Green Tea, Diabetes & Drug Interactions

 

PERSONAL EXPERIENCE

I could be ranting and raving till the cows come home about the personal benefits to me from drinking green tea. I suffer from a variety of gastrointestinal conditions, therefore coffee and I should not be on speaking terms. But I love my coffee, in fact I am an out and out coffee snob.

Every so often I do a coffee detox and the weight flies off. No more stomach cramps and bloating, I have a stomach like a washboard. The secret I am convinced of is green tea.

I worked with a nurse from Vietnam, whose family happened to be farmers of tea leaves. She informed me that the budget green tea I was buying was not actually green tea, but ordinary tea with dye added. She was appalled and began to educate me on green tea by allowing me to sample some of her families own green tea. I was completely converted, and have now become a green tea snob since. I have two simple rules, it must be loose, and if it does come in a tea bag, it must be a clear one. Lily’s Emerald Green Tea which is Irish owned, is a wonderful green tea, which can be bought/ordered in certain Super Valu’s is idea. Yes it might be more expensive, but too much green tea can be a bad thing. I only drink 1-2 cups a day which is enough.

Also I never drink ‘real’ green tea on an empty stomach, you will be guaranteed to puke!

BENEFITS TO PEOPLE WITH DIABETES

My fascination with green tea got me thinking about the benefits to people with diabetes. Randomized controlled trials (RCTs) have indicated that green tea is effective in decreasing blood pressure, low density lipoprotein cholesterol, oxidative stress, and a marker of chronic inflammation [1].RCTs are regarded as being the most clinically robust trials out there.

Because people with diabetes have a significantly higher risk of developing cardiovascular disease, the anti-oxidative and anti-inflammatory properties in green tea are beneficial. But the direct benefits on blood sugar levels between the two types of diabetes is telling. Green tea is probably more beneficial to those with Pre-Diabetes & Type 2 Diabetes as it increases insulin sensitivity and prevents impaired fasting glucose from a significant increase [2].

In people with Type 1 Diabetes, there is no direct impact on blood sugar levels, as this group does not produce insulin. It has overall health benefits, but not directly on glycaemic control.

DRUG INTERACTIONS

One of the biggest issues I have come across is people with diabetes recommended to drink green tea by some dubiously qualified health nuts, who have no idea that green tea may interact with some of their medication. The following is a list of drugs that green tea may interact with:

Major Drug Interactions

  • Amphetamines interacts with GREEN TEA
    Stimulant drugs such as amphetamines speed up the nervous system. By speeding up the nervous system, stimulant medications can make you feel jittery and increase your heart rate. The caffeine in green tea might also speed up the nervous system. Taking green tea along with stimulant drugs might cause serious problems including increased heart rate and high blood pressure. Avoid taking stimulant drugs along with caffeine.
  • Cocaine interacts with GREEN TEA
    Stimulant drugs such as cocaine speed up the nervous system. By speeding up the nervous system, stimulant medications can make you feel jittery and increase your heart rate. The caffeine in green tea might also speed up the nervous system. Taking green tea along with stimulant drugs might cause serious problems including increased heart rate and high blood pressure. Avoid taking stimulant drugs along with caffeine.
  • Ephedrine interacts with GREEN TEA
    Stimulant drugs speed up the nervous system. Caffeine (contained in green tea) and ephedrine are both stimulant drugs. Taking green tea along with ephedrine might cause too much stimulation and sometimes serious side effects and heart problems. Do not take caffeine-containing products and ephedrine at the same time.

Moderate Drug Interactions

  • Adenosine (Adenocard) interacts with GREEN TEA
    Green tea contains caffeine. The caffeine in green tea might block the affects of adenosine (Adenocard). Adenosine (Adenocard) is often used by doctors to do a test on the heart. This test is called a cardiac stress test. Stop consuming green tea or other caffeine-containing products at least 24 hours before a cardiac stress test.
  • Antibiotics (Quinolone antibiotics) interacts with GREEN TEA
    The body breaks down caffeine to get rid of it. Some antibiotics might decrease how quickly the body breaks down caffeine. Taking these antibiotics along with green tea can increase the risk of side effects including jitteriness, headache, increased heart rate, and other side effects.
    Some antibiotics that decrease how quickly the body breaks down caffeine include ciprofloxacin (Cipro), enoxacin (Penetrex), norfloxacin (Chibroxin, Noroxin), sparfloxacin (Zagam), trovafloxacin (Trovan), and grepafloxacin (Raxar).
  • Birth control pills (Contraceptive drugs) interacts with GREEN TEA
    The body breaks down the caffeine in green tea to get rid of it. Birth control pills can decrease how quickly the body breaks down caffeine. Taking green tea along with birth control pills can cause jitteriness, headache, fast heartbeat, and other side effects.
    Some birth control pills include ethinyl estradiol and levonorgestrel (Triphasil), ethinyl estradiol and norethindrone (Ortho-Novum 1/35, Ortho-Novum 7/7/7), and others.
  • Cimetidine (Tagamet) interacts with GREEN TEA

    Green tea contains caffeine. The body breaks down caffeine to get rid of it. Cimetidine (Tagamet) can decrease how quickly your body breaks down caffeine. Taking cimetidine (Tagamet) along with green tea might increase the chance of caffeine side effects including jitteriness, headache, fast heartbeat, and others.

