Vitamin B12 Deficiency: Causes and How to Prevent and Treat It

Would you throw away 98% of your nutrients?

Not intentionally, but if you're taking oral Vitamin B12 supplements you might be!

B12 is one of eight vitamins in the B complex. Like many of the B vitamins, the body cannot make it. B12 only comes from food or supplements. One of the most-known B vitamins is B9 (Folate) because of its importance in preventing birth defects. B12 is also vital to help prevent birth defects,1 but that's just one out of close to 100 body processes that involve Vitamin B12.

B12 Injections On Sale

Vitamin B12 At A Glance

  • B12 is an essential vitamin.
  • The body cannot produce B12.
  • Sufficient dietary sources of Vitamin B12 are mainly animal products.
  • Women who are pregnant or breastfeeding are prone to temporary B12 deficiency.
  • B12 deficiency, if not corrected, can cause irreversible damage to the brain and nervous system.2
  • It's essential for healthy nerve and red blood cell development.
  • DNA synthesis and central nervous system (CNS) require B12.
  • B12 enables metabolism of proteins, amino acids and fatty acids.
  • B12 helps produce energy.
  • B12 slows aging by keeping your vital organs, CNS, DNA and red blood cells healthy.
  • B12 lowers homocysteine, an amino acid in the blood. Homocysteine rises with age. Higher levels have been linked to decreased eye health, dementia, stroke, heart disease, stroke, and osteoporosis.3

An article in Harvard Health calls Vitamin B12 deficiency "sneaky and harmful" because the symptoms are slow to develop or are often incorrectly attributed to other conditions. Side effects of prolonged deficiency may become permanent. Staying on top of your B12 levels is key to preventative medicine.4

B Vitamins At-Home Test Kit

Signs of low B122,5

  • Dizziness
  • Inability to focus
  • Fatigue and weakness
  • Diarrhea or constipation
  • A red, inflamed tongue
  • Paleness
  • Pins and needle sensation from nerve damage (temporary or permanent)
  • Difficulty walking
  • Shortness of breath
  • Anemia stemming from enlarged, unhealthy red blood cells

Pernicious Anemia

One of the most dangerous causes of prolonged B12 deficiency is pernicious anemia, an autoimmune disease in which the body restricts absorption of B12, the very thing it needs to recover! Pernicious anemia can lead to temporary or permanent heart and brain damage.

Another challenge is that Rx and over the counter medications may cause B12 deficiencies. Among them:

  • Rx Metformin to treat Type II diabetes5
  • Rx and OTC H2 receptor blockers to treat acid reflux: Famotidine (Pepcid, Pepcid AC); Cimetidine (Tagamet, Tagamet HB); Ranitidine (Zantac)5
  • Rx and OTC Proton-pump inhibitors to treat gastroesophageal reflux disease (GERD): Omeprazole, (Prilosec OTC and Rx, OmePPi, Zegerid OTC and Rx)5
  • Birth control pills containing estrogen. To learn how to choose the best birth control pill for you, visit our blog Birth Control Pills Explained. 

On top of that, surgeries to improve health like bariatric surgery make it difficult or impossible to absorb B12 from food or oral supplements. Diseases like Crohn's and Celiac and atrophic gastritis, are to blame for deficiencies as well. Some people are low in Vitamin B12 for no known reason. It's a forgone conclusion that elderly adults, vegans and vegetarians are at risk for B12 deficiency but medication side effects are far from common knowledge.

Peptide BPC-157

Then there's the issue with low intrinsic factor. The glycoprotein intrinsic factor binds to B126 and delivers it to the last 3/5 of the small intestine called the ileum where it is absorbed into the bloodstream. Malabsorption for the reasons just listed is essentially the main cause for B12 deficiency unless it's diet related. Intrinsic factor secretion begins just prior to the production of gastric acids. This is one of the reasons medications or conditions that reduce GI acid inhibit B12 absorption.

What is done in these cases? B12 shots to the rescue! Seriously, B12 shots may be given for several months to some individuals and then oral B12 supplements are recommended. In the majority of situations, especially with the elderly, severe cases and deficiencies triggered by diseases, B12 shots are permanent treatments.7

How Do I Give Myself A B12 Shot?

