Vitamin B12: Do you really need that injection?

Sep 25, 2015 | 2 comments

By Susan Burke March, MS, RDN, LDN, CDE

Before starting to work with a new client, whether it is for weight loss, or to help manage a health condition such as high blood pressure or diabetes, I ask them to complete a fairly comprehensive medical and lifestyle (diet and activity) survey.chl susan logo2

Jean (not her real name) said she wanted to lose some weight and eat better — she wanted to feel better about what she was eating. She did a great job in filling out the survey; she was very specific about her typical daily activities and meals. As requested, she included her most recent labs, and all conditions she was being treated for. Although all her labs were within normal limits, something jumped out at me: she had recently gotten an injection of vitamin B12.

I asked Jean about tB12Injectionhis. She said that she’d been tired recently, and her friend suggested that she get a B12 shot. Ah, I said, who gave you the injection? My acupuncturist, she said. I questioned: Did the acupuncturist test you for a B12 deficiency? No, she said, but the doctor said that it would help just the same.

Is more better in the world of vitamins and minerals? Often not. In fact, vitamins and minerals are not benign, and if someone is not deficient, administering excess, whether it’s from a pill or injection, could have negative outcomes.

Vitamin Alphabet Soup

All vitamins are either water-soluble or fat soluble — the classification describes how they’re absorbed and stored in your body. There are 13 different vitamins everyone needs to live healthfully: the B-group vitamins account for eight of those 13.

“B” vitamins include B1 (thiamin), B2 (riboflavin), B3 (niacin), B5 (pantothenic acid), biotin, B6 (pyridoxine), B9 (folate or folic acid when included in supplements), and B12.

Fat-soluble vitamins, A, E, D, and K, are stored in fatty tissue and the liver, and used as needed.

Water-soluble vitamins, vitamin C and B-vitamins are more quickly eliminated from the body compared to fat-soluble vitamins.B12Foods

According to, a slight deficiency of vitamin B-12 can lead to anemia, fatigue, mania, and depression, while a long term deficiency can cause permanent damage to the brain and central nervous system. Vitamin B12 can only be manufactured by bacteria and can only be found naturally in animal products, however, synthetic forms are widely available and added to many foods like cereals. Vitamin B12 excess is excreted by the body or stored in the liver and stores can last for up to a year.

As my Nutrition 101 professor taught us, when you take in excess water-soluble vitamins, your kidneys excretes most of the excess in urine. This is why some people say that Americans have the most expensive urine in the world. Much is spent on costly vitamin supplements, which end up in the toilet. Because we store little water soluble vitamins, they need to be consumed daily and deficiencies can show up rapidly, so it’s important to consume a continuous source of water-soluble vitamins daily — ideally from your diet.

Like all vitamins, the B-vitamins don’t provide energy directly. All vitamins are essential catalysts to the chemical reactions that make our bodies “go”. details that taking an excess of certain water-soluble vitamins can cause problems: too much vitamin B6 can cause nerve problems, excess niacin can cause flushing, and excess vitamin C can cause kidney stones. Excess folic acid may also mask a vitamin B12 deficiency, which is more common in people over age 50.

Deficiency and Malabsorption

Vitamin B12 deficiency can occur because your diet lacks it, or because your body can’t absorb the vitamin properly. The stomach produces hydrochloric acid which separates vitamin B12 from the protein to which vitamin B12 is attached in food — then B12 combines with intrinsic factor in the stomach — this step is crucial for absorption. No intrinsic factor, no absorption, which leads to pernicious anemia, one of the conditions that may require B12 injections.

Crohn’s disease, celiac disease, and alcoholism make it hard for the body to absorb B12 and so do:

– Gastritis and H. pylori infection

– Intestinal effects and consequences of from gastrointestinal disease, cancer, or HIV

– Reduced gastric acid secretion secondary to drug therapy like proton pump inhibitors

– Other drugs, like the diabetes drug metformin, which can have gastrointestinal effects

– After gastric bypass supplementation is necessary since there’s inadequate opportunity to absorb sufficient B12 from foods

Other conditions may increase your need for vitamin B12: alcoholism, hemolytic anemia, chronic fever/infections, kidney and liver disease, pancreatic and stomach disease, thyroid disease and worm infections.

Diagnosis and Treatment

To definitively diagnose deficiency, it’s necessary to measure blood levels for vitamin B12. However, the test measures total, not active, B12 and deficiency can exist even when levels look “normal”. The U.S. National Library of Medicine gives the normal range of vitamin B12 as 200 – 900 pg/mL (picograms per milliliter).Vitamin_B12_050112

Depending on the severity of deficiency, eating a better diet and/or taking B12 supplements can bring levels back to normal.

