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Effect of Raw Garlic vs Commercial Garlic Supplements on Plasma Lipid Concentrations in Adults With Moderate Hypercholesterolemia: A Randomized Clinical Trial

Gardner CD, Lawson LD, Block E, Chatterjee LM, Kiazand A, Balise RR, Kraemer HC
Arch Intern Med. 2007 Feb 26;167(4):346-53

Alcune evidenze hanno promosso l’aglio a ruolo di agente ipocolesterolizzante, tuttavia, tale effetto non è stato del tutto confermato e gli studi condotti hanno prodotto risultati non omogenei. Una nuova indagine, pubblicata sugli Archives of Internal Medicine, ha verificato la capacità dell’aglio e di due integratori a base dello stesso vegetale, nell’abbassare i livelli di colesterolo LDL in 192 adulti affetti da ipercolesterolemia moderata (livelli di LDL: 130-190 mg/dl).
I partecipanti sono stati suddivisi in 4 gruppi e hanno assunto sei volte alla settimana, per sei mesi: aglio oppure uno dei due integratori in esame oppure un placebo. Mensilmente veniva prelevato un campione di sangue per la determinazione dei livelli di LDL e del profilo lipidico in generale.
Nel corso e al termine dello studio in nessuno dei quattro gruppo si sono osservate significative differenze nei livelli di colesterolo LDL, HDL, trigliceridi o nel rapporto colesterolo totale/HDL. Tali risultati confuterebbero le teorie secondo le quali l’aglio sarebbe utile per la salute cardiovascolare, tuttavia, puntualizzano gli autori, non è possibile escludere che l’aglio possegga un’azione diretta antinfiammatoria, antitumorale o antipertensiva.

BACKGROUND: Garlic is widely promoted as a cholesterol-lowering agent, but efficacy studies have produced conflicting results. Garlic supplements differ in bioavailability of key phytochemicals. We evaluated the effect of raw garlic and 2 commonly used garlic supplements on cholesterol concentrations in adults with moderate hypercholesterolemia. METHODS: In this parallel-design trial, 192 adults with low-density lipoprotein cholesterol (LDL-C) concentrations of 130 to 190 mg/dL (3.36-4.91 mmol/L) were randomly assigned to 1 of the following 4 treatment arms: raw garlic, powdered garlic supplement, aged garlic extract supplement, or placebo. Garlic product doses equivalent to an average-sized garlic clove were consumed 6 d/wk for 6 months. The primary study outcome was LDL-C concentration. Fasting plasma lipid concentrations were assessed monthly. Extensive chemical characterization of study materials was conducted throughout the trial. RESULTS: Retention was 87% to 90% in all 4 treatment arms, and chemical stability of study materials was high throughout the trial. There were no statistically significant effects of the 3 forms of garlic on LDL-C concentrations. The 6-month mean (SD) changes in LDL-C concentrations were +0.4 (19.3) mg/dL (+0.01 [0.50] mmol/L), +3.2 (17.2) mg/dL (+0.08 [0.44] mmol/L), +0.2 (17.8) mg/dL (+0.005 [0.46] mmol/L), and -3.9 (16.5) mg/dL (-0.10 [0.43] mmol/L) for raw garlic, powdered supplement, aged extract supplement, and placebo, respectively. There were no statistically significant effects on high-density lipoprotein cholesterol, triglyceride levels, or total cholesterol-high-density lipoprotein cholesterol ratio. CONCLUSIONS: None of the forms of garlic used in this study, including raw garlic, when given at an approximate dose of a 4-g clove per day, 6 d/wk for 6 months, had statistically or clinically significant effects on LDL-C or other plasma lipid concentrations in adults with moderate hypercholesterolemia.