Does B12 actually make you more energetic? Here are the facts you need to know.

Part of staying healthy is keeping an eye on all the nutrients and vitamins your body needs to stay strong. We step out into the sun for our vitamin D, we stock up on vitamin C from orange juice, and we take fish oil supplements to lower our blood pressure and keep our brains functioning at their highest capacity. Vitamin B12 is supposedly the vitamin that gives us a ton of energy when we’re lacking it. Most of the time, when we hear vitamin B12 uttered, we’re also hearing about people who are either really tired or are vegetarians who need B12 they’re not getting from meat.

But what’s the real truth about B12?

Is it really a magical vitamin that gives us a boost of energy when we’re feeling low? Or is it a bunch of hogwash? The answer lies somewhere in between, so let’s walk through what we know for sure about vitamin B12.

Do you have a vitamin B12 deficiency? Answer these 5 questions to find out: https://t.co/ASPXa5veX3 pic.twitter.com/WQFRylvapL

— Women's Health (@WomensHealthMag) February 25, 2017

First of all, it’s important to know that B12 is an essential vitamin your body needs to function properly. You can find B12 naturally in meat, fish, and dairy products, or you can take it as a supplement. One way of getting B12 into your system isn’t any better than the other. B12 is needed to keep your DNA and your red blood cells healthy. It also plays a significant role in detoxifying your insides.

Google vitamin B12 and the first thing you’ll see is its claim to increase your energy levels. All sorts of people, from health enthusiasts to doctors, recommend taking vitamin B12 if you’re feeling rundown or exhausted.

However, that’s not the whole story. There are a few other things you need to know.

The only time B12 actually gives you energy is if you’re deficient in the vitamin.

So if you’re not lacking vitamin B12, it doesn’t matter how much B12 supplement you take or how many B12 injections you get, you aren’t going to immediately wake up and feel ready to run the world, Beyoncé-style. Your body has to need it in order to get energy from it.

Susan B. Shurin, M.D., deputy director of the National Heart, Lung, and Blood Institute, spoke before Congress in 2008 about vitamin B12. She said there’s no clinical evidence proving that B12 can make you more energetic if your body has enough of it — no matter how tired you may feel at the time. So all those stories about how Margaret Thatcher used to get her boundless energy from B12 injections might be just an urban myth.

That being said, there are quite a few Americans who are lacking B12.

According to the United States Department of Agriculture, a study in Framingham, MA showed that almost two-fifths of American adults suffer from a vitamin B12 deficiency.

In adults over the age of 50, more than 3 percent suffer from seriously low levels of vitamin B12 and 20 percent are on the borderline of low levels of B12. Experts say it’s especially important for elderly folks to keep up their B12 levels in order to maintain a healthy lifestyle.

The major symptoms of B12 deficiency include: weakness or fatigue, shortness of breath, loss of appetite, depression, digestive issues, and brain fog. If any of these sound painfully familiar, get in touch with your doctor and ask them to run some tests to see if you truly suffer from a B12 deficiency. If you let it go untreated, you could cause permanent damage to your brain and your nerves. Some causes for B12 deficiency include vegan or vegetarian diets, MTHFR gene mutations, and inflammation of the intestines.

For teens and adults, 2.4 mcg of vitamin B12 a day is recommended. If you’re not getting that much, you may experience exhaustion, and in that case filling up on B12 would more than likely give you a pep in your step. If you are getting 2.4 mcg or more on the daily and you’re feeling super tired, pounding back the B12 isn’t going to do you any good. You should look at other potential culprits to see what the cause is of your fatigue.