Vitamin B12 Deficiency and Cancer: Is There a Connection?

Many people ponder upon whether indeed having low vitamin B12 levels may serve as a red flag for cancer. Fatigue, dizziness, and numbness overlap symptoms with many diseases raising question “Should I worried that vitamin B12 deficiency means cancer?”

As far as vitamin B12 deficiency is concerned, this by itself is not a good indicator for cancer. In most cases, it arises from dietary deficiency, problems with absorption, or faulty lifestyle. Scientific evidence suggests that abnormal levels of B12, whether too low or high be associated with certain cancers or treatment.

This blog is on vitamin B12, its common deficiency symptoms as seen today among men and women, its links to cancer as presented by research, and what to do when you suspect a deficiency.

DISCLAIMER– These articles are for information purposes only and not a substitute for professional medical assistance. Always consult a qualified healthcare professional for diagnosis and treatment.

What Is Vitamin B12 and Why Is It Important?

Vitamin B12, also called cobalamin, is an essential nutrient:

For the formation of red blood cells
For the function of the brain and nerves
For producing DNA
For energy metabolism

Mainly B12 is obtained from:

Meat, poultry, and fish
Eggs and dairy products
Fortified cereals and plant-based milks

Since the body cannot make B12, deficiency can set in if there is poor intake or absorption.

Common Symptoms of Vitamin B12 Deficiency in Men & Women

Due to changes in dietary and lifestyle practices, deficiency has become an increasing concern for both men and women.
In Men

Chronic fatigue and weakness
Tingling or numbness in the feet or hands
Brain fog/Memory issues
Low mood or irritability
Hair thinning and pale skin
Muscle weakness and decreased stamina

In Women

Unexplained fatigue and dizziness
Frequent headaches
Pain in the tongue or mouth ulcers
Hair loss and brittle nails
Depression and anxiety
Irregular menstrual cycles in some cases

These symptoms do not point directly to cancer, as they are more frequently attributed to dietary/alcohol/absorption problems.

Main Causes of Vitamin B12 Deficiency

Dietary deficiency- Vegan/vegetarian diet without supplementation.
Pernicious anemia- An autoimmune disorder which affects absorption.
Digestive- This includes Crohn’s disease and celiac disease or undergoing gastric surgery.
Age-related decline- Older adults secrete less stomach acid.
Medication-for example, Metformin in the case of diabetes or proton pump inhibitors against acidity.
Heavy use of alcohol- Damages the stomach lining and thus reduces absorption.

Research Overview- Vitamin B12 Deficiency and Cancer: Studies

Low B12 and Stomach Cancer

In the Helsinki Study, it has been reported that men with the lowest B12 levels had a roughly 5.8-fold increased risk of non-cardia gastric cancer compared to men with higher levels (PubMed, 2017).
This suggests that sometimes low B12 could be an indicator for stomach ailments that could progress to cancer.

B12 Intake and Risk of Gastric Cancer

A meta-analysis in 2022 documented no evidence of a consistent protection against high B12 intake. Contrarily, in the case of H. pylori infection, higher B12 intake was linked with higher risk (PubMed, 2022).
Thus infection status could sway the defined relationship between B12 and cancer.

High B12 Levels and Cancer

Some cancer patients reportedly have a very high blood B12 level, often linked to more advanced disease (PubMed, 2020).
Instead, elevated B12 may serve more as a marker for established cancer rather than a causative agent.

Cancer Patients with Deficiency

A study in 2024 nearly 800 cancer patients having low or depleted B12 levels (PubMed, 2024).
Most probably due to cancer affecting the nutritional aspect and not the other way around.

Major Points from Research

Deficiency alone is not proof of cancer.
Usually, low and high B12 patients coexist in cancer patients; this is mostly influenced by the disease or treatment.
In most cases, deficiency is associated with dietary or absorption problems and not with cancer.

Other Neglected Risks of Untreated Deficiency

Even if cancer was ruled out, untreated B12 deficiency can lead to:

Severe anemia
Nerve damage (sometimes permanent)
Cognitive decline or dementia-like symptoms
Loss of balance and frequent falls
Developmental delays in infants (if mother is deficient during pregnancy)

When to See a Doctor

Reach out to a healthcare provider if experiencing:

Ongoing fatigue despite restful sleep
Numbness or “pins and needles” sensation in limbs
Pale or jaundiced skin
Problems with memory or concentration
Low mood or anxiety without any known cause

There are blood tests that can determine B12 deficiency. If one are diagnosed, the treatment will be a combination of dietary change, oral intake of B12 supplements, and maybe B12 injections.

Can Vitamin B12 Deficiency be Prevented? absolutely yes.

Eat wholesome diet : Fish, meat, dairy or fortified plant food.
Vegans/vegetarians: get fortified cereals, plant milks, or B12 supplements.
Older adults & patients on long-term treatment: should have routine B12 level checks.

Final Thoughts

So is vitamin B12 deficiency a sign of cancer? No for most purposes.Low B12 is linked to diet, absorption issues, and age far more rampant. Some studies relate these with stomach cancers but deficiency should rather be understood as suggestive of an underlying problem and not of a strong association with cancer.
Bottom-line: Do not ignore any symptoms of deficiency, but rather, do not panic. Ensure that you get tested and have a medical treatment plan drawn up for you.