Vitamin B12 starts working relatively quickly, with injections showing improvements in energy/blood cell production within days, while oral tablets might take a few weeks to a few months for full effects, depending on deficiency severity, with mild improvements in energy often seen in 2-4 weeks and neurological symptoms taking longer. Faster results (days) are typical with injections, but consistent supplementation is key for oral forms to build up levels, with doctors often checking bloods after 7-10 days and 8 weeks to track progress.
B12 is a moderate stimulant when taken so int the first few days people often feel a bit more alert and energetic, but once levels rise, this effect ceases. If you don't feel better quickly then the chances are that B12 deficiency is not the cause of your symptoms.
It may take a few weeks before your vitamin B12 levels and symptoms (such as extreme tiredness or lack of energy) start to improve.
Some people report feeling a boost in energy within just a few hours. Those with a severe B12 deficiency may notice the biggest and most immediate improvement in fatigue, brain fog, and mood. Others may experience a gradual increase in alertness and vitality over the next day.
Yes, Vitamin B12 can help with vertigo, especially if a deficiency is the underlying cause, as low B12 levels can lead to neurological problems, anemia, poor nerve function, and reduced blood flow to the brain, all contributing to dizziness and imbalance, with supplementation showing promise in improving symptoms.
Benign Paroxysmal Positional Vertigo (BPPV) has been linked with low vitamin D levels for many years. While BPPV typically occurs without a known cause, decreased levels of vitamin D in the blood has been associated with increased recurrence of BPPV (1).
B12 deficiency can trigger specific food cravings, most notably for meat, fish, or eggs, as the body seeks animal-based sources to replenish the vitamin, especially in those on vegetarian/vegan diets or older adults. While cravings for sugary or salty foods can also signal general B-vitamin issues, the distinct urge for protein-rich animal products is a key indicator, but professional testing is crucial for confirmation.
Symptoms of vitamin B12 and folate deficiency anaemia include:
In fact, some studies have even suggested the opposite. For instance, one study noted that individuals who regularly took vitamin B12 supplements gained between 2.5 to 17 fewer pounds (1.2 to 7.7 kg) over a decade than those who didn't supplement.
How to use an at-home vitamin B12 blood test
B12 is a key nutrient for nervous system health. It is important for producing serotonin and dopamine, which are mood-enhancing neurotransmitters. As a result, vitamin B12 can help to prevent and treat depression and anxiety. It can improve focus and memory as well.
Lane recommends waiting at least 60 minutes between consuming coffee and supplements—especially for iron, magnesium, and B12.
The best form of B12 is often considered methylcobalamin, as it's a naturally occurring, active form the body uses immediately, though adenosylcobalamin is also an active form, with a combination often recommended for better results, especially for deficiency or absorption issues, while cyanocobalamin, a cheaper synthetic option, is effective but requires conversion and is less ideal for some. For general supplementation, natural forms like methylcobalamin or adenosylcobalamin are preferred for better retention.
Morning is the best time to take vitamin B12, ideally on an empty stomach. Here's why: B12 helps convert food into cellular energy (via methylation and ATP production), so taking it earlier supports your body's natural circadian rhythm.
Possible interactions include:
In conclusion, our results show that lower vitamin B12 was associated with insomnia symptoms and sleepiness in specific groups of participants. However, further research with objective measurements of sleep is crucial to assess the relationship between sleep and vitamin B12.
While Vitamin B12 is generally safe, potential disadvantages (side effects) can occur, especially with high doses or injections, including headaches, nausea, diarrhea, weakness, skin issues (rash, itching), and rarely, more serious heart or allergic reactions (like anaphylaxis), though toxicity from oral intake is rare as excess is usually excreted. Conversely, a deficiency can cause serious problems like irreversible nerve damage, memory loss, fatigue, infertility, and increased risk of certain cancers, making proper intake crucial.
Strengthens Hair Follicles to Promote Growth
This vitamin supports the production of keratin, the protein that makes up hair strands, helping them grow thicker and more resilient. When your body lacks B12, hair follicles may become weaker, leading to slower growth and thinning hair.
Boost your metabolism
Vitamin B12 also gives your body the tools it needs to convert food into energy, a process known as metabolism. B12 injections may boost the metabolic process and make it more efficient, which in turn helps you burn fat more efficiently when you exercise.
Cutaneous manifestations associated with vitamin B12 deficiency are skin hyperpigmentation, vitiligo, angular stomatitis, and hair changes. A diagnosis of vitamin B12 deficiency is often overlooked in its early stages because these signs are not specific to vitamin B12 deficiency alone.
The foods highest in Vitamin B12 are animal products, with clams and liver (beef, lamb) being exceptionally rich sources, often providing several hundred percent of the daily value in a single serving, alongside seafood like mussels, sardines, and salmon, dairy, eggs, and fortified cereals and nutritional yeast for vegans.
Lack of vitamin B12 in your diet: People who don't eat enough foods that have vitamin B12 or don't eat foods fortified with B12 can develop a deficiency. Gastritis: Gastritis is inflammation of the stomach lining, and it's a common cause of vitamin B12 deficiency.
Foods or drinks to avoid
May improve brain health
One study found that low B12 levels, even within the lower normal range, can in part lead to poor memory performance. Vitamin B12 is an important nutrient for the neurons in your brain. Brain atrophy, which refers to the loss of neurons in your brain, is connected to memory loss and dementia.