Is Vitamin B12 the Muscle Nutrient You’ve Been Missing?

The mitochondria is the “powerhouse of the cell,” but B12 is what keeps the lights on. Here’s the latest science on how it affects your energy levels.

Protein powder, creatine, pre-workouts… There are more supplements than ever promising to elevate your performance in the gym. But if you walked into a supplement shop asking for vitamin B12 for muscle growth, you’d probably raise a few eyebrows.

Recent scientific evidence indicates it’s not that silly, though — beyond its reputation as the “energy vitamin,” B12 also has a role to play in powering your muscles. Here’s what we know, and how you can capitalize on it. 

What You Should Know About B12 and Your Muscles

When we think of feeding our muscles, our brains rightfully dart to protein and calories — nutrients required to build and repair muscle tissue. Physically active folks use their muscles more, so they need larger quantities of these major fuel sources.

But protein doesn’t “keep the lights on” in your muscles. Zooming in, your body relies on vitamin B12 for cellular repair and function. Particularly, the DNA inside mitochondria, those famous cellular “power plants” that generate energy.

Just as long periods of caloric deprivation can leave you feeling fatigued, an insufficient vitamin B12 intake can depower your muscles’ capabilities. And it gets trickier from there:

• Scholars believe age-related losses in muscle have to do with mitochondrial dysfunction.
• The majority of natural B12 comes from animal foods, but only about half is effectively absorbed.
• Deficiency is more common in some groups than others: adults over 50, vegans and vegetarians, people with digestive conditions, and anyone who’s had stomach surgery.
• Vitamin B12 deficiency goes beyond making you feel tired. It’s linked to anemia, nerve symptoms, muscle weakness, and even cognitive impairment in older people.

Low B12 doesn’t just make you tired. It saps your muscles of an essential mechanistic puzzle piece, according to the latest research.

Going Deeper on the B12–Mitochondria Link

In 2026, scientists from Cornell University and the University of Alabama at Birmingham set out to determine how vitamin B12 deficiency affects skeletal muscle. Rodent subjects were split into two groups:

• Young-adult male mice that were either genetically prone to impaired B12 use or fed a B12-deficient diet for seven weeks.
• Older mice (roughly equivalent to older adults in human years) that received weekly B12 injections for eight weeks.

In the B12-deficient group, the mitochondria couldn’t work at full capacity — those mice’s muscles produced and utilized about 25 percent less energy. They also showed around 10 times more DNA errors in their mitochondria, a sign of instability that can further impair energy production. In the older mice, weekly B12 injections doubled the activity of a key energy-producing component in their leg muscles, suggesting supplementation may help restore mitochondrial function with age.

Before we get practical, bear in mind that this study was conducted on mice, not humans. It also doesn’t say that B12 supplementation enhances performance; it helps us understand the mechanics of cellular energy production.

The Takeaway

Vitamin B12 supplementation has been recommended by institutions like the Mayo Clinic for years, but when it comes to muscle health and functionality, other supplements tend to steal the spotlight.

The latest research argues that you should, in fact, sweat the little things, especially if you’re over 50. Incorporate vitamin B12-rich foods into your diet to ensure you meet the recommended daily intake of 2.4 mcg. Some options are:

• Clams and beef liver
• Fish such as salmon and tuna
• Eggs
• Fortified nutritional yeast

Scholars have pointed to fortified breakfast cereals as practical, accessible sources of B12 for elderly people in particular. If you’re over 50, follow a plant-based diet, or have a digestive condition, ask your doctor about checking your levels — a methylmalonic acid (MMA) test gives a more sensitive read on your B12 status. And since B12 supports the mitochondria in your muscles, pairing it with enough protein and regular strength training may help you hold onto muscle function as you age.

Bottom Line

Here’s what we know: Getting adequate micronutrients, such as vitamins like B12, is just as important as hitting the big benchmarks — even if you don’t always feel the effects right away.

Feeling strong and energetic can make a massive difference in your overall quality of life, but requires you to pay attention to more than just calories or protein. If you’re feeling fatigued and are part of a cohort that tends to suffer from B12 deficiency, upping your intake might make a noticeable difference.

That said, the muscle findings so far come from a short animal study, so human trials are the next step to watch for — and we still need more research on whether B12 supplementation helps people who aren’t prone to deficiencies. In the meantime, there’s no harm in keeping your bases covered.