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How Garlic Can Help Lower Blood Sugar

Garlic lovers rejoice! There is one more reason to love this aromatic herb: current literature suggests both fresh garlic and garlic supplements can lower blood sugar when eaten consistently. Learn how much to eat to harness these benefits.

cloves of raw garlic on a wood table
Table of Contents

There is evidence that Hippocrates himself, the famous doctor from ancient Greece, prescribed garlic to treat various health conditions.1 Today, garlic continues to be popular in health circles because of its potent antioxidants and immune function support, not to mention the yummy flavor it adds to meals! The next frontier for this ancient herb? Investigation into the potential link between garlic and lowering blood sugar levels. 

<p class="pro-tip"><strong>Learn about </strong><a href="/blog/spices-that-may-lower-blood-sugar">other herbs and spices that may lower blood sugar</a></p>

Can Garlic Really Reduce My Blood Sugar?

The general consensus on this question is yes, regular intake of garlic can help lower blood sugar. 

A review of studies in 2015 gathered the strongest data available that investigated the consumption of garlic on blood sugar control.2 Researchers compared the findings from all the studies and the final conclusion: garlic helps to lower fasting blood sugar, but the exact mechanism of how it works is still unknown. 

A study conducted in 2018 had participants eating raw crushed garlic twice a day with their standard meals over a four-week period.3 The addition of fresh garlic cloves had a beneficial effect on the symptoms associated with metabolic syndrome, including:

The conclusions of the study support the recommendation that garlic should be added to a diet to support better blood glucose control and reduce the risk of heart disease. 

<p class="pro-tip"><strong>Learn more about </strong><a href="/blog/average-glucose-ranges">normal blood sugar levels for people without diabetes</a></p>

How Quickly Can Garlic Lower Blood Sugar?

Taking a garlic supplement can reduce fasting blood sugar within 1-2 weeks.4 That’s an amazing turnaround time! 

<p class="pro-tip"><strong>Learn about </strong><a href="/blog/lower-blood-sugar-fast">11 natural ways to lower blood sugar</a></p>

woman riding a peloton bike indoors with windows in the background
Studies have linked garlic to a wide range of potential benefits, including immunity and athletic performance.

Other Health Benefits of Garlic

The most potent health-promoting ingredient in garlic is allicin.5 To activate allicin, you need to crush the garlic bulb and expose it to air.6 Cooking or pickling garlic will reduce some bioavailability of allicin (how much your body can absorb) but it will still be present. 

Research has linked garlic to an impressive range of health benefits, from reducing the risk of getting a cold to protecting against heavy metal toxicity. Some of the most significant benefits in terms of metabolic health include:

Inhibiting Tumor Growth

Allicin has been linked to shrinking tumors,7 specifically in people with colon cancer.Further studies are needed to determine potential adverse effects of herb-drug interactions for patients undergoing cancer treatment.

Antibacterial Agent

Allicin also contributes to garlic’s antibacterial properties and is often used to protect against harmful pathogenic microbes.9 Allicin has sulfur amino acid groups, so it can deactivate proteins in thiol groups (organic compounds that have a sulfur atom instead of an oxygen atom), which compromises the bacterial membrane.10

Improving Cardiovascular Health

Garlic is widely recommended to prevent and treat various cardiovascular diseases. It has also been linked to: 

  • Lowering high blood pressure 
  • Lowering LDL cholesterol levels 
  • Reducing harmful plaque buildup in the arteries 

The Mediterranean diet boasts many health benefits and relies heavily on garlic and several other ingredients. Many Mediterranean dishes include garlic with other herbs and spices potent in antioxidants and vitamins. Alone, these ingredients are healthful, but a theory within the Mediterranean diet is that the ingredients have a synergistic effect when they are cooked together.11 Following a Mediterranean diet has been shown to decrease inflammation and support excellent health.12

Popular Mediterranean dishes often include garlic, onion, tomato, olive oil, and green herbs such as parsley and oregano.

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How to Include More Garlic in Your Diet

The biggest barrier to regular garlic intake is the dreaded bad breath after eating it! Some people are extra sensitive, and will even notice a garlic smell seeping from their pores hours after consuming large amounts of fresh garlic. 

A trick to reduce the strong taste of raw garlic is to chop or mince it and set it aside for ten minutes. After oxygen has reacted with the garlic, the intensity should subside, resulting in a mellower flavor. Now you can add fresh garlic to salads or your favorite dressings!

Try this versatile vegan summer salad dressing with fresh garlic: 

  • ⅓ cup olive oil 
  • ⅓ cup red wine vinegar or lemon juice 
  • 1 tsp honey 
  • 1 tbsp grainy dijon mustard 
  • 1 garlic clove, crushed and minced
  • ½ tsp each: dried basil, dried oregano, dried parsley

Mix all ingredients and refrigerate in an airtight container for up to one week

Cooked garlic is less pungent and easier to incorporate into meals. You can either cook garlic into your stovetop recipes, like soups, or roast a bulb of garlic and add it to your meals after. 

roasted garlic in a cast iron skillet
Garlic is not only low in calories, it’s a good source of vitamins B1, B6, and C.

