Vitamin B12 and Depression



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I’m a Naturopath, MTHFR & Methylation Specialist. I’m dedicated to helping you achieve your health goals so you can live a vibrant & fulfilling life

Vitamin B12 and Depression


Vitamin B12 is essential for the proper functioning of the nervous system. It actively synthesizes protein structures in the myelin sheath and nerve cells.

B12 is essential for the conversion of homocysteine to methionine for the production of SAMe to provide methyl groups for the biosynthesis of monoamine neurotransmitters, serotonin, epinephrine and dopamine.  Without adequate SAMe, neurotransmitter levels decrease in the cerebrospinal fluid, contributing to depression.

What causes B12 deficiency?

  • Inadequate intake, which is likely to occur on a vegan or vegetarian diet.
  • Impaired gastric function with low hydrochloric acid, which impairs absorption of B12.
  • Insufficient zinc levels require zinc to produce hydrochloric acid.
  • Use of protein pump inhibitors (eg Nexium) for reflux as they reduce hydrochloric acid.
  • Impaired pancreatic function which decreases the pH of the intestinal tract and impairs the release of B12.
  • Pernicious anemia, which is an autoimmune condition that impairs the release of intrinsic factor. Intrinsic factor is necessary for the absorption of B12.
  • Impaired intestinal function including celiac disease or Crohn’s disease.
  • Intestinal parasites can impair B12 absorption.
  • Excessive alcohol intake. Alcohol depletes all B vitamins.

Signs & Symptoms of B12 deficiency

  • Fatigue
  • Muscle weakness
  • Memory loss
  • Irritability
  • Confusion
  • Depression
  • Apathy
  • Insomnia
  • Pain or numbness or tingling
  • Sore mouth and tongue
  • Laboured breathing

Testing B12

There are 3 main tests available to assess B12 levels.

  • Serum B12 measures both the inactive and active form.  Levels should be >500pmol/L

  • Serum Holotranscobalamin measures specifically the fraction of B12 which enters the cells for metabolic activities (‘active B12’).  Levels should be >128pmol/L.

  • Methylmalonic acid (MMA) is a functional measure of B12 status and raised serum methylmalonic acid is evidence of tissue B12 deficiency. Doctors often order this test only once a patient has tested for low serum and/or active B12 levels. Both blood and urine can be used for testing it. The urine test is the most accurate for detecting tissue-cellular B12 deficiency.

Correcting a Vitamin B12 deficiency

  • If the deficiency results from insufficient dietary intake of animal protein, one needs to make dietary adjustments to include animal protein OR supplementation becomes essential.
  • If the deficiency results from the overuse of proton pump inhibitors (Nexium), one needs to address the underlying cause of acid reflux and gradually discontinue the drug for the patient. There are many wonderful herbs that can help with this process. Supplementation with B12 during this process is also important.
  • Impaired gut function such as celiac or Crohn’s disease – here it is often important to bypass the gut with either the use of B12 injections of transdermal creams.
  • Zinc levels need to be optimal (approx. 17) to ensure adequate hydrochloric acid production. Increasing zinc intake in the diet or supplementation is very important.
  • To ensure proper B12 absorption, it’s necessary to remove gut parasites from the gut. There are many very effective herbs to treat gut parasites.

“Supplementing with B12 is crucial until you achieve adequate levels, while addressing the underlying cause of your B12 deficiency.”

Which form of B12 to use?

  • Used in many ‘retail’ supplements.
  • Other forms of B12 are metabolized and utilized more effectively than cyanocobalamin.

  • Individuals tolerate this form very well, and it is unlikely to induce side effects.
  • Hydroxycobalamin will covert into adenoslycobalamin and methylcobalamin.
  • The hydroxyl form is good for people with low homocysteine as it will mop up nitric oxide caused by a CBS pathway up regulation.
  • Use this form if you are not sure if you will have an adverse reaction to methylcobalamin.

  • Adenosylcobalamin plays a role in converting methylmalonyl-CoA to succinyl-CoA, a process essential for the proper functioning of the Krebs cycle. The Krebs cycle is the body’s energy cycle inside each cell.
  • This form is currently not available for sale in Australia.

  • Methylcobalamin is neurological B12 .
  • Methylcobalamin is essential for folate metabolism and the proper functioning of the methylation cycle via the recycling of homocysteine to methionine.
  • Serious side effects, including suicidal thoughts, CAN result from taking this form. Therefore, it should only be taken under the prescription of a trained practitioner.

“Correcting a Vitamin B12 deficiency can help significantly with mood. If you suspect you have a deficiency, it’s crucial that you undergo testing, as B12 deficiency can lead to irreversible neurological damage.”

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