Common Vitamin Has a Complicated Link to Cancer, Experts Reveal

Vitamins are usually sold to us as a pretty straightforward, good thing to add to your diet.

Get enough, and you'll look and feel great; get too little, and your body might notice.

But the reality is messier – and few vitamins prove that better than B12.

For decades, vitamin B12 has been one of the heroes of nutrition. If you're foggy-headed or tired – or on a plant-based diet – you might be recommended B12 to help pep you up.

But it might not be so straightforward.

A growing number of scientific papers have detected both too little and too much of it in the blood of people with cancer – of the lungs, the breast, the esophagus, and the colon.

That's right, too little AND too much.