Which Foods to Avoid While Taking Metformin

Metformin is a common medication and is often the first line treatment to help control blood sugar for people with Type 2 diabetes. But like with many other medications, the kinds of food you eat can interact with the medication and cause adverse effects. In this article, we look at whether there are foods to avoid while taking Metformin.

While we didn’t find any specific foods that need to be completely avoided, there are some foods you should try to limit – like alcohol – because they can increase the chances of Metformin side effects.

What Is Metformin?

Metformin Hydrochloride (aka Metformin) is used to lower high blood sugar or glucose and is often the first line treatment for diabetes. It’s a common generic drug that has been in circulation for decades, initially approved by FDA in the 1990s. It’s also available under the common brand names Glucophage, Frotamet, Glumetza, and Riomet.

metformin tablets and bottle

Aside from diabetes, it’s also used to treat other conditions such as polycystic ovary syndrome, non-alcoholic fatty liver disease, and hyperinsulinar obesity.  

How Metformin Works

Metformin lowers both baseline (basal) and after-meal (postprandial) blood sugar by decreasing the glucose produced by the liver and reducing glucose absorbed in the intestines.  It also improves insulin sensitivity by increasing glucose uptake and usage within the limbs. 

Simply put, Metformin doesn’t change the amount of inulin created but makes your body use and store glucose more effectively.

Taking Metformin

Metformin is often taken as a pill and available as extended release or immediate release.

When used to treat Type 2 diabetes, Metformin dosage for immediate release typically starts at 500 mg twice daily or 850 mg once a day and is taken with meals. Extended release dosage starts at 500 mg to 1000 mg taken once daily.

woman holding medicine pill and water

If your blood sugar isn’t improving enough with the starting dosage, your care provider may increase dosage. Dosage is usually adjusted up in increments of 500 mg per week with a max dosage usually set 2,000 mg per day.

Foods to Avoid While on Metformin

Fortunately, Metformin’s product labeling does not list any specific foods or diets that have to be avoided. In fact, it’s generally recommended to take this medication with food to help with absorption (but always tell your care provider about any food allergies before taking any medication).

However, there is some data showing grapefruit being associated with potential adverse side effects. This study looked at the glucose tolerance effects of drinking grapefruit juice while taking Metformin.

grapefruit sliced in half

While the study found that blood glucose levels decreased, it also showed an increase in lactic acidosis – a condition when the body has too much lactic acid and causes an imbalance to the body’s pH level. But it’s important to note that this study was conduced only on rats so it’s unclear how well the results apply to humans.

Metformin and Alcohol Consumption

Alcohol is one food that should be consumed minimally while taking Metformin because of its effects on the liver. One of the liver’s important functions is to remove toxins from the blood. And when you drink alcohol, about 90% of the alcohol consumed is broken down by the liver and releases toxins as part of that process.

alcohol poured into glass

One serious (but very rare) side effect of this drug is Metformin induced lactic acidosis. Lactic acidosis is a condition of high lactate levels due to increased lactate production and/or lactate not adequately removed by the liver or kidneys.

A scientific review found that metformin associated lactic acidosis is more likely in people with impaired kidney function but also found that alcohol is a risk factor. Because alcohol is mostly broken down by the liver, this could make it harder for the liver to also clear lactate and cause lactic acid build-up.

Alcohol Induced Hypoglycemia

Another reason to limit drinking alcohol while on Metformin is the potential of low blood sugar (hypoglycemia), especially at night. When you sleep, the liver creates glucose for the body to prevent glucose levels from being too low.

However drinking alcohol before you sleep can disrupt this process and prevent the liver from creating the glucose the body needs. And if you’re also on Metformin, alcohol increases the risk of hypoglycemia even more because the medication is designed to lower blood sugar levels.

Foods That Can Upset Your Stomach

beans

One of the most common side effects of Metformin are gastrointestinal (GI) issues like diarrhea, gas, or upset stomach. These generally happen at the start of treatment and are usually minor but you should talk to your care provider if it last for several days or you can’t tolerate it.

It’s not fully known why this is happens but this scientific review notes that the release of lactate and/or microbiome changes as a result of Metformin could play a role in GI intolerance.

So if you’re already sensitive to GI or stomach issues, you may want to limit foods that tend to upset your stomach when starting Metformin. This could mean different foods for different people but some common examples are:

  • Dairy products like cream, yogurts and cheese especially if you’re prone to lactose intolerance.
  • Spicy or acidic foods which can lead to indigestion and heart burn.
  • Beans, legumes or other high-fiber foods which can contribute to intestinal gas.
pile of spicy peppers

Again, you don’t have to completely avoid these foods but it’s a good idea to limit their intake and see if they cause any GI issues.

Tips When Taking Metformin

  • Taking the medication with food helps with better absorption rather than on an empty stomach.
  • If you’re taking immediate release Metformin but not tolerating it well, ask your healthcare provider about converting to extended release version. This could be easier to tolerate and more convenient because it combines doses.
  • Be sure to tell your care provider that you’re taking Metformin before any medical procedure or screenings. For procedures that require you to fast, Metformin could increase the chance of hypoglycemia. And body screenings or X-rays that using contrast dyes could affect how well the kidneys clear Metformin.

Summary

Metformin is one of the most widely used type 2 diabetes medicines to lower blood sugar levels. And fortunately, there’s not much data showing foods to avoid while taking Metformin. But there are some foods you should limit as they could increase the risk of developing side effects of Metformin.

Alcohol should be kept to a minimum because it has been linked to Metformin induced lactic acidosis, which is a rare side effect where lactate levels are too high and cause imbalance in the body’s pH. Alcohol intake at night could also lead to hypoglycemia by preventing the liver from creating glucose when you sleep.

You should also be picky with foods that can upset your stomach – like dairy or high-fiber foods – because gas, stomach aches, and other GI issues are common side effects when starting Metformin.

Overall you have a lot of food options when it comes to Metformin. But you still have to be mindful of your diet to help control blood sugar levels and manage type 2 diabetes long-term.

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