How to Roast Garlic: 

  • Preheat oven to 400°F
  • Slice entire garlic bulb in half (across the cloves) and drizzle with one teaspoon olive oil 
  • Loosely wrap garlic in aluminum foil and place in oven to bake 
  • Check after thirty minutes. It is ready to eat when the cloves have browned. 
  • Allow the bulb to cool completely before gently squeezing the cloves out. You can store roasted garlic in the refrigerator for up to a week.

Slow-roasting caramelizes the cloves and reduces the harsh taste. Roasted garlic is slightly sweet and can be used in a variety of foods like salads, sandwiches, stir fry, potatoes, spreads, and much more.

<p class="pro-tip"><strong>Explore </strong><a href="/blog-category/recipes">healthy recipes from Signos</a></p>

If the smell of fresh garlic is too much for you, consider opting for a supplement. Choose a brand with the highest concentration to ensure you still get all the health benefits. 

Garlic salt and garlic powder are ineffective replacements if you want to reap the blood sugar and health benefits of garlic. Although garlic salt and powder contain trace amounts of garlic, it’s is not enough to have an impact on your overall health. 

Are Garlic Supplements Worth It?

All garlic supplements are not created equal. Some of the formulas completely strip away the sulfur compounds that we know contain medicinal properties. Without these compounds present, certain garlic supplements will be significantly less effective. 

A review from 2016 presented positive findings on the use of garlic supplements and reducing the risk of cardiovascular outcomes. They reported an overall reduction in blood pressure by up to 16 points and reduced total cholesterol from approximately 7-28mg/dL.13

It is worth noting that participants across the studies who consumed aged garlic displayed the most significant improvements in their bloodwork. 

Aged garlic is created by heating regular garlic so the active compounds can become more stable. The result is a bulb that is more potent with antioxidants, and the strong odor is usually neutralized, which may appeal to some people.14

Some garlic products have not yet been researched for their role in lowering blood sugar, including:

  • Garlic oil 
  • Pickled garlic
  • Garlic tea
  • Garlic powder

These kinds of garlic products are likely not potent enough compared to fresh garlic or concentrated garlic supplements. You can certainly enjoy garlic products like these, but they may not be effective in lowering your blood glucose. 

<p class="pro-tip"><strong>Read about </strong><a href="/blog/powder-supplements">how to choose a powder supplement</a></p>

Potential Negative Side Effects and Interactions

People who are sensitive to acid reflux should limit their intake of raw garlic. Even small amounts can trigger symptoms and cause discomfort. 

People who have irritable bowel syndrome (IBS) or other digestive sensitivities may not tolerate garlic well, even cooked. There are compounds within garlic that can be difficult to break down, and they can produce large amounts of gas. Although this will not harm your health, it is very uncomfortable. 

<p class="pro-tip"><strong>Learn more about </strong><a href="/blog/gut-health-and-weight-loss">gut health, blood sugar, and weight loss</a></p>

Though there are historical records of people applying garlic to wounds to promote healing and prevent infections, this use is not recommended. Garlic can cause chemical burns and severe discomfort.  

Any person who regularly takes Warfarin (a blood thinner) should avoid garlic supplements, because they can interfere with the medication and cause bleeding. Eating foods with small amounts of garlic should be fine, but double-check with your doctor if you’re on Warfarin therapy.

If you are taking any prescription medication or have an upcoming or recent surgery, consult with your healthcare team before starting a garlic supplement. 

How Can I Tell if Garlic Is Improving My Blood Sugar Levels? 

The easiest and fastest way to tell if a change in your diet is improving your blood sugar is to look at the data! A CGM device takes a blood glucose reading every five minutes and gives you an accurate picture of how your glucose levels are changing throughout the day. 

Studies suggest that moderate amounts of garlic can lower your blood sugar after one week, but for some people, it could be longer. There is also some evidence that eating garlic more frequently can help. 

Try to make a point of adding garlic to at least two of your meals per day and see what your fasting glucose numbers are after one week. To increase your chances of seeing significant improvement, try to include low glycemic index foods as often as possible. Low-GI carbohydrates are filling and should have little impact on your blood sugar. 

If you prefer, you can buy garlic supplements (most of them are very affordable) and follow a similar regimen. After two weeks you should see some improvements, even if they are minor. 

<p class="pro-tip"><strong>Read about </strong><a href="/blog/lower-blood-sugar-fast">natural ways to lower blood sugar quickly</a></p>

Key Takeaways

Both fresh garlic and garlic supplements can help support your overall health and lower your blood sugar. Choose fresh garlic rather than supplements whenever possible because is has more bioavailable allicin compounds. 

To enhance the benefits of fresh garlic and dial back the sharp taste, crush or mince some garlic and let it rest exposed to air for ten minutes. 

