Vitamin B12 and Hashimoto's: A Hidden Connection You Don’t Want To Ignore

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What Are the Symptoms of a B12 Deficiency?

Vitamin B-12 deficiency can be relatively common. Studies show that in the United States and the United Kingdom, the prevalence of vitamin B12 deficiency is approximately 6% in persons younger than 60 years, and nearly 20% in those older than 60 years.

A deficiency of Vitamin B12 may have several potential symptoms, such as:

• Fatigue and weakness
• Pale or yellow skin
• Numbness and tingling
• Impaired cognitive performance
• Mouth ulcers and sore tongue
• Heart palpitations
• Loss of appetite
• Impaired digestion
• Headaches
• Lethargy
• Mood changes and irritability
• Neurological damage

Diagnosing a B12 deficiency can involve a combination of methods, including:

• Symptom evaluation
• Medical history
• A physical exam
• Blood tests

A doctor will ask about your symptoms, medical history, and dietary habits. They may also perform a physical exam to check for signs of anemia, such as pallor, fatigue, and weakness. 

Several blood tests may be used to confirm if you have a B12 deficiency, such as:

• Serum vitamin B12 level test: Measures the amount of vitamin B12 in the blood

• Complete blood count (CBC): Checks for anemia and other abnormalities in the blood

• Methylmalonic acid (MMA) test: A more specific indicator of B12 deficiency, as B12 is needed to metabolize MMA



• Homocysteine test: Elevated levels can indicate a B12 or folate deficiency

In some cases, additional tests may be necessary to determine the underlying cause of B12 deficiency.

A gastric biopsy may be performed to check for intestinal diseases, like Crohn's or celiac disease, that can impair B12 absorption. If an autoimmune disorder is suspected and interfering with B12 absorption, a doctor may test for anti-intrinsic factor or anti-parietal cell antibodies.

Are you concerned and want to know if your Hashimoto's and B12 deficiency could be aggravating your symptoms?

Offering holistic services in Brooklyn, NY, Dr. Sergi at HealthierU can find the cause of your symptoms and address them without traditional medication. We do this by creating a customized plan that includes nutritional support, lifestyle guidance, and supplementation to help permanently correct your health concerns.

Hashimoto's disease is an autoimmune condition in which the immune system attacks the thyroid gland.

Individuals with autoimmune thyroid disease may have a high prevalence of vitamin B12 deficiency. One study found that 28% of the 115 people polled with autoimmune thyroid disease had a B12 deficiency.

Low levels of vitamin B-12 can exacerbate inflammation in the thyroid gland and worsen Hashimoto’s thyroiditis symptoms. A 2020 study found that 46% of the 130 patients with Hashimoto's disease had a vitamin B-12 deficiency. 

Research suggests that patients with thyroid dysfunction should be screened for vitamin B12 status and treated accordingly.

In one study, more than 50% of cases with thyroid disorder and anti-thyroperoxidase antibody (ATA) positivity showed deficiency of vitamin B12 (hypothyroidism, 63.3% hyperthyroidism, 51.8%).

Hashimoto's thyroiditis is often associated with impaired digestion, which can lead to a vitamin B12 deficiency.

Many people with thyroid conditions may have low stomach acid — a condition known as hypochlorhydria — which is necessary to break down digested proteins and food. Studies show that up to 40% of patients with autoimmune gastritis also have Hashimoto’s thyroiditis.

With a lack of digestive enzymes, you may not be able to properly extract nutrients from your foods, resulting in severe deficiencies and uncomfortable symptoms such as:

• Gas
• Heartburn
• Bloating
• Heaviness in the stomach

People with hypothyroidism, especially those with Hashimoto's, can have slowed gastric motility, which can lead to bacterial overgrowth in the small intestine. 

Small intestinal bacterial overgrowth (SIBO) is a digestion-related risk factor for B12 deficiency. The breakdown of nutrients by the excess bacteria can damage the lining of the small intestine, making it harder for the body to absorb nutrients, including B12. SIBO may result in multiple intestinal symptoms, such as:



• Abdominal pain and cramps
• Bloating
• Diarrhea
• Fatty stool
• Weight loss
• Malabsorption

Hashimoto’s often co-occurs with other autoimmune conditions, such as pernicious anemia.



Research reveals that 35% of people with pernicious anemia report having one or more additional autoimmune disease diagnoses. At 21%, Hashimoto's is the most frequently reported co-existing condition.

In pernicious anemia, the immune system attacks the parietal cells in the stomach lining that produce a protein called intrinsic factor. Without the intrinsic factor protein, the body can’t absorb enough vitamin B12, which can lead to a vitamin B12 deficiency.

