How to Take Vitamin B12 the Right Way: Timing, Dosage & Benefits

Vitamin B12 is essential for every cell in the body because it plays a role in making and repairing DNA. It is also required to produce healthy red blood cells, which carry oxygen throughout the body, and it supports the normal functioning of the nervous system (1).

Types of Vitamin B12

There are four different types of vitamin B12:

• Methylcobalamin: The most bioavailable and naturally occurring type, found in animal-based foods such as meat, fish, milk, and eggs. It is the most active form and is mainly used in the liver, brain, and nervous system.
• Adenosylcobalamin: Another naturally occurring coenzyme form of vitamin B12. It works together with methylcobalamin to provide complete “B12 cover” for the body. It supports mitochondria within cells and is a key component of the myelin sheath, which protects nerve cells and enables faster responses to stimuli.
• Cyanocobalamin: A synthetic form of vitamin B12 that the body converts into the active forms methylcobalamin and adenosylcobalamin.
• Hydroxocobalamin: Produced naturally by bacteria in the digestive tract and sometimes developed in a laboratory from microorganisms. In supplement form, it is only available on prescription and usually administered by injection under medical supervision (2).

Best Time to Take Vitamin B12

Morning is the best time to take vitamin B12, ideally on an empty stomach, because:

• It helps convert food into cellular energy (via methylation and ATP production), supporting the body’s natural circadian rhythm.
• Taking it later in the day may increase alertness and interfere with sleep.
• Many people notice an energy boost within hours of taking it, making the morning an ideal time to benefit (3).

Dosage

The recommended dietary allowance (RDA) for vitamin B12 for people aged 14 and older is 2.4 micrograms (mcg). However, exact needs vary depending on age, health, and lifestyle.

Adults under age 50

For those over 14, the RDA is 2.4 mcg. Most people can meet this through diet alone. For example, eating the following in one day would more than double your daily B12 requirement:

• Two eggs for breakfast (1 mcg of B12)
• 85 g of tuna for lunch (2.5 mcg of B12)
• 85 g of beef for dinner (2.4 mcg of B12)

For healthy adults in this age group, supplementation is usually unnecessary.

Adults over age 50

Older adults are more prone to vitamin B12 deficiency because the body produces less stomach acid and intrinsic factor with age. Stomach acid is needed to release vitamin B12 from food, and intrinsic factor is required for absorption. For this reason, adults over 50 are advised to meet most of their B12 needs through supplements and fortified foods.

Pregnant people

Pregnant individuals require slightly more vitamin B12 than average. Low maternal levels have been linked to birth defects. The RDA during pregnancy is 2.6 mcg.

Breastfeeding people

Breastfeeding individuals need 2.8 mcg of vitamin B12 daily. Deficiency in nursing infants has been associated with lethargy, poor appetite, and failure to thrive, as well as developmental delays.

Vegans and vegetarians

The RDA for adults under 50 remains 2.4 mcg. However, because vitamin B12 is not naturally found in plant-based foods, those following vegan or vegetarian diets often need B12 supplements to avoid deficiency (4).

Benefits of Vitamin B12 Supplementation

• Helps with red blood cell formation and anaemia prevention
  Low levels of vitamin B12 reduce red blood cell production and cause cells to develop abnormally, often becoming large and oval rather than small and round. This condition, known as megaloblastic anaemia, results in cells not entering the bloodstream effectively, leading to fatigue and weakness.
• May prevent major birth issues
  B12 deficiency during early pregnancy has been associated with neural tube defects and increased risks of premature birth or pregnancy loss (5).
  One study found that individuals with vitamin B12 levels below 250 mg/dL were 2.5–3 times more likely to have children with birth defects compared with those with adequate levels. Those with severe deficiency, below 150 mg/dL, had a fivefold risk increase (6).
• May support bone health and prevent osteoporosis
  Adequate levels of vitamin B12 are linked to better bone mineral density, which reduces fragility and fracture risk over time. Low levels may increase the likelihood of osteoporosis (7).
• May support healthy hair, skin, and nails
  Both low and excessively high vitamin B12 levels can cause changes in skin, hair, and nails. Deficiency may lead to hyperpigmentation, nail discoloration, hair changes, loss of skin color in patches, and canker sores (5).

Frequently Asked Questions (FAQs)