Introduction: The Search for Novel Environmental Biomarkers in CAD
Coronary artery disease (CAD) remains the leading cause of morbidity and mortality worldwide. While traditional risk factors—such as dyslipidemia, hypertension, and diabetes—are well-established, they do not fully account for the variance in disease progression and clinical presentation observed in the global population. This has led researchers to investigate the role of trace elements and minerals as potential modulators of cardiovascular risk. Among these, silicon (Si) has emerged as a subject of periodic scientific interest due to its purported roles in connective tissue integrity and vascular health. However, clinical evidence linking long-term silicon exposure to the severity of atherosclerosis has remained sparse and contradictory.
A recent pilot study, published in the journal Nutrients (2025), sought to clarify this relationship by examining hair silicon concentrations as a marker of long-term mineral exposure in patients with angiographically confirmed CAD. Unlike blood or urine levels, which reflect acute intake and are subject to homeostatic fluctuations, hair analysis provides a unique longitudinal window into mineral status over several months.
Background: The Silicon Hypothesis in Vascular Health
Silicon is one of the most abundant elements in the Earth’s crust and is found in varying concentrations in human tissues. Historically, the “silicon hypothesis” emerged in the 1970s and 80s, suggesting that silicon might play a protective role against atherosclerosis. Early animal models indicated that silicon supplementation could prevent the formation of lipid plaques in the aorta of rabbits fed high-cholesterol diets. Mechanistically, silicon is thought to be essential for the synthesis and cross-linking of collagen and elastin, which are critical components of the arterial wall.
Furthermore, silicon has been hypothesized to possess antioxidant and anti-inflammatory properties, potentially interfering with the oxidative stress pathways that drive endothelial dysfunction. Despite these theoretical benefits, the transition from bench to bedside has been challenging. Most human studies have focused on dietary intake or serum levels, which do not necessarily reflect the cumulative tissue exposure relevant to a chronic, decades-long process like atherosclerosis.
Study Design and Methodology
This pilot study enrolled 130 patients (mean age 67 years, 28% women) with CAD confirmed via coronary angiography. To ensure a robust assessment of disease burden, the researchers utilized two distinct scoring systems:
1. Coronary Artery Surgery Study Score (CASSS)
This score quantifies the extent of disease based on the number of major coronary vessels with significant stenosis (at least 70% luminal narrowing).
2. SYNTAX Score
This more complex anatomical tool assesses the complexity of coronary lesions, accounting for bifurcation, calcification, and lesion length, which helps guide decisions between percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG).
Long-term silicon exposure was measured using hair samples. Hair silicon concentration was determined by inductively coupled plasma optical emission spectrometry (ICP-OES), a highly sensitive analytical technique capable of detecting trace minerals at parts-per-million (ppm) levels. The study also analyzed a comprehensive range of clinical parameters, including BMI, lipid profiles (LDL, HDL, triglycerides), and systemic inflammatory markers such as C-reactive protein (CRP) and the neutrophil-to-lymphocyte ratio (NLR).
Key Findings: A Profile of Metabolic Neutrality
The median hair silicon concentration among the cohort was 21.3 ppm, with a wide range (0.7 to 211.0 ppm). Despite the high sensitivity of the measurements, the statistical analysis yielded largely neutral results:
Association with CAD Severity
There were no significant differences in hair silicon levels across different CASSS categories (H = 2.51; p = 0.47). Similarly, no correlation was found between silicon concentration and the SYNTAX score (r = 0.079; p = 0.37). Whether a patient had single-vessel or multi-vessel disease, their long-term silicon exposure appeared to be an independent, unrelated variable.
Clinical Phenotype and Prior Events
One of the critical questions was whether silicon levels differed between patients with stable angina and those presenting with acute coronary syndromes (ACS). The data showed no such association (p = 0.57). Furthermore, there were no significant differences in silicon levels between individuals with or without a history of myocardial infarction.
Correlation with Risk Factors and Inflammation
The study found that hair silicon concentration was unrelated to age, BMI, or traditional cardiovascular risk factors. Notably, there was no correlation with systemic inflammatory indices. This finding is particularly significant given the hypothesized anti-inflammatory role of silicon; in this cohort of patients with established CAD, silicon did not seem to modulate the inflammatory milieu characteristic of advanced atherosclerosis.
Expert Commentary: Contextualizing the Neutral Results
The results of this study suggest that in the context of advanced, angiographically visible coronary artery disease, silicon exposure is likely metabolically neutral. However, several nuances deserve consideration:
Primary vs. Secondary Prevention
It is possible that silicon’s protective effects are most relevant during the very early stages of vascular remodeling or primary prevention. By the time patients present with symptoms requiring angiography, the atherosclerotic process may be too advanced for trace mineral status to exert a detectable influence. The “silicon hypothesis” might still hold weight in the context of early-life exposure and the prevention of initial fatty streak formation.
Hair as a Diagnostic Matrix
While hair is an excellent matrix for assessing long-term exposure to heavy metals (like lead or mercury), its utility for essential or semi-essential trace elements like silicon is still being refined. External factors, such as hair care products or environmental dust, can contaminate samples, although the researchers in this study employed standardized washing procedures to mitigate this risk.
The Limitations of Pilot Data
As a pilot study with 130 participants, the power to detect very subtle associations might be limited. However, the lack of even a trend toward significance across multiple scoring systems suggests that silicon is unlikely to become a major diagnostic or prognostic biomarker in the near future.
Conclusion: Moving Forward in Mineral Research
The study by Dziedzic et al. (2025) provides a necessary reality check for the role of silicon in cardiovascular medicine. While silicon remains an interesting element in terms of bone health and connective tissue biology, its relevance as a biomarker for coronary artery disease severity appears negligible in the clinical setting.
For clinicians, these findings reinforce the importance of focusing on proven interventions—statin therapy, blood pressure control, and lifestyle modification—rather than unverified mineral supplements for the management of CAD. Future research may pivot back toward the role of silicon in the early prevention of vascular aging, but for the patient with established coronary lesions, silicon status does not appear to provide additional prognostic value.
References
1. Dziedzic EA, Dudek Ł, Osiecki A, Gąsior JS, Kochman W. Hair Silicon as a Long-Term Mineral Exposure Marker in Coronary Artery Disease: A Pilot Study. Nutrients. 2025; 17(24):3956. https://doi.org/10.3390/nu17243956
2. Schwarz K. A bound form of silicon in glycosaminoglycans and polyuronides. Proc Natl Acad Sci U S A. 1973;70(5):1608-1612.
3. Loeper J, Loeper J, Fragny M. The physiological role of silicon and its anti-atheromatous action. In: Biochemistry of Silicon and Related Problems. Springer; 1978:281-296.
