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Overview: Banaba is a plant called Lagerstroemia speciosa. It is a tree that grows in Southeast Asia. The supplement is usually made from the leaves of the tree. People take banaba most often to help lower their blood sugar levels. The benefits of banaba are not well defined, and evidence in humans is limited. Banaba seems to be well tolerated, but there is not enough research to know all of its possible side effects. Before taking banaba, make sure to tell your health care provider about any health conditions you have or medicines you are taking.

Uses

What is banaba used for?

Banaba (Lagerstroemia speciosa) is a tree that grows in Southeast Asia. The leaves are the part used to make supplements. The benefits of banaba are not well defined, and evidence in humans is limited. Some common reasons for taking banaba include the following.

Note: The FDA has not reviewed banaba for safety and effectiveness. Learn more about dietary supplements here.

How does banaba work (mechanism of action)?

Banaba is the common name for Lagerstroemia speciosa, a tree in the loosestrife family. The leaves are the part used to make supplements. The leaves naturally contain many chemicals. The most studied is corosolic acid, a type of natural chemical called a triterpene. Because of its effects on blood sugar, corosolic acid is sometimes called “plant insulin.” Banaba leaves also contain other chemicals thought to affect blood sugar, such as ellagitannins (including one called lagerstroemin) and gallotannins.

In laboratory and animal research, these chemicals have been studied for several effects. Corosolic acid and the tannins in banaba seem to act a little like insulin, the hormone that controls blood sugar. They may help move sugar out of the blood and into cells. Corosolic acid may also help the body respond better to insulin. In laboratory studies, it turns on a cell signal called AMPK, which may lower the amount of fat made by the liver and reduce the buildup of fat cells. Some research suggests banaba may slow the digestion of carbohydrates. These effects may help explain why banaba is taken for controlling blood sugar, weight, and blood fats.

A small number of studies in people suggest banaba may help lower blood sugar levels and improve some signs of metabolic syndrome. But the benefits of banaba are not well defined. Most of what is known comes from laboratory research and animal research. Evidence in humans is limited.

Herbal products such as banaba naturally contain many different chemicals, such as corosolic acid. The amounts of each chemical in a specific banaba product may vary. Different amounts of corosolic acid may change the effects of banaba on the body. Some banaba dietary supplements are made to contain a certain amount of these substances. There are also some dietary supplements made from banaba that only contain corosolic acid.

How should I store banaba?

You should store banaba according to the product label. Most dietary supplements should be kept in a cool, dry location that is out of the reach of children and pets and not in direct sunlight.

Side Effects

What are the most common side effects of banaba?

Banaba seems to be well tolerated. But there is not enough research to know what the common side effects may be. Tell your health care provider if you have any side effects that bother you.

Contact your health care provider if you think you are having a side effect of a supplement. In the U.S., you can report side effects to the FDA at www.safetyreporting.hhs.gov or by calling 888-SAFEFOOD (888-723-3366). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of banaba?

While less common, the most serious side effects of banaba are described below, along with what to do if they happen.

Severe Allergic Reactions. Banaba may cause allergic reactions, which can be serious. Stop taking banaba and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching or skin rash
  • Bumps on the skin called hives that can be red, pink, white, or brown depending on your skin tone
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Low Blood Sugar (Hypoglycemia). Banaba can cause low blood sugar (especially if you also take medicines to lower your blood sugar), which can be serious. You may need to check your blood sugar more often if you have changes to your diet, exercise regimen, or medicines for diabetes. Stop using banaba and call your health care provider right away if you have any of the following symptoms of hypoglycemia.

  • Headache
  • Crankiness or anxiety
  • Hunger
  • Dizziness or confusion
  • Blurry vision
  • Slurred speech
  • Sweating
  • Feeling jittery or shakiness
  • Fast heartbeat
  • Seizures

Warnings & Precautions

Who should not use banaba?

Allergies to Ingredients. People who are allergic to any of the following should not take banaba.

  • Banaba
  • Banaba leaf
  • Corosolic acid
  • Crape or crepe myrtle
  • Giant crape myrtle
  • Lagerstroemia speciosa
  • Pride of India
  • Queen’s crape myrtle
  • Queen’s flower
  • Any of the ingredients in the specific product

Your pharmacist can tell you all of the ingredients in the specific banaba products they stock.

What should I know about banaba before using it?

Banaba is a dietary supplement. It cannot be marketed to treat or cure a disease.

Banaba is available in many forms. Common forms include capsules, tablets, leaf teas, powders, and liquid extracts. Many products are standardized to contain a set amount of corosolic acid, such as 1%. Read and follow the directions on the specific product you are taking, or take it as recommended by your health care provider.

Keep banaba out of the reach of children.

Herbal products, such as banaba, naturally contain many different chemicals. The amount of each chemical in a specific banaba product can change for many reasons, including the area where the plant was grown, the weather during growth, the time of year when it was harvested, and the way that the plant was processed after it was harvested. If you switch to a new bottle or a different brand, you may not have the same effects or side effects because of this variability. Talk to your health care provider if you have questions or concerns.

The FDA has not tested banaba products to confirm that they contain the ingredients stated on their labels. Some dietary supplements have been tested by third-party organizations to confirm that they contain the ingredients listed on their labels and do not contain any harmful chemicals. Learn more about how to choose a safe dietary supplement product here.

What should I tell my health care provider before using banaba?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. Also tell them if you have an upcoming surgery planned. Sharing this information will help your health care provider know if this or other supplements are right for you.

In particular, make sure that you discuss any of the following.

Diabetes. Banaba may lower blood sugar. If you have diabetes or problems with low blood sugar levels, talk to your health care provider before taking banaba. If you take banaba, you may need to monitor your blood sugar more closely. Talk to your health care provider if you have concerns.

Other Medicines and Supplements. Before taking banaba, tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Pregnancy. It is not known if or how banaba could affect pregnancy or harm a fetus. Tell your health care provider if you are pregnant or plan to become pregnant.

Breastfeeding. It is not known if banaba passes into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed.

Interactions

Does banaba interact with foods or drinks?

There are no known interactions between banaba and foods or drinks.

It is unknown if drinking alcohol will affect banaba.

Does banaba interact with medicines (drug interactions)?

Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using so they can watch for any potential interactions.

In particular, make sure that you discuss if you are taking any medicines for diabetes, such as glimepiride (Amaryl), glipizide (Glucotrol), insulin, or metformin (Glucophage, Glumetza, and others). Both banaba and these medicines can lower your blood sugar levels. If you are using any diabetes medicines, your health care provider may want to watch your blood sugar more closely if you also take banaba.

The interactions between banaba and medicines are not fully understood. As with most dietary supplements, the research on drug interactions with banaba is incomplete. Always check with your health care provider before taking banaba with any medicines.

Overdose/Missed Dose

What should I do if I accidentally use too much banaba?

If you or someone else has used too much banaba, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

Banaba is available as capsules, tablets, leaf teas, powders, and liquid extracts. Read the product label closely, and speak with a health care provider about how to use banaba safely. Do not take double or extra doses, even if you miss a dose.