Fatigued? You Could be B12 Deficient

Fatigued? You Could be B12 Deficient

In This Article

Almost 40% Have A Vitamin B12 Deficiency. Do You? 

Read on and learn how this amazing vitamin can help support your heart, mind, mood, and energy. Find out where to get it, how to absorb it, and how to make sure you’re getting the most active form. 

Can Low B12 cause Your Brain to Actually Shrink? 

A recent study reveals vitamin B12 may protect against brain shrinkage as we age.36 The study measured 107 people ages 61-87 for five years with brain scans and MRIs. 

The study found people with higher vitamin B12 levels were less likely to experience brain shrinkage compared to those with lower levels. None in the study had clinical B12 deficiency.38 You do not have to be clinically deficient in B12 to see brain shrinkage! Even low B12 levels still in normal range can put you at risk. 

In a three-year Swedish study of 370 healthy elderly adults at least 75, those with even slightly low levels of vitamin B12 and folate had twice the risk of cognitive and memory concerns as those with normal levels.37 

The Current Level for Diagnosing B12 Deficiency is Too Low 

Current research suggests the accepted blood serum level for a diagnosis of B12 deficiency is just too low.1,2 Anything above just 200 picograms per milliliter (pg/mL) is considered normal while3 many people experience symptoms of deficiency with B12 levels well within the normal range. 

Many health organizations, including the National Institute of Health, now recognize that patients with B12 blood serum levels between 200-350 pg/ml are “low-normal” and would benefit from B12 supplementation.4,5 But even this is probably too low. 

Current research shows those with blood serum levels less than 678 pg/ml, especially older individuals, may receive clinical benefits from B12 supplementation and that physicians should consider supplementation in all patients with levels below 407 pg/mL.1 

Vitamin B12 Deficiency in the US 

While many researchers focus on testing and treating B12 deficiency in the developing world, there still hasn’t been a major population study in the United States to measure this critical deficiency since the Framingham Offspring study at Tufts University in 2000Researchers there found that  40% of the population tested “low-normal” or deficient for vitamin B12, but the latest research shows that the 39% of folks at 350 pg/mL or lower should really be considered deficient. 6 

Vegetarians, the elderly, those who have had gastric bypass surgery, and those on long-term use of certain medications (particularly anti-acid medications) are at much higher risk for deficiency. This is due to reduced absorption and intake of vitamin B12 from food sources which requires a strong digestive fire.2,7-9 

B12 Supports a Healthy Mood

b<sub>12</sub> brain on treadmill image, b<sub>12</sub> deficiency

The main function of B12 is to support the nervous system while maintaining healthy brain chemistry and synthesizing neurotransmitters like dopamine, serotonin, and epinephrine. These govern mood, energy, sleep, appetite, drive, motivation, movement, cognition, and numerous other brain functions. 

Studies show that people with certain mood issues and cognitive concerns respond well to B12 supplementation, especially older individuals. There is a strong correlation between low B12 levels and cognitive issues associated with aging. One study reported 50% of subjects with mood issues were also deficient in vitamin B12.10-13 

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B12 Supports a Healthy Heart 

Low levels of B12 are linked to elevated levels of the amino acid homocysteine, which can negatively affect multiple systems of the body. The relationship between B12 and homocysteine is so strong that measuring homocysteine levels is one of the tests to measure B12 levels.14 

homocysteine levels b12 heart stethoscope image

Perhaps B12’s most valuable function concerns the heart. Chronic high levels of homocysteine are linked to multiple heart health concerns.15-17 The most active form of B12methylcobalamine, is essential for converting homocysteine into methionine (a naturally occurring amino acid) through a process called methylation. Folate is required for this conversion, as it works in concert with B12 to lower homocysteine levels. New studies reveal high homocysteine levels are also correlated with the presence of certain mood imbalances and cognitive concerns.18-20 

Why Are We B12 Deficient? 

