Support for the Beneficial Effects of DGL
Deglycyrrhizinated licorice exemplifies a widely accepted natural agent that “works” when assessed empirically but has yet to meet criteria for inclusion in an evidence-based, conventional medical paradigm.
Clinical Evidence to Date
|Journal Citation||Form of DGL Used||Dosage Used||
|Summary of Design||Summary of Outcome||Authors’ Conclusions|
|Gut. 1968;9(1):48-51||Caved-S||2 tablets, chewed 3x/d after meals||8 wk, with 4-wk crossover||Double-blind RCT of 6 gastric and 48 duodenal ulcer patients. Crossover was done in all gastric ulcer patients and 15/48 patients with duodenal ulcers. All patients were classified as “good,” “improved,” or “not improved” based on reported pain levels. Radiological imaging was also used before and after intervention. Usage of antacid was recorded in all patients.||All patients with gastric ulcers achieved symptomatic and radiographic improvements. There was less use of antacid in the Caved-S group and a trend toward improvements in observed symptoms in the duodenal ulcer intervention group. Follow-up imaging of duodenal ulcer patients suggests a spasmolytic effect of DGL at the level of the duodenal bulb.||“Duodenal ulcer patients showed marked improvements, with radiographical improvements in a few cases.” All gastric ulcer patients showed healing of ulcers. There appears to be a spasmolytic effect of DGL in patients with duodenal ulcers.|
|Gut. 1969; 10(4):299-302||DGL 380mg/ capsule||2 capsules, 3x/d after meals||4 wk||Double-blind RCT of 33 patients with radiographic evidence of gastric ulcerations greater than 10 mm2. Healing of ulcers was assessed through radiography.||The group receiving DGL had an average reduction in ulcer size of 76%, vs 34% for the placebo group. No side effects were reported.||DGL represents a therapeutic alternative to carbenoxolone without the risk of mineral corticoid side effects.|
|Gut. 1971;12(6):449-451||Caved-S||2 tablets, chewed 3x/d after meals||4 wk||Double-blind, placebo-controlled study of 47 patients with active duodenal ulcer for a minimum of 6 mo. Inclusion included baseline radiographic evidence of deformed duodenal bulb or ulcer niche as well as abdominal pain. Assessment was through symptom questionnaire. Intervention consisted of 4 wk of treatment.||There was no significant difference in symptom reports between the 2 groups. Electrolytes, complete blood count, blood urea nitrogen, and urinalysis were unchanged in both groups. No side effects were reported.||There is no advantage to the addition of DGL in symptom management in patients with duodenal ulcers.|
|Br Med J. 1971;3(5773): 501-503||DGL, 380 mg/ capsule||2 capsules, 3x/d after meals||6 wk||Multicenter RCT in the United Kingdom. 90 men with recurrent duodenal ulcers. Symptoms assessed through patient reports and practitioner observation, fortnightly. Frequency of alkali medication for symptom relief was also tracked. Serum pepsinogen measured in both groups.||No measurable difference in subjective pain reports. No difference in the amount of alkali medication consumed for symptomatic relief. No difference in practitioner reported observations of patient’s relief of symptoms. No change in serum pepsinogen levels.||The difference between carbenoxolone and DGL is statistically not significant. As it has no side effects, DGL represents a safe alternative to carbenoxolone.|
|Practitioner. 1973;210(260): 820-823||Caved-S||8 tablets, 8x/d for 8 wk, or 12 tablets, 8x/d for 16 wk||1 y||Double-blind trial using 2 different doses of Caved-S in 40 duodenal ulcer patients with unremitting pain and greater than 6 relapses in 12 mo. Relapse was defined through the presence of pain, and relapse-free defined by its absence. All patients had been referred for surgical intervention.||None of the patients required surgical intervention during the year of follow-up. Most of the patients receiving 8 tablets/d did have a relapse of symptoms within the y. Patients receiving 12 tablets/d did not suffer relapse. This difference was statistically significant.||Higher doses of Caved-S confer a greater protection from relapse of duodenal ulcer symptoms. Caved-S demonstrated efficacy even in patients with severe, relapsing duodenal ulcers who were referred for surgical intervention.|
|Gut. 1973;14(9):711-715||DGL, 380 mg/capsule||2 capsules, taken orally 3x/d||8 wk, with 4-wk crossover||Double-blind, placebo-controlled trial of 68 patients with radiographically confirmed gastric ulcer(s). Assessment was done through radiographic follow-up.||There was no statistical difference in the healing of the intervention group vs placebo.||The location of the ulcer in the stomach, as well as the initial size, influences the healing time. With these considerations, previous studies showing efficacy may have had placebo groups unmatched to interventional groups.|
