## 2 Drifting from Molecular to Clinical Evidence
### Cardioprotective Activity
#### 2.1.2 Hyperlipidemia and Hypertension  
Multiple clinical trials have been performed to assess the effects of garlic and its derived products on hyperlipidemia and hypertension (Table 1). A 12-week double-blind study was carried out to compare standard garlic powder tablet and placebo effects on serum lipids, lipoproteins, blood pressure, and glucose levels. During that study, 42 healthy adults (19 men, 23 women, mean age of 52 \(\pm\) 12 years) were enrolled, whose serum total cholesterol (TC) was greater than or equal to 220 mg/dL [30]. All the subjects received, either standardized garlic powder in form of a tablet (dose 300 mg, 3 times/day) or a placebo, in a randomized, double-blind study design. Daily diets and physical activity were unchanged. After 12 weeks, the obtained data clearly showed a decrease in TC (262 \(\pm\) 34 mg/dL to 247 \(\pm\) 40 mg/dL) in the group receiving the standardized garlic powder tablet, when compared to the placebo group (276 \(\pm\) 34 mg/dL to 274 \(\pm\) 29 mg/dL, _p_\(<\) 0.01). Low-density lipoprotein cholesterol (LDL-c) levels decreased 11% in garlic-treated subjects, and only 3% in the placebo group (_p_\(<\) 0.05). No significant changes in serum high-density lipoprotein cholesterol (HDL-c), triglycerides, blood pressure, and glucose levels were observed. Thus, standardized garlic treatment (900 mg/day) seemed to be most effective in reducing LDL-c levels [30]. Conversely, aged garlic extract supplementation was shown to be more effective than the placebo in lowering systolic blood pressure, similar to current first-line medications, in patients with treated but uncontrolled hypertension [27]. Kwai (900 mg garlic pill/day), for instance, was effective in treating mild and moderate arterial hypertension [28]. Quite the opposite, the same preparation had no significant effects on LDL oxidation, plasma lathosterol-I-cholesterol ratio (a measure of cholesterol synthesis), nor LDL receptor expression in lymphocytes. Therefore, it was proposed by [PERSON] et al. (1995) that garlic ingestion did not provide pronounced effects on lipids and lipoproteins [31]. Likewise, Kwai garlic (standardized to 0.6% alicin and 1.3% alilin) supplement cannot change the oxidized LDL levels. The results of this study do not support the hypothesis that dietary garlic supplementation decreases the LDL susceptibility to oxidation, and that LDL fraction patterns in plasma might be involved. lipoprotein levels in plasma also were unchanged, although other mechanisms of cardiovascular protection were not excluded [41]. A meta-analysis did not suggest a significant effect of garlic supplementation on lipoprotein(a) (Lp (a)) level reduction [32]. A garlic treatment with a dose of 900 mg garlic extract/tablet for 12 weeks does not affect major plasma lipoproteins and has no impact on HDL-c subclasses, Lp (a), apolipoprotein B, postprandial triglycerides or LDL-c subclass distribution [34]. Moreover, no significant effects on cardiovascular risk factors were stated in pediatric patients with familial hyperlipidemia [35], as well as being ineffective in reducing cholesterol levels [36]. Another study highlighted that a garlic powder preparation used in moderately hypercholesterolemia adults did not significantly affect plasma lipid levels, suggesting that there was no indication of a better effect by garlic doses over 0, 500, and 1000 mg/day [40]. Other authors also reported no significant changes in serum HDL-c, triglycerides, blood pressure, and glucose levels [30]. A garlic powder (800 mg/day) treatment, for example, led to a significant increase in walking distance ability and to a decrease in diastolic blood pressure, spontaneous thrombocyte aggregation, plasma viscosity, and cholesterol concentration [29]. Similarly, 900 mg of garlic powder per day for four months significantly lowered total cholesterol, triglycerides, and blood pressure [33].