Foods to avoid while taking Metformin

Metformin is medication used in treating type 2 diabetes. Since diabetes is closely related to metabolism, it is important to know wich foods should patient avoid while using Metformin.

Foods to avoid while taking Metformin
Viktor Simunović, Viktor Simunović
20 Mar 2024.

Metformin, commonly known as Glucophage, is a first-line medication extensively used to treat type 2 diabetes. This drug functions by reducing the amount of glucose your liver produces and increasing your body's response to insulin. By doing so, Metformin helps to lower the patient's blood sugar levels, effectively managing the symptoms of diabetes.

Certain dietary choices may impede the medication's effectiveness or exacerbate its side effects when taking Metformin.


One significant dietary consideration for individuals on Metformin is the consumption of alcohol, which can lead to serious health complications. Alcohol is one of the key foods to avoid due to its potential to dangerously interact with Metformin, leading to a rare but serious condition called lactic acidosis. This can cause symptoms like muscle pain, fatigue, and difficulty breathing.

Additionally, alcohol can directly affect your blood sugar levels, making it harder for Metformin to control these levels effectively. Metformin may also increase the intoxicating effects of alcohol, leading to rapid intoxication.

Simple and refined carbohydrates

Besides alcohol, simple and refined carbohydrates also pose a significant challenge for individuals taking Metformin. These carbohydrates are typically found in foods high in sugar and processed foods, such as white bread, pasta, and pastries. The consumption of these foods can cause rapid spikes in blood glucose levels, which is counterproductive when using Metformin for PCOS or diabetes management.

Saturated and trans fat

Foods high in saturated and trans fats also present a significant hurdle for those utilizing Metformin for health management. Consuming these types of fats can lead to weight gain, undermining the medication's effectiveness. It's essential, therefore, to identify the food to avoid while taking Metformin.


You might ask, how does sodium impact those taking Metformin? Intake of specific foods high in sodium can exacerbate the risk of lactic acidosis, a rare but serious side effect of Metformin. This condition can be life-threatening and is more likely to occur if your kidneys are not working properly. Hence, individuals on Metformin need to monitor their sodium intake.

High-fiber foods

Just as sodium intake requires careful attention for those on Metformin, it is equally important to contemplate the role of high-fiber foods in the diet. Although high-fiber foods, like whole grain, are typically recommended for individuals with Polycystic Ovary Syndrome (PCOS), Metformin users must exercise caution.

Fiber can slow the digestion of carbohydrates and the absorption of sugar, which can affect the drug's efficacy. While beneficial for PCOS, whole-grain products are exceptionally high in fiber. Consuming them in large quantities could hinder Metformin's effectiveness.

Fried and processed foods

These food types are typically high in unhealthy fats and sodium, which can exacerbate the side effects of Metformin, such as nausea, stomach upset, and diarrhea. Additionally, they can lead to weight gain, which might impede the effectiveness of this medication.

Furthermore, processed foods often contain additives, including preservatives and artificial colors, that could interfere with Metformin's mechanism of action.


High sugar intake can exacerbate the side effects of Metformin, leading to problems like nausea, stomach pain, and bloating. Additionally, consuming excessive sugar while on this medication could impair its efficacy in controlling blood glucose levels, defeating its administration's purpose.


Grapefruit is known to interfere with numerous medications. It contains compounds inhibiting cytochrome P450 3A4 enzymes, essential for drug metabolism. This can lead to an increase in the concentration of Metformin in the blood, amplifying its effects and potentially causing hypoglycemia.

Additionally, it may increase the risk of lactic acidosis. Regular grapefruit or its juice consumption should be avoided when on Metformin therapy.


In the context of Metformin use, caffeine consumption requires careful consideration due to its potential effects on insulin sensitivity and blood glucose levels. Caffeine, a central nervous system stimulant, can temporarily raise blood glucose levels, potentially counteracting the effects of Metformin. It also reduces insulin sensitivity, which may complicate the management of type 2 diabetes.

Metformin patients should be aware that many foods and beverages contain caffeine, including coffee, tea, chocolate, and some medications. While moderate consumption might not substantially impact blood glucose levels, large amounts can cause fluctuations.

