Most people get enough vitamin B12 through the diet, but those with inadequate intake experience symptoms of vitamin B12 deficiency. (healthyeating.sfgate.com)
Reasons for inadequate intake include poorly balanced vegetarian diets, chronic fad or crash dieting and having limited access to a wide range of fresh foods. (womenshealthandfitness.com.au)
But before you start popping supplements, you should know there's a difference between inadequate intake and a true deficiency. (health.com)