If you have been prescribed metformin to help control your blood sugar, you may be wondering what foods to avoid while taking the medication.
Metformin is a common drug used to treat type 2 diabetes, especially if you are obese. It helps your body use insulin more effectively and can also help with weight loss too.
While taking metformin, it is important to follow a healthy diet and avoid foods that can interfere with the medication’s effectiveness.
In this article, we will discuss foods to avoid while taking metformin and foods that are beneficial while you are taking the medication.
What is metformin?
Metformin is a prescription medication used to treat primarily type 2 diabetes and prediabetes although it can also be used for weight gain caused by certain medications, and polycystic ovary syndrome (PCOS).
It comes in two different forms, metformin and metformin XR which is an extended-release tablet. The regular form of metformin is available for anyone over the age of 10 while the extended-release version is for adults only.
The best way to use metformin is in combination with a healthy diet and regular exercise or physical activity to have the best glycemic control which means keeping your blood sugar levels in the target range.
Metformin is the generic name of the brand name drugs called Fortamet, Glucophage, Glucophage XR, Glumetza, and Riomet.
How does metformin work?
Metformin works by decreasing your blood sugar levels in several different ways. When you have diabetes mellitus, also known as diabetes, your blood sugar called glucose builds up in your bloodstream after being absorbed from the food in your stomach.
The reason this happens with type 2 diabetes is that your cells have become insulin resistant.
Insulin is a hormone that allows your cells to convert the blood glucose into energy and when they acquire insulin resistance, the glucose goes unused causing a spike in your blood sugar levels.
There are three different ways that metformin is known to help lower your blood glucose levels.
First, it helps to make your cells more insulin sensitive which means they use insulin more often to take the glucose from your blood.
Metformin also lowers the amount of glucose that gets absorbed from your stomach and intestines into your bloodstream after the food or drink you ingest is broken down.
Finally, you naturally have glucose production in your liver and metformin lowers the amount your body produces.
What are the side effects of taking metformin?
Most of the adverse effects caused by metformin are mild and involve your gastrointestinal (GI) tract.
The most common side effects of metformin include:
- Nausea
- Vomiting
- Diarrhea
- Gas or bloating
- Cramping
- Upset stomach
Please talk to your doctor if they persist or if they become severe symptoms.
There is a rare and severe potential side effect called lactic acidosis that can also be caused by taking metformin.
Lactic acid is a building block for glucose, so when metformin stops your stomach and intestines from making glucose it can lead to a buildup of lactic acid which is called lactic acidosis.
The symptoms of lactic acidosis include:
- Fatigue or tiredness
- Difficulty breathing
- Stomach pain
- Muscle aches and pain
When left untreated, lactic acidosis can cause severe damage to your lungs, kidneys, blood vessels, and heart, and can even be fatal in some circumstances.
If you have these symptoms, please see your doctor or health care provider for emergency medical attention immediately.
Are there any foods to avoid while taking metformin?
There are no foods that you need to avoid while taking metformin.
However, there are foods that are not beneficial to eat on a diabetes diet that can raise your blood sugar more than others and it is best to eat these foods in moderation or avoid them altogether.
These foods include:
Foods high in fat
Specifically, foods high in saturated or trans fat although foods high in healthy fats such as avocados, olive oil, nuts, and seeds are healthy to eat in moderation.
Fried or processed foods
Fried foods and processed foods are generally high in unhealthy fats, calories, and sodium which can all lead to weight gain and other health problems.
Processed foods also usually contain refined carbohydrates that have been processed and often contain added sugar.
Examples of refined carbs include white bread, pastries, white rice, and pasta which can cause a blood sugar level spike.
Sugary foods and drinks
These foods contain high amounts of simple carbohydrate sugar that easily breaks down into glucose.
Examples of these include foods and sugary drinks like candy, cookies, cake, soda, fruit juice, honey, syrup, and sports drinks. It is best to limit these foods or avoid them altogether.
Red meat
Red meat is high in saturated fat and calories which can lead to weight gain.
It is best to limit red meat consumption or choose leaner cuts of meat such as chicken or fish.
Alcohol
While moderate alcohol consumption is generally safe, it can cause problems if you have diabetes and consume excessive amounts of alcohol as it can cause your blood sugar to drop which can lead to hypoglycemia.
It can also make it harder for your body to process glucose and can raise your triglyceride levels. Triglycerides are a type of fat in your blood that can increase your risk of heart disease.
Drinking alcohol while taking metformin can also lead to higher levels of lactic acid in your blood which is what causes lactic acidosis.
