Friday Jan 27 | BY |
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Doctor Vitamin B12

Vitamin B12 is critical for health. Without enough B12, red blood cells do not mature correctly. B12 is necessary for DNA synthesis. A low B12 level in your blood leads to DNA damage, which may cause Alzheimer’s, autism, cardiovascular disease, and many types of cancer including colorectal and breast cancers. Insufficient DNA repair triggers rapid aging.

Long term B12 deficiency leads to megaloblastic anemia, characterized by large numbers of oversized red blood cells. Untreated megaloblastic anemia can lead to degeneration of the nervous system, including permanent changes in the brain.

Intrinsic factor is a substance secreted by the stomach that is essential to the absorption of B12. Not enough B12 combined with low intrinsic factor activity inhibits B12 synthesis and leads to pernicious anemia, a disease of too few red blood cells. Your body cannot absorb enough B12, so even foods rich in B12 or taking supplements won’t correct the deficiency.

How to Know If You Are B12 Deficient

Symptoms of vitamin B12 deficiency can be subtle, so it’s not always easy to tell without blood testing. However, many telltale signs provide a whole-body picture of B12 deficiency.

Think B12 deficiency if you have persistent fatigue, difficulty remaining awake in the afternoon, waking up tired, forgetfulness, shortness of breath, muscle weakness, a sore tongue, a pale face, or dizziness.

Other symptoms linked to severe B12 deficiency include disorientation, unsteady walking, and nerve pain in the feet and legs. At least 74 percent of patients with low B12 have neurological symptoms. Chronic B12 deficiency is a factor in many of the symptoms of chronic fatigue syndrome (CFS/CFIDS), including brain fog.

You don’t have to have all of these symptoms to be B12 deficient.

Women have a higher risk for B12 deficiency. Vegans and vegetarians are at risk for slow progressive B12 deficiency. Older people are prone to chronic B12 deficiency due to poor digestion from low hydrochloric acid in the stomach.

The body’s need for B12 varies during one’s lifetime. It’s higher in childhood, stabilizes in young adults, drops off during pregnancy but ticks upward in nursing mothers, and plummets during aging.
As we age, parietal cell function is reduced. People over 70 years old are prone to B12 deficiency. At least 70 percent of seniors have difficulty producing intrinsic factor, which leads to chronically low B12. Vitamin B12 deficiency associated with aging can start insidiously with the first warning signs appearing in people over 50 years.

Conditions That Inhibit Intrinsic Factor:

  • Drinking more than four cups of coffee daily
  • Smoking cigarettes
  • Drinking too much alcohol
  • Bacterial infections in the stomach and small intestine

Vitamin B12 deficiency is rare among affluent modern people. But, there is a surprising number of symptoms associated with even a mild B12 deficiency or in the presence of poor utilization.

Warning Signs of Vitamin B12 Deficiency:

  • Weakness, tiredness
  • Light-headedness
  • Rapid heartbeat and shallow breathing
  • Pale skin
  • Sore tongue
  • Easy bruising or bleeding, including bleeding gums
  • Moodiness and brain fog
  • Chronically upset stomach
  • Unexplained weight loss
  • Diarrhea or constipation

Check your tongue if you suspect a B12 deficiency. About half of those with severe low B12 lose the little bumps along the edges of their tongues. If your tongue is glossy and smooth, you may have a B12 deficiency.

To know if you’re deficient, get a vitamin B12 blood test.

What’s Your B12 Level?

Vitamin B12 blood testing is inexpensive and accurate. You can order your own without a doctor’s prescription from a variety of online and walk-in blood testing centers, like PersonaLabs. Simple, blood spot testing is available in some countries, and hopefully soon in the U.S.

The laboratory reference range for vitamin B12 in serum is 211-946 pg/mL. For optimal health, I recommend B12 levels between 650-900 pg/mL. For some, higher levels are necessary. But, it’s hard to get high levels without supplements.

We do not know the lower limits of vitamin B12 levels necessary for optimal health, so even moderately low B12 levels can lead to symptoms of B12 deficiency. That’s why I recommend that my patients go for the upper end of the optimal range.

Having adverse effects from too much B12 is rare. There is no upper tolerable limit of how much you can take. However, if you use super high doses of B12, balance it with extra folic acid, vitamin B6, and a B vitamin complex.


Knowing your B12 level helps determine if you are low and guides how much supplemental B12 you need. In six months, after you add B12 rich foods to your diet or take supplements, retest your level.

The Risks of Not Enough Dietary B12

Vegetarians, especially raw food vegans, are susceptible to B12 deficiency. In my clinical experience, long-term vegans often have low levels of vitamin B12 as found on a blood test.

A study in 2014 found that up to 86 percent of vegetarian adults were B12 deficient and nearly half of all children raised as vegetarians suffered from B12 deficiency. A British study found that vegans had the lowest levels of serum B12. Studies in India and China among Buddhist monks who eat a low calorie vegetarian diet tend towards B12 deficiency.

Because dietary sources of vitamin B12 are mainly from meat, eggs, fish, and shellfish, it’s hard to get enough B12 from plants to meet your body’s needs. Organ meats, especially liver and kidney, are the richest B12 food sources.

However, certain fermented foods contain biologically active B12, notably bancha batabatacha, a fermented Japanese black tea. Chlorella green algae and Spirulina contain some B12, but researchers have not found the B12 from these sources to be biologically active. Kombucha drinks have trace amounts of B12. But these health drinks are not enough to correct a severe B12 deficiency.

Alcohol can deplete B12 levels. Because smoking cigarettes damages DNA methylation, heavy smokers need more B12.

Best Treatments for Severe Vitamin B12 Deficiency

If you suspect B12 deficiency, get tested. If your B12 level is low, take B12 supplements. If your intrinsic factor is adequate, oral methylcobalamin works well. Methylcobalamin is a form of B12. In most cases, taking methylcobalamin capsules are absorbed, but patches work faster to raise B12 blood levels.

If you have a severe B12 deficiency, methylcobalamin or hydroxycobalamin injections work best.

In the U.S., a synthetic form of B12 called cyanocobalamin is often used for B12 injections. However, cyanocobalamine requires conversion to active forms of B12, like methylcobalamin, hydroxycobalamin, or adenosylcobalamin. It does not absorb well in capsule form.

Outside the U.S., hydroxycobalamin is the most commonly used B12 injection. And, it’s cheap. The next time you’re vacationing in Mexico, pick up Bedoyecta. You don’t need a prescription.

If you suspect intrinsic factor deficiency, you have to use B12 patches or get injections. Vitamin B12 is considered safe, and without toxic effects even at very high dosages. You may also need to take 5-methytetrahydrofolate and animal-derived intrinsic factor.

If you suspect pernicious anemia or other forms of severe vitamin B12 deficiency, see your doctor for comprehensive evaluation.

Dr. J. E. Williams


Dr. Williams is a pioneer in integrative and functional medicine, the author of six books, and a practicing clinician with over 100,000 patient visits. His areas of interest include longevity and viral immunity. Formerly from San Diego, he now resides in Sarasota, Florida and practices at the Florida Integrative Medical Center. He teaches at NOVA Southeastern University and Emperor’s College of Oriental Medicine.

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