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Liquorice-induced rise in blood pressure: a linear dose-response relationship


To clarify the dose-response and the time-response relationship between liquorice consumption and rise in blood pressure and explore the inter-individual variance this intervention study was designed and executed in research laboratories at University hospitals in Iceland and Sweden. Healthy, Caucasian volunteers who also served as a control for himself/herself consumed liquorice in various doses, 50–200 g/day, for 2–4 weeks, corresponding to a daily intake of 75–540 mg glycyrrhetinic acid, the active substance in liquorice. Blood pressure was measured before, during and after liquorice consumption. Systolic blood pressure increased by 3.1–14.4 mm Hg (P < 0.05 for all), demonstrating a dose-response but not a time-response relationship. The individual response to liquorice followed the normal distribution. Since liquorice raised the blood pressure with a linear dose-response relationship, even doses as low as 50 g of liquorice (75 mg glycyrrhetinic acid) consumed daily for 2 weeks can cause a significant rise in blood pressure. The finding of a maximal effect of liquorice after only 2 weeks has important implications for all doctors dealing with hypertension. There does not seem to be a special group of responders since the degree of individual response to liquorice consumption followed the normal distribution curve.


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We thank Mr O Petursson, the Drift liquorice sweet factory in Iceland and the Malaco sweet factory in Sweden for kindly supplying all liquorice, and to Sverker Jern head of the Clinical Experimental Laboratory, Sahlgrenska University Hospital/Östra for constructive discussion and statistical help. This study was supported by a grant from the Science Fund of the Reykjavik City Hospital and The Göteborg Medical Society. (Competing interests: None declared.)

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Correspondence to H Á Sigurjónsdóttir.

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  • 11 β-hydroxysteroid dehydrogenase
  • liquorice
  • glycyrrhetinic acid

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