It is difficult to detect a B12 deficiency because the related health issues may not appear for some five or six years.3,5 Another problem is that of the several biomarkers regularly used for measuring B12 levels, none are entirely accurate and all of them have their benefits and drawbacks. Even measuring B12 blood serum levels may not provide an accurate picture of how much is available to the body on the cellular level.21,22 

When you combine the facts that many people have stopped eating red meat (which is high in B12); that B12 is a large, bulky, and hard-to-absorb vitamin; and that as we age, digestive strength necessary to break down B12 can diminish,23 you can start to understand why this is such a prevalent health issue. 

Food Sources of B12   

Some of the foods richest in B12 are fish, meat, eggs, and dairy, which is why vegetarians and vegans are at such great risk for B12 deficiency. Vegetarian sources do exist, but there are not many of them and they generally are not a significant source unless fortified during food production.24 

Weak Digestion Makes for Poor B12 Absorption 

Dietary B12 is released from certain foods in the stomach by hydrochloric acid (HCl). If digestive acids are low, B12 absorption is also low. When HCl levels are optimal, production and secretion of pepsin (the enzyme responsible for unbinding B12 from ingested foods) is also held in balance. This allows free B12 to bind to another protein, called the intrinsic factor, which carries it to the distal part of the small intestine for processing, and eventually to the liver, where it is stored.  

Intrinsic factor is required for B12 to assimilate into the bloodstream. Without strong stomach acid, proper amounts of intrinsic factor protein are not produced in the stomach, which is why long-term use of antacids will deplete intrinsic factor and B12

As we age, digestive strength typically weakens and production of pepsin can decrease up to 40% independent of any other factors, resulting in significantly reduced absorption and bioavailability of B12. While I don’t believe this necessarily has to happen to everyone, seniors are at significant risk for this reason.25-27 

The more likely cause of this, rather than just aging, is the insidious congestion of bile and pancreatic enzyme ducts due to ingestion of processed foods. For more on this, check out my articles on digestion, bile, and gallbladder health. 

What Type of B12 is Best? 

Perhaps the most common form on the market today is cyanocobalamin. While it is the most inexpensive form, it is not the most active. Cyanocobalamin must be converted to methylcobalamin, the most active and more effective form of vitamin B12

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For years, B12 injections were trendy for boosting energy. It was believed that absorption of B12 orally in the cobalamin form was low. New research shows sublingual supplementation with methylcobalamin is just as effective and carries the added benefits of lower cost and ease of administration.28,29 Hooray!!! No more shots! 

In addition, adequate amounts of folate and mood-supportive chemical SAMe are needed to convert (or methylate) cyanocobalamin into methylcobalamin. Using methylcobalamin orally, this cumbersome process of activating B12 is already accomplished. B12 and folate support healthy methylation through their roles in synthesizing methionine from homocysteine, as well as synthesizing S-adenosylmethionine (SAMe), a naturally-occurring compound found in almost every tissue and fluid in the body.30,31 

The Best Folate: 5-MTHF (5-methyltetrahydrofolate) 

5-MTHF is the most biologically active form of folate. Folic acid is a synthetic form of folate and, while not harmful, is not as effective as folate or 5-MTHF. It is the predominant type of folate present in food and the form into which the body must convert all other forms of folate.  

Along with vitamin B12, folate serves as a donor of methyl groups in many nervous system and metabolic processes, including conversion of homocysteine to methionine, synthesis of monoamine neurotransmitters, production of melatonin, and synthesis of DNA.32,33 In addition, red blood cells require vitamin B12 and folate for proliferation and manufacturing.34 B12 is also essential for neurological health, and chronic insufficiency can affect the spinal cord, peripheral nerves, the optic nerve, and the brain.35 

B12 Dosage Recommendations 

The best way to take B12 is in a sublingual form. Be sure it is a combination of methylcobalamin and folate in the 5-MTHF form. LifeSpa’s B12 Boost has 2,500 mcg of B12 and the active 5-MTHF form of folate to deliver an effective clinical dose. It is best taken in the morning for a B12 boost all day. 

Try LifeSpa’s B12 Boost Quick Dissolve Tablets and let us know what you find. 

