Garlic is a seasoning used as both a food flavoring and a traditional medicine across various cultures. Its bioactive compounds, like allicin and ajoene, provide health benefits. Garlic helps with atherosclerosis, hypertension, and insulin resistance, and promotes gut health by increasing good bacteria. It also improves inflammation, obesity, and liver issues. Garlic can support weight loss and reduce fat accumulation. Some studies on garlic's effects in people with metabolic syndrome have shown beneficial results.
A double-blind, randomized controlled clinical trial investigated the effect of garlic supplementation on metabolic syndrome components, insulin resistance, fatty liver index, and appetite in subjects with metabolic syndrome. Ninety subjects were assigned to either receive 1,600 mg/d garlic powder (4 tablets of 400 mg each, containing 6 mg/d allicin or ~ 2 g of raw garlic) or placebo for 3 months. The study participants were asked to consume two tablets an hour before lunch and two tablets an hour before dinner. The primary outcomes included metabolic syndrome components. The secondary outcomes included insulin resistance, fatty liver index, and appetite (1).
Garlic supplementation compared with the placebo led to a significant increase in high-density lipoprotein-cholesterol (4.5 vs. -1.8, mg/dL, p < .001) and a reduction in waist circumference (-1.3 vs. 0.0, cm, p = .001), diastolic blood pressure (-6.7 vs. 0.0, mmHg, p < .001), systolic blood pressure (-7.7 vs. 0.5, mmHg, p < .001), triglyceride (-40.0 vs. 0.1, mg/dL, p < .001), γ-glutamyl transferase (-3.2 vs. 0.6, IU/L, p = .01), fatty liver index (-5.5 vs. 0.1, p < .001), insulin (-2.9 vs. -1.1, mU/L, p < .001), homeostatic model of assessment for insulin resistance (-0.5 vs. -0.3, p < .001) and appetite (hunger: -11.7 vs. 1.7, p < .001; fullness: 10.0 vs. 0.3, p = .001; desire to eat: -6.7 vs. 2.1, p < .001; and ability to eat: -11.5 vs. -1.0, p < .001). These results showed that garlic supplementation improved metabolic syndrome components, insulin resistance, fatty liver index, and appetite (1).
One study investigated the effect of raw crushed garlic on components of metabolic syndrome. A total of 40 metabolic syndrome patients were randomly selected from the diabetic center of SP Medical College, Bikaner, Rajasthan, India. They underwent treatment with 100 mg/kg body weight raw crushed garlic 2 times a day with the standard diet for 4 weeks; their anthropometric and serum biochemical variables were measured at the beginning and the end of the study (2).
Raw crushed garlic significantly reduced components of metabolic syndrome including waist circumference (101.41 ± 8.59 to 97.95 ± 6.58 cm, p < 0.05), systolic blood pressure (150.25 ± 14.65 to 140.22 ± 5.39 mmHg, p < 0.001) and diastolic blood pressure (96.40 ± 9.21 to 84.10 ± 3.65 mmHg, p < 0.001), triglycerides (170.49 ± 40.24 to 146.46 ± 36.21 mg/dL, p < 0.01), fasting blood glucose (165.02 ± 25.10 to 120.14 ± 10.18 mg/dL, p < 0.0001), and significantly increased serum high-density lipoprotein cholesterol (40.36 ± 4.51 to 46.27 ± 3.92 mg/dL, p < 0.0001). No significant difference was found in the body mass index of patients with metabolic syndrome after consuming raw crushed garlic for 4 weeks. Raw crushed garlic showed beneficial effects on components of metabolic syndrome. Garlic can be used as an accompanying remedy for preventing and treating patients with metabolic syndrome (2).
A randomized, double-blind, placebo-controlled trial examined the effects of garlic extract on arterial stiffness and markers of endothelial function in obese people. Ninety-two study participants were randomly assigned to receive 400 mg of garlic extract or placebo daily for 3 months. The arterial stiffness index and markers of endothelial function such as high-sensitivity C-reactive protein, cholesterol (total, LDL, HDL), triglycerides, and plasminogen activator inhibitor 1, as well as total antioxidant status, were quantified at baseline and the end of the study (3).
At the end of the study arterial stiffness index (p = 0.01), high-sensitivity C-reactive protein (p < 0.001, plasminogen activator inhibitor 1 (p < 0.001), LDL cholesterol (22% reduction, p < 0.001) were reduced and total antioxidant status (p < 0.01) were increased in the garlic extract-supplemented group, but not in the placebo group. Total cholesterol levels in the garlic and placebo groups were 5.01 ± 0.74 and 5.32 ± 0.92 mmol/L at baseline and were significantly different at the end of the study 4.84 ± 0.82 and 5.44 ± 0.84 mmol/L (p<0.001). The garlic extract-supplemented group also had a significant average of 3 kg in body weight reduction at the end of the study compared to the baseline (p < 0.01) (3).
These results demonstrated that supplementation with garlic extract favorably modified endothelial biomarkers associated with cardiovascular risk and suggested that garlic extract can suppress chronic inflammation in obese individuals (3).
Garlic contains a sulfur compound called alliin, which turns into allicin when the garlic is crushed or chopped. The allicin content in garlic varies depending on how it's prepared and consumed. Fresh garlic contains about 2.5 to 4.5 mg of allicin per gram of raw garlic. Allicin helps lower cholesterol by blocking key enzymes involved in cholesterol production, like HMG-CoA synthase. Garlic reduces cholesterol production in the liver and lowers triglycerides by stopping the formation of fatty acids.
The prevalence of metabolic syndrome is increasing. It is closely linked to nonalcoholic fatty liver disease. Consuming rich sources of allicin such as garlic, onion, scallion, and leek can be beneficial for managing metabolic syndrome.
References:
1. Sangouni AA, Alizadeh M, Jamalzehi A, Parastouei K. Effects of garlic powder supplementation on metabolic syndrome components, insulin resistance, fatty liver index, and appetite in subjects with metabolic syndrome: A randomized clinical trial. Phytother Res. 2021 Aug;35(8):4433-4441. doi: 10.1002/ptr.7146. Epub 2021 May 11. PMID: 33974725.
2. Choudhary PR, Jani RD, Sharma MS. Effect of Raw Crushed Garlic (Allium sativum L.) on Components of Metabolic Syndrome. J Diet Suppl. 2018 Jul 4;15(4):499-506. doi: 10.1080/19390211.2017.1358233. Epub 2017 Sep 28. PMID: 28956671.
3. Szulińska M, Kręgielska-Narożna M, Świątek J, Styś P, Kuźnar-Kamińska B, Jakubowski H, Walkowiak J, Bogdański P. Garlic extract favorably modifies markers of endothelial function in obese patients -randomized double blind placebo-controlled nutritional intervention. Biomed Pharmacother. 2018 Jun;102:792-797. doi: 10.1016/j.biopha.2018.03.131. Epub 2018 Apr 5. PMID: 29604599.
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