Helicobacter pylori (
H. pylori) infection is currently the most important controllable risk factor for gastric cancer, with 90% of noncardia gastric cancers being associated with
H. pylori infection [
1‐
5]. China is one of the countries with a high prevalence of
H. pylori infection, with an overall infection rate of 56.22%. The infection rate of
H. pylori in Tibet is as high as 84.62%, ranking first in the world [
6]. There are variations and trends in
H. pylori infection rates among different regions in China. Using the carbon-urea breath test as the diagnostic method for current infection, the lowest current infection rate was found in Guangdong Province at 42%, while the highest was in Shaanxi Province at 64%. Therefore, preventing
H. pylori infection is crucial for reducing the incidence of gastric cancer in China.
Vitamin D is a micronutrient that regulates bone metabolism. However, several studies have found that vitamin D3 decomposition product 1 (VDP1) can induce cell membrane collapse, leading to the lysis of
H. pylori cells [
7,
8]. Additionally, vitamin D3 can reactivate the acidification and degradation function of autolysosomes through the activation of the PDIA3-STAT3-MCOLN3-Ca
2+ axis, thereby eliminating the survival of
H. pylori hidden in the autophagy of cells [
9]. Vitamin D3 can also induce the VDR-CAMP signaling pathway to eradicate
H. pylori in the stomach [
10]. Furthermore, it can protect gastric mucosal epithelial cells against
H. pylori infection-induced apoptosis through the VDR-dependent c-Raf/MEK/ERK pathway [
11].
However, there is currently controversy regarding the relationship between serum vitamin D levels and
H. pylori infection in clinical studies. In a cross-sectional study conducted in 2007 on end-stage renal disease patients undergoing maintenance dialysis, a significant positive correlation was found between serum vitamin D levels and serum
H. pylori− specific IgG antibody titers (r = 0.36, P = 0.043) [
12]. This suggests that vitamin D analogs may have antibacterial effects against
H. pylori. Another study conducted in Japan on healthy elderly women aged 70–99 years in nursing homes found that the prevalence of
H. pylori infection was significantly lower in subjects receiving vitamin D3 supplementation than in unheated individuals (p < 0.05), indicating a suppressive effect of long-term vitamin D3 intake on
H. pylori infection [
13]. Antonio Antico et al. also found that serum vitamin D levels were significantly lower in
H. pylori− related gastric inflammation patients than in healthy individuals, suggesting that individuals with lower serum vitamin D levels may be more susceptible to
H. pylori infection [
14]. A clinical study conducted in Italy found that the proportion of vitamin D deficiency in the
H. pylori+ group was significantly higher than that in the
H. pylori− group (86% vs. 67.3%, P = 0.014) [
15]. A cross-sectional study of 294 patients who visited a hospital in Lebanon in 2016 for dietary habits and
H. pylori infection found that participants with a university degree or higher education (OR = 2.74; CI = 1.17–6.44), patients with a history of peptic ulcer disease (OR = 3.80; CI = 1.80–8.01), stomach adenocarcinoma (OR = 3.99; CI = 1.35–11.83), and those with vitamin D levels below normal (OR = 29.14; CI = 11.77–72.13) had a higher risk of
H. pylori infection [
16]. A cross-sectional study of individuals aged 65 and older found that the proportion of patients with
H. pylori+ and vitamin D deficiency (< 20 ng/mL) was higher than that of the
H. pylori− group (86% vs. 67.3%, p = 0.014). The proportion of
H. pylori+ patients decreased with increasing serum vitamin D levels (p = 0.010) [
17]. A large cross-sectional study conducted in infants and young children found that the prevalence of vitamin D deficiency in the
H. pylori+ and
H. pylori− groups was 20.7% and 12.1%, (P < 0.001) [
18]. A study of a large electronic database of medical records from the Israeli population’s health maintenance organization found a negative correlation between serum vitamin D levels and
H. pylori infection (p < 0.001). The odds of
H. pylori detection being positive were 31% higher in patients with serum vitamin D levels < 20 ng/mL than in those with levels ≥ 20 ng/mL (OR 1.31, 99% CI 1.22–1.4, p < 0.001) [
19]. However, a community-based study from Taiwan, which included 1126
H. pylori+ and 987
H. pylori− patients, found no significant difference in the average serum vitamin D levels between the two groups. Further stratification by age also did not reveal any differences [
20].
Due to the limited and controversial clinical studies on the relationship between serum vitamin D levels and H. pylori infection, we conducted a retrospective analysis of a cohort study to determine the impact of serum vitamin D levels on H. pylori infection and whether low serum vitamin D levels independently increase the risk of H. pylori infection.