Long before cobalt became a line in a chemistry textbook, it was a miner’s headache. In the mountains of Saxony, certain ores looked promising—perhaps silver, perhaps copper—but refused to deliver the expected metal. Worse, heating them could release toxic arsenic fumes. Miners blamed the trouble on kobolds, mischievous underground goblins. The name stuck.
There was one beautiful clue hiding in all that frustration: cobalt-bearing minerals could make glass and pottery an extraordinary blue. Craftspeople used cobalt blue for centuries before anyone knew which element was responsible. Then, in the 1730s, Swedish chemist Georg Brandt studied a dark blue ore from copper workings and showed that the color came from a previously unrecognized metal, not from bismuth or some vague impurity. Cobalt had moved from goblin lore into chemistry.
For runners, the story takes another turn. Cobalt is not a mineral we normally need to chase by itself. Its nutritional importance comes from the fact that one cobalt atom sits at the center of vitamin B12. That distinction matters, because vitamin B12 is essential nutrition; swallowing cobalt salts in pursuit of a blood or performance effect is something very different.
The blue element with a complicated personality
Cobalt’s famous color is not simply “the color of cobalt.” The metal’s compounds can appear blue, pink, violet, green, yellow, or brown depending on its oxidation state and the molecules or ions arranged around it. Those neighbors change the spacing of cobalt’s d-electron energy levels. When light hits the compound, certain wavelengths are absorbed and the rest reach our eyes. Change the chemical neighborhood and you can change the color.
That is why cobalt can color glass a deep blue yet sit inside vitamin B12 without turning your breakfast—or you—blue. Chemistry is wonderfully particular. The same element can behave very differently depending on the molecule holding it.
The cobalt atom inside vitamin B12
Vitamin B12 is the only vitamin built around a metal atom. Its cobalt center is held inside a large ring-shaped structure called a corrin ring, which is why B12 compounds are also called cobalamins. Methylcobalamin and adenosylcobalamin are two metabolically active forms.
The body needs vitamin B12 for normal red blood cell formation, DNA synthesis, and healthy nervous-system function. Those are essential jobs for everyone. They are especially relevant to runners because training asks the circulatory and nervous systems to do reliable work, week after week, while the rest of life continues to pile onto the calendar.
Still, “essential” does not mean “more is faster.” Correcting a deficiency helps restore normal function. In people whose B12 status is already adequate, supplemental B12 has not been shown to improve endurance or athletic performance. That is the honest dividing line between meeting a nutritional requirement and promising a performance boost.
Where runners get vitamin B12
The adult Recommended Dietary Allowance for vitamin B12 is 2.4 micrograms per day. B12 occurs naturally in animal foods and is also added to some fortified foods. Plants do not naturally provide reliable B12, so runners eating vegan or mostly plant-based diets need to pay particular attention to fortified foods or supplements.
| Food | Serving | Vitamin B12 |
|---|---|---|
| Cooked salmon | 3 ounces | 2.6 mcg |
| Canned light tuna | 3 ounces | 2.5 mcg |
| Cooked ground beef | 3 ounces | 2.4 mcg |
| 2% milk | 1 cup | 1.3 mcg |
| Plain yogurt | 6 ounces | 1.0 mcg |
| Large egg | 1 | 0.5 mcg |
Food should do most of the work. A salmon dinner, a yogurt at breakfast, or a cup of milk with a meal can contribute meaningfully. Fortified nutritional yeast and fortified breakfast cereals can help plant-based runners, but amounts vary widely, so the package information matters.
Absorption also deserves attention. Vitamin B12 must be released from food and then handled through a multistep process involving stomach acid and intrinsic factor. Adults over 50 may absorb food-bound B12 less efficiently. Metformin and acid-suppressing medicines can also affect B12 status, as can certain gastrointestinal disorders or surgeries. That does not mean every tired runner has a B12 problem. Fatigue has many possible causes, and guessing from symptoms is not a diagnosis. If your diet, medicines, or medical history put you at risk, discuss testing with a qualified clinician.
