New research is shedding light on the connection between vitamin B12 and muscle health, showing that low levels of this nutrient may affect more than just energy levels.
Vitamin B12 has long been called the “energy vitamin,” but it does not provide a direct jolt of energy like caffeine. Instead, it works at the cellular level, helping mitochondria produce the energy muscles need to function. When B12 runs low, muscle cells may struggle to generate energy efficiently, and the damage can start at the level of DNA.
How B12 works in the body
B12 plays a key role in helping cells build and repair DNA. When B12 is low, this process stalls, and mitochondrial DNA becomes more prone to errors. Mitochondrial DNA contains the blueprints for proteins that mitochondria need to produce energy. When this DNA is damaged, cells cannot generate energy as effectively.
Study findings on B12 deficiency
Researchers at Cornell University and the University of Alabama at Birmingham studied how B12 deficiency affects energy production in muscles. They looked at two groups of mice: young-adult males that were either genetically prone to impaired B12 use or fed a B12-deficient diet for seven weeks, and older mice that received weekly B12 injections for eight weeks.
The study found that in mice with low B12, the mitochondria in their muscles could not work at full capacity. Energy output from key parts of the mitochondria dropped by about 25% in muscle tissue rich in mitochondria. Mice on the B12-deficient diet had roughly 10 times more DNA errors in their mitochondria, a sign of instability that can further impair energy production.
In older mice, B12 injections doubled the activity of a key energy-producing component in their leg muscles. This suggests supplementation may help restore mitochondrial function with age.
Groups at higher risk for low B12
B12 deficiency is more common in certain groups. Adults over 50 become less efficient at absorbing B12 from food as they age, partly because they produce less stomach acid. Vegans and vegetarians are at risk because B12 is found almost exclusively in animal products. People with digestive conditions like Crohn’s disease, celiac disease, or a history of stomach surgery may also have difficulty absorbing B12.
The study notes that B12 deficiency has been linked to muscle weakness, mitochondrial problems, and increased risk of frailty in older adults.
Practical steps for maintaining B12 levels
For those concerned about their B12 levels, eating B12-rich foods such as clams, beef liver, fish like salmon and trout, eggs, and fortified nutritional yeast can help. Testing may be useful for people over 50, those on a plant-based diet, or those with digestive issues. A test for methylmalonic acid can give a more sensitive reading on B12 status.
Since B12 supports muscle mitochondria, combining adequate B12 with strength training and enough protein may help maintain muscle function as people age. For those who are deficient or at risk, a quality B12 supplement can help, and a doctor can recommend the right form and dose.
This research adds to growing evidence that B12 plays a key role in how muscles produce energy. For anyone focused on healthy aging, keeping B12 levels in check through diet, testing, and supplementation when needed is a way to support mitochondria and muscles over time.
