Researchers compared vitamin D and B12 levels in people with and without Hashimoto’s thyroiditis, a common autoimmune disease that affects the thyroid gland. They found that people with this thyroid condition tended to have lower levels of both vitamins compared to healthy people. The study suggests that these vitamin deficiencies might play a role in developing or worsening the disease, though more research is needed to prove whether the low vitamins actually cause the thyroid problems or just happen alongside them.

The Quick Take

  • What they studied: Whether people with Hashimoto’s thyroiditis (an autoimmune thyroid disease) have different levels of vitamin D and vitamin B12 compared to people without the disease
  • Who participated: Two groups of people visiting a family medicine clinic: one group with confirmed Hashimoto’s thyroiditis and one group of healthy people without thyroid disease or other chronic conditions
  • Key finding: People with Hashimoto’s thyroiditis had significantly lower vitamin D and B12 levels than healthy people. Older age, being female, and having low levels of these vitamins were all independently linked to higher risk of having the disease
  • What it means for you: If you have Hashimoto’s thyroiditis, checking your vitamin D and B12 levels may be worth discussing with your doctor. However, this study doesn’t prove that low vitamins cause the disease—only that they tend to occur together. More research is needed before making treatment recommendations

The Research Details

This was a case-control study, which is like comparing two groups of people to find differences between them. Researchers looked back at medical records from people who visited a family medicine clinic. One group had Hashimoto’s thyroiditis (confirmed by blood tests showing thyroid antibodies), and the other group was healthy people without thyroid disease. They collected information about each person’s age, sex, vitamin D levels, vitamin B12 levels, and thyroid antibody levels, then analyzed the data to see what factors were connected to having the disease.

The researchers used a statistical method called logistic regression to figure out which factors independently predicted who had Hashimoto’s thyroiditis. This helps separate out which factors matter most when multiple things are happening at the same time.

Case-control studies are useful for finding connections between health conditions and other factors, especially for diseases that develop slowly over time. By comparing people who have the disease with similar people who don’t, researchers can spot patterns that might be important. This approach is efficient and relatively quick, making it good for exploring new ideas before doing larger, more expensive studies

This study has some strengths: it used confirmed diagnoses based on blood tests and compared similar groups. However, there are limitations to keep in mind. The study looked at past medical records rather than following people forward in time, which makes it harder to know if low vitamins came before the disease or after. The sample size wasn’t specified in the abstract, so we don’t know how many people were studied. The study was done at one clinic, so results might not apply to everyone. Most importantly, finding a connection between two things doesn’t prove one causes the other

What the Results Show

The study found a clear statistical connection between vitamin D levels and Hashimoto’s thyroiditis. People with the disease had lower vitamin D levels than healthy people. Similarly, vitamin B12 levels were lower in people with Hashimoto’s thyroiditis compared to the control group.

When researchers looked at multiple factors together using statistical analysis, they found that three things independently increased the risk of having Hashimoto’s thyroiditis: being older, being female, and having lower vitamin D and B12 levels. This means that even when accounting for age and gender differences, the low vitamin levels were still connected to the disease.

Vitamin D levels also showed connections with other disease markers, including the level of thyroid antibodies (anti-TPO and anti-Tg) and vitamin B12 levels. Interestingly, there was no significant connection between vitamin D levels and gender, meaning men and women with the disease had similarly low vitamin D.

The study found that vitamin D and B12 levels were correlated with each other, suggesting these nutritional factors might work together in the body. The research also confirmed that older age and female gender are risk factors for Hashimoto’s thyroiditis, which aligns with what doctors already know about this disease. A history of hypothyroidism (low thyroid hormone) was also connected to vitamin D levels, suggesting these factors may be related in how the disease develops

This research adds to growing evidence that vitamin D and B12 may play roles in autoimmune diseases, including thyroid conditions. Previous studies have suggested links between vitamin D deficiency and various autoimmune conditions. This study specifically focuses on Hashimoto’s thyroiditis and confirms that both vitamin D and B12 deficiencies appear in this disease more often than in healthy people. However, most previous research hasn’t clearly established whether fixing these vitamin deficiencies actually improves the disease, which is why the authors call for more research

This study has several important limitations. First, it’s a retrospective study, meaning researchers looked backward at existing medical records rather than following people forward in time. This makes it impossible to know whether low vitamins came before the disease developed or resulted from it. Second, the sample size wasn’t reported, so we don’t know how many people were studied or whether the groups were large enough to draw firm conclusions. Third, the study was conducted at a single clinic, so the results might not apply to all populations or different geographic areas. Fourth, the study shows association (things occurring together) but cannot prove causation (that one thing causes the other). Finally, the researchers didn’t measure other factors that might influence vitamin levels or thyroid disease, such as diet, sun exposure, or other health conditions

The Bottom Line

Based on this research, people with Hashimoto’s thyroiditis may want to discuss vitamin D and B12 testing with their doctor (moderate confidence level). If deficiencies are found, supplementation might be considered as part of overall disease management. However, this study alone doesn’t prove that supplements will improve the disease, so treatment decisions should be made with a healthcare provider. People without Hashimoto’s thyroiditis should not assume they need vitamin D or B12 supplements based on this study alone

This research is most relevant to people who have been diagnosed with Hashimoto’s thyroiditis or suspect they might have it. It’s also important for doctors treating thyroid disease. People with a family history of autoimmune thyroid disease might find this information interesting. However, healthy people without thyroid disease don’t need to change their behavior based on this single study. Anyone considering vitamin supplements should consult their doctor first

If vitamin deficiencies are corrected through supplementation, it typically takes several weeks to months to see changes in blood levels and potentially longer to notice improvements in symptoms. Thyroid disease management is usually a long-term process, so patience is important. Benefits wouldn’t be expected overnight

Want to Apply This Research?

  • Track your vitamin D and B12 levels quarterly by recording lab test results. Note the date, value, and unit of measurement. Also track any changes in thyroid symptoms like fatigue, weight changes, or temperature sensitivity to see if they correlate with vitamin level changes
  • If you have Hashimoto’s thyroiditis and your doctor recommends it, set a daily reminder to take vitamin D and B12 supplements at the same time each day. Log when you take them in the app to maintain consistency and track adherence over time
  • Create a long-term tracking dashboard showing your vitamin D and B12 levels over time alongside your thyroid antibody levels (if available) and symptom severity. This visual representation can help you and your doctor identify patterns and determine if supplementation is making a difference in your specific case

This research suggests an association between low vitamin D and B12 levels and Hashimoto’s thyroiditis, but does not prove that vitamin deficiencies cause the disease. This study should not be used to self-diagnose or self-treat thyroid conditions. Anyone with symptoms of thyroid disease or concerns about vitamin levels should consult with a qualified healthcare provider for proper testing and personalized treatment recommendations. Do not start, stop, or change any medications or supplements without medical supervision. This information is for educational purposes only and is not a substitute for professional medical advice.