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Dr. John


  1. https://www.ncbi.nlm.nih.gov/pubmed/22092891 
  2. http://www.aafp.org/afp/2011/0615/p1425.html 
  3. https://medlineplus.gov/ency/article/003705.htm 
  4. http://ajcn.nutrition.org/content/89/2/693S.full 
  5. https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/ 
  6. https://www.ncbi.nlm.nih.gov/pubmed/10648266 
  7. http://www.health.harvard.edu/blog/vitamin-b12-deficiency-can-be-sneaky-harmful-201301105780 
  8. https://www.ncbi.nlm.nih.gov/pubmed/23356638 
  9. https://www.ncbi.nlm.nih.gov/pubmed/27520327 
  10. https://www.ncbi.nlm.nih.gov/pubmed/19355913 
  11. https://www.ncbi.nlm.nih.gov/pubmed/28145420 
  12. https://www.ncbi.nlm.nih.gov/pubmed/10896698 
  13. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3856388/ 
  14. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3573090/ 
  15. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4326479/ 
  16. http://circ.ahajournals.org/content/111/19/e289.full 
  17. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4288948/ 
  18. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4186289/ 
  19. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4164291/ 
  20. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4200070/ 
  21. http://www.dsm.com/campaigns/talkingnutrition/en_US/talkingnutrition-dsm-com/2013/09/vitamin-B12-measurement-controversy-HCY2013.html 
  22. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3827408/ 
  23. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5130103/ 
  24. https://ods.od.nih.gov/factsheets/VitaminB12-Consumer/ 
  25. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4519257/ 
  26. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2599964/ 
  27. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4546438/ 
  28. https://www.ncbi.nlm.nih.gov/pubmed/9694707 
  29. https://www.ncbi.nlm.nih.gov/pubmed/21556950 
  30. http://umm.edu/health/medical/altmed/supplement/sadenosylmethionine 
  31. https://www.ncbi.nlm.nih.gov/pubmed/20595412 
  32. https://www.ncbi.nlm.nih.gov/pubmed/9108574 
  33. https://www.ncbi.nlm.nih.gov/pubmed/1516676 
  34. https://www.ncbi.nlm.nih.gov/pubmed/15189115 
  35. http://www.bmj.com/content/349/bmj.g5226.long 
  36. https://www.ncbi.nlm.nih.gov/pubmed/18779510
  37. https://www.ncbi.nlm.nih.gov/pubmed/11342684
  38. https://www.ncbi.nlm.nih.gov/pubmed/18779510

10 thoughts on “Fatigued? You Could be B12 Deficient”

  1. The Tufts study showed that 39% were found WITHIN the low normal range of b-12. “A careful look at 3,000 men and women in the ongoing Framingham Offspring Study found 39 percent with plasma B12 levels in the “low normal” range–below 258 picomoles per liter.”

    That does not equal 40% being deficient. Deficient does not equal low normal.

    Please correct this as it spreads misinformation that gives strict vegans over-confidence in their b-12 status.

    • Hi David:
      Thanks for your comment. What I found to be the case in my practice is the normal ranges for common deficiencies like vitamin D3 and B12 are not accurate and I have found that people need much higher B12 and D3 levels to avoid deficiency symptoms than what the medical normal range states.

  2. Hi
    I have a genetic mutation that messes with my methylation process. Mthfr. Taking b12 didn’t cut it so I swapped to transdermal b12 oil. My iron levels went up and so did my energy. The other tricky part to this issue about b12 and methylation is folate/folic acid the folic acid required by poor methylaters is a methylated form. Methyl folate or colonic acid and to avoid food with added folate which acts as a blocker to both b vitamins. A really helpful website I found was Mthfr.net , Dr Ben Lynch writes a lot on this subject. Because of individual needs getting the right supplementation is imperative. I have not yet found a natural way to assist my b12 levels, so I am still supplementing. I hope that recommending another website is ok on here. It. Good luck everyone with putting your puzzle pieces together for your wellbeing.

  3. Some people lack intrinsic factor in their stomach and have trouble taking up B12 by their digestive system. These people are advised to take melt tablets with the adenosyl or methyl form of cobalamine, together with folic acid in most cases. So they take it up via the buccal. Some people are more a adenosyl person, others a methyl person I have been told. Dr. Douillard, what are your thoughts on missing the intrinsic factor, which I read is a consequence of an autoimmune disorder?


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