Severe rather than mild Heart Failure 3.4X more likely if low Vitamin D
Association of Serum Vitamin D Levels With the Severity of Chronic Heart Failure: A Retrospective Study
Cureus 18(8): e114248, August 10, 2026, https://doi.org/10.7759/cureus.114248
Farah Nazir, Tayyaba Shabbir, Semil Saleem, Behroze Khalid, Saad Binliaquat, Sadia Yousaf, Somia Bibi
Summary by Claude - August, 2026
Among 276 heart failure patients hospitalized in Rawalpindi, Pakistan, those with severe disease (NYHA Class III-IV) averaged 17.9 ng/mL of vitamin D, while those with milder disease averaged 25.8 ng/mL — an 8 ng/mL gap. Three-quarters of the whole group (75%) were below 30 ng/mL. Note that anyone who had recently taken vitamin D or calcium was excluded, so this is an unsupplemented population.
After adjusting for age, sex, diabetes, hypertension, prior ischemic heart disease, dyslipidemia, smoking, and physical inactivity, vitamin D insufficiency was the strongest surviving predictor of severe heart failure: 3.4X the odds (adjusted OR 3.36, 95% CI 1.88-6.02). Vitamin D also tracked with pumping strength — a moderate correlation with left ventricular ejection fraction (r = 0.48).
In-hospital outcomes went the same direction. Patients under 30 ng/mL
- stayed 2.2 days longer (7.5 vs 5.3 days),
- were more than twice as likely to need coronary care (29.8% vs 13.2%), and
- were 2.4X as likely to die during the admission (17.8% vs 7.4%).
What this does not show / limitations
This is a retrospective chart review at one hospital, not a trial — no one was given vitamin D, so it cannot say that raising levels would help. The authors themselves write that the outcome findings "should be interpreted as associations rather than evidence of a causal or independent effect." Reverse causation is the central worry: severe heart failure leaves people housebound and breathless, which lowers sun exposure and food intake on its own. Vitamin D was measured once, and body weight, kidney function, nutrition, inflammation, heart failure drugs, and season were never adjusted for. The in-hospital outcome comparisons in Table 4 were not adjusted at all. Two randomized trials of vitamin D in heart failure (EVITA, 4,000 IU/day for 3 years; and Boxer 2013) found no mortality benefit — a reminder that a strong association here has not translated into a proven treatment effect.