Best Time of Day to Take Vitamin B12 for Maximum Absorption

The red blood cells that course through your veins, the protective covering that surrounds your nerve fibers and the genetic information that is tightly packed into your cells all rely on one key nutrient—vitamin B12. Yet nearly 12.5% of the people in the U.S. aged 19 or older are not getting enough of this essential vitamin. This is particularly common among older adults, people who follow a vegetarian or vegan diet and individuals with certain digestive disorders. If you fall into one of these groups, you may have been advised to take a vitamin B12 supplement. However, in order to unlock your supplement’s full potential, timing may be just as important as the supplement itself. So, we asked dietitians for their expertise on the best time to take vitamin B12 for maximum absorption.

Types of Vitamin B12 Supplements

You can find vitamin B12 supplements in four different forms: cyanocobalamin, methylcobalamin, hydroxocobalamin and adenosylcobalamin. Edwina Clark, M.S., RD, CSSD, a registered dietitian, highlights their unique properties:

• Cyanocobalamin: The most common, cost-effective and stable form with a well-established record for safety and efficacy. It is synthetically produced and must be converted into active forms that the body can readily use.
• Methylcobalamin: An active form naturally found in animal foods that is readily used by the body. It also has a strong track record for safety and efficacy.
• Hydroxocobalamin: Often given as an injection, this form of vitamin B12 lasts longer in the bloodstream and is used to treat severe deficiencies.
• Adenosylcobalamin: A naturally active form that is present in the mitochondria (powerhouse of the cell) and involved in energy production. However, it is less commonly available and not as well studied as other forms.

“The dosage and delivery (supplement vs. intramuscular injection) should be personalized to the individual and adjusted as lab levels change. For those with malabsorption issues, intramuscular B12 injections may be necessary. For others, oral B12 supplements can be effective for raising vitamin B12 and typically cost far less,” Clark explains.

Oral B12 supplements can vary in form, with options ranging from tablets and sprays to drops placed under the tongue. Studies suggest there is no difference in efficacy between the different delivery methods.

Optimal Timing for Vitamin B12 Intake

While research hasn’t nailed down a set-in-stone time for optimal absorption, taking your vitamin B12 supplement in the morning before breakfast is often recommended. Here’s why: Alexandra Caspero, M.A., RD, a registered dietitian specializing in plant-based nutrition, shares that vitamin B12 absorption peaks around 7 hours after taking it, which is why many practitioners suggest incorporating it into your morning routine to reap its benefits throughout the day.

To make it easier to remember, Clark recommends pairing your B12 supplement with an existing habit, like brushing your teeth in the morning. After all, B12 is a water-soluble vitamin, meaning it doesn’t stick around in your body. Therefore, consistency is crucial for keeping your B12 levels up and correcting any deficiency.

Factors Affecting Vitamin B12 Absorption

Getting the timing right is just one part of the equation. Other factors can either help or hinder the absorption of vitamin B12.

Factors That Enhance Absorption

When it comes to enhancing vitamin B12 absorption, the dose matters. “B12 is absorbed differently than other B vitamins, and that’s because of intrinsic factor, a protein found in the stomach that is needed for proper B12 absorption. We only absorb about 1 microgram of B12 at a time, though that number can vary based on the dose,” says Caspero. For this reason, you will notice that vitamin B12 supplements contain a higher amount of B12 than is normally found in food.

“For those who consume B12 throughout the day from animal products, this isn’t usually a concern. However, for vegans and vegetarians, if taking only a single supplement, then a higher dose is needed,” Caspero explains. As such, she suggests that adults take at least 25 micrograms of vitamin B12 daily, with higher doses of 50 to 250 micrograms during pregnancy and lactation to support absorption and address deficiencies. However, it’s always best to consult your health care provider to evaluate your B12 levels and determine the dosage that’s right for you.

Factors That Prevent Absorption

Absorbing vitamin B12 isn’t always a smooth process, as there are several factors that can complicate its uptake in the body. For instance, inadequate stomach acid and intrinsic factor can hinder absorption. “Stomach acid helps cleave B12 from food, and intrinsic factor is essential for transporting B12 into the small intestine. However, various conditions and medications can reduce stomach acid and intrinsic factor, raising your risk of B12 deficiency,” says Clark. These include pernicious anemia, certain medications like antacids and metformin, gastric bypass surgery and even older age. Additionally, Clark points out that gastrointestinal (GI) conditions, such as celiac disease, Crohn’s disease and ulcerative colitis, can impair absorption in the small intestines, contributing to low B12 levels.

Potential Side Effects and Considerations

Vitamin B12 supplements are well-tolerated and safe for most people. In fact, the Food and Nutrition Board hasn’t set a Tolerable Upper Intake Level (UL) for B12, which is the maximum safe dose unlikely to cause adverse health effects. This is because B12 is water-soluble, so your body uses what it needs and flushes the rest out through your urine. Therefore, even in large doses, B12 is considered safe.

However, Clark highlights that, on rare occasions, some people experience adverse reactions after taking vitamin B12, including diarrhea and itchy skin. Caspero adds that there have also been reports of acne-like symptoms when vitamin B12 is taken in large, daily doses over 1000 micrograms.

The Bottom Line

Optimal levels of vitamin B12 are required for red blood cell formation, DNA synthesis and to protect nerve fibers. Supplementation is often recommended for those following a plant-based eating pattern, older adults and individuals with digestive conditions. To get the most out of your supplement, dietitians recommend taking it first thing in the morning. However, the most important factor is to remember to take your supplement consistently. Just be sure to consult with your health care provider to discuss potential medication interactions and determine the best form and dosage for your individual needs.