Proper nutrition is important to health and vitality. Prolonged vitamin deficiencies can cause a variety of physiological issues. Vitamin B-12 is a water soluble vitamin that plays a crucial role in the healthy formation of red blood cells, tissues and DNA. B-12 deficiency can manifest as a variety of symptoms, including fatigue. However, you may not know that there is a connection between B-12 deficiency and autoimmune disorders.

Physiological Role of B-12

Vitamin B-12 is naturally found in foods such as meat, fish, poultry, eggs and dairy. It exists in several forms and contains the mineral cobalt. B-12 is involved in DNA synthesis, red blood cell formation and neurological function. It is also a co-factor to close to 100 proteins, hormones and lipids. Your body absorbs B-12 bound to protein in food through the activity of intrinsic factor, an enzyme produced in your stomach.

B-12 Deficiency

The recommended dietary allowance for individuals 14 years or older is 2.6 mcg. daily. Under normal circumstances, you receive enough B-12 from your diet to meet your needs. Your chances of developing B-12 deficiency increase if you follow a vegetarian or vegan diet. You can also develop B-12 deficiency if you lack intrinsic factor. Pernicious anemia is an autoimmune condition where your immune system identifies intrinsic factor as a pathogen, attacking it. Without enough intrinsic factor, you cannot absorb B-12 properly.

Autoimmune Thyroiditis

The are more than 80 types of autoimmune diseases 2. Autoimmune disorders cause your body's immune system to identify your own tissues and cells as pathogens, and launch an attack. This can occur anywhere in your body. In autoimmune thyroiditis, also known as Hashimoto's thyroiditis, this happens in your thyroid tissues. Your thyroid gland plays a critical role in producing metabolic hormones that regulate mood, appetite and metabolism. When your immune system attacks your thyroid over a prolonged period, hypothyroidism can occur. Hypothyroidism means your thyroid is not producing enough thyroid hormones. Hashimoto's is the most common hypothyroidism in Americans.

B-12 Deficiency and Autoimmune Thyroiditis

According to a 2006 study published in "The American Journal of the Medical Sciences," patients with autoimmune thyroiditis have a prevalence of B-12 deficiency, particularly of pernicious anemia 3. In the study, 28 percent of patients had low B-12 levels. Further, the prevalence of pernicious anemia in patients with low B-12 levels was 31 percent. These results suggest a strong connection between B-12 deficiency and autoimmune thyroiditis.

B-12 Deficiency and Chronic Urticaria

Urticaria is a condition that causes welts known as hives to develop on the skin. Recent studies suggest the involvement of autoimmunity in chronic idiopathic urticaria, or CIU, with a link to low B-12 levels. According to a 2004 study published in the "Journal of Investigational Allergology and Clinical Immunology," 33 percent of patients with CIU had low B-12 levels 4. To add to the mystery, anti-thyroid antibodies were detected in 54 percent of patients with low B-12 levels. This means study participants with low B-12 levels suffered from autoimmune thyroiditis as well as autoimmune urticaria. Such findings suggest a strong link between B-12 deficiency and autoimmunity.