Sites of B12 shots are either intramuscular or subcutaneous. Due to the ample supply of blood vessels in muscles, intramuscular injection is faster than subcutaneous. Intramuscular shots are usually given in the vastus lateralis, and the ventrogluteal. Subcutaneous injections are given in the tissue between the skin and the fat. A common site is the stomach about two inches from the hips but not in the naval (belly button).

Where Does The B12 In Shots Come From?

B12 that does not come from food sources is man-made. This includes all supplements. Cyanocobalamin and methylcobalamin are the two most common B12 forms used for injection.

Do B12 Pills Work?

Yes and no. It depends on a lot of factors as mentioned above but the best way to understand the limitations of oral B12 supplements is this:

The only way oral B12 supplements (and food sources) can be absorbed is in the small intestine. Oral B12 supplements include pills, tablets, capsules, gels, oils, gummies, fortified food or sublingual drops. In ideal absorption environments, only about 2% 7 of that B12 can be used by the body in roughly a 12-hour period. Unfortunately, there are plenty of false claims that oral B12 is on par with shots, but sheer science makes it impossible. B12 injections directly enter the bloodstream avoiding the potential for poor absorption. Think of a B12 shot like a hospital IV. Hospitals don't just give you tablets and glasses of water, do they? And don't worry about overdoing it with B12. The body can't get too much.7 Whatever is not used is released in urine.

With all that being stated, there's no evidence that a person with "decent" intestinal uptake of B12 whether through food or oral supplements will have any issues obtaining enough B12!

How Can I Increase B12 Absorption?

  • Ask your physician if you should add a Vitamin B9 supplement to your diet. There is a strong interrelation between Vitamin B9 and B12. In particular, B9 enhances B12 uptake.
  • If you are taking oral B12 supplements, divide your doses throughout the day because the body can only use small amounts at a time.
  • Take B12 on an empty stomach because an acidic environment promotes absorption by stimulating the secretion of intrinsic factor.
  • Avoid taking B12 at night because it may interfere with sleep.

Benefits Of B12 Shots

To understand the potential of B12 injections bioavailability and direct delivery methods must be appreciated. Bioavailability means that a substance can be used by the body. Internal presence of a substance doesn't guarantee that it can be used by the body. This is the case with hormones nutrients, medications and more.

Delivery forms, especially those that bypass the gastrointestinal tract (GI) like topical pain medications, and skin treatments have high bioavailability because they quickly and efficiently reach the desired area, have less potential for breakdown in the GI. An added benefit, particularly in the case of medications that can be "hard on the liver," they have less potential for metabolism in the liver. They are called targeted or localized treatments.

Injections on the other hand are also direct delivery methods but they mostly enter the bloodstream directly. This means that they are circulated through the body but the advantage is that they avoid the GI. 

B12-Rich Food

  • Beef liver
  • Clams
  • Fish
  • Poultry
  • Dairy products
  • B12 fortified foods such as cereals, nutritional yeasts and flours

Vegan and strict vegetarians who do not take B12 dietary supplements or eat fortified non-animal foods are at risk for low B12. B12 in plants is non-existent or negligible except in a few cases like the novel aquatic plant duckweed. 8


1 Dunham, Will. Vitamin B12 can prevent major birth defects. Reuters. March 2, 2019 Accessed: September 4, 2019.

2 Vitamin B12 Deficiency. Ada Health GmbH 2019 Accessed: September 4, 2019.

3 In brief: B vitamins and homocysteine Harvard Health Publishing. Published: March 2014. Accessed: September 3, 2019.

4 Patrick J. Skerrett. Vitamin B12 deficiency. 
Harvard Health Publishing. Published: Updated February 11, 2019. Accessed: September 3, 2019.

5 Vitamin B12 Fact Sheet for Health Professionals. Accessed September 4, 2019.

6 Intrinsic Factor.

7 Vitamin B12 Deficiency. Harvard Health Publishing. Published March 2019. Accessed: September 3, 2019.

8 Kaplan, Alon et al. Protein bioavailability of Wolffia globosa duckweed, a novel aquatic plant, - A randomized controlled trial. December 11, 2018. Clin Nutr. 2018 Dec 11. doi: 10.1016/j.clnu.2018.12.009.

These statements have not been evaluated by the Food and Drug Administration (FDA). Please consult your physician before starting any exercise or nutritional supplement program before using this or any products if you are pregnant or have a serious medical condition

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