Dairy products

Lactose, a sugar found in milk and other dairy products, can spike blood sugar levels. This can counteract the blood sugar-lowering effect of Metformin. Hence, consuming large amounts of dairy products could potentially lead to suboptimal blood glucose control.

It should be noted that not all dairy products are high in lactose. For instance, hard cheeses and yogurt have lower lactose content. Choose lactose-free or reduced-lactose dairy products if you're lactose intolerant or sensitive.

What foods to eat while taking Metformin?

Complex carbs

Unlike simple carbohydrates, complex carbohydrates are digested slowly. They provide a steady energy source and cause a slower rise in blood glucose levels, which benefits those on Metformin. Foods rich in these carbohydrates include whole grains, legumes, fruits, and vegetables.

These food items are high in fiber, which further aids in the slow digestion and absorption of sugars, helping to maintain steady blood glucose levels. Additionally, they are packed with essential vitamins and minerals that support overall health.

Healthy fats

Balancing the intake of healthy fats is essential for patients on Metformin, as these nutrients provide essential fatty acids and aid in the absorption of fat-soluble vitamins. Healthy fats include monounsaturated and polyunsaturated fats in foods such as avocados, nuts, seeds, and fatty fish like salmon, mackerel, and trout. These foods also contain omega-3 and omega-6 fatty acids that support brain function and heart health.

Fruits and vegetables

Incorporating a variety of fruits and vegetables in one's diet can offer numerous health benefits for individuals taking Metformin due to its rich content of dietary fiber, vitamins, and minerals.

These nutrients can contribute to maintaining stable blood sugar levels and promote overall well-being. Fruits such as berries, cherries, peaches, apricots, apples, oranges, and pears are low in glycemic index, making them ideal for consumption. On the other hand, vegetables like broccoli, spinach, bell peppers, and zucchini are high in fiber and can aid digestion.

However, it's essential to moderate consumption of starchy vegetables like potatoes and corn, as they can elevate blood sugar levels. Consuming a colorful assortment of fruits and vegetables enhances meal quality and optimizes health outcomes when taking Metformin.

Lean meat

Incorporating lean meats into your diet while taking Metformin can provide essential proteins and vitamins without drastically affecting blood sugar levels. Meats like chicken, turkey, or fish are prime lean protein sources. They are low in unhealthy fats and carbs, which can spike blood sugar levels. Additionally, lean meats are rich in B vitamins, particularly B12, essential for nerve function and the production of red blood cells. They also contain minerals like iron and zinc, which are necessary for overall health.

However, it is critical to prepare these meats healthily - avoid frying or adding heavy sauces. Instead, opt for grilling, steaming, or baking to maintain their nutritional value.

Nuts and seeds

Incorporating nuts and seeds into your diet while on Metformin can provide a wealth of nutritional benefits without causing a spike in your blood sugar levels. Rich in healthy fats, protein, fiber, vitamins, and minerals, these nutrient-dense foods can support peak health. For example, almonds, walnuts, flaxseeds, and chia seeds can help maintain glycemic control due to their low glycemic index.

However, moderation is crucial. Consuming excessive amounts can result in weight gain due to their high caloric content. Also, choose unsalted, raw, or dry-roasted varieties over salted or candied ones to avoid additional sodium or sugar.


Regularly eating fish, particularly fatty varieties like salmon, mackerel, and sardines, can benefit those taking Metformin due to their high omega-3 fatty acids, which can help regulate blood sugar levels. These types of fish provide essential proteins and have a low glycemic index, which means they won't spike blood sugar levels post-consumption.

It is important to consume fish in moderation and opt for steamed, broiled, or grilled preparation methods over fried or breaded versions to maintain a healthy diet. Additionally, avoid fish high in mercury, such as king mackerel, swordfish, or tilefish, as mercury can intensify Metformin's side effects.


To sum up, managing dietary intake while on Metformin is crucial. Avoiding alcohol, simple and refined carbs, saturated and trans fat, sodium, caffeine, and certain dairy products may reduce potential side effects and enhance medication efficacy. A balanced diet rich in lean proteins, complex carbs, and unsaturated fats can create a supportive environment for Metformin. Ultimately, understanding and implementing dietary changes can significantly contribute to better health outcomes for Metformin users.

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