The Health Benefits of Garlic

by | Oct 24, 2024 | Botanicals, Garlic, Recent Articles

Written by Harold Oster, MD. Garlic, commonly consumed worldwide, has several bioactive compounds, giving it significant health benefits as a spice and a supplement.

garlicGarlic is a member of the Amaryllidaceae family and is well known for its taste and odor. It has been cultivated as a spice and a medicine for over a thousand years. Garlic’s therapeutic effects are due to several compounds, including allicin, an organic sulfide responsible for garlic’s characteristic flavor and aroma, polyphenols, saponins, and polysaccharides. These compounds have anti-inflammatory and antioxidant properties and affect multiple enzymatic and signaling pathways. In vitro and in vivo studies demonstrate garlic’s probiotic, chemopreventive, antidiabetic, and cardioprotective effects1,2.

Garlic’s Anti-Inflammatory and Immune System Benefits

Chronic inflammation and the oxidative stress that follows can accelerate the effects of aging3 and lead to numerous conditions, including diabetes, heart disease, neurological disease, and cancer4. Allicin and other compounds in garlic significantly affect the immune system, suppressing inflammation through its effects on enzymatic pathways and oxidative stress. Finally, garlic may have antimicrobial properties, perhaps improving resistance to infection5.

Garlic’s Effect on the Intestinal Microbiome

The intestinal microbiome has been implicated in various diseases, including diabetes, cardiovascular disease, cancer6, and cognitive decline7. As a prebiotic, garlic can help increase intestinal bacterial diversity and improve dysbiosis8.

Metabolic Effects of Garlic

The incidence of diabetes is increasing globally, mainly due to the increased incidence of obesity. Diabetes is a risk factor for cardiovascular disease, retinopathy, and renal failure. While study results have been mixed, and the effects are modest, garlic may lower glucose levels in diabetics and those with metabolic syndrome9. Antioxidant and anti-inflammatory properties are thought to be behind these effects. Garlic also appears to improve cholesterol levels, likely by reducing its absorption and endogenous production10. Metabolic dysfunction-associated steatotic liver disease is commonly associated with diabetes and obesity and has become one of the leading causes of cirrhosis in the United States. Garlic, through its effects on insulin resistance and inflammation, may improve this condition11.

Garlic and Cardiovascular Disease

Despite improvements in treatment and prevention, cardiovascular disease remains the most common cause of death in the United States. The risk factors of heart disease include hypertension12, diabetes, and chronic inflammation13. Garlic can help lower blood pressure in individuals with hypertension due to its antioxidant properties, effects on endothelial function, and inhibition of angiotensin-converting enzyme14. As expected with garlic’s effects on blood pressure and other risk factors, the incidence of coronary disease decreases in those taking garlic supplements. Studies suggest garlic supplements may reduce coronary calcification, low attenuation plaque, vascular conductance, carotid intima-media thickness, and platelet activity15.

Garlic and Cancer

In vitro studies have shown allicin and other compounds in garlic to have significant anti-cancer effects. Perhaps because of garlic’s low bioavailability, conclusive results in human studies have been sparse16. The most compelling evidence in humans is with gastrointestinal cancers.  A recent meta-analysis suggests that garlic intake is associated with a 35% reduction in the risk of stomach cancer and a 25% reduction in the risk of colorectal cancer17.

Garlic supplementation is generally safe. There is a low risk of allergy, and at high doses, there may be gastrointestinal side effects18. Discussion with a provider is wise before taking a regular supplement because of the possibility of side effects or drug interactions.

Harold Oster, MD graduated from medical school in Miami, Florida in 1992 and moved to Minnesota in 2004. After more than 25 years of practicing Internal Medicine, he recently retired. Dr. Oster is especially interested in nutrition, weight management, and disease prevention. Visit his website at haroldoster.com.

References:

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