Does timing matter? The answer might surprise you!

Vitamin B12 plays a crucial role in your body, helping with energy metabolism, red blood cell and DNA production, and supporting a healthy brain and nervous system. While most people get enough B12 through their diet, some may need a supplement (we’ll dive into that soon!).

But here’s the thing—it’s not just about taking a B12 pill. Several factors, including your diet, age, health conditions, and medications, can affect how well your body absorbs the nutrient. So, does the timing of your B12 supplement matter?

We asked a registered dietitian to find out. Keep reading to discover the best time to take vitamin B12, what affects its absorption, and expert tips for maximizing the benefits of your supplement.

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Factors Affecting Vitamin B12 Absorption

Most healthy adults require 2.4 micrograms of vitamin B12 per day. However, if you’re pregnant, that requirement increases to 2.6 mcg, and it goes up to 2.8 mcg if you’re breastfeeding.

While vitamin B12 is generally easy for the body to absorb, certain factors can impact how well it’s absorbed. Here are a few things to keep in mind:

Stomach Acid

Vitamin B12 in food is tightly bound to a protein, which can make it harder for your body to digest, explains Trista Best, RD. During digestion, stomach acid breaks down this bond, allowing B12 to be freed and absorbed easily.

However, when it comes to B12 supplements, the vitamin isn’t bound to a protein, so the amount of stomach acid you produce—whether high or low—doesn’t affect its absorption.

Intrinsic Factor

What really matters for B12 absorption is the presence of a protein produced in your stomach called intrinsic factor. This protein is essential for helping your body absorb B12, whether it comes from food or supplements. Without enough intrinsic factor, your body won’t be able to properly absorb the vitamin, regardless of its source.

Medications

Certain medications can interfere with your body’s ability to absorb vitamin B12 effectively. One of the most notable is metformin, a drug commonly prescribed for prediabetes and diabetes. Although the exact reason isn’t fully understood, metformin has long been associated with B12 deficiency. If you’re taking metformin, it’s a good idea to talk to your doctor about testing for B12 deficiency, which can cause symptoms like anemia, neuropathy, cognitive issues, and depression.

Medications for heartburn and gastroesophageal reflux disease (GERD) may also impact B12 absorption by reducing stomach acid. However, since B12 supplements don’t rely on stomach acid for absorption, this issue is mainly a concern for getting B12 from food.

Health Conditions

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

• Pernicious anemia
• Atrophic gastritis
• Celiac disease
• Crohn’s disease
• Surgical removal of all or part of the stomach or small intestine

Age

As you age, your stomach’s ability to produce acid naturally decreases, which can increase the risk of vitamin B12 deficiency. Because of this, the National Institutes of Health recommends that people over 50 either take a B12 supplement or include B12-fortified foods in their diet to ensure they’re getting enough of this essential nutrient.

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 individuals who have difficulty absorbing B12 due to low intrinsic factor or gut issues, taking B12 sublingually (under the tongue) or receiving B12 injections can be a highly effective alternative, says Best. These methods bypass the digestive system, ensuring better absorption of the vitamin.

Optimal Timing for Vitamin B12 Intake

Vitamin B12 is a water-soluble vitamin, which means it dissolves in water (unlike fat-soluble vitamins like A, D, E, and K, which require fat for absorption). While B12 isn’t stored in large amounts, your body can store some of it. According to the NIH, we typically store about 1,000 to 2,000 times the amount of B12 we consume daily.

Since water-soluble vitamins like B12 don’t need other nutrients to aid in absorption, the best time to take your B12 supplement is whenever it’s most convenient for you. Whether you take it with breakfast, dinner, or even on an empty stomach between meals, it will be effective.

However, if you’re taking metformin, it’s important to space your supplement and medication several hours apart to optimize absorption.

Potential Side Effects and Considerations

Since B12 is water-soluble, any excess is usually excreted through urine, making toxicity rare. However, the most common form of supplemental B12, cyanocobalamin, may be a concern for people with kidney failure, as it contains aluminum.

That said, before starting any new supplement, it’s always a good idea to consult with your healthcare provider. They can confirm whether you have a B12 deficiency through a blood test, says Best.

The Bottom Line

Vitamin B12 is essential for overall health, supporting 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 vital nutrient. However, if you’re over 50, taking metformin for diabetes, living with a digestive disorder, or following a vegan or strict vegetarian diet, you may need a supplement.

If you’re wondering about the best time to take your B12 supplement, the good news is that any time of day works, as long as it’s not combined with medications that could interfere with absorption, like metformin. Still, before starting any new supplement, it’s always best to check with your healthcare provider to ensure it’s right for your individual nutritional needs.

Reference Eating Well