As you age, your body’s ability to absorb vitamin B12 from food slows—4 out of every 100 women ages 40 to 59 are B12 deficient, and many more are borderline. But celebrating another birthday isn’t the only cause: Avoiding meat, taking certain drugs—like Metformin (commonly prescribed to people with type 2 diabetes or polycystic ovary syndrome) or some common heartburn medications—and even having weight loss surgery all up your odds. The result of coming up short on the vitamin can be anything from intense fatigue to wonky vision. If the symptoms here sound familiar, ask your doctor to run a blood test to check your levels. If they’re low, a supplement or injections will have you back to your old self in a couple of weeks.
1. You can barely stay awake in the afternoon—even if you slept 8 hours.
“Fatigue is one of the first signs of B12 deficiency,” says Lisa Cimperman, RD, a spokesperson for the Academy of Nutrition and Dietetics. That’s because your body relies on the vitamin to make red blood cells, which carry oxygen to your organs. And without enough oxygen in your cells, you’ll feel tired no matter how long you sleep. Fatigue can mean a number of things, though, so you can’t assume you’re B12 deficient if feeling sleepy is your only complaint—doctors usually are tipped off if you’ve got fatigue plus other symptoms.