|Br Med J. 1977;2(6095): 1123||DGL 450 mg/ capsule (Ulcedal) or 450 mg/block chewing gum||2 capsules, 5x/d or 2 blocks, chewed for 30 min 5x/d between meals||8 wk||Controlled trial of 34 patients with duodenal ulcers. DGL consumed as capsules or chewing gum vs placebo of either capsules or chewing gum of inert substance. Endoscopy was used to assess efficacy.||There was no difference in healing of ulcers between the intervention group vs placebo.||The results do not support the concept of DGL usage in duodenal ulcer. Saliva introduced through chewing did not confer any benefit to healing either. Since symptoms do not correlate with healing, trials should be endoscopically controlled.|
|Br Med J. 1978;1(6106):148||
DGL (Ulcedal) 450 mg/capsule
|5 capsules/d||2 y||Double-blind, placebo-controlled trial of 33 patients with healed gastric ulcerations. Assessment was through gastroscopy and barium imaging every 6 mo. Patients were followed for up to 2 y.||Relapse rates were 45% and 59% for the DGL and placebo groups respectively. This was not statistically significant.||Although the results did not reach statistical significance, the need for prophylaxis in this patient population lends itself to the use of DGL given the trend of less recurrence combined with a low toxicity profile.|
DGL (Ulcedal) 450 mg/capsule
|2 capsules 4x/d||4 wk||Double-blind RCT of 96 patients with endoscopy-verified gastric ulcers. Assessment was through repeat endoscopy and radiological assessment. Ulcer healing was defined as re-epithelialization of lesion on visualization through gastroscopy. Radiographical healing was defined as disappearance of the ulcer crater on repeat imaging.||Median percentage change in the ulcer area was comparable in both groups. Symptom improvement was also comparable in the 2 groups. Endoscopic and radiographic results had little concordance.||This trial was designed to show a statistically significant benefit of DGL if there was a doubling of the assumed placebo-healing rate of 30%. It did not show this; therefore there is no justification for continued use of DGL.|
Abbreviations: DGL, deglycyrrhizinated licorice; RCT, randomized controlled trial.
aOnly clinical trials published in English with the full text available in electronic or hard copy are included above.
- Shibata S. A drug over the millennia: pharmacognosy, chemistry, and pharmacology of licorice. Yakugaku Zasshi. 2000;120(10):849-862.
- Blumenthal M. The ABC Clinical Guide to Herbs. Austin, TX: American Botanical Council; 2003.
- Asl MN, Hosseinzadeh H. Review of pharmacological effects of Glycyrrhiza sp. and its bioactive compounds. Phytother Res. 2008;(6):709-724.
- Revers FE. Does succus of licorice have a healing effect on the stomach ulcer? Ned Tijdschr Geneeskd. 1946;90:135-137.
- Revers FE. The treatment of gastric ulcer and duodenal ulcer with licorice succus therapy. Ned Tijdschr Geneeskd. 1948:92;2968-2973.
- Borst JG, Blomhert G, Molhuysen JA, Gerbrandy J, Turner KP, de Vries LA. Excretion of water and electrolytes during a 24-hour period and under influence of licorice extract. Acta Clin Belg. 1950;5(4):405-409.
- Revers FE. Licorice juice without glycyrrhizinic acid in peptic ulcer therapy. Ned Tijdschr Geneeskd. 1952;96(38):2338-2341.
- Krausse R, Bielenberg J, Blaschek W, Ullmann U. In vitro anti-Helicobacter pylori activity of Extractum liquiritiae, glycyrrhizin and its metabolites. J Antimicrob Chemother. 2004;54(1):243-6.
- Fukai T, Marumo A, Kaitou K, Kanda T, Terada S, Nomura T. Anti-Helicobacter pylori flavonoids from licorice extract. Life Sci. 2002;71(12):1449-1463.
- van Marle J, Aarsen PN, Lind A, van Weeren-Kramer J. Deglycyrrhizinised liquorice (DGL) and the renewal of rat stomach epithelium. Eur J Pharmacol. 1981;72(2-3):219-225.
- Rees WD, Rhodes J, Wright JE, Stamford LF, Bennett A. Effect of deglycyrrhizinated liquorice on gastric mucosal damage by aspirin. Scand J Gastroenterol. 1979;14(5):605-607.
- Tewari SN, Wilson AK. Deglycyrrhizinated liquorice in duodenal ulcer. Practitioner. 1973;210(260):820-823.
- Larkworthy W, Holgate PF, McIllmurray MB, Langman MJ. Deglycyrrhizinised liquorice in duodenal ulcer. Br Med J. 1977;2(6095):1123.
- Malhotra SL, Saigal ON, Mody GD. Role of saliva in the aetiology of peptic ulcer. Br Med J. 1965;1(5444):1220-1222.
- Morgan AG, Pacsoo C, McAdam WA. Maintenance therapy: a two year comparison between Caved-S and cimetidine treatment in the prevention of symptomatic gastric ulcer recurrence. Gut. 1985;26(6):599-602.
- Morgan AG, Pacsoo C, Taylor P, McAdam WAF. Does Caved-S decrease the gastric ulcer relapse rate during maintenance treatment with ranitidine? Aliment Pharmacol Ther. 1987;1(6):633-638.