Can Fixing a Vitamin D Deficiency Ease PTSD Symptoms? A New VA Study Says Maybe
A recent study out of the VA Loma Linda Healthcare System asked a simple question: in Gulf War veterans who show up at the GI clinic with chronic diarrhea, does correcting a vitamin D deficiency also help their PTSD or traumatic brain injury symptoms? The researchers reviewed charts for 55 veterans with PTSD and 22 with TBI, all of whom also had IBS-D. Nearly all were low in vitamin D, averaging around 19-20 ng/mL — well under the 30 ng/mL considered sufficient. After three months of daily vitamin D (3,000-5,000 IU), levels normalized to about 30 ng/mL, calcium stayed safely in range, and roughly 80% of the PTSD group reported feeling less depressed, less anxious, and generally healthier. The authors frame this as a strong argument for screening veterans with GI complaints and psychiatric symptoms for vitamin D deficiency before reaching for another prescription.
It's an appealing idea, and the biological rationale, that vitamin D's role in inflammation regulation and neuroprotection is reasonable. But the design of this study makes it hard to know how much of the improvement was actually due to vitamin D. There was no placebo group and no randomization; every veteran got the supplement and was then asked whether they felt better, so there's nothing to compare against. Symptom improvement wasn't measured with a validated PTSD or depression scale, it was based on the treating physician's impression during follow-up visits, which is a much softer measure than something like the PCL-5. The researchers also didn't have access to the actual mental health notes, so they were essentially assessing psychiatric symptoms from the gastroenterology clinic without full visibility into what the psychiatric team was seeing or changing. Roughly a third of the PTSD group was also on antidepressants or anti-anxiety medications during the study period, which muddies any attempt to credit vitamin D alone, though interestingly, the authors note the most consistent improvement was in patients who weren't on psychiatric medication changes, which is worth watching in future work. Several of the correlations reported (deployment history, BMI, CRP) were weak and not statistically significant, though they're sometimes described in the text in ways that imply more certainty than the numbers support. The sample is also small, all male, and drawn from a single VA site, which limits how far these findings can be generalized.
None of this means the core idea is wrong, vitamin D deficiency is common, correcting it is low-risk, and there's a real biological story connecting it to mood and inflammation. But this study is best read as a hypothesis-generating pilot, not proof that vitamin D treats PTSD. The authors themselves call for a placebo-controlled trial with validated symptom scales, which is exactly the next step needed before this becomes a clinical recommendation rather than a promising lead.
This is exactly why Spruce Creek Integrative approaches mental health as more than a chemical imbalance to be managed with a prescription pad. A finding like this, that something as basic as vitamin D status can shape depression, anxiety, and PTSD symptoms is a reminder that the brain doesn't operate in isolation from the rest of the body. At Spruce Creek Integrative, we look at the full picture: nutritional status, gut-brain axis health, genetics, and lifestyle factors alongside conventional psychiatric care, because the root cause of a symptom isn't always where you'd expect to find it.
Kesavan C, Strong DD, Strong RM. Correction of Vitamin D Deficiency Improves PTSD Symptoms in Gulf War Veterans. Brain Sci. 2025;15(11):1135. Published 2025 Oct 23. doi:10.3390/brainsci15111135