If you hate the taste or smell of garlic, a supplement may be a good option for you. Try to find one with aged garlic extract in the formula, because aged garlic tends to offer the best results based on bloodwork. 

Garlic supplements should not be consumed if you regularly take blood-thinning medication or have surgery. Always talk to your doctor before starting a new supplement.

<p class="pro-tip"><strong>Learn more about </strong><a href="/blog/cgm-data-weight-loss">using CGM data to track your blood glucose response</a></p>

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References

  1. Rivlin, R. S. (2001). Historical Perspective on the Use of Garlic. The Journal of Nutrition, 131(3), 951S-954S. https://doi.org/10.1093/jn/131.3.951s 
  2. Hou, L., Liu, Y., & Zhang, Y. (2015). Garlic intake lowers fasting blood glucose: meta-analysis of randomized controlled trials. Asia Pacific Journal of Clinical Nutrition, 24(4), 575–582. https://doi.org/10.6133/apjcn.2015.24.4.15 
  3. Choudhary, P. R., Jani, R. D., & Sharma, M. S. (2017). Effect of Raw Crushed Garlic (Allium sativumL.) on Components of Metabolic Syndrome. Journal of Dietary Supplements, 15(4), 499–506. https://doi.org/10.1080/19390211.2017.1358233 
  4. Wang, J., Zhang, X., Lan, H., & Wang, W. (2017). Effect of garlic supplement in the management of type 2 diabetes mellitus (T2DM): a meta-analysis of randomized controlled trials. Food & Nutrition Research, 61(1), 1377571. https://doi.org/10.1080/16546628.2017.1377571 
  5.  Bayan, L., Koulivand, P. H., & Gorji, A. (2014). Garlic: a review of potential therapeutic effects. Avicenna journal of phytomedicine, 4(1), 1–14. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4103721/#:~:text=Allicin%20 
  6. Lawson, L. D., & Hunsaker, S. M. (2018). Allicin Bioavailability and Bioequivalence from Garlic Supplements and Garlic Foods. Nutrients, 10(7), 812. https://doi.org/10.3390/nu10070812 
  7. Oommen, S., Anto, R. J., Srinivas, G., & Karunagaran, D. (2004). Allicin (from garlic) induces caspase-mediated apoptosis in cancer cells. European journal of pharmacology, 485(1-3), 97–103. https://doi.org/10.1016/j.ejphar.2003.11.059
  8. Sarvizadeh, M., Hasanpour, O., Naderi Ghale-Noie, Z., Mollazadeh, S., Rezaei, M., Pourghadamyari, H., Masoud Khooy, M., Aschner, M., Khan, H., Rezaei, N., Shojaie, L., & Mirzaei, H. (2021). Allicin and Digestive System Cancers: From Chemical Structure to Its Therapeutic Opportunities. Frontiers in oncology, 11, 650256. https://doi.org/10.3389/fonc.2021.650256
  9. Ankri, 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
  10. Bhatwalkar, S.B., Mondal, R., Krishna, S.B.N., Adam, J.K., Govender, P., & Anupam, R. (2021) Antibacterial Properties of Organosulfur Compounds of Garlic (Allium sativum). Frontiers in Microbiology, 12:613088. https://www.frontiersin.org/articles/10.3389/fmicb.2021.613077/full
  11. Dennett, MPH, RDN, CD, C. (2016, May). Key Ingredients of the Mediterranean Diet — The Nutritious Sum of Delicious Parts - Today’s Dietitian Magazine. Key Ingredients of the Mediterranean Diet — The Nutritious Sum of Delicious Parts. Retrieved July 2022, from https://www.todaysdietitian.com/newarchives/0516p28.shtml 
  12. Tsigalou, C., Konstantinidis, T., Paraschaki, A., Stavropoulou, E., Voidarou, C., & Bezirtzoglou, E. (2020). Mediterranean Diet as a Tool to Combat Inflammation and Chronic Diseases. An Overview. Biomedicines, 8(7), 201. https://doi.org/10.3390/biomedicines8070201
  13. Varshney, R., & Budoff, M. J. (2016). Garlic and Heart Disease. The Journal of Nutrition, 146(2), 416S-421S. https://doi.org/10.3945/jn.114.202333 
  14. Elosta, A., Slevin, M., Rahman, K., & Ahmed, N. (2017). Aged garlic has more potent antiglycation and antioxidant properties compared to fresh garlic extract in vitro. Scientific reports, 7, 39613. https://doi.org/10.1038/srep39613

About the Author

Julia Zakrzewski is a Registered Dietitian and nutrition writer. She has a background in primary care, clinical nutrition, and nutrition education. She has been practicing dietetics for four years.
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Please note: The Signos team is committed to sharing insightful and actionable health articles that are backed by scientific research, supported by expert reviews, and vetted by experienced health editors. The Signos blog is not intended to diagnose, treat, cure or prevent any disease. If you have or suspect you have a medical problem, promptly contact your professional healthcare provider. Read more about our editorial process and content philosophy here.

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