The Best Time of Day to Take B12 for Maximum Absorption

Vitamin B12 does lots of important things for your body, like helping you metabolize energy, aiding in red blood cell and DNA production, and promoting a healthy brain and nervous system. While most of us get enough of this nutrient, sometimes a supplement is necessary (more on this soon!).

However, getting the most out of your vitamin B12 supplement isn’t about just popping a pill. Factors like diet, age, health conditions and medications you take can all impact how well your body absorbs B12. But does when you take your B12 supplement matter?

To find out, we asked a registered dietitian. Read on to learn the best time to take vitamin B12, factors that influence its absorption, plus expert tips for getting the most out of your supplement. 

Factors Affecting Vitamin B12 Absorption

Most healthy adults need 2.4 micrograms of vitamin B12 per day. However, that number jumps to 2.6 mcg if you’re pregnant and 2.8 mcg if you’re breastfeeding.

This nutrient is easily absorbed, but there are some factors that affect its absorption, like these:

Stomach Acid

Vitamin B12 in food is tightly attached to a protein that prevents its digestion, explains Trista Best, RD. During the digestive process, acid that’s naturally present in your stomach breaks apart this bond, freeing B12 from this protein for easy absorption.

As critical as stomach acid is for B12 uptake from food, B12 in supplements isn’t bound to a protein. So, the amount of stomach acid you do–or don’t–produce doesn’t matter.

Intrinsic Factor

What does matter is the availability of a protein produced in the stomach, called intrinsic factor, that facilitates B12 absorption. Whether you get your B12 from food or supplements, you won’t be able to absorb it without sufficient intrinsic factor.

Medications

Certain medications may prevent your ability to effectively absorb vitamin B12. Perhaps the most important is metformin, used to treat prediabetes and diabetes. While health experts aren’t sure why metformin impairs B12 uptake, this drug has long been linked to B12 deficiency. If you are taking metformin, be sure to speak with your doctor to find out if you should be tested for B12 deficiency, which can present with symptoms such as anemia, neuropathy, cognitive issues and depression.

Medications for heartburn and gastroesophageal reflux disease may also impair vitamin B12 absorption by reducing stomach acid. However, because supplementary B12 doesn’t require stomach acid for absorption, this is only an issue for B12 from food.

Health Conditions

People living with certain health conditions are more likely to have difficulty absorbing B12, especially:

Age

Your stomach’s ability to produce acid naturally declines as you age, which increases the risk of B12 deficiency. As a result, the National Institutes of Health recommends that people over 50 take a B12 supplement or add B12-fortified foods to their diet.

Diet

You can only get meaningful amounts of B12 from animal foods. Top sources include beef liver, clams, oysters, salmon and ground beef, although it’s also found in nutritional yeast. If you eat animal foods and don’t have an underlying issue that predisposes you to deficiency, you’re probably getting enough B12. However, if you’re a strict vegetarian or a vegan, a B12 supplement is critical.

The Form of Your Supplement

For those who struggle to absorb B12 due to low intrinsic factor or gut issues, taking B12 sublingually (under the tongue) or receiving B12 injections is an excellent alternative, says Best.

Optimal Timing for Vitamin B12 Intake

B12 is a water-soluble vitamin, meaning it dissolves in water (by comparison, fat-soluble vitamins, such as vitamins A, D, E and K, require fat for absorption). While B12 is not stored in large quantities in the body, you can store some of it. According to the NIH, our bodies typically store 1,000 to 2,000 times the amount of vitamin B12 that we eat in a day.

Because water-soluble vitamins, like B12, do not require other nutrients to assist with their absorption, the best time to take your B12 supplement is when it’s most convenient for you. If that’s with breakfast, great, but taking it with dinner or even on an empty stomach between meals will work equally well.

However, if you take metformin, you’ll want to make sure to take your supplement and your medication several hours apart. 

Potential Side Effects and Considerations

Because B12 is water-soluble, excess amounts are typically excreted in urine. So toxicity is rare. However, cyanocobalamin, the most commonly used form of supplemental vitamin B12, may be problematic for people with kidney failure as this form of B12 contains aluminum.

That said, before taking any new supplement, it’s wise to speak with your health care provider, who can confirm if you have a deficiency through a blood test, says Best.

The Bottom Line

Vitamin B12 is a vital nutrient for overall health as it helps support red blood cell and DNA production, energy metabolism, nerve function and brain health. The good news is that most of us get enough of this nutrient. However, if you’re over 50, are taking the diabetes medication metformin, are living with a digestive disorder, or are a vegan or strict vegetarian, you may need a supplement.

If you’re wondering about the best time to take your B12 supplement, any time of day works as long as you don’t combine it with medications that interfere with its absorption, like metformin. That said, before taking any new supplement, it’s always a good idea to consult your health care provider to make sure it is right for your unique nutrition needs.