Most physicians will recommend a B12 supplement if deficiency is obvious, but randomized trials have demonstrated that injections may be no better than oral supplementation since injections have drawbacks; they can be painful and may be unnecessary. However, there are certainly occasions when injections may be needed. Read more about testing here.

A supplement is recommended if you’re taking certain medications that interfere with B12 absorption, such as chemotherapy meds, bile acid sequestrants, H2 blockers, metformin, and proton pump inhibitors (PPIs).

Although an “Upper Tolerable Intake Level” has not been established for B12, there are some reports of doses of 20 micrograms (mcg) per day or higher causing outbreaks of acne and rosacea. There is also a study that showed that a high-dose B complex supplement (with 1,000 mcg of B12) hurt, rather than helped, people with diabetes and advanced kidney disease.B12Sources

According to, Recommended dietary amounts (RDAs) are 2.4 micrograms daily for ages 14 years and older, 2.6 micrograms daily for pregnant females, and 2.8 micrograms daily for breastfeeding females.

Those over 50 years of age should meet the RDA by eating foods reinforced with B12 or by taking a vitamin B12 supplement. Supplementation of 25-100 micrograms daily has been used to maintain vitamin B12 levels in older people. A doctor and a pharmacist should be consulted for use in other situations.

In speaking with Jean, she said that over the past six months, she’s been under a lot of stress. Her husband had been in the hospital, and now that he was home, she hadn’t resumed a normal schedule. She said she’d been grabbing fast food and snacks, and her diet had been “horrible”. She hadn’t been sleeping well and her usual social life had almost stopped.

Feeling “tired all the time” can indicate something much more serious than a B12 deficiency, and although a deficiency in B12 can definitely make you tired, what if you’re not deficient? There are dozens of reasons someone could be tired all the time. I visited the WebMD Symptoms Checker, put in my sex and age, and my symptom “fatigue – not relieved by rest”. No surprise, there are dozens of reasons for being “tired all the time”, ranging from acute stress to depression type 1 diabetes to…B12 deficiency.

Tired All The Time? Take a look at your diet and your lifestyle

– Replace refined foods — white flour, sugar, white rice — snacks, sodas, fruit juices all are quickly absorbed and play havoc with your blood sugar, lower immunity and can contribute to low energy.

– Cut back on alcohol — besides interfering with intrinsic factor (preventing absorption of B12), high alcohol intake over a period of just two weeks can cause a noticeable decrease in the amount of B12 absorbed from the gastrointestinal tract.

Get enough sleep — duh, right? But it’s not just the time in bed that counts, it’s the hours spent sleeping that allow you to wake refreshed. The advises avoiding caffeine and alcohol for at least 4 hours before going to sleep. Are you a smoker? A ‘vaper’? You may already know that nicotine interferes with sleep. Click here to assess your personal sleep needs.

Eat your way to better energy. The best sources of Vitamin B12 include eggs, milk, cheese, milk products, meat, fish, shellfish and poultry. Some soy and rice beverages as well as soy based meat substitutes are fortified with vitamin B12. To see if a product contains vitamin B12 check the Nutrition Facts on the food label.

Avoiding animal products? The Vegan Society notes that the only reliable vegan sources of B12 are foods fortified with B12: plant milks (soy, almond, rice – read the labels), other soy products, and some breakfast cereals. They note that In over 60 years of vegan experimentation only B12 fortified foods and B12 supplements have proven themselves as reliable sources of B12, capable of supporting optimal health. It is very important that all vegans ensure they have an adequate intake of B12, from fortified foods or supplements.”

If you’re following a vegan diet (avoiding all animal products including dairy), or eating very few animal products, the Vegan Society recommends:

  1. Eat fortified foods two or three times daily to get at least 3 micrograms (mcg or ug) of B12
  2. Or take one B12 supplement providing at least 10 micrograms daily
  3. Or take a weekly B12 supplement providing at least 2000 micrograms daily


Susan Burke March, a Cuenca expat, is a Registered and Licensed Dietitian, a Certified Diabetes Educator who specializes in smart solutions for weight loss and diabetes-related weight management. She is the author of Making Weight Control Second Nature: Living Thin Naturally—a fun and informative book intended to liberate serial dieters and make healthy living and weight control both possible and instinctual over the long term. Do you have a food, nutrition or health question? Write to me at


Susan Burke March

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