The tempting wrong turn: cobalt salts and blood
Cobalt can activate pathways related to the body’s response to low oxygen, which has led to interest in whether cobalt salts might stimulate red blood cell production. Here the molecule, dose, population, and outcome all matter.
In a small 2018 randomized trial, 24 healthy young men who were recreationally trained or sport students received either placebo or 5 milligrams of ionized cobalt per day for three weeks. Hemoglobin mass increased by about 2% in the cobalt group. But mean maximal oxygen uptake did not improve. In other words, the researchers found a biomarker change, not a demonstrated average performance benefit. Urinary cobalt also rose sharply.
Five milligrams of ionized cobalt is not vitamin B12 nutrition. It is not comparable with the cobalt atom bound safely inside microgram quantities of B12 in food or a multivitamin. Historical medical use of cobalt salts produced serious adverse effects involving the gastrointestinal tract, thyroid, heart, and sensory systems. Cobalt is also listed by the World Anti-Doping Agency among prohibited HIF-activating agents, prohibited at all times.
For runners, the practical advice is refreshingly uncomplicated: do not use cobalt salts as a shortcut to more red blood cells or faster running. Meet your vitamin B12 needs instead.
Where PEREGRUNE fits
We include 67 mcg of vitamin B12 as methylcobalamin in every two-tablet serving of PEREGRUNE Runner Multivitamin. At the center of that B12 molecule is a single cobalt atom. We include B12 to help runners consistently meet their daily nutritional needs, even when work, family, travel, and training make a perfectly balanced diet difficult.
Why include B12? Because it is an essential nutrient, and real diets are not assembled in a laboratory. Work travel happens. Family schedules happen. Lunch occasionally becomes whatever was closest to the meeting. A daily multivitamin can help maintain nutritional coverage alongside a varied diet, especially for runners whose food choices or absorption risks make B12 worth watching. It is nutritional backup, not permission to stop eating well and not a claim that extra B12 turns adequate status into extra speed.
Frequently asked questions
Is the cobalt in vitamin B12 the same as cobalt chloride?
No. Vitamin B12 is a complex cobalamin molecule with cobalt securely incorporated into its structure. Cobalt chloride is an inorganic cobalt salt. They are not nutritionally or physiologically interchangeable.
Does vitamin B12 improve running performance?
Vitamin B12 is essential for normal physiology, and correcting deficiency can restore normal function. Research does not show an endurance benefit from supplemental B12 in people who already have adequate status.
Should runners take a stand-alone cobalt supplement?
No. There is no nutritional reason to supplement cobalt salts for running performance, the safety concerns are real, and cobalt is prohibited in sport as a HIF-activating agent. Choose appropriate B12 nutrition, not free cobalt.
Who should pay closer attention to B12?
Vegans and some vegetarians, adults over 50, people with certain gastrointestinal conditions or surgeries, and those using metformin or acid-suppressing medicines may be at greater risk of low B12 status. A clinician can help decide whether testing is appropriate.
The bottom line
Cobalt’s path from cursed ore to brilliant blue pigment to the center of vitamin B12 is a terrific piece of chemistry. The runner’s takeaway is simpler: cobalt matters because vitamin B12 matters. Build your foundation with B12-containing or fortified foods, use a thoughtfully formulated multivitamin as daily nutritional backup, and leave cobalt salts to the history books and the prohibited list.
Dietary supplement disclaimer: This article is for educational purposes and is not medical advice. Dietary supplements are not intended to diagnose, treat, cure, or prevent disease. Talk with a qualified healthcare professional about individual needs, medications, testing, and supplement use.
Sources
- Royal Society of Chemistry: Cobalt—history, properties, and uses
- NIH Office of Dietary Supplements: Vitamin B12 Fact Sheet for Health Professionals
- Hoffmeister et al. (2018): Low-dose cobalt, hemoglobin mass, and aerobic performance
- Ebert and Jelkmann (2014): Intolerability of cobalt salt as an erythropoietic agent
- World Anti-Doping Agency: 2026 Prohibited List
