Maximizing the Health Benefits of Garlic
Prepared by Dr. James Dennis C. Gumpal, M.D., J.D.
Garlic (Allium sativum) is famous for its numerous health benefits, which are largely attributed to its bioactive compounds like allicin, diallyl disulfide, and S-allylcysteine.
These compounds are formed and activated depending on how garlic is prepared. While raw garlic is often considered the healthiest, how you use and store garlic can impact its health-promoting properties.
Raw Garlic: The Healthiest Option
Raw garlic is packed with allicin, a sulfur compound that forms when the garlic is chopped or crushed. Allicin is responsible for many of garlic’s health benefits, such as:
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Heart health: Garlic can help lower blood pressure and improve cholesterol levels. Research by Ried et al. (2013) shows that garlic supplements can reduce high blood pressure by 4-5 mmHg for systolic pressure and 2-3 mmHg for diastolic pressure in people with hypertension. It also helps reduce “bad” LDL cholesterol, both of which are major contributors to heart disease.
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Antioxidant and anti-inflammatory effects: Garlic contains powerful antioxidants that neutralize harmful molecules called free radicals, reducing damage to cells (Rahman, 2007). It also boosts antioxidant enzymes like superoxide dismutase and glutathione peroxidase, which further protect cells from damage. Garlic’s anti-inflammatory properties can lower levels of CRP, a marker of inflammation tied to chronic diseases like heart disease and arthritis (Harun et al., 2016).
Fighting infections: Allicin has strong antimicrobial effects, helping to fight off bacteria, fungi, and viruses. Research by Ankri and Mirelman (1999) shows that garlic is particularly effective against infections like Helicobacter pylori (which causes stomach issues) and Staphylococcus aureus. This makes raw garlic a natural way to boost your immune system and fight infections.
Crushed and Left to Sit Before Cooking:
The Next Best Option
When garlic is fried at high temperatures, it loses many of its health benefits. The key compound in garlic, allicin, which is responsible for its ability to improve heart health and lower blood pressure, breaks down quickly when exposed to heat.
Although frying garlic might still leave some antioxidants intact, the benefits are greatly reduced, and harmful substances like acrylamide can form, especially when cooking starchy foods at high temperatures.
Studies show that the heart health benefits of garlic, like its ability to reduce blood pressure and cholesterol, mainly come from its sulfur compounds, particularly allicin. Frying garlic destroys much of this, which lowers its effectiveness in promoting heart health (Rahman, 2007).
While frying garlic reduces its overall health benefits, it may still retain some antioxidant properties, though far less than raw or lightly cooked garlic (Li et al., 2022; Bioactive Compounds and Biological Functions of Garlic, 2022)
Pickled Garlic: A Milder, Easier Option
Pickling garlic involves preserving it in a vinegar or brine solution, which can extend its shelf life and soften its sharp flavor. However, the pickling process reduces allicin levels, so the health benefits are not as robust as those of raw garlic.
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Moderate antioxidant activity: Pickled garlic retains some antioxidant compounds, though at lower concentrations compared to raw garlic. According to Thomson and Ali (2003), garlic’s anti-cancer and heart-protective properties are tied to its sulfur compounds, which are reduced during pickling.
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Probiotic benefits: If the garlic is fermented during the pickling process, it can offer probiotic benefits that may support gut health, though further studies are needed to fully understand these effects in humans.
Aged Garlic Extract: A Heart-Healthy Supplement
Aged garlic extract (AGE) is produced by fermenting raw garlic over time, allowing it to form stable, potent compounds like S-allylcysteine. AGE has been widely studied and is considered one of the most effective garlic supplements, particularly for cardiovascular health.
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Heart health benefits: AGE has been shown to improve blood pressure and cholesterol levels. A study by Sobenin et al. (2019) found that AGE supplementation reduced systolic blood pressure by 7-9 mmHg and diastolic pressure by 4-6 mmHg, making it an effective treatment for hypertension.
Reduced side effects: AGE is also less harsh on the digestive system and doesn't cause garlic breath, which makes it a better option for people who are sensitive to raw garlic.
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Storing crushed garlic in olive or coconut oil in the refrigerator can help preserve some of its antioxidant properties, but it’s important to note that allicin breaks down quickly—within hours of crushing or chopping. While other compounds (like S-allylcysteine) remain stable, the highest levels of allicin, and therefore peak health benefits, will diminish over time. Refrigeration slows this process, but allicin degrades even in cold storage.
Oxidation protection: Olive and coconut oils help protect garlic from air, reducing oxidation and preserving antioxidants, but the loss of allicin is inevitable over time (Rahman, 2007).
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Botulism risk: One major concern with storing garlic in oil is the potential for Clostridium botulinum to grow in this anaerobic environment, leading to botulism. To reduce this risk, always store garlic in oil in the refrigerator and use it within one week. For longer storage, freeze the garlic-oil mixture in small portions.
Storing Garlic in Oil: Does It Retain Health Benefits?