H. pylori, also known as Helicobacter pylori, is a type of bacteria that infects your stomach. It can cause sores and inflammation in the lining of your stomach or the upper part of your small intestine and can impair your body's ability to absorb vitamin B12.

Having a history of an H. pylori infection can make you more susceptible to developing pernicious anemia and B12 deficiency. H. pylori triggers antibody production against intrinsic factor and can eventually progress to vitamin B12 deficiency.

In one study, H. pylori was detected in 77 (56%) of 138 patients with vitamin B12 deficiency. Eradication of H. pylori infection successfully improved anemia and serum vitamin B12 levels in 31 (40 %) of the 77 infected patients.

B12 deficiency is a significant health concern that can manifest in various stages:

• Stage 1: Serum depletion – Lab testing will show declining levels of vitamin B12 and holotranscobalamin.

• Stage 2: Cellular depletion – As the deficiency progresses, the vitamin B12 levels within your cells decrease, but clinical symptoms are still minimal.

• Stage 3: Biochemical deficiency – Methylmalonic acid (MMA) and homocysteine are elevated, also called hyperhomocysteinemia. Vague symptoms may begin to appear, such as fatigue, weakness, and difficulty remembering things.

• Stage 4: Severe deficiency – This stage has a wide range of significant and progressive symptoms, marked by megaloblastic anemia, a late indicator of the condition. Symptoms may include severe and potentially irreversible nerve damage, depression, paranoia, dementia, significant fatigue, and shortness of breath.

You can make dietary changes to help reverse vitamin B12 deficiency by eating more animal products like meat, seafood, dairy, and eggs, or breads and plant-based milks fortified with Vitamin B12.

If you are deficient in B12 and cannot get enough B12 from diet alone, you may need to supplement B12.

Different types of B12 supplementation include:

• Oral pills or capsules
• Sublingual
• B12 injections

At HealthierU, Dr. Sergi is committed to helping patients get well and stay healthy naturally through nutrition and lifestyle guidance. 

We take a more personalized approach by getting to know YOU — your body and the foods you react both positively and negatively to. From there, we’ll create an individualized, comprehensive diet that can work for you.

Request a consultation today, and join us on this journey towards embracing a healthier, more holistic approach to living.

For Hashimoto's and B12 deficiency, doses of 400-1,000 micrograms of a B12 oral supplement per day are suggested. However, an activated form like methylcobalamin or hydroxycobalamin may improve absorption and bypass potential intestinal issues. A healthcare provider should be consulted for personalized advice on the appropriate dosage and type of B12 for your specific needs.

According to the Office of Dietary Supplements (ODS), vitamin B12 has not been shown to cause any harm, even at high doses.

That being said, taking too much vitamin B12 may cause some of the following symptoms:



• Headaches
• Diarrhea
• Nausea and vomiting
• Skin rashes
• Fatigue or weakness
• Tingling of the hands and feet

There can be medication interactions with vitamin B12, such as Metformin and proton pump inhibitors (PPIs). If you are taking other medications, be sure to speak with a medical professional before taking B12 supplementation.

Yes, you can take vitamin B12 with thyroid medication, but it's critical to separate the timing of your doses by at least four hours. Taking B12 supplements too close to your thyroid medication can reduce the effectiveness of your thyroid medication.

If you have a thyroid condition, like autoimmune thyroid disease, have your B12 levels checked by a doctor before supplementing.

Vitamin B12 can play an important role in your thyroid health. You may be able to address Hashimoto's symptoms with a wholesome approach centered around getting adequate amounts of the best nutrients for your thyroid health.

B12 is naturally found in animal products. For people who can absorb B12 effectively through the gut, the following are excellent dietary sources:

• Beef
• Seafood
• Poultry
• Eggs
• Dairy

For vegetarians or vegans, fortified foods and supplements may be necessary sources.

Generally speaking, a diet with a variety of nutrient-dense foods provides adequate amounts of the nutrients that support thyroid health, but every patient is different in terms of:

• Nutrient absorption
• Dietary needs
• Underlying circumstances that affect how the body responds to different substances



HealthierU can request the right exams to evaluate your body’s needs and create a list of supplements that are most likely to make a positive difference in your experience with Hashimoto’s.

If you’re searching for natural treatment for hypothyroidism, Hashimoto's, and B12 deficiency, you’ve come to the right place. 

Your symptoms are your body’s way of telling you what it needs.

For nearly three decades, Dr. Sergi has served clients in the Brooklyn area, helping them find safer, more natural ways to address their health issues. 

By following our comprehensive and personalized guidance, you can develop dietary and lifestyle habits that have a positive and lasting impact on your thyroid health.

Find relief with HealthierU, schedule a complimentary consultation with Dr. Donna Sergi today.