It’s been estimated that up to a whopping 25% of all adults are deficient in a crucial compound known as vitamin B12. But recent research is finding that our estimates may be way off and that percentage might actually be significantly higher thanks to some fallibilities in the way we test for a deficiency in this vital vitamin.
Today we’re going to explore exactly why vitamin B12 is so important, the consequences of being deficient in this nutrient, the problem with conventional B12 testing, and most importantly – what steps you can take if you’re concerned about a deficiency. Let’s dive in.
Vitamin B12: What Is It and What Role Does It Play In the Body?
Vitamin B12, more formally known as cobalamin, is a water-soluble vitamin that our bodies rely on for countless functions that keep us alive and well such as:1,2
- The development, function, and preservation of the neurons and nerve cells that make up your brain and central nervous system
- Healthy red blood cell formation
- The synthesis, structure, and stability of DNA
- As a cofactor or “helper molecule” for numerous enzymatic reactions
- As a nutrient necessary for a healthy pregnancy and proper fetal development
- The production of serotonin and other important neurotransmitters that influence your mood
- And much more
With so many critical roles, it’s no surprise that a deficiency in this vital vitamin can have some serious side effects.
Vitamin B12 Deficiency Symptoms
A deficiency in vitamin B12 can lead to a wide variety of symptoms ranging from unpleasant to quite serious and can include:3,4
- Fatigue, brain fog, and muscle weakness
- Digestive issues and intestinal problems
- Nerve damage and neurological changes that can result in numbness or tingling in the hands and feet
- Mood disturbances like depression and anxiety
- An increased risk of neurodegeneration which can lead to conditions like dementia
- An increased risk of cardiovascular disease and stroke
- Anemia (low red blood cell count) and/or megaloblastic anemia (large, abnormally nucleated red blood cells that don’t function properly)
- Low counts of white blood cells (specialized immune cells) and/or low platelets (components of your blood that form clots to stop bleeding)
- Weight loss
- Disturbances in fetal development like neural tube defects, developmental delays, and failure to thrive
With such potentially serious side effects, you’re probably curious about exactly how a vitamin B12 deficiency develops and who is most at risk of becoming deficient in this critical compound.
Who Is At Risk of A Vitamin B12 Deficiency?
Our bodies are unable to produce vitamin B on their own – meaning we must obtain all of our vitamin B12 from the foods we ingest. Because we must rely on our ability to consume and absorb adequate amounts of this key vitamin, there are some people that are much more likely to develop a deficiency. You may be at an increased risk of becoming deficient in vitamin B12 if you:5,6
- Have impaired absorption or an imbalance in your gut such as celiac disease, inflammatory bowel disease, bacterial overgrowth, leaky gut syndrome, or inadequate stomach acid production
- Have had bariatric surgery or surgery on your digestive tract that may impede absorption
- Have an immune system condition like graves disease, lupus, or any other form of autoimmunity
- Are on medications that impair the absorption of vitamin b12 – like certain heartburn medications and the diabetes medication Metformin
- Drink heavily or consume large amounts of alcohol on a regular basis
- Follow a strict vegan or vegetarian diet (as most B12-rich foods come from things like meat, eggs, and dairy)
The factors listed above certainly can put you at an increased risk of developing a vitamin B12 deficiency. But research is finding that vitamin B12 deficiency may be much much more prevalent than previously believed – even in those with no clear risk factors.
This is because many vitamin B12 deficiencies go undetected thanks to inconsistencies in the way that a deficiency is typically diagnosed. To understand how vitamin B12 levels are evaluated and how standard testing falls short, you must first understand how vitamin B12 is absorbed and utilized within your body.
How Is Vitamin B12 Absorbed? The Journey of Vitamin B12
To be appropriately broken down and used by your cells, vitamin B12 undergoes a process that goes something like this:7
- Vitamin B12 contained within the food you consume is released in your stomach’s acidic environment and is bound to a protein known as haptocorrin.
- The B12 is then severed from this haptocorrin molecule by pancreatic enzymes once it makes its way into your small intestine
- After this bond is severed, a compound known as intrinsic factor is secreted by the parietal cells in your gastric mucosa and binds with vitamin B12.
- Intrinsic factor is required for proper absorption of vitamin B12, which takes place in your terminal ileum – the very final section of your small intestine
- Once absorbed, B12 makes its way into your bloodstream where it’s bound to transport proteins called transcobalamins I and II
- These transport proteins then deliver vitamin B12 to your tissues where it can be utilized as well as to your liver where excess B12 can be stored for later use
Now let's explore how a vitamin B12 deficiency is typically diagnosed.
Vitamin B12 Deficiency Diagnosis: The Problem With Vitamin B12 Tests
In conventional medicine and laboratories, the measurement of plasma vitamin B12 (cobalamin) is considered the” gold standard” for diagnosing a vitamin B12 deficiency. To measure plasma B12 levels:8,9
- A blood sample is drawn and saturated with predetermined levels of vitamin B12 in a process known as a competitive binding luminescence assay.