Notes
[1] Antioxidants are natural compounds in certain foods that help protect our bodies from damage caused by harmful molecules called free radicals. Think of your body like a car engine: as the car runs, waste builds up, which can eventually cause harm. Similarly, when we eat, exercise, or are exposed to things like pollution and sunlight, our bodies produce free radicals that can damage cells, leading to aging, inflammation, and diseases such as heart disease and cancer.
Antioxidants act like rust protectors for the body, preventing these free radicals from causing too much harm. They help keep our cells healthy and lower the risk of health problems. You can find antioxidants in many foods, including fruits like berries and oranges, vegetables like spinach and broccoli, and even in nuts and green tea.
Research shows that antioxidants help slow down cell damage and support overall health by neutralizing these harmful molecules.
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Peer-reviewed journal references:
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Tian, Y., Liu, S., & Zhang, L. (2017). Antioxidants and their beneficial effects on health. Journal of Medicinal Food, 20(6), 509-517. https://doi.org/10.1089/jmf.2017.0036
Xiao, J., Wang, Q., & Zhang, L. (2019). The role of antioxidants in human health: A review. Critical Reviews in Food Science and Nutrition, 59(9), 1401-1413. https://doi.org/10.1080/10408398.2018.1507672
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[2] Helicobacter pylori is a major cause of stomach and duodenal ulcers. This bacterium damages the protective lining of the stomach and small intestine, leading to inflammation (gastritis) and the formation of ulcers. H. pylori infection is highly associated with peptic ulcer disease, and treating the infection can significantly reduce the recurrence of ulcers.
Peer-reviewed journal references:
Malfertheiner, P., Chan, F. K. L., & McColl, K. E. L. (2009). Peptic ulcer disease. The Lancet, 374(9699), 1449–1461. https://doi.org/10.1016/S0140-6736(09)60938-7
Suerbaum, S., & Michetti, P. (2002). Helicobacter pylori infection. The New England Journal of Medicine, 347(15), 1175–1186. https://doi.org/10.1056/NEJMra020542
Fock, K. M., Katelaris, P., Sugano, K., Ang, T. L., Hunt, R., Talley, N. J., Lam, S. K., Xiao, S. D., & Tan, H. J. (2009). Second Asia–Pacific Consensus Guidelines for Helicobacter pylori infection. Journal of Gastroenterology and Hepatology, 24(10), 1587–1600. https://doi.org/10.1111/j.1440-1746.2009.05982.x
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[3] Staphylococcus aureus is a bacterium that can cause a wide range of infections in the human body. It can affect various parts of the body, including the skin, bones, joints, heart valves, and respiratory system. The bacterium can also lead to severe infections, such as sepsis and toxic shock syndrome.
Some effects of Staphylococcus aureus on the body include:
Skin Infections: It is a common cause of skin infections like boils, abscesses, and cellulitis.
Respiratory Infections: It can cause pneumonia, especially in individuals with weakened immune systems.
Bone and Joint Infections: S. aureus can lead to osteomyelitis (bone infection) and septic arthritis (joint infection).
Toxic Shock Syndrome: A rare but life-threatening condition caused by toxins produced by the bacteria.
Sepsis: A systemic infection that can result in organ failure and death if untreated.
Staphylococcus aureus can also become antibiotic-resistant, particularly the Methicillin-resistant Staphylococcus aureus (MRSA) strain, which makes it more difficult to treat.
Peer-reviewed journal references:
Kahl, B. C., & Herrmann, M. (2009). Staphylococcus aureus infections in humans. Infectious Disease Clinics of North America, 23(1), 17-34. https://doi.org/10.1016/j.idc.2008.11.002
Lowy, F. D. (1998). Staphylococcus aureus infections. New England Journal of Medicine, 339(8), 520-532. https://doi.org/10.1056/NEJM199808203390806
Chambers, H. F., & DeLeo, F. R. (2009). Methicillin-resistant Staphylococcus aureus: Advancing disease, changing therapy. Nature Reviews Microbiology, 7(7), 529-536. https://doi.org/10.1038/nrmicro2160
Peer-reviewed journal references:
Rahman, K. (2007). Effects of garlic on platelet biochemistry and physiology. Molecular Nutrition & Food Research, 51(11), 1335-1344. https://doi.org/10.1002/mnfr.200600281
Ried, K., Fakler, P., & Stocks, N. P. (2013). Effect of garlic on blood pressure: A systematic review and meta-analysis. BMC Cardiovascular Disorders, 13(1), 1-8. https://doi.org/10.1186/1471-2261-13-48Ankri, S., &
Mirelman, D. (1999). Antimicrobial properties of allicin from garlic. Microbes and Infection, 1(2), 125-129. https://doi.org/10.1016/S1286-4579(99)80003-3
Sobenin, I. A., Andrianova, I. V., Demidova, O. M., & Gorchakova, T. V. (2019). The effects of time-released garlic powder tablets on multifunctional cardiovascular risk in patients with arterial hypertension. Russian Journal of Cardiology, 24(1), 75-81. https://doi.org/10.15829/1560-4071-2019-1-75-81
Thomson, M., & Ali, M. (2003). Garlic [Allium sativum]: A review of its potential use as an anticancer agent. Current Cancer Drug Targets, 3(1), 67-81. https://doi.org/10.2174/1568009033333756