# Serum Vitamin A Is Associated with Variations in the Relationship between Plasma B6 Vitamers and Cardiovascular Disease Risk

## TL;DR

This study found that vitamin A levels influence how vitamin B6 forms relate to heart attack risk, suggesting a complex interaction between these vitamins and cardiovascular health.

## Contribution

The study reveals that vitamin A modifies the relationship between B6 vitamers and cardiovascular disease risk, adding new insight into their combined roles.

## Key findings

- Low PLP and high PA/PL ratio were linked to increased AMI risk in patients with high vitamin A.
- Vitamin A positively correlates with PLP and PA/PL ratio at baseline.
- The interaction between Vit-A and B6 vitamers persisted after adjusting for multiple variables.

## Abstract

Low concentrations of biologically active B6 vitamer, pyridoxal 5'-phosphate (PLP) are associated with an increased risk of cardiovascular disease (CVD). Vitamin A (Vit-A) promotes lipid homeostasis and the transport cholesterol. Vit-A may also stimulate the intracellular transport of PLP.

This study aimed to investigate whether Vit-A is associated with variations in the relationship of systemic B6-vitamers with incident acute myocardial infarctions (AMIs).

A total of 4091 patients undergoing elective coronary angiography for suspected stable angina pectoris were studied. Associations of different plasma B6 vitamers, including PLP, pyridoxal (PL), 4-pyridoxic acid (PA), and PA/PL ratio with the risk of AMI according to median concentrations of Vit-A, were explored in Cox regression models.

Serum Vit-A demonstrated positive associations with PLP and PA/PL ratio at baseline (P < 0.001 for both). During a median follow-up of 7.5 y, 521 (12.7%) patients suffered an AMI. In age and sex-adjusted analyses, plasma PLP, PA, and PA/PL ratio showed an overall association with incident AMI {hazard ratio (HR) [95% confidence interval (CI)] per SD: 0.90 [0.82, 0.99; P = 0.02], 1.14 [1.05, 1.23; P < 0.001], and 1.28 [1.18, 1.39; P < 0.001], respectively}. However, low plasma PLP and high PA/PL ratio were associated with an increased risk of AMI primarily among patients with high compared with low Vit-A concentrations [HR (95% CI) per SD: 0.77 (0.68, 0.88; P < 0.001, P-interaction = 0.002) and 1.36 (1.23, 1.49; P < 0.001, P-interaction = 0.05), respectively]. The interactions persisted after multivariable adjustment (both P-interactions ≤ 0.04).

The relationship between vitamin B6 indexes and AMI risk varied according to serum Vit-A concentrations. Additional research