Vitamin B12 may play a much broader role in metabolism and healthy aging than previously thought. Traditionally associated mainly with nervous system function, the vitamin is now increasingly linked to energy production, muscle maintenance, and resilience during aging.

Researchers from Cornell University, publishing in the Journal of Nutrition, reported that vitamin B12 supports several key metabolic processes and may influence muscle health long before classic deficiency symptoms appear.

How Vitamin B12 Affects Muscle Function

Lead author Martha Field, associate professor of nutritional sciences at Cornell University, said the study is the first to demonstrate that vitamin B12 deficiency directly disrupts mitochondrial energy production in skeletal muscle.

Skeletal muscles require large amounts of energy to function properly, making them particularly sensitive to metabolic disturbances. Even mild impairments in mitochondrial activity may therefore affect muscle performance and recovery.

Previous studies on vitamin B12 deficiency mainly focused on advanced clinical consequences such as:

• megaloblastic anemia,
• neuropathy,
• cognitive impairment.

The new research instead examined the biological mechanisms underlying early metabolic dysfunction and how vitamin B12 interacts with critical cellular pathways.

In mouse models, researchers found that vitamin B12 deficiency appeared to impair muscle growth and maintenance, potentially contributing to earlier development of frailty and age-related physical decline.

Why Mild Vitamin B12 Deficiency Matters

The study linked low vitamin B12 levels with reduced muscle mass and potentially decreased muscle strength.

This connection is particularly important in older adults because progressive muscle loss — known as sarcopenia — is associated with:

• weakness,
• falls,
• reduced mobility,
• earlier loss of independence.

Vitamin B12 deficiency remains common worldwide, especially among:

• older adults,
• vegetarians,
• vegans,
• individuals with gastrointestinal disorders affecting absorption.

Researchers estimate that up to one in four older adults in developed countries may have suboptimal vitamin B12 levels.

Although severe deficiency is relatively uncommon in many high-income regions, borderline deficiency is frequent and may still impair the body’s ability to respond to:

• metabolic stress,
• inflammation,
• immune challenges,
• age-related physiological decline.

Sources of Vitamin B12

Vitamin B12 is naturally produced by bacteria and certain algae species.

Humans primarily obtain vitamin B12 through:

• meat,
• fish,
• eggs,
• dairy products,
• fortified foods,
• dietary supplements.

Researchers have also developed methods to cultivate spirulina and other algae under laboratory conditions so they produce biologically active forms of vitamin B12 that humans can absorb.

Some studies suggest that carefully cultivated spirulina may contain vitamin B12 concentrations comparable to those found in high-quality fish or beef.

Scientists believe such biotechnology-based production methods could improve global access to vitamin B12, particularly in populations with limited access to animal-derived foods.

Expanded use of fortified plant-based foods and supplements may also help reduce deficiency rates worldwide.

Who Should Consider Testing?

Experts recommend that the following groups discuss vitamin B12 screening with their healthcare providers:

• older adults,
• strict vegetarians,
• vegans,
• individuals with digestive disorders,
• people taking medications that impair B12 absorption.

Early detection and treatment of low vitamin B12 levels may help support:

• muscle health,
• energy metabolism,
• cognitive function,
• healthier aging overall.