Vitamin D3 for Epilepsy: Can It Help Reduce Seizures?

clinical-trial PMID: 38980968

Quick Summary: A recent study found that taking Vitamin D3 for a longer period (about a year) may help reduce seizures in people with epilepsy that doesn't respond well to medication. Short-term use didn't show the same benefits.

Does Vitamin D3 Help with Seizures?

This research looked at whether Vitamin D3 could help people with epilepsy who still have seizures even while taking medication. The study found that while short-term Vitamin D3 didn't make a big difference, taking it for a longer time (about a year) seemed to reduce the number of seizures.

Study Details

Who was studied: 88 adults (mostly women) aged 17-74 with epilepsy that wasn't controlled by their current medications. All participants had low Vitamin D levels.

How long: The study had two parts. The first part was a 3-month "blinded" phase where neither the patients nor the doctors knew who was getting Vitamin D3 and who was getting a placebo (a dummy pill). The second part was a 9-month "open-label" phase where everyone received Vitamin D3.

What they took: Some people took Vitamin D3 (100,000 IU) monthly for 3 months, then continued for 6 more months. Others took a placebo for 3 months, then switched to Vitamin D3.

What This Means For You

Talk to your doctor: If you have epilepsy and low Vitamin D, ask your doctor if Vitamin D3 might be right for you.

Long-term is key: The study suggests that it takes time for Vitamin D3 to have an effect.

Get your levels checked: Your doctor can test your Vitamin D levels to see if you're deficient.

May improve quality of life: Participants reported feeling less tired and an improved quality of life.

Study Limitations

Short-term results were unclear: The initial 3-month period didn't show a clear benefit.

Everyone got Vitamin D3 eventually: This made it harder to compare the effects.

Mostly women: The results might be different for men.

More research needed: This study suggests a link, but more studies are needed to confirm these findings.

Key Findings

The study found that short-term vitamin D3 supplementation (3 months) did not significantly reduce seizure frequency (SF) compared to placebo in patients with drug-resistant epilepsy. However, long-term supplementation (12 months) correlated with a 30% median SF reduction, a 33% responder rate, and a 52% reduction in bilateral tonic-clonic seizures (BTCS). Significant improvements in fatigue (M-FIS) and quality of life (QOLIE-31) scores were observed across all patients. A key threshold effect emerged: SF reduction was associated with sustained 25(OH)D levels >30 ng/mL for >6 months.

Study Design

This was a multicenter, double-blind, placebo-controlled RCT followed by an open-label extension. 88 adults (17–74 years, 56 females) with drug-resistant focal/generalized epilepsy and baseline 25(OH)D <30 ng/mL were enrolled. 75 patients (85% of cohort) were randomized to experimental (EG, n=40) or control (CG, n=34) groups. The blinded phase lasted 3 months, followed by a 9-month open-label period where both groups received vitamin D3.

Dosage & Administration

The EG received 100,000 IU of cholecalciferol monthly for 3 months (blinded phase), then continued for 6 more months (total 9 months). The CG received placebo for 3 months, then switched to the same EG regimen (5 doses over 3 months, followed by monthly maintenance). Supplementation was oral, with monitoring of calcium, albumin, and creatinine to assess safety.

Results & Efficacy

Blinded phase (3 months): No significant difference in SF reduction between EG and CG.
Open-label phase (6–12 months):
30% median SF reduction (p<0.05 vs. baseline, no between-group comparison due to crossover design).
52% reduction in BTCS (p<0.01).
33% responder rate (≥50% SF reduction at 12 months).
M-FIS scores improved by 15.2 points (p<0.001) and QOLIE-31 scores increased by 10.7 points (p=0.002).
25(OH)D levels >30 ng/mL for >6 months were linked to greater SF reduction (r=0.41, p=0.001).

Limitations

Blinded phase lacked power: No significant between-group differences at 3 months, possibly due to small sample size (n=74) or short duration.
Crossover design confounds interpretation: Both groups received vitamin D3 after 3 months, eliminating a true control arm in later phases.
High female prevalence (64%): Results may not generalize to males.
No standardized antiseizure medication adjustments: Potential confounding from concurrent therapies.
Open-label bias: Unblinded supplementation could inflate perceived efficacy.

Clinical Relevance

For patients with drug-resistant epilepsy and vitamin D deficiency, long-term supplementation (≥6 months) to maintain 25(OH)D >30 ng/mL may reduce seizures and improve quality of life. However, benefits may not manifest within 3 months. Clinicians should consider screening for vitamin D deficiency in this population and implementing sustained supplementation regimens. The lack of short-term efficacy underscores the need for patience and adherence to long-term protocols. Safety monitoring (calcium, creatinine) is critical to avoid hypercalcemia. Further RCTs with extended blinded phases and larger cohorts are needed to confirm these findings.

Takeaway: Vitamin D3 may complement seizure management in deficient individuals, but timing and duration matter.