Garlic (Allium sativum) is an herb used for its flavor, scent, and potential therapeutic properties. It is most commonly used to flavor food, but garlic can also be processed and made into dietary supplements. In some cultures, garlic is used for medicinal purposes. The chemical in garlic of most interest for health purposes is allicin, which gives garlic its strong taste and odor. One of the claims for garlic is that the rates of certain diseases are lower in countries where lots of garlic is consumed. However, it has not been proven that garlic (and not some other factor such as lifestyle) is the reason.
Summary of the research findings
Few rigorous studies have been conducted on garlic, allicin, or both, for type 2 diabetes. In the studies that have been done, findings have been mixed. There are some intriguing basic science studies that suggest that garlic has some biological activities that are relevant to the treatment of diabetes. However, the evidence so far does not support that there is any benefit from garlic for type 2 diabetes.
Side effects and other risks
Garlic is safe for most adults. However, garlic appears to interact with various types of drugs. For example, when combined with certain medicines used to treat HIV/AIDS (NNRTIs and saquinavir), garlic may decrease their effectiveness. Garlic may also interact with and affect the action of birth control pills, cyclosporine, medications that are broken down by the liver, and blood thinners (including warfarin). Other possible side effects of garlic include an odor on the breath or skin, an allergic reaction, stomach disorders, diarrhea, and skin rash.
- There is limited scientific evidence on the effectiveness of dietary supplements as complementary and alternative medicine (CAM)A group of diverse medical and health care systems, practices, and products that are not presently considered to be part of conventional medicine. Complementary medicine is used together with conventional medicine, and alternative medicine is used in place of conventional medicine. for type 2 diabetes. The evidence that is available is not sufficiently strong to prove that any of the six supplements discussed in this report have benefits for type 2 diabetes or its complications. A possible exception may be the use of omega-3 fatty acids — essential nutrients that the body cannot make on its own but can obtain from foods such as fish and flaxseed, or from dietary supplements to lower triglyceride levels.
- It is very important not to replace conventional medical therapy for diabetes with an unproven CAM therapy.
- To ensure a safe and coordinated course of care, people should inform their health care providers about any CAM therapy that they are currently using or considering.
- The dietary supplements reviewed in this section appear to be generally safe at low-to-moderate doses. However, each can interact with various prescription medications, affecting the action of the medications. People with type 2 diabetes need to know about these risks and discuss them with their health care provider. Prescribed medicines may need to be adjusted if a person is also using a CAM therapy.
National Center for Complementary and Alternative Medicine. Research Report: Treating Type 2 Diabetes with Dietary Supplements (PDF). (Accessed 5/7/08.)
Reviewed by Susan Weiner, R.D., M.S., C.D.E., C.D.N. 10/08
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