Vitamin B12: Vegetarians, Metformin Users, and Acid Blocker Users Beware Deficiency Risks

Vitamin B12 is a vital nutrient for maintaining healthy nerve cells. That that means your brain function and the feeling in your feet. This article aims to sound an alarm for vegetarians and all the people taking metformin for diabetes or using proton pump inhibitors (PPIs) for heartburn (GERD). Understanding the importance of B12 and recognizing the signs of deficiency can help these groups ensure they’re meeting their nutritional needs.

And if B12 supplements are right for you, this article will show you the best place to buy vitamin B12 online. Supplement-Sciences has partnered with Fullscript’s professional-grade supplement formulary to provide a 20% discount on every order, so you always have access to the highest quality supplements. For more on Vitamin B12, check out our full article titled: Vitamin B12: Essential for Brain, Nerves, and Heart Health. In this article, we’ll be focusing on how Metformin, acid blockers, and a vegetarian diet can conspire to rob you of this vital nutrient.

The Metformin-B12 Connection

Metformin is an indispensable medication for treating insulin resistance that comes with Type 2 Diabetes. But comes with a risk for reducing Vitamin B12 levels. Millions of people take medications for GERD that reduce stomach acid and B12 absorption. And healthy, plant based foods contain almost no Vitamin B12. This article discusses the interaction between metformin, acid reducing drugs and B12 and discusses symptoms of deficiency, available testing, and supplementation to correct low levels. [PMC5874849, PMC6109862, PMC4866329]

It is critical that people taking metformin understand that this medication will reduce Vitamin B12 absorption. This disruption is believed to occur as metformin affects certain calcium-dependent processes in the gastrointestinal tract, impacting the absorption of vitamin B12.

How GERD Medications Reduce B12 Absorption


Gastroesophageal reflux disease (GERD) is often treated with medications such as proton pump inhibitors (PPIs) and H2 blockers. Examples of PPIs include omeprazole, lansoprazole, and esomeprazole. H2 blockers include drugs like ranitidine, cimetidine, and famotidine. These medications work by reducing the production of stomach acid. However, this acid is crucial for the absorption of vitamin B12. Long-term use of these drugs could lower stomach acid levels to the point where B12 absorption is compromised. This can potentially lead to a B12 deficiency, especially in older adults who might already have decreased stomach acid production.

Vitamin B12 Lacking in Plant-Based Diets

Plant-based diets, such as vegetarian and vegan diets, are often praised for their health benefits, including lowering the risk of heart disease, high blood pressure, diabetes, and obesity. But, one downside of these diets is the risk of vitamin B12 deficiency.

This is because Vitamin B12 is found almost exclusively in animal foods, such as meat, fish, eggs, and dairy. It is not generally present in plant foods, unless those foods are fortified with the vitamin. So, people who follow a strict plant-based diet without proper supplementation face a higher risk of developing a B12 deficiency.

It is crucial for those following a plant-based diet to ensure they are getting enough B12. This can be achieved by consuming fortified foods, like plant-based milks, breakfast cereals, and some types of yeast, or through direct supplementation. It’s always a good idea for individuals following a strict plant-based diet to discuss their nutritional needs with a dietitian to ensure they are meeting all their complex dietary requirements.

Symptoms of B12 Deficiency

Symptoms of B12 deficiency are vague and very easy to dismiss. Worse, they can mimic diabetes complications and other health problems, which makes B12 much more difficult to spot. Early signs may include feelings of weakness, fatigue, or lightheadedness. While these symptoms might be initially dismissed, untreated vitamin B12 deficiency can lead to serious complications such as nerve damage, depression, and anemia. In severe cases, significant neurological issues can arise.

While most people with mild B12 deficiency will only notice a general lack of energy, symptoms vary from person to person, depending on the severity of the deficiency and individual health factors. Here are some common symptoms associated with vitamin B12 deficiency:

  • Weakness and Fatigue: This can occur because your body needs B12 to produce red blood cells, which transport oxygen throughout your body. If your cells aren’t getting enough oxygen, you can feel tired and weak.
  • Tingling or Numbness: Vitamin B12 is crucial for a healthy nervous system. A deficiency can lead to feelings of numbness, tingling, or a “pins and needles” sensation in the hands and feet. This is called peripheral neuropathy.
  • Mood Changes: Adequate B12 is critical to maintaining brain health. B12 deficiency has been linked to depression and dementia, although the connection is not entirely understood.
  • Balance Problems: Severe B12 deficiency can affect balance and coordination, making a person more prone to stumbling or falling.
  • Glossitis and Mouth Ulcers: Glossitis is an inflammation of the tongue, which can make it red, swollen, and painful. Mouth ulcers and a feeling of pins and needles in the mouth or tongue can also occur.
  • Breathlessness and Dizziness: If the deficiency is causing anemia, it might result in shortness of breath and dizziness.

