CJ. Chronic consumption of raw but not boiled Welsh onion juice inhibits rat platelet function. J Nutr 2000;130:34–7.

31. Kendler BS. Garlic (Allium sativum) and onion (Allium cepa): A review of their relationship to cardiovascular disease. Prev Med 1987;16:670–85 [review].

32. Kleijnen J, Knipschild P, ter Riet G. Garlic, onions and cardiovascular risk factors: A review of the evidence from human experiments with emphasis on commercially available preparations. Br J Clin Pharmacol 1989;28:535–44 [review].

33. Hertog MGL, Feskens EJ, Hooman PC, et al. Dietary antioxidant flavonoids and the risk of coronary heart disease: The Zutphen Elderly Study. Lancet 1993;342:1007–11.

34. Rimm ER, Katan MB, Ascherio A, et al. Relation between intake of flavonols and risk for coronary heart disease in male health professionals. Ann Intern Med 1996;125:384–9.

35. Louria DB, McAnally JF, Lasser N, et al. Onion extract in treatment of hypertension and hyperlipidemia: A preliminary communication. Curr Ther Res 1985;37:127–131.

36. Sharma KK, Chowdhury NK, Sharma AL, Misra MB. Studies on hypocholestraemic activity of onion. I. Effect on serum cholesterol in alimentary lipaemia in man. Indian J Nutr Diet 1975;12:288–91.

37. Dorant E, van der Brandt PA, Goldbohm RA, Sturmans F. Consumption of onions and a reduced risk of stomach carcinoma. Gastroenterology 1996;110:12–20.

38. Challier B, Perarnau JM, Viel JF. Garlic, onion and cereal fibre as protective factors for breast cancer: A French case-control study. Eur J Epidemiol 1998;14:737–47.

39. Dorant E, van den Brandt PA, Goldbohm RA. A prospective cohort study on the relationship between onion and leek consumption, garlic supplement use and the risk of colorectal carcinoma in the Netherlands. Carcinogenesis 1996;17:477–84.

40. Tjokroprawiro A, Pikir BS, Budhiarta AA, et al. Metabolic effects of onion and green beans on diabetic patients. Tohoku J Exp Med 1983;141(suppl):671–6.

41. Jain RC, Sachdev KN. A note on hypoglycemic action of onion in diabetes. Curr Med Pract 1971;15:901–2.

42. Bordia T, Mohammed N, Thomson M, Ali M. An evaluation of garlic and onion as antithrombotic agents. Prostaglandins Leukot Essent Fatty Acids 1996;54:183–6.

43. Tjokroprawiro A, Pikir BS, Budhiarta AA, et al. Metabolic effects of onion and green beans on diabetic patients. Tohoku J Exp Med 1983;141(suppl):671–6.

44. Chen JH, Chen HI, Tsai SJ, Jen CJ. Chronic consumption of raw but not boiled Welsh onion juice inhibits rat platelet function. J Nutr 2000;130:34–7.

45. Ali M, Bordia T, Mustafa T. Effect of raw versus boiled aqueous extract of garlic and onion on platelet aggregation. Prostaglandins Leukot Essent Fatty Acids 1999;60:43–7.

46. Allen ML, Mellow MH, Robinson MG, Orr WC. The effect of raw onions on acid reflux and reflux symptoms. Am J Gastroenterol 1990;85:377–80.

47. Valdivieso R, Subiza J, Varela-Losada S, et al. Bronchial asthma, rhinoconjunctivitis, and contact dermatitis caused by onion. J Allergy Clin Immunol 1994;94:928–30.

48. Wuensch KL. Exposure to onion taste in mother’s milk leads to enhanced preference for onion diet among weanling rats. J Gen Psychol 1978;99(2d Half):163–7.

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Onion

Related Topics

Parts Used & Where Grown

Onion has been used in connection with the following health conditions:

Type 1 Diabetes

Type 2 Diabetes

Asthma

Cough

Eczema

Hypertension

Infection

Traditional Use (May Not Be Supported by Scientific Studies)