Vitamin D Supplementation & Atrial Fibrillation – a Benefit or Risk Factor?

If you’re interested in supplementation and understanding the body’s nutritional needs, you’ve undoubtedly heard that most of the US population is deficient in vitamin D. Vitamin D is a critical nutrient that we obtain from sun exposure and, to a much lesser degree, through foods, including eggs, fortified cereals, milk products, some grains and more. Vitamin D is crucial in calcium absorption for healthy bones and is significant in several other physical and psychological factors. To that end, body hackers and doctors emphasize maintaining appropriate vitamin D levels for optimal health.

Why Are So Many of Us Deficient in Vitamin D?

The primary reason for a vitamin D deficiency is that our lifestyles do not lend themselves to getting adequate sunlight, such that blood vitamin D levels start declining. There are a few reasons for this. More and more, our free time and work are spent indoors rather than outside in the sun. Furthermore, with a better understanding of how the sun can age our skin, most of us are quick to put on sunscreen that blocks harmful rays, reducing the absorption and, thus, synthesis of vitamin D.

How May Vitamin D Affect Afib and Its Risk?

Studies on vitamin D and atrial fibrillation are, frankly, all over the place. Some studies have shown a significant reduction in the incidence and severity of Afib in patients with normal or even high vitamin D levels in their blood. The exact mechanism by which vitamin D may reduce the risk of Afib is not entirely known; however, there is a working theory that vitamin D may help regulate blood pressure, one of the most significant risk factors for Afib. Vitamin D is also a potent antioxidant and reduces systemic inflammation in the body, thus helping the heart. One often-overlooked potential vitamin D benefit also revolves around stress and overall mood. Patients with low vitamin D are usually found to have psychological concerns, including depression and anxiety. They may be more susceptible to stress, all of which can be risk factors for worsened Afib.

On the other end of the spectrum, some studies have raised concerns about excessive vitamin D consumption, typically due to supplementation. Supplements can range from 1,000 international units up to 10,000 or more. While the body is very good at removing excess vitamin D, high levels have been shown to potentially increase the risk of Afib.

Interesting Studies and Statements

Liu, X., Wang, W., Tan, Z. et al. The relationship between vitamin D and risk of atrial fibrillation: a dose-response analysis of observational studies. Nutr J 18, 73 (2019).

Ajabshir, S., Asif, A., & Nayer, A. (2014). The effects of vitamin D on the renin-angiotensin system. Journal of nephropathology, 3(2), 41–43.

Virtanen JK, Hantunen S, Lamberg-Allardt C, Manson JE, Nurmi T, Uusitupa M, Voutilainen A, Tuomainen TP. The effect of vitamin D3 supplementation on atrial fibrillation in generally healthy men and women: The Finnish Vitamin D Trial. Am Heart J. 2023 Oct;264:177-182. doi: 10.1016/j.ahj.2023.05.024. Epub 2023 Jun 10. PMID: 37302737.

2020 AHA Statement: https://newsroom.heart.org/news/fish-oil-and-vitamin-d-supplements-not-effective-for-preventing-atrial-fibrillation#:~:text=DALLAS%2C%20Nov.,science%20for%20health%20care%20worldwide.

The Conflicting Data and What That Means

It’s tough to isolate vitamin D as a protective mechanism versus risk factor for Afib. Furthermore, there is insufficient funding for studies to understand whether vitamin D plays a significant role. As such, we have to live with limited data and ultimately assume that adequate vitamin D levels can be exceptionally beneficial in all aspects of our lives, not just for Afib. That said, too much of a good thing can be bad, including vitamin D. So, work closely with your doctor and have regular blood work done to understand the appropriate vitamin D supplemental dosage, should you need it. Of course, we always want you to get your nutrients in the most natural way possible. So, speak to your doctor and dermatologist about what kind of unprotected sun exposure is appropriate for you, allowing you to balance the health benefits of the sun but avoid the problems associated with excessive sun exposure.

What to Do Next

If you are concerned about the potential effects of low vitamin D, speak with your primary care physician about getting a complete blood count, including vitamin D levels, to determine if you are deficient. If you are found to have low serum vitamin D levels, your doctor may recommend lifestyle changes, including spending more time outside and potentially taking a supplement. In a follow-up blood test, you should be able to see the results of these changes.

If you already have Afib and wonder if a vitamin D deficiency may be the cause, Dr. Tordini often suggests a dual-pronged approach to the problem. First, establish a baseline for your atrial fibrillation. By working with a knowledgeable electrophysiologist and a doctor specializing in the heart’s electrical functions, you’ll have the tools to understand exactly how often and how severe your atrial fibrillation is. At the same time, you must speak to your primary medical care team about getting your vitamin D levels to a normal baseline.

If improving your vitamin D levels reduces the risk, severity, and frequency of Afib episodes, you can keep an eye on your heart health with Dr. Tordini, knowing that should Afib progress, as it often does, there are many ways including advanced procedural techniques like pulsed-field ablation (PFA) to treat it.

Longer-Term Afib

Many of our patients have lived with Afib for years, and it may have progressed from paroxysmal, where it was occasional, to something more regular. As Afib progresses, it becomes harder to treat, and the many excellent treatment options available to us often become less effective. If you have been living with Afib for a while, improving your vitamin D levels may not prevent further Afib episodes. You must speak to a qualified electrophysiologist like Dr. Tordini to understand your treatment options and aggressively treat the root cause of the problem.

The Bottom Line

If lifestyle choices cause new or worsened Afib, it’s likely a constellation of potential concerns. Addressing the most common causes of Afib can help reduce the frequency and severity of these episodes and make medical or procedural treatment options more effective. Be sure to speak to your primary care physician and an electrophysiologist to understand your options.

Dr. Tordini is a part of Florida Medical Clinic Orlando Health