Athletes should get at least the minimum recommended daily intake of 2.4 mcg of vitamin B12 for optimum athletic performance. But, athletes of bodybuilding may benefit from much higher doses of 1,000 mcg from supplements! Maintaining healthy levels of vitamin B12 may relieve pain, and increase muscle growth and strength.
Vitamin B12 deficiency is bad for muscle growth
Athletes of bodybuilding should be very cautious with vitamin B12 intakes. They have to maintain normal vitamin B12 levels for muscle growth and recovery.
First, vitamin B12 deficiency may cause muscle pain. In fact, vitamin B12 has been used to treat pain for years. In some countries, vitamin B12 is still used as an analgesic drug. It has neuroprotective and analgesic properties. Indeed, vitamin B12 may reduce or eliminate pain. Especially if it’s combined with other drugs.[1,2]
Moreover, vitamin B12 deficiency may cause fatigue, muscle weakness, or muscle cramps. According to a 2019 study, people with vitamin B12 deficiency improved the symptoms of muscle weakness and muscle cramps after 6 months of treatment with vitamin B12 supplements.[3]
Also, vitamin B12 is required for red blood synthesis and proper neurological function. Red blood cells transport oxygen to the lungs and the muscles. In addition, they deliver the produced CO2 to the lungs for expiration. This process is vital for athletic performance and recovery after strenuous exercise.[4]
Hence, it’s also vital for endurance athletes to have healthy levels of vitamin B12.
Furthermore, vitamin B12 deficiency results in severe oxidative stress. Oxidative stress may be bad for muscle recovery. It’s important to fully recover after resistance exercise. Working out for muscle hypertrophy produces high amounts of free radicals, which can lead to oxidative stress.[5]
Eating foods high in antioxidants, such as fruits and vegetables, fights oxidative stress, which can be dangerous for health. Zinc, vitamin D, vitamin C, and omega-3s are also beneficial for muscle growth and recovery.
How much vitamin B12 should I take for bodybuilding?
The recommended daily intake of vitamin B12 is 2.4 mcg. But, athletes of bodybuilding with low levels of vitamin B12 could consume even 1,000 mcg of vitamin B12 a day for muscle hypertrophy. Actually, athletes can perform better with vitamin B12 concentrations higher than 400 pg/mL.
So, you could take high dosages of vitamin B12 until you reach optimum vitamin B12 concentrations. You could take even higher dosages of vitamin B12 if you have vitamin B12 concentrations significantly lower than 400 pg/mL. Lower vitamin B12 concentrations may be bad for your energy levels, muscle recovery, and muscle growth.[6]

As, vitamin B12 deficiency is a common nutrient deficiency, athletes of bodybuilding should regularly check their vitamin B12 levels.
Moreover, vitamin B12 supplementation is considered pretty safe. Even high vitamin B12 dosages of 1,000 mcg have almost no risk of toxicity.
The best time to take vitamin B12 supplements is at breakfast.
Foods with vitamin B12 for athletes
Meat, poultry (e.g. chicken), fish, milk, eggs, and dairy are the richest common foods in vitamin B12. They’re good for muscle growth, as they’re also particularly high in protein!
In fact, tuna, chicken and turkey sandwiches are great post-workout snacks.
On the other hand, plant-based foods contain negligible amounts of vitamin B12. Only fortified plant-based foods can help us meet our daily needs.
In addition, a cheap way to maintain normal vitamin B12 levels is by taking vitamin supplements. You can find a wide variety on iHerb.
Do vitamin B12 injections build muscle mass?
Intramuscular injections are effective for treating severe vitamin B12 deficiency. It’s a common practice for athletes.
Athletes shouldn’t be injected with vitamin B12 without the advice of their physician, though. Intramuscular injections may result in vitamin B12 concentrations of over 1,000 pg/mL within a week, or 3,000 pg/mL in just 4 weeks!
Hence, injections of vitamin B12 in athletes should only be applied in acute cases of vitamin B12 deficiency. Otherwise, injections can cause unnecessary, extremely high vitamin B12 concentrations.
Certainly, vitamin B12 injections don’t have a beneficial effect on muscle growth if an athlete has normal levels of vitamin B12.
Always consult your healthcare provider before changing your diet or taking any dietary supplement.