Can you eat grapefruit while taking Metformin for diabetes?

This is an automatically translated article.

Grapefruits are a good source of potassium and vitamin C, both of which are essential nutrients for good health. However, the US Food and Drug Administration (FDA) warns against eating grapefruit or drinking grapefruit juice while taking certain medications. In this article, we will look at whether grapefruit interacts with metformin and what to avoid while taking metformin.

1. What is Metformin?

Metformin is a medication prescribed to treat type 2 diabetes. People with type 2 diabetes cannot use insulin normally. This means they cannot control their blood sugar. Metformin helps people with type 2 diabetes control their blood sugar in a number of ways; These include reducing the amount of sugar the body absorbs from food, reducing the amount of sugar produced by the liver, and increasing the body's response to insulin the body makes on its own.
Although very rare, Metformin can cause a very serious and life-threatening condition called lactic acidosis. Therefore, people with liver, kidney or heart problems should avoid metformin.
Doctors prescribe metformin as a first-line treatment for people with type 2 diabetes to lower blood sugar. Doctors also sometimes recommend metformin treatment for people with polycystic ovary syndrome.
Some drugs have the potential to interact with metformin and may decrease effectiveness or increase the risk of adverse effects. These drugs include:
Birth control pills. Diuretics and other thiazides. Corticosteroids . Phenytoin. Nicotinic acid. Sympathomimetic drugs. Phenothiazines. Glyburides. Calcium blockers. Seizure medications, such as topiramate. Thyroid medication. Isoniazid. Nifedipine . Furosemide. Because there are many drugs that can interact with it, before taking metformin, patients should inform their doctors and pharmacists of any medications they are taking. Using alcohol while taking metformin can increase your risk of low blood sugar. People taking metformin should avoid alcohol or drink only in moderation.

2. Drug interactions with grapefruit

There are more than 85 drugs that interact with grapefruit. Of these drugs, 43 interacted with all forms of grapefruit products including fresh juice, frozen grapefruit concentrate.
Certain chemicals found in grapefruit can bind to and disable an enzyme found in the intestines and liver that helps break down medications. Normally, when a medication is taken by mouth, it is broken down a bit by enzymes before it reaches the bloodstream. This means that the body's blood is receiving slightly less of the drug than it was originally taken in. But when the enzyme is inhibited and when it interacts with the chemicals in grapefruit, a larger amount of the drug enters the bloodstream. This leads to a higher risk of overdose. Therefore, pay close attention to the interaction between grapefruit and drugs.
Compounds in grapefruit called furanocoumarins can block the function of CYP3A4, a digestive enzyme that helps the body metabolize about 50% of drugs.
Blocking this enzyme means that some drugs stay in the body longer than usual and build up in the bloodstream. This can increase the risk of harmful effects and in some cases, death.
The effect of furanocoumarins on CYP3A4 is irreversible and it can take about 3 days for the body to produce new CYP3A4. Just 200ml of grapefruit juice, which is less than 1 cup, may be enough to cause this interaction.
Grapefruit juice also contains flavonoids, including naringin and hesperidin. Research shows that these flavonoids can block a protein called organic anion-transporting polypeptide, or OATP. This protein helps the body move drugs into cells. This means that eating grapefruit can decrease the body's absorption of some medications, making them less effective. However, this interaction was only temporary, lasting about 4 hours. Therefore, people who are taking medications that rely on OATP for absorption may still be able to consume grapefruit products if they leave a 4-hour gap between taking the pill and eating the fruit.

3. How Does Grapefruit Affect Metformin?

It is important to know that Metformin is not broken down by the same enzymes as some other drugs. It is not processed by the body and is excreted in the urine. Currently, not much is known about whether eating grapefruit while taking metformin will affect people with type 2 diabetes.

A 2009 paper talked about the effects of grapefruit with metformin on non-diabetic rats. Some of the rats were given both grapefruit juice and metformin, others were exposed to metformin only. The researchers found that there was an increase in lactic acid production in the mice that were exposed to grapefruit juice and metformin. Researchers believe that grapefruit juice enhances the accumulation of metformin in the liver. This increases lactic acid production. Therefore, the researchers suggest that drinking grapefruit juice may lead to an increased risk of lactic acidosis in people taking metformin. However, these results were observed in rats without diabetes, not in humans with type 2 diabetes. To date, no human studies have shown that taking metformin with grapefruit juice leads to to lactic acidosis.

4. Effects of grapefruit on diabetics

Drinking grapefruit juice can actually be beneficial if you have diabetes. One animal study showed that drinking grapefruit juice reduced both fasting sugar levels and weight gain. This observation also did not show an enhanced effect when grapefruit and metformin were used together. Importantly, these observations were made in a mouse model of diabetes.
An overview study on the role of grapefruit in the diet and drug interactions also shows that grapefruit is associated with weight loss, improved insulin resistance. A compound in grapefruit juice (naringin) has been shown to improve hyperglycemia and high cholesterol in animal models of type 2 diabetes.
Grapefruit is a healthy source of nutrients but it also contains Compounds can affect the way some medicines work. However, there is currently no evidence that eating grapefruit can affect metformin use.
Although grapefruit contains sugar, there is some evidence that consuming this fruit may be good for people with diabetes. Researchers don't fully understand why, but compounds in grapefruit may help lower blood sugar levels.
In a 2014 study, researchers gave 25 to 50% sweet grapefruit juice preparations to healthy rats that were following a high-fat or low-fat diet. The study found that rats on a high-fat diet had lower fasting blood sugar levels, fasting blood insulin levels, and body weight compared to mice that didn't drink grapefruit juice. However, the mice on the low-fat diet had only reduced fasting blood insulin levels. The researchers believe this result is due to compounds in grapefruit juice that block the production of glucose in the livers of rats.
Although these studies suggest potential benefits of drinking grapefruit juice for people with diabetes, more studies are needed to confirm these findings in humans.

Grapefruit can lead to negative interactions with some medications. However, there are no case studies showing that drinking grapefruit juice while taking metformin leads to adverse effects in humans. There are a few experimental studies that show that including grapefruit in your diet can help promote weight loss and lower fasting blood sugar levels. If you're taking metformin and are concerned about drug-food interactions, talk to your doctor to get your questions answered.
Readers, please follow Vinmec.com website for more useful information about nutrition.

Please dial HOTLINE for more information or register for an appointment HERE. Download MyVinmec app to make appointments faster and to manage your bookings easily.

References: healthline.com, medicalnewstoday.com, nhs.uk