More Medicines That Rob You Of B12

  • Cholestyramine: Prescribed to lower cholesterol, this medication can bind to vitamin B12, limiting its absorption in the body.
  • Colchicine: This gout treatment may interfere with the normal absorption and metabolism of vitamin B12.
  • Antibiotics: Long-term use of certain antibiotics can affect gut flora and, as a result, the absorption of vitamin B12.

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B12 Supplement Options

Methyl B12

Methyl B12 – 1000 mcg

Methylcobalamin has been shown to encourage healthy cognitive, memory, emotional, and nerve function.

Amount Per Capsule
vitamin B12 …
 1, 000mcg (as methylcobalamin)

Methyl B12 with Intrinsic Factor

People who might benefit from a B12 supplement that includes intrinsic factor typically have conditions affecting the stomach or small intestine that impair the natural production or function of intrinsic factor. Examples:

  • Pernicious Anemia: This autoimmune condition is one of the most common causes of vitamin B12 deficiency due to a lack of intrinsic factor, which is necessary for B12 absorption.
  • Bariatric Surgery: Procedures that alter the stomach can reduce intrinsic factor production and B12 absorption.
  • Gastritis: Chronic inflammation of the stomach lining can lead to atrophy, reducing both acid and intrinsic factor production, essential for B12 absorption.
  • Long-term Antacid Use: Medications that reduce stomach acid can affect intrinsic factor and, in turn, B12 absorption.
  • Pancreatic Insufficiency: Since the pancreas aids in B12-intrinsic factor complex absorption in the small intestine, any condition impairing pancreatic function can affect B12 absorption.

Methyl B12 with Intrinsic Factor and Folate-Progressive Labs

This B12 option contains an ingredient called intrinsic factor, which can improve absorption in people who have trouble absorbing B12 on their own. Intrinsic factor is a protein that is naturally produced by the stomach and is necessary for the absorption of B12 in the small intestine.

When intrinsic factor is included in a B12 supplement, it can help ensure that the B12 is properly absorbed and used by the body. This can be particularly beneficial for older adults or people stomach conditions that might reduce the ability of the stomach to produce intrinsic factor.

Testing-It is considered critical to keep B12 levels above 500 for optimal brain function. Labs can be tested separately, or as a part of a more comprehensive lab test (affiliate links).

B Complex Including B12

As a general principle when choosing vitamin supplements, it is usually a better strategy to choose supplements with a broader set of nutrients that are in balanced to work together. When mixing and matching single nutrient supplements, there is a much greater chance of missing some nutrients while getting excesses of others.

B Complex Vitamins – Vital Nutrients

B-Complex is a balanced high potency B Vitamin complex supportive to the metabolism of protein and fats, the maintenance of muscle tone in the gastrointestinal tract and conversion of carbohydrates into energy.* B-Complex also supports healthy nerve cells and helps promote the conversion of homocysteine, thus supporting heart health.* B-Complex is an important tonifier in times of mild stress and fatigue.* This formula contains the methylated forms of B12 (methylcobalamin) and Folate (Metafolin L-5-MTHF), and the activated form of B6 (pyridoxal 5’ phosphate) – all considered to be the most bioavailable and physiologically active forms for these vitamins.*

supports a healthy nervous system*
maintains healthy protein, fat, and carbohydrate metabolism*
promotes the conversion of homocysteine*
Take 1 capsule per day, or as directed by a healthcare practitioner.

Serving Size: 1 vegetarian capsule

Amount Per Serving
Thiamin … 100mg (as thiamine HCl)
Riboflavin … 25mg
Vitamin B6 … 25mg (as pyridoxine HCl)
Folate Metafolin® … 680mcg DFE (as L-5-MTHF)
Vitamin B12 … 500mcg (as methylcobalamin)
Biotin … 400mcg 1333%
Pantothenic Acid … 200mg (as calcium pantothenate)
Riboflavin 5’ Phosphate … 10mg
Pyridoxal 5’ phosphate … 15mg
Niacinamide … 75mg

“To Sum It Up”

B12 is crucial, especially for vegetarians and those on medications like metformin or PPIs that interfere with its absorption. B12 supplements offer a reliable way to support your brain and nerve function, energy production, and the creation of DNA and red blood cells. By including a B12 supplement in your routine, you’re taking a step to safeguard your overall well-being and ensure that your body gets this vital nutrient it might be missing from diet alone. Don’t forget to check out our full article titled: Vitamin B12: Essential for Brain, Nerves, and Heart Health.

This Article is Not a Substitute for Medical Advice

Dietary supplements are not designed to diagnose, treat, cure, or prevent any disease. The Supplement Sciences website seeks to provide comprehensive access to the most relevant supplement information along with convenient online ordering. We do not provide medical advice and cannot guarantee that every product suggested is completely without risk. Since each person is unique in their health history and medication use, it is important to discuss supplements with your personal physician. Specifically, pregnant women and individuals being treated for cancer or liver or kidney problems must consult their physician about every nutritional supplement they plan to take. People taking medications for the treatment of HIV or with a history of organ transplant must not take supplements without consulting with their physician.

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