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Busting Fatigue: The Essential Role of Vitamin B12

Fatigue can often disrupt our daily lives, leaving us feeling drained and low on energy. Fortunately, Vitamin B12 plays a crucial role in combating fatigue and revitalizing our energy levels.

Woman jumping with lots of energy

When exploring the root causes of fatigue, three crucial labs always catch my attention: Vitamin B12, Vitamin D, and thyroid levels. These three play a significant role in our energy levels, and if any of them are deficient, it can lead to fatigue. The good news is that identifying and addressing these deficiencies can lead to remarkable improvements in energy and overall well-being.

During my practice in New Hampshire, I regularly conducted vitamin testing in my patients, and it was quite common to find low levels of Vitamin D and Vitamin B12. Eight years ago, when I moved to Texas, I expected to see fewer nutrient deficiencies due to the higher red meat consumption and the region's sunny climate. However, to my surprise, many individuals I test in Texas are still deficient in these vital nutrients. This indicates that deficiencies in Vitamin B12 and Vitamin D are not limited to specific geographical regions and can affect people from various backgrounds. It also means that I continue to test my patients who complain of fatigue.

Addressing these deficiencies is of utmost importance, as low Vitamin B12, Vitamin D, or thyroid levels can contribute to ongoing fatigue. By identifying and rectifying these deficiencies, we can make significant strides in restoring energy and improving overall health. Therefore, it is crucial to remain proactive in testing and addressing nutrient imbalances to ensure that fatigue is not holding us back from leading vibrant and fulfilling lives.

How Vitamin B12 Supports Energy Metabolism:

For us to understand why vitamin B12 plays such an important role in how we feel we should understand what it does in our bodies.

Vitamin B12, also known as cobalamin, plays a vital role in energy production within our bodies. It acts as a coenzyme, facilitating the conversion of carbohydrates into glucose, which serves as the primary energy source for our cells. Additionally, B12 aids in the breakdown of fats and proteins, further contributing to energy generation.

Linking B12 Deficiency to Chronic Fatigue:

Tired man

Vitamin B12 has been associated with chronic fatigue syndrome (CFS), a complex condition characterized by persistent and debilitating fatigue that does not improve with rest. While the exact cause of CFS is not fully understood, B12 deficiency has been identified as a potential contributing factor. B12 plays a crucial role in energy production within the body, as it is involved in the synthesis of adenosine triphosphate (ATP), the primary energy currency of cells. Insufficient B12 levels can lead to reduced ATP production, resulting in a lack of energy and prolonged fatigue.

Vitamin B12, Cognitive Function and Fatigue

Vitamin B12 plays a crucial role in cognitive function and is closely linked to the prevention of cognitive decline and fatigue. B12 is essential for the production of myelin, a protective sheath that surrounds nerve cells, ensuring efficient nerve signal transmission. Adequate B12 levels support optimal brain health and cognitive processes, such as memory, concentration, and problem-solving. Studies have shown that B12 deficiency is associated with cognitive impairments and an increased risk of neurodegenerative diseases, such as Alzheimer's and dementia. Additionally, B12 is involved in the synthesis of neurotransmitters like serotonin and dopamine, which are essential for regulating mood and emotions. Low B12 levels can contribute to mood disturbances, irritability, and even depression, which can further exacerbate feelings of fatigue and mental exhaustion.

Vitamin B12, Blood Disorders and Fatigue

Vitamin B12's impact on red blood cell formation and oxygen transport also plays a role in reducing fatigue. Fatigue is often linked to anemia, a condition characterized by low red blood cell counts or inadequate hemoglobin levels. B12 deficiency can lead to megaloblastic anemia, where the body produces larger, immature red blood cells that are unable to efficiently transport oxygen. As a result, the body's tissues and organs receive less oxygen, leading to feelings of tiredness and weakness. By supporting red blood cell production and ensuring optimal oxygen transport, B12 helps combat fatigue and promotes better energy levels. Ensuring sufficient B12 intake through dietary sources or supplementation can significantly contribute to cognitive sharpness and combat feelings of fatigue, leading to improved overall well-being.

