Globe artichoke

Globe artichoke is a common name for the plant Cynara cardunculus L. subsp. cardunculus (synonym: Cynara scolymus L.; Asteraceae), an herbaceous perennial plant native to the Mediterranean region. Globe artichoke has a long history of use as both food and medicine. The leaves have been used as a traditional herbal medicine for their reputed therapeutic benefits, including hepatoprotective, choleretic, diuretic, and lipid-lowering properties.¹ Today, globe artichoke is cultivated extensively worldwide for its large immature inflorescences, known as capitula or flowerheads. This part of the plant has edible fleshy leaves (bracts) and a receptacle, and serves as an important component of the Mediterranean diet.

Common names

Artichoke, artischocke, alcaucoe, artichaut, carcioffa, cardoon, folium cynarae, harshaf-e-barri and many others.

Preparations

In food use, globe artichokes are cooked, fried, or baked, and also canned or preserved in olive oil after cooking. Traditional medicine preparations of artichoke include comminuted (fragmented) dried leaf used with boiling water to make a tea, and other water extracts of dried or fresh leaves. Contemporary preparations of globe artichoke in the global market include leaf extracts presented as oral dose forms (tablets, capsules, liquid) formulated as single- or multi-ingredient products with other herbal and/or non-herbal ingredients. Some marketed products are labelled as being standardised for caffeoylquinic acid content (eg 5–18% for different products). In New Zealand, natural health products containing globe artichoke are available as tablets, capsules, liquid extracts, and teas.

Manufacturers’ claims

Commercial products containing globe artichoke are marketed as supporting digestion and healthy liver function, to aid detoxification, to ‘protect’ the liver, to maintain normal cholesterol ‘levels’, and help with bowel irregularities, among other claims.

Active constituents

Globe artichoke is a rich source of a range of bioactive compounds. Important constituents of the leaf include caffeoylquinic acid derivatives and flavonoids; sesquiterpene lactones, such as cynaropicrin, are also present.²

Evidence for efficacy

Preclinical studies have provided some evidence to support the reputed antioxidant, hepatoprotective, anticholesterolaemic, anti-cancer, prebiotic, hypoglycaemic, anti-insulin resistance, renoprotective, anti-inflammatory, cardioprotective, neuroprotective, and anti-obesity effects of globe artichoke leaf extracts and/or specific isolated constituents.³ Effects described in preclinical studies do not necessarily translate to the human clinical context.

Clinical research on globe artichoke leaf preparations has focused on effects on liver enzyme and lipid concentrations, blood pressure, anthropometric indices, and glycaemic control. However, there is currently no definitive evidence supporting the effects of globe artichoke leaf on these parameters.

A systematic review and meta-analysis of eight randomised, controlled clinical trials (RCTs) evaluating the effect of different globe artichoke preparations taken for 4–12 weeks on liver enzymes across various patient populations (N = 622, of which 331 were assigned to intervention groups) found significant reductions in aspartate aminotransferase (AST) (SMD: −1.20, 95% CI: −1.91 to −0.48; P = 0.001) and alanine transaminase (ALT) (SMD: −0.55, 95% CI: −1.00 to −0.10; P = 0.016) concentrations for globe artichoke when compared to placebo.⁴ Four studies were conducted under double-blind (participant, assessor) conditions. Another systematic review of five RCTs (two of which were included in the previous systematic review), involving a total of 333 patients with fatty liver, reported similar results, with statistically significant reductions in AST and ALT, but not alkaline phosphatase (ALP), concentrations.⁵ Both meta-analyses noted some (statistical) heterogeneity across results of different studies. Further, studies tested different product formulations, with some involving multi-ingredient products. Dosages tested also varied, and most included studies had some risk of bias.

