What Foods You Should Avoid While Taking Metformin

Metformin has been used for more than a century as a diabetes drug. It is currently recommended for adults and children age 10 or older with type 2 diabetes. It is also sometimes prescribed for women with polycystic ovary syndrome (PCOS). More recently, metformin has been researched as an anti-aging drug and for a variety of medical conditions. Are there any foods that should be avoided when taking metformin? Read on to learn what foods you should avoid, and what you can eat while taking it.

Key takeaways:
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    Metformin is currently recommended as the first-line therapy for type 2 diabetes management and to treat polycystic ovary syndrome (PCOS).
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    More recently, metformin has been researched as an anti-aging drug and for a variety of medical conditions, including cancer and heart diseases.
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    Some foods should be avoided when taking metformin, as this drug works best in combination with an anti-diabetes diet.

What is metformin used for?

Metformin is a drug that can be used to treat many different diseases.

Diabetes management

Metformin works by reducing the amount of glucose absorbed from the intestine, decreasing the amount of glucose made in the liver, and improving insulin sensitivity.

PCOS treatment

Metformin is used in the management of PCOS to improve insulin resistance. Some studies suggest metformin may also restore ovulation, manage weight gain, decrease androgen levels, and decrease the risk of miscarriage in women with PCOS.


Studies in animal models found that metformin can extend the lifespan. In human studies, metformin shows the ability to extend the lifespan in individuals with age-related diseases like diabetes, heart disease, and cognitive decline. For example, metformin helps reduce the risk of diabetes-related death by 42%. The use of metformin as an anti-aging drug has just started.

Other conditions

In recent years, scientists have found that metformin has anti-cancer qualities and may work against several types of cancer. This drug may also help manage various cardiovascular diseases, liver conditions, obesity, kidney diseases, and neurodegenerative diseases. More research is needed to confirm these benefits.

Foods to avoid while taking metformin

Metformin lowers blood sugar levels but is most effective when used along with a healthy, balanced diet. Although there is no official list of foods to avoid while on Metformin, it is best to limit or avoid foods that increase blood sugar levels.


The amount of alcohol should be limited (i.e. one drink per day or less) because alcohol impairs the liver's function and may cause hypoglycemia.

Simple carbs

Foods rich in simple carbs (sodas and cookies) and refined carbs (white bread and pasta) negatively impact insulin levels.


It is best to avoid excess sodium when taking metformin. Limiting sodium intake to less than 2300 mg daily is also good to prevent high blood pressure and maintain overall health.

High fiber foods

Eating high amounts of fiber can decrease the absorption of metformin. Decreased absorption means the drug may become less effective. Make sure you do not exceed the recommended daily intake of 30 grams of fiber daily.

Fried foods

Fried foods should be consumed in limited amounts, as diabetes is often associated with high levels of blood lipids. Deli meats, sausages, and ready-to-eat meals contain trans fats, the most harmful type of saturated fats, and should be consumed sparsely.

Foods to avoid when taking metformin for PCOS

When it comes to foods that should be avoided when taking metformin for PCOS, it is best to choose a diabetes-friendly diet. This diet helps improve insulin resistance and manage symptoms associated with PCOS.

Sugary food and drinks

Drinks like soda and fruit juices harm insulin resistance and can worsen PCOS symptoms. Sweetened yogurt and Starbucks beverages are loaded with sugar, too.

Fried foods

Metformin can cause an upset stomach and fried foods can further aggravate digestive problems, as fatty foods take longer to digest. Instead of frying vegetables and meats, choose to steam, boil, or oven-roast.

Other foods to avoid

Highly processed foods, refined grains, and alcohol should also be avoided. They all harm blood sugar levels, impair liver function and promote weight gain.

Foods to include when taking Metformin

There are plenty of healthy foods that can be enjoyed while taking metformin. These include nutritious foods that are rich in vitamins and minerals, healthy fats, lean proteins, and complex carbs.

Complex carbs

Complex carbs are low in unhealthy carbs, but high in fibers. Whole-grain bread and legumes are all good sources of complex carbs.


Non-starchy vegetables like leafy greens, lettuce, cucumbers, bell peppers, radishes, green beans, asparagus, cabbage, broccoli, and cauliflower are all diabetes-friendly foods. Broccoli and leafy greens are recommended when taking metformin for weight loss and diabetes management.

Lean meat and fish

Chicken, turkey, and fish are great sources of protein. Proteins take longer to digest compared with carbs, which leaves you feeling full longer and supports a healthy weight. Fatty fish is also rich in omega-3 fatty acids, which have anti-diabetes effects.

Nuts and seeds

Consumed in moderation, nuts and seeds are good sources of healthy, unsaturated fats, proteins, and fibers. All these nutrients help stabilize blood sugar levels, fight inflammation, and support hormonal balance.

When should you take metformin?

Metformin is typically recommended two or three times daily; it is best taken with a meal to help reduce the digestive side effects. Extended-release metformin is taken once a day in the evening, with dinner. Taking a dose of metformin late in the evening helps manage glucose levels overnight.

Side effects of metformin

A common side effect is a diarrhea. Fatty foods, fructose-rich foods like fruits, dairy products, high FODMAP foods, coffee, fried, fatty foods, spices, and artificial sweeteners do not directly interact with Metformin, but they add to the laxative effects of the drug.

Other side effects associated with metformin include nausea, vomiting, bloating, and stomach cramping. Metformin can also cause low blood sugar. A rare but potentially serious adverse reaction is called lactic acidosis, due to an increase in lactic acid in the blood. Metformin-associated lactic acidosis causes stomach pain, difficulty breathing, fatigue, and muscle aches and pains. Extended-release tablets seem to be associated with fewer side effects.

Metformin can interact with other drugs, including iodinated contrast materials, (used for some types of X-rays and CT scans), gatifloxacin, tafenoquine, and risdiplam. Taking metformin with other anti-diabetic drugs or supplements can lead to hypoglycemia.

Natural alternatives to Metformin

Based on a research study, the herb berberine showed similar efficacy as metformin to improve blood glucose metabolism.

The supplement inositol was compared with metformin in women with insulin resistance, in another research paper. The scientists concluded that both have similar positive effects on insulin levels and fasting blood glucose levels.

Cinnamon, curcumin, and omega-3 fatty acids also have anti-diabetes effects.

People seeking natural metformin alternatives should talk to a healthcare provider to learn more about the optimal dosage and potential interaction with prescription drugs.

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