If you do drink alcohol, it is best to monitor your alcohol intake and do so in moderation and also talk to your doctor first.
Grapefruit
Grapefruit and grapefruit juice in all forms is known to have interactions with many drugs.
There was one study on rats published in 2009 that found nondiabetic rats that were given metformin and grapefruit juice had higher levels of lactic acid and had also gained more weight.
There has been no case study on humans to date and more research is needed on the effects of grapefruit juice and metformin to draw any firm conclusions about this study.
What foods are beneficial while taking metformin?
There are certain foods that can help to lower blood sugar levels and are generally healthy if you have diabetes. These foods include:
Foods high in fiber
Fiber is a type of carbohydrate that your body cannot digest such as beans, legumes, whole grains, nuts, and seeds.
Dietary fiber can help to slow down the absorption of sugar into your bloodstream which can help to keep blood sugar levels from rising too high after eating.
Leafy green vegetables and non-starchy vegetables
Leafy green vegetables are low in calories and carbohydrates and are a good source of vitamins, minerals, and antioxidants, and include foods like spinach, kale, collard greens, and Swiss chard.
Non-starchy vegetables are also low in calories and carbohydrates but are not as high in vitamins and minerals as leafy greens. These include foods like carrots, tomatoes, peppers, and cucumbers.
Lean proteins
Proteins are integral to any diet but some are far healthier than others.
Lean proteins are a good source of nutrients and help to keep you feeling full and include foods like skinless chicken, turkey, fish, tofu, legumes, and eggs.
Whole grains
Processed grains found in foods like white bread are not as healthy as whole grains which provide a good source of fiber, vitamins, and minerals and include foods like whole wheat bread, oats, quinoa, and brown rice.
Healthy fats
Not all fats are bad for you as there are healthy fats that help to keep you feeling full and can actually help to lower your cholesterol levels. As noted above, these include foods like avocados, olive oil, nuts, and seeds.
Complex carbohydrates
Complex carbs are carbohydrates that are high in fiber and take longer for your body to break down which means that they do not cause spikes in blood sugar levels like simple carbs.
Good sources of complex carbs include foods like sweet potatoes, whole-grain bread, and beans.
What is the proper way to take metformin?
In most cases, it is taken orally two or three times a day with meals depending on your dose of metformin.
The extended-release form of the drug is usually taken once a day with the evening meal.
If you are taking the extended-release form, it is not advised to crush or chew the tablets as this can cause them to release their contents too quickly and increase the risk of side effects.
You also need to drink plenty of fluids throughout the day to prevent dehydration as metformin can cause you to lose too much water through your urine.
It is not recommended to take metformin without food and it is best taken during or after a meal to avoid any gastrointestinal side effects.
Who needs to avoid taking metformin?
There are certain reasons you may need to avoid taking metformin or use caution when taking the drug.
You need to avoid taking metformin if you have any of the following medical conditions:
- Kidney problems such as chronic kidney disease
- Liver problems such as liver disease or liver failure
- An allergy to metformin
- History of heart disease. heart attack, or congestive heart failure
- Diabetic ketoacidosis
- Lactic acidosis
- Type 1 diabetes, as people with type 1 diabetes have low insulin levels and lack reduced insulin sensitivity
- If you are above the age of 65
Metformin can also have potential drug interactions with other medications so let your doctor know if you are taking any of the following:
- Other diabetes drugs such as insulin
- Oral contraceptives/birth control pills
- Anticonvulsants such as topiramate (Topamax)
- Certain diuretics, including amlodipine
- Antipsychotic medications
- Blood pressure medications
Be sure to tell your doctor about your medical history and any medications you are taking before you start taking metformin because if there is a chance for an interaction your doctor may suggest an alternate medication.
If you are pregnant or breastfeeding, metformin is considered safe to use despite it being present in breast milk.
Please talk to your doctor if you have any further questions about whether it is safe for you to take.
Summary
Metformin is a medication used to treat type 2 diabetes, prediabetes, polycystic ovary syndrome, and weight gain due to other medications but there are certain foods you need to avoid while taking it for better blood sugar control.
These include foods that are high in sugar, unhealthy fats, and alcohol as well as several others listed above. It is generally considered safe to use although you need to also avoid taking metformin if you have kidney or liver problems, are allergic to the drug, have a history of heart disease, or are taking certain medications.
If you have any questions about whether it is safe for you to take metformin or what food you need to avoid while taking it, please talk to your doctor or health care provider.
References and sources:
Drugs.com
Mayo Clinic
GoodRx Health
- What Is Metformin Used for, and How Does It Work Exactly?
- Metformin Side Effects: What You Need to Know
NIH
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