Two micrograms. That’s less than a tiny fragment of a grain of table salt, and yet it’s roughly the daily amount of vitamin B12 adults need to keep their red blood cells, nerves, and DNA production humming along. In 2026, we’ll mark 100 years since George Minot and William Murphy reported that a liver-rich diet could treat pernicious anemia - then often fatal - a discovery that eventually led scientists to identify B12 as the active ingredient. But the real hero of the story might be George Whipple, who noticed that liver helped anemic dogs recover. (Yes, dogs. Because sometimes medical breakthroughs start with a very good boy.)

Despite a century of progress, B12 deficiency remains common, especially among older adults, vegans, vegetarians, and people with absorption issues. Some people don’t eat enough animal products; others produce less stomach acid with age or develop autoimmune gastritis, where the immune system attacks the cells needed to absorb B12. Weight-loss surgery and certain diabetes or acid reflux meds can also sabotage absorption. The symptoms - exhaustion, weakness, shortness of breath, numbness, poor balance, memory problems, brain fog - often get mistaken for normal aging. Because why have one crisis when you can have a quiet, creeping one?

But anemia might not be the whole story. B12 is needed for just two enzymes in humans: one for DNA production, the other for mitochondria to process fats and proteins. A 2026 study found that low B12 can mess with mitochondrial DNA and reduce energy production in lab muscle cells. Another study in aged female mice showed B12 supplements improved mitochondrial health. So that fatigue you feel before obvious anemia shows up? Your mitochondria might be staging a slow-motion protest. This doesn’t mean B12 supplements are a fountain of youth or an energy hack for people with normal levels - but it does suggest the little cobalt-containing molecule has more tricks up its sleeve.

So should you rush to a wellness clinic for B12 shots? Probably not, unless you have a diagnosed deficiency and impaired absorption (in which case the NHS uses hydroxocobalamin injections). For everyone else, the evidence that B12 shots boost energy, weight loss, or performance is about as solid as a wet noodle. Better to figure out why you’re tired in the first place. A century after liver therapy saved dying patients, researchers are still learning how this tiny molecule keeps cells energized - and reminding us that sometimes the smallest things pack the biggest punch.