It’s a rather common scene. A woman presents to my clinic with a complaint such as the inability to lose weight despite trying “everything” or just “needing more energy”. They heard about a friend who received a Vitamin B12 shot from their doctor, so they come in wanting one from me. I then ask them if they have low vitamin B12 and they have no idea.
Vitamin B12 is a vitamin that helps the body make blood cells. Some common signs of this deficiency include enlarged red blood cells and anemia (low red blood cell count). If it is severe enough, it can cause the following symptoms (to name a few):
- Numbness/tingling in the legs
- Problems with balance
- Memory loss and thinking problems
- Fatigue or tiredness
- Painful, swollen tongue
The patients that have low Vitamin B12 usually have one of the following characteristics:
- Strict vegan that does not take in any B12 from diet
- History of a surgery on the stomach (because they no longer have the cells on the lining of their stomach that make it possible to absorb Vitamin B12 in the gut)
- History of an autoimmune condition in which their own white blood cells attack those same cells that make it possible to absorb B12
Vitamin B12 deficiency is often associated with older patients as well, but in the past 6 months the 2 cases of Vitamin B12 that I diagnosed in my clinic were in a man and a women in their 30s and 40s respectively. I tested both of them because they presented with numbness and tingling in their feet/legs that had been going on for several months. The man had been a strict vegan since adolescence so his diagnosis made sense. The woman did not have any clear risk factors so I’m still trying to figure that one out. Neither of them were anemic.
It was clear-cut that they had low B12, so I gave them the option of either the shots or pills. They both chose pills. But like I mentioned earlier, I get many patients with no documented history of low Vitamin B12 but still want a shot anyway because they believe that it will help them “feel better”. Before you go to the doctor begging for this shot I want you to remember these 2 things:
Vitamin B12 injections are really used for special situations. These mainly include cases in which a person is not able to absorb B12 through the gut. This happens with patients who have had stomach surgeries like partial removal of the stomach and bariatric/weight loss surgery. It also happens to patients with autoimmune conditions that attack the cells in the stomach responsible for making a substance called intrinsic factor, which latches on to B12 so that it can be absorbed in the intestines. If your B12 is low but you don’t fall into one of these categories, you will do just fine with a vitamin pill.
Even though B12 is “just a vitamin”, we’re finding out that it might be harmful if you take too much of it. A large study released in 2017 showed that large doses of Vitamin B12 (and Vitamin B6) supplements much higher than the recommended daily values increased the risk of lung cancer in men, regardless of whether or not they were smokers. That study did not show an increase in lung cancer in women, but a separate analysis did show a link between high Vitamin B12 levels and cancer. So if your Vitamin B12 level is normal and you take injections, not only is this unlikely to help, but it can place you at risk for a serious condition. Still ready for the needle?
Bottom line, if you have symptoms like fatigue or numbness and tingling, or have been found to be anemic, you can ask your doctor to order a Vitamin B12 test for you to make sure you are not deficient. Some common medications that can cause low B12 levels include Metformin (in fact, the new diabetes guidelines recommend that all patients taking this medication be checked regularly for low B12) and antacids. Anyone taking these medications should be tested. If you’re just curious about your levels and would like to see if they are contributing to any symptoms that you may have, don’t hesitate to discuss this with your doctor. Please don’t just blindly ask for the shot hoping for a miracle.