7 reasons why you are vitamin B12 deficient and how it is affecting more than just your energy.

Vitamin B12 is a vital nutrient for energy, brain health, hormone function and pregnancy. Which is why a vitamin B12 deficiency impacts more than just energy.
And deficiency is more common than you might think.
Vitamin B12 Deficiency is Common
Depending on which study you look at, anywhere from 20-40% of the U.S. population has sub-optimal levels of this nutrient. And these numbers are based on traditional lab values, not optimal functional values!
While 20-40% may not sound so bad, what if I told you that vitamin B12 can have profound effects on your energy, cognitive health and pregnancy?
Effects of Vitamin B12 in the Body
- Vitamin B12 is an essential nutrient for brain and heart function, both of which lend themselves to overall health and vitality.
- B12 works together with folate to aid in red blood cell formation and DNA synthesis.
- It also helps to lower levels of the amino acid homocysteine, which, at elevated levels, is linked to serious conditions such as heart disease, osteoporosis, depression, and dementia.
This means that without B12, you can experience depression and other mood disorders, brain fog, fatigue, muscle weakness, lack of coordination, and hair loss. Worse – chronic depletion of B12 could mimic the signs and symptoms of brain diseases like dementia.
Vitamin B12 in Preconception and Pregnancy
For my prenatal ladies, lack of adequate B12 can also lead to neural tube defects, like spina bifida.
While folate is most commonly taken to prevent this, in the absence of B12, folate can not be effectively metabolized and utilized by the body. The neural tube defect is estimated to occur between the 3rd and 4th week after conception, which is too early for most women to notice they are pregnant.
For this reason, I recommend both folate and B12 supplementation as part of a complete prenatal 3 months prior to conception. If you’re a woman and there is a chance you could become pregnant (even a slight one), I recommend at least having a complete B12 complex as part of your daily routine.
Click to Tweet –> I recommend both folate and B12 supplementation as part of a complete prenatal 3 months prior to conception
Signs of Vitamin B12 Deficiency:
- Paleness
- Headaches
- Tongue soreness
- Loss of appetite
- Fatigue
- Anemia
- Numbness/ tingling of hands and/or feet
- Memory loss
- Disorientation/ Dementia
- Low blood pressure
- Intermittent constipation or diarrhea
7 Reasons Why B12 Deficiencies Occur?
There are several reasons you might be deficient in vitamin B12. Here are 8 common reasons:
1. You’re vegan or vegetarian
Approximately 50% of vegetarians and 80% of vegans are deficient in B12!
The most common reason for B12 deficiency is a vegan or vegetarian diet. B12 occurs naturally in animals and animal-derived products, so you may experience a deficiency if you avoid these foods.
Approximately 50% of vegetarians and 80% of vegans are deficient in B12. It is a common misconception that you can easily get B12 from non-animal sources. Plant based sources that claim to have adequate B12 actually have forms of B12 that block your B12 and increase the demand!
2. You have low stomach acid levels
While the word “acid’ doesn’t necessarily conjure thoughts about health and vitality, hydrochloric acid, or HCl, is vital to your body’s absorption of vitamin B12.
HCl is produced in the stomach to help you break down your food so it can be absorbed in the small intestine. As you age, your production of HCl naturally declines, but there are other causes for decreased production of HCl. Poor dietary practices, over the counter and prescription medications and autoimmune conditions like Hashimoto’s, Crohn’s and celiac disease can also inhibit HCl production and absorption of B12.
3. Gut trouble
Gut health is vital to B12 absorption.
If there are other digestive issues at play, like SIBO (small intestinal bacterial overgrowth), leaky gut (or intestinal permeability), or other signs of gut dysbiosis, it’s possible you’re simply not absorbing the nutrients from your food.
Gut health is vital to B12 absorption. If you suspect any of these conditions, talk to your doctor about treatment options.
You don’t have to have a disease to have poor gut health! It is important to evaluate your digestion as a contributing factor for B12 deficiency. You need:
- Stomach acid to liberate B12
- Intrinsic factor to ready it for absorption
- A healthy small intestine to absorb it
4. Your intrinsic factor isn’t doing its job
Intrinsic factor is a protein that is excreted from the parietal cells in the stomach. Its primary function is to enable your body to absorb B12.
Pernicious anemia, atrophic gastritis, or antibodies that are directly attacking your intrinsic factor can all keep you from being able to absorb B12.
5. Your medication is interfering
Certain prescription and over the counter medications can inhibit your ability to absorb, utilize or maintain a healthy B12 level. Proton Pump Inhibitors (PPI) and other acid blocking drugs for heartburn (aka GERD or reflux) can decrease the amount of B12 available to you in your food.
Common cholesterol, gout, and diabetic drugs are also known to inhibit absorption. Talk to your doctor about B12 testing if you are taking any of these medications.
6. You have an autoimmune condition
Atrophic gastritis, pernicious anemia, Crohn’s disease, and celiac disease all affect your ability to liberate B12 from your food and absorb it.
If you have a family history of autoimmune disease or have an autoimmune disease, you should speak with your doctor about having proper testing to determine if this is the cause of your B12 deficiency.
7. You have hypothyroidism
Hypothyroidism is a condition in which you have too little thyroid hormone. Thyroid hormone is necessary for stomach acid production and gut health. Read more about the connection between hypothyroidism and low stomach acid here.
How to Test for B12 Deficiency
A good Naturopathic or Functional Medicine Doctor will be able to tell you whether or not you should start supplementation based on your symptoms and medical history. Blood tests are available, but are not always 100% accurate, so if you or your doctor suspect a deficiency, it’s best to begin supplementation.
If you and your doctor do decide to test, vitamin B12 concentrations and serum methylmalonic acid levels can be tested to help determine the severity and root cause of your deficiency. I also recommend testing:
- Folate
- Homocysteine
- Checking for a common gene mutation, MTHFR.
Investigate your red blood cells
A simple CBC (complete blood count) can also tell you the size of your red blood cells.
- A large red blood cell, which can be revealed by an elevated MCV (mean corpuscular volume) is a sign of poor B12 status or utilization.
- An elevated MCV may also be due to folate and B6 deficiency.
In my practice, I begin supplementation any time the MCV is 92 or higher.
If you are supplementing and continue to show signs of deficiency, ask your doctor to test you for a condition known as pernicious anemia. It is an autoimmune disease which makes it impossible to absorb B12 via the gut.
How do I Get a B12 Boost?
Vitamin B12 can be stored in the liver of a healthy person for up to 5 years and is synthesized in the small intestine, so it may take a while for a deficiency to present. Please note: a healthy person.
If you suspect that you have absorption issues or you’re not getting adequate amounts of B12 from dietary sources, you might want to consider supplementation.
In fact, if you suffer from any of the following symptoms, you may want to consider B12 supplementation:
- Fatigue, anemia
- Frequent colds, flues
- Thyroid and adrenal imbalances
- Anxiety, depression, insomnia
- PMS, menopause, acne
- Allergies, herpes, psoriasis
- Nerve pain, dementia, brain fog
- Obesity, heart disease
- and many more…
B12 in your diet
The best way to get optimum levels of vitamin B12 is directly from your food.
B vitamins work synergistically with each other and other nutrients to give your body exactly what it needs to function optimally, so when in doubt, eat real whole foods.
Foods high in B12 and other B vitamins include:
- Meat: poultry, organ meat, high quality dairy products (great if you’re not sensitive to these) and egg yolk
- Fish: trout, herring and mackerel
**Please note that it’s not possible to correct true B12 deficiencies with food alone.
What about plant sources of B12?
Nutritional yeast and seaweed are high in B12, but there’s some evidence that non-animal products may offer a type of B12 that isn’t as active in the body, so I wouldn’t rely on these sources. In addition, the form of B12 from seaweed may actually block B12 utilization by the body!
How do I Supplement Vitamin B12?
Pill or capsule form
When purchasing a B12 supplement, it’s important to look for the active form of the vitamin. Methycobalamin is the active form of the nutrient and if preferred over cyanocobalamin. In fact, all B vitamins should be taken in their activated methylated forms.
Remember, B vitamins work together, so it is often best to take a B complex. When supplementing a single B vitamin alone, it is possible to create additional needs for other B vitamins in the body. This is because replenishing one B vitamin can increase metabolic processes that increase the demands for other B vitamins.
I recommend B-Supreme for my patients because it has an array of B vitamins and additional co-factors that help you utilize the B vitamins.
B Complex with Active B Vitamins
Sublingual B12
Sublingual B12 allows you to absorb the vitamin directly into your bloodstream, bypassing the gut, without an injection.
NOTE: Sublingual means “under the tongue”, which is where you place the tablet instead of swallowing it.
This is generally recommended when there is an issue with gut absorption — SIBO, leaky gut, low stomach acid, atrophic gastritis, etc. Or it may be recommended if you’ve been taking a B complex for an extended period of time without results.
Of course, you can always safely opt for the sublingual form of B12 to give your brain and body a boost.
I generally recommend a sublingual B12 with activated folate sublingual because your body depends on each of these nutrients and they work together synergistically. One chew daily can help you increase your energy, boost your mood, and support healthy detox (which makes for some awesome hormonal health).
B12 injection
Injecting B12 directly into the bloodstream is an efficient option when treating B12 deficiency or addressing ongoing issues with fatigue, depression or decreased cognitive function. Shots are injected directly into the muscle (usually the gluteal butt muscles or upper arm) and are quick and relatively painless.
Treatment plans may vary from one injection per month to several over a span of weeks, depending on the condition. Generally, 1,000 mcg of B12 is injected per session.
You don’t have to have a chronic B12 deficiency to warrant a B12 shot; sometimes they’re prescribed as energy boosters for athletes or those who suffer from adrenal fatigue.
Taking Care of You
I work with all of my patients to determine the most effective way to supplement to ensure optimal intake and absorption of targeted nutrients. If you think you might be deficient in B12, talk to a qualified practitioner about supplementation or dietary changes for vibrant health.
If you’re a new mom and struggling with low energy, brain fog, decreased exercise tolerance, depression or anxiety please check out my book Healing Your Body Naturally After Childbirth. In it, I share a lot of energy boosting information that has helped many of my patients.