Signs and Symptoms of B12 Deficiency:

Vitamin B12 deficiency can manifest in various signs and symptoms that, if left unaddressed, can significantly impact overall health.

Common symptoms of B12 deficiency include:

  • Fatigue and weakness: Insufficient energy production can lead to persistent tiredness and weakness.

  • Shortness of breath and dizziness: Inadequate red blood cell formation affects oxygen transportation, causing breathlessness and dizziness.

  • Peripheral neuropathy: Tingling or numbness in hands and feet due to nerve damage.

  • Cognitive issues: Memory problems, difficulty concentrating, and mental fogginess.

  • Oral manifestations: Smooth and sore tongue, mouth ulcers, and altered taste perception.

  • Megaloblastic anemia risk: Abnormally large red blood cells exacerbate fatigue, weakness, and cognitive problems.

Red blood cells

Recognizing these signs and symptoms is crucial for early detection and intervention to prevent long-term complications associated with B12 deficiency.

Who Should Be Tested for B12 Deficiency?

It is interesting that in my experience it is not always easy to predict who may be B12 deficient. I have found that regular people, eating a regular, healthy, omnivorous diet may be deficient and we do not know until we test. So even if there are no glaring risk factors it can be very helpful to test for deficiency.

What we do know is that certain individuals are at an increased risk of Vitamin B12 deficiency due to various factors that can hinder B12 absorption or intake. Vegetarians and vegans are particularly susceptible to B12 deficiency since the vitamin is primarily found in animal-based foods. As plant-based sources of B12 are limited, individuals following these diets may not obtain sufficient B12 through their food choices alone. Older adults are also at higher risk as aging can lead to reduced stomach acid production, which is essential for releasing B12 from food and promoting absorption. Additionally, the production of intrinsic factor, necessary for B12 absorption, may decline with age, further exacerbating the risk.

Individuals with certain gastrointestinal conditions, such as celiac disease, Crohn's disease, or other malabsorption disorders, may also be at risk. These conditions can damage the lining of the stomach or small intestine, impairing the absorption of B12 from food. Individuals who have undergone gastrointestinal surgeries, such as weight loss surgeries or procedures that involve the removal of parts of the stomach or intestine, may have reduced B12 absorption capacity.

B12 Testing and Supplementation

Blood draw for B12 testing

B12 testing is interesting as it is a little more nuanced than just running a blood test and the lab reference ranges that are returned do not always give the full picture. In this second blog article on vitamin B12 “Vitamin B12 Testing and Supplementation: The Nuances of a Common Test” I explain my approach to testing B12 levels, which labs to choose, where to find vitamin B12 in your diet and how to supplement if you are deficient.

Busting B12 Myths

Vitamin B12 is surrounded by various misconceptions that can lead to confusion about its role and importance in our health. One common misconception is that B12 provides an instant energy boost similar to caffeine or other stimulants. While vitamin B12 is indeed vital for energy production within our cells, taking a B12 supplement won't result in an immediate surge of energy. B12 works in conjunction with other nutrients to support overall energy metabolism, but its effects are gradual and more focused on maintaining sustained energy levels over time. Another misconception is that excessive B12 intake can enhance athletic performance or cognitive function. While B12 is crucial for nerve health and cognitive function, taking excessive amounts beyond the body's needs won't lead to enhanced benefits. The body has specific mechanisms to regulate vitamin B12 absorption, and any excess is excreted through urine.


Vitamin B12 has an intricate role in energy production, nerve function, and red blood cell formation, and its deficiency can be a significant contributor to persistent fatigue. Recognizing the symptoms, understanding the risk factors, and adopting a balanced diet or appropriate supplementation can go a long way in maintaining optimal B12 levels and banishing fatigue. Although there are some risk factors for B12 deficiency which would prompt testing, deficiencies can also appear in people who have no risk factors. This is, as we say, a modifiable factor, so testing for deficiencies even for people who have sub-clinical symptoms is worth consideration as it is a fixable problem. Read Part 2 to this blog "Vitamin B12 Testing and Supplementation: The Nuances of a Common Test" which explores testing and supplementation.

When it comes to combating weariness and embracing vitality, ensuring your body gets its B12 is a step towards a brighter, more energetic tomorrow.


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