A meta-analysis of 14 RCTs, involving a total of 960 patients, examining the effect of globe artichoke leaf extracts or artichoke juice (one study) on lipid profiles found significant reductions in triglyceride (TG) (weighted mean difference (WMD): −17.01 mg/dL, 95% CI: −23.88 to −10.13; P = 0.011), total cholesterol (TC) (WMD: −17.01 mg/dL, 95% CI: −23.88 to −10.13; P < 0.001), and LDL-C concentrations (WMD: −17.48 mg/dL, 95% CI: −25.44 to −9.53; P < 0.001), and no significant effect on HDL-C concentrations (WMD: 0.78 mg/dl, 95%CI: −0.93, 2.49, P = 0.371). However, the analysis highlighted limitations similar to those described above, with high heterogeneity among studies, testing of varying dosages of artichoke extract (50–2700 mg/day) and treatment durations ranging from 5 to 12 weeks.⁶

Systematic reviews have also evaluated the effects of globe artichoke preparations on blood pressure, anthropometric indices, and glycaemic control. A pooled analysis of data from eight RCTs involving 512 patients found no significant effect for globe artichoke on systolic blood pressure (SBP) or diastolic blood pressure (DBP) compared to placebo. However, subgroup analyses based on health status indicated that globe artichoke when used by patients with hypertension (three studies) significantly reduced SBP (WMD: −3.19 mmHg, 95% CI: −3.32 to −3.06) and DBP (WMD: −2.33 mmHg, 95% CI: −2.43 to −2.23).⁷ A pooled analysis of nine RCTs (512 patients) demonstrated that globe artichoke significantly reduced fasting blood glucose (WMD: −5.28 mg/dL, 95% CI: −8.95 to −1.61; P = 0.005). However, no significant changes were noted in other glycaemic indices, including fasting insulin and haemoglobin A1c (HbA1c) concentrations.⁸ A pooled analysis of 10 RCTs involving 588 patients reported that globe artichoke significantly reduced waist circumference (WMD: −1.11 cm, 95% CI: −2.08 to −0.14; P = 0.025), but had no significant effect on weight or BMI.⁹

A limitation of most of the systematic reviews described here is the non-specific target population: reviews included RCTs involving patients with various health conditions, including hypertension, diabetes, hypercholesterolaemia, and liver disease. This limits the ability to draw precise conclusions about the effects of globe artichoke interventions in specific patient groups, contributing to heterogeneity. The evidence is also limited by small sample sizes of clinical trials and short durations for most trials, making them unable to determine long-term effects. Larger, longer, methodologically robust trials testing well-characterised products are needed. Trial reports should provide comprehensive descriptions of the globe artichoke preparations tested, including whether products meet accepted standards for pharmaceutical quality.

Adverse effects

At present, there are no known safety concerns with globe artichoke products when consumed at recommended doses, but there is limited information on the effects of long-term and/or excessive use. Post-marketing surveillance studies involving patients with non-specific gastrointestinal complaints who received globe artichoke leaf extract for up to 6 months reported small numbers of mild, non-serious adverse events (weakness, hunger, flatulence).

Allergic contact dermatitis, including cross-sensitivity to other plants from the Asteraceae (Compositae) family, has been reported with globe artichoke. Cynaropicrin and other potentially allergenic sesquiterpene lactones are present in globe artichoke. VigiBase, the World Health Organization’s (WHO) global database of individual case safety reports (spontaneous reports) of suspected adverse drug reactions, maintained by the Uppsala Monitoring Centre on behalf of WHO, contains reports of hypersensitivity reactions and skin reactions associated with use of globe artichoke. Causality has not necessarily been established in these cases. Published case reports have described occupational contact urticaria syndrome (generalised urticaria, angioedema, and respiratory symptoms after handling globe artichokes, with skin-prick tests confirming a type-I allergy, in a 20-year-old woman) and allergy following ingestion of globe artichoke as a food.

The European Medicines Agency Community Herbal Monograph for Globe Artichoke leaf states that this substance is contraindicated in hypersensitivity to the active substance or to other plants of the Asteraceae family, and in obstruction of the bile duct, cholangitis, liver disease, gallstones and any other biliary disorders that require medical supervision and advice.¹⁰ Due to insufficient safety data, use of products containing globe artichoke in children, and by pregnant or breastfeeding women, should be avoided.

With respect to preclinical safety data, adequate tests on reproductive toxicity, genotoxicity and carcinogenicity have not been performed.

A comprehensive investigation of the clinical safety profile of globe artichoke leaf extracts, their constituents, and contemporary products, including where used in a pharmaceutical/medicinal context, is required.

Interactions

No drug interactions with globe artichoke have been reported. However, the potential for preparations of globe artichoke leaf to interact with other natural health products and medicines administered concurrently, particularly those with similar or opposing pharmacological effects, should be considered.