Why Would B12 and Folic Acid Be Low?

According to the National Institutes of Health, older adults, vegans, and those with gastrointestinal disorders are among the groups most at risk for vitamin B12 deficiency. Understanding why would B12 and folic acid be low is crucial, as these vitamins are essential for producing red blood cells and maintaining nervous system health.

Quick Summary

This article explores the multiple factors contributing to low vitamin B12 and folic acid levels, including dietary restrictions, malabsorption issues from underlying medical conditions, and certain medications that interfere with vitamin absorption.

Key Points

• Pernicious Anemia: An autoimmune condition is a primary cause of low B12, as it prevents the production of intrinsic factor, which is necessary for absorption.

• Dietary Restrictions: Vegan and vegetarian diets are significant risk factors for B12 deficiency due to the lack of animal products, the main natural source of the vitamin.

• Malabsorption Issues: Chronic diseases such as Crohn's and celiac disease, or past gastrointestinal surgeries, can directly impair the body's ability to absorb both B12 and folic acid.

• Medication Interference: Certain drugs, including proton pump inhibitors (PPIs), metformin, and specific anticonvulsants, can negatively affect vitamin absorption.

• Lifestyle and Genetic Factors: Excessive alcohol consumption and certain genetic mutations, like MTHFR, can disrupt the metabolism and storage of these vitamins.

• Increased Physiological Demand: Conditions such as pregnancy, lactation, and certain cancers increase the body's need for these vitamins, potentially leading to deficiency if not adequately managed.

Vitamin B12 and folic acid (vitamin B9) are vital nutrients for cell function, DNA synthesis, and healthy red blood cell production. Low levels can lead to megaloblastic anemia, characterized by large, ineffective red blood cells. The reasons why B12 and folic acid would be low are varied, ranging from dietary factors to complex health issues.

Dietary Insufficiency

Inadequate dietary intake is a primary cause. B12 is mainly in animal products, making vegans and vegetarians vulnerable without supplements or fortified foods. Folate is widespread in leafy greens, legumes, and fortified grains. While poor diet can cause folate deficiency, it's less common in areas with food fortification. Cooking can also destroy folate.

Malabsorption Disorders

Even with sufficient intake, certain conditions can prevent absorption, particularly for B12. B12 needs intrinsic factor, a stomach protein, to be absorbed.

Conditions affecting absorption

• Pernicious Anemia: An autoimmune condition where the body attacks intrinsic factor-producing stomach cells.
• Atrophic Gastritis: Thinning of the stomach lining reduces stomach acid and intrinsic factor.
• Gastrointestinal Surgeries: Procedures like gastric bypass can impact intrinsic factor production or absorption sites.
• Intestinal Diseases: Crohn's and celiac disease can damage the small intestine, hindering B12 and folate absorption.
• Parasitic Infections: Fish tapeworms compete for B12.

Medications and Lifestyle Factors

Medications and lifestyle choices can also affect vitamin levels.

Factors influencing vitamin levels

• Medications:
  • Proton Pump Inhibitors (PPIs): Reduce stomach acid needed for B12 release.
  • Metformin: Can decrease B12 absorption.
  • Anticonvulsants and Methotrexate: Interfere with folate.
• Excessive Alcohol Use: Impairs B12 and folate absorption and storage.
• Increased Demand: Pregnancy, lactation, and conditions with rapid cell turnover increase the need for these vitamins.

Genetic and Age-Related Causes

Genetics and aging also play a role.

Inherited and physiological factors

• Age-Related Atrophic Gastritis: Decreased stomach acid in older adults hinders B12 absorption.
• MTHFR Gene Mutation: Can impair folate conversion to its active form.
• Hereditary Folate Malabsorption: A rare genetic disorder impacting folate transport.
• Inherited Intrinsic Factor Deficiency: Prevents B12 absorption despite intrinsic factor production.

B12 vs. Folic Acid Deficiency: A Comparison

Aspect	Vitamin B12 Deficiency	Folic Acid Deficiency
Common Causes	Pernicious anemia, vegan/vegetarian diet, gastric surgery, age-related malabsorption	Poor diet (less common in fortified regions), malabsorption (celiac disease), increased physiological demand (pregnancy)
Dietary Sources	Animal products (meat, eggs, dairy), fortified foods	Green leafy vegetables, legumes, fortified grains
Absorption Mechanism	Relies on intrinsic factor for absorption in the small intestine	Primarily absorbed in the jejunum; sensitive to heat
Neurological Symptoms	Can cause severe neurological issues, including nerve damage, memory problems, and confusion	Typically does not cause neurological symptoms, though psychiatric issues can occur
Diagnosis	Blood tests for serum B12, homocysteine, and MMA; intrinsic factor antibodies	Blood tests for serum and red cell folate; elevated homocysteine

Conclusion

Low B12 and folic acid levels have numerous potential causes, from dietary choices like veganism to chronic conditions such as pernicious anemia or Crohn's disease that affect absorption. Medications, alcohol use, and genetics also contribute. Identifying the specific cause is key to effective treatment, whether through diet, supplements, or addressing an underlying issue. A healthcare provider is essential for diagnosis and personalized treatment for symptoms like fatigue or neurological changes.

Visit MedlinePlus for more comprehensive information on B12 and folate deficiencies.

Frequently Asked Questions

What is the most common cause of B12 deficiency?

The most common cause of a vitamin B12 deficiency, particularly in the UK, is pernicious anemia, an autoimmune condition where the body attacks the stomach cells that produce intrinsic factor, a protein essential for B12 absorption.

How does a vegan diet cause low B12?

A vegan diet can lead to low B12 because this vitamin is naturally found almost exclusively in animal products. Without supplementation or the consumption of B12-fortified foods, vegans are at a high risk of developing a deficiency.

What medical conditions cause malabsorption of these vitamins?

Conditions such as Crohn's disease, celiac disease, and gastrointestinal surgeries (like gastric bypass) can disrupt the digestive process and prevent the proper absorption of B12 and folate in the small intestine.

Which medications can interfere with B12 and folic acid levels?

Common medications that can interfere include proton pump inhibitors (PPIs) and H2 blockers, which reduce stomach acid, as well as metformin, certain anticonvulsants, and methotrexate.

Can genetics play a role in low folate or B12?

Yes, genetic factors can play a role. For example, a mutation in the MTHFR gene can impair folate metabolism, while hereditary folate malabsorption is a rare genetic disorder affecting folate transport.

What are the key differences in symptoms between B12 and folate deficiency?

While both can cause megaloblastic anemia symptoms like fatigue, severe B12 deficiency is more likely to cause neurological problems such as tingling, memory loss, and difficulty walking. Folate deficiency typically does not cause these neurological issues.

Does excessive alcohol use affect vitamin levels?

Yes, chronic and excessive alcohol use can significantly contribute to both B12 and folate deficiency by damaging the digestive system and interfering with absorption and storage.