  • Clozapine (Clozaril) interacts with GREEN TEA

    The body breaks down clozapine (Clozaril) to get rid of it. The caffeine in green tea seems to decrease how quickly the body breaks down clozapine (Clozaril). Taking green tea along with clozapine (Clozaril) can increase the effects and side effects of clozapine (Clozaril).

  • Dipyridamole (Persantine) interacts with GREEN TEA

    Green tea contains caffeine. The caffeine in green tea might block the affects of dipyridamole (Persantine). Dipyridamole (Persantine) is often used by doctors to do a test on the heart. This test is called a cardiac stress test. Stop drinking green tea or other caffeine-containing products at least 24 hours before a cardiac stress test.

  • Disulfiram (Antabuse) interacts with GREEN TEA

    The body breaks down caffeine to get rid of it. Disulfiram (Antabuse) can decrease how quickly the body gets rid of caffeine. Taking green tea (which contains caffeine) along with disulfiram (Antabuse) might increase the effects and side effects of caffeine including jitteriness, hyperactivity, irritability, and others.

  • Estrogens interacts with GREEN TEA

    The body breaks down the caffeine in green tea to get rid of it. Estrogens can decrease how quickly the body breaks down caffeine. Taking estrogen pills and drinking green tea can cause jitteriness, headache, fast heartbeat, and other side effects. If you take estrogen pills limit your caffeine intake.
    Some estrogen pills include conjugated equine estrogens (Premarin), ethinyl estradiol, estradiol, and others.

  • Fluvoxamine (Luvox) interacts with GREEN TEA

    The body breaks down the caffeine in green tea to get rid of it. Fluvoxamine (Luvox) can decrease how quickly the body breaks down caffeine. Taking green tea along with fluvoxamine (Luvox) might cause too much caffeine in the body, and increase the effects and side effects of caffeine.

  • Lithium interacts with GREEN TEA

    Your body naturally gets rid of lithium. The caffeine in green tea can increase how quickly your body gets rid of lithium. If you take products that contain caffeine and you take lithium, stop taking caffeine products slowly. Stopping caffeine too quickly can increase the side effects of lithium.

  • Medications for depression (MAOIs) interacts with GREEN TEA

    The caffeine in green tea can stimulate the body. Some medications used for depression can also stimulate the body. Drinking green tea and taking some medications for depression might cause too much stimulation of the body and serious side effects including fast heartbeat, high blood pressure, nervousness, and others.
    Some of these medications used for depression include phenelzine (Nardil), tranylcypromine (Parnate), and others.

  • Medications that can harm the liver (Hepatotoxic drugs) interacts with GREEN TEA

    Green tea extracts might harm the liver. Taking green tea extracts along with medication that might also harm the liver can increase the risk of liver damage. Do not take green tea extracts if you are taking a medication that can harm the liver.
    Some medications that can harm the liver include acetaminophen (Tylenol and others), amiodarone (Cordarone), carbamazepine (Tegretol), isoniazid (INH), methotrexate (Rheumatrex), methyldopa (Aldomet), fluconazole (Diflucan), itraconazole (Sporanox), erythromycin (Erythrocin, Ilosone, others), phenytoin (Dilantin) , lovastatin (Mevacor), pravastatin (Pravachol), simvastatin (Zocor), and many others.

  • Medications that slow blood clotting (Anticoagulant / Antiplatelet drugs) interacts with GREEN TEA

    Green tea might slow blood clotting. Taking green tea along with medications that also slow clotting might increase the chances of bruising and bleeding.
    Some medications that slow blood clotting include aspirin, clopidogrel (Plavix), diclofenac (Voltaren, Cataflam, others), ibuprofen (Advil, Motrin, others), naproxen (Anaprox, Naprosyn, others), dalteparin (Fragmin), enoxaparin (Lovenox), heparin, warfarin (Coumadin), and others.

  • Nicotine interacts with GREEN TEA

    Stimulant drugs such as nicotine speed up the nervous system. By speeding up the nervous system, stimulant medications can make you feel jittery and increase your heart rate. The caffeine in green tea might also speed up the nervous system. Taking green tea along with stimulant drugs might cause serious problems including increased heart rate and high blood pressure. Avoid taking stimulant drugs along with caffeine.

  • Pentobarbital (Nembutal) interacts with GREEN TEA

    The stimulant effects of the caffeine in green tea can block the sleep-producing effects of pentobarbital.

  • Phenylpropanolamine interacts with GREEN TEA

    Green tea contains caffeine. Caffeine can stimulate the body. Phenylpropanolamine can also stimulate the body. Taking green tea and phenylpropanolamine together might cause too much stimulation and increase heartbeat, blood pressure and cause nervousness.

  • Riluzole (Rilutek) interacts with GREEN TEA

    The body breaks down riluzole (Rilutek) to get rid of it. Drinking green tea can decrease how quickly the body breaks down riluzole (Rilutek) and increase the effects and side effects of riluzole.

  • Theophylline interacts with GREEN TEA

    Green tea contains caffeine. Caffeine works similarly to theophylline. Caffeine can also decrease how quickly the body gets rid of theophylline. Taking green tea along with theophylline might increase the effects and side effects of theophylline.

  • Verapamil (Calan, Covera, Isoptin, Verelan) interacts with GREEN TEA

    The body breaks down the caffeine in green tea to get rid of it. Verapamil (Calan, Covera, Isoptin, Verelan) can decrease how quickly the body gets rid of caffeine. Drinking green tea and taking verapamil (Calan, Covera, Isoptin, Verelan) can increase the risk of side effects for caffeine including jitteriness, headache, and an increased heartbeat.

  • Warfarin (Coumadin) interacts with GREEN TEA

    Warfarin (Coumadin) is used to slow blood clotting. Large amounts of green tea have been reported to decrease the effectiveness of warfarin (Coumadin). Decreasing the effectiveness of warfarin (Coumadin) might increase the risk of clotting. It is unclear why this interaction might occur. Be sure to have your blood checked regularly. The dose of your warfarin (Coumadin) might need to be changed.

Minor Drug Interactions

  • Alcohol interacts with GREEN TEA
    The body breaks down the caffeine in green tea to get rid of it. Alcohol can decrease how quickly the body breaks down caffeine. Taking green tea along with alcohol might cause too much caffeine in the bloodstream and caffeine side effects including jitteriness, headache, and fast heartbeat.
  • Fluconazole (Diflucan) interacts with GREEN TEA
    Green tea contains caffeine. The body breaks down caffeine to get rid of it. Fluconazole (Diflucan) might decrease how quickly the body gets rid of caffeine and cause caffeine to stay in the body too long. Taking fluconazole (Diflucan) along with green tea might increase the risk of side effects such as nervousness, anxiety, and insomnia.
  • Medications for diabetes (Antidiabetes drugs) interacts with GREEN TEA
    Green tea contains caffeine. Caffeine might increase blood sugar. Diabetes medications are used to lower blood sugar. Taking some medications for diabetes along with caffeine might decrease the effectiveness of diabetes medications. Monitor your blood sugar closely. The dose of your diabetes medication might need to be changed.
    Some medications used for diabetes include glimepiride (Amaryl), glyburide (DiaBeta, Glynase PresTab, Micronase), insulin, pioglitazone (Actos), rosiglitazone (Avandia), chlorpropamide (Diabinese), glipizide (Glucotrol), tolbutamide (Orinase), and others.
  • Mexiletine (Mexitil) interacts with GREEN TEA
    Green tea contains caffeine. The body breaks down caffeine to get rid of it. Mexiletine (Mexitil) can decrease how quickly the body breaks down caffeine. Taking Mexiletine (Mexitil) along with green tea might increase the caffeine effects and side effects of green tea.
  • Terbinafine (Lamisil) interacts with GREEN TEA
    The body breaks down the caffeine in green tea to get rid of it. Terbinafine (Lamisil) can decrease how fast the body gets rid of caffeine. Taking green tea along with terbinafine (Lamisil) can increase the risk of caffeine side effects including jitteriness, headache, increased heartbeat, and other effects.

So if you are thinking of trying green tea for the first time, please get professional advice to ensure it does not interact with any of the medication you are on.

REFERENCES

[1] Nantz MP, Rowe CA, Bukowski JF, Percival SS. Standardized capsule of Camellia sinensis lowers cardiovascular risk factors in a randomized, double-blind, placebo-controlled study. Nutrition. 2009;25:147–154

[2] Toolsee, Naushad Ali, et al. “Effectiveness of green tea in a randomized human cohort: relevance to diabetes and its complications.” BioMed research international 2013 (2013).