- The vitamin B12 introduced to the sample then binds to intrinsic factor – the protein necessary for proper absorption of vitamin B12.
- From there, the blood sample is analyzed to measure specific levels of unbound intrinsic factor and vitamin B12 levels.
- Lab values vary slightly, but any measurement under 200 pg/mL is typically considered a deficiency of this crucial compound.
While these standard blood tests can certainly detect some cases of vitamin B12 deficiency, there is a major gap in the capabilities of the test that allows for inaccurate and even entirely false readouts – with measurements coming in with a false normal or a false high. A couple of reasons these tests may not be able to give us an accurate snapshot of vitamin B12 levels include:9,10,11
- Intrinsic factor antibodies: In some cases, your immune system may be producing antibodies specific to intrinsic factor. These antibodies may bind to the test intrinsic factor reagent (the chemical used for chemical analysis of the blood sample) – interfering with the test readout and subsequently delivering a false normal or false high.
- Functional B12 deficiency: In some cases, you may indeed have adequate levels of B12 floating around within your body. But simply testing serum B12 levels doesn’t always give us a clear picture of whether or not your body is able to appropriately utilize the B12 that’s available.
These inconsistencies and gaps in the capabilities of standard testing mean there are a vast number of people who may be unknowingly walking around with a B12 deficiency and suffering with unnecessary symptoms. So what’s the solution and how can you correct a deficiency of this mighty vitamin?
How Can I Get More Vitamin B12?
If you suspect a vitamin B12 deficiency or are experiencing unexplained symptoms, one of the very best ways to begin collecting clues to find the root of the problem is to have a full laboratory workup that includes evaluating your B12 levels along with several other tests that I go over in depth in my article 15 Essential Lab Tests Everyone Should Consider by the Time They're 30. It can also be immensely valuable to partner with an Integrative and Functional Medicine Practitioner rather than simply requesting laboratory testing from your general practitioner.
You see, the Functional Medicine approach is geared towards identifying and addressing the root cause of any imbalances you may have – allowing you to focus on healing and optimizing health rather than simply focusing on the management of symptoms. If your Functional Medicine Practitioner does in fact identify a B12 deficiency they will likely prescribe a multi-pronged approach that may include the following:
- Eat a B12-rich diet: It can be helpful to ensure you’re eating a well-rounded diet that includes plenty of B12-rich foods like eggs, beef liver, clams and shellfish, dairy products (if you tolerate them), fish (like salmon and trout), poultry, and red meat.
- Take B12 supplements: Sometimes it can be challenging to get adequate B12 through diet alone, so it can be useful to take a high-quality B12 supplement like my Methyl B-12 capsules.
- Prioritize gut health: If your gut is imbalanced or inflamed it can interfere with B12 absorption. So supporting your gut health by minimizing inflammatory foods and incorporating supplements like probiotics, spore-based probiotics, collagen, and Gut Shield can help supercharge your vitamin absorption.
- Lifestyle modifications: Our bodies are complex and intricately interconnected, meaning there can be numerous factors that may contribute to an imbalance. So your Functional Medicine doctor may prescribe a variety of lifestyle adjustments to help your body heal and thrive.
While the consequences of an ongoing B12 deficiency can be quite serious, the good news is that this imbalance is often quite straightforward to treat and reverse.
Are You Concerned About A Vitamin B12 Deficiency?
If you suspect a vitamin B12 deficiency or are experiencing unexplained symptoms I cannot overemphasize the importance of partnering with a practitioner who can help you address the imbalance at the source. Our bodies are complicated, highly interconnected, and rely on countless compounds to function optimally. And partnering with a clinician who understands the nuances and complexities of addressing the root of health issues – rather than simply masking symptoms – is the key to true healing and optimal well-being.
If you’re new to the Functional Medicine approach, I encourage you to browse through the hundreds of resources available on my blog and on my YouTube channel, and to sign up for my exclusive weekly newsletter. All you have to do is enter your name and email address into the form at the bottom of this page.
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- Vitamin B12 – Health Professional Fact Sheet (nih.gov)
- Vitamin B12 – an overview | ScienceDirect Topics
- Vitamin B-12 – Mayo Clinic
- Vitamin B12 – Health Professional Fact Sheet (nih.gov)
- Vitamin B12 | The Nutrition Source | Harvard T.H. Chan School of Public Health
- Vitamin B-12 – Mayo Clinic
- Vitamin B12 Deficiency – Nutritional Disorders – Merck Manuals Professional Edition
- Vitamin B12 – Testing.com
- False elevations of vitamin B12 levels due to assay errors in a patient with pernicious anemia (nih.gov)
- Undetected vitamin B12 deficiency due to false normal assay results (nih.gov)
- Why B12 Deficiency Is Significantly Underdiagnosed | RHR (chriskresser.com)
* These statements have not been evaluated by the Food and Drug Administration. The product mentioned in this article are not intended to diagnose, treat, cure, or prevent any disease. The information in this article is not intended to replace any recommendations or relationship with your physician. Please review references sited at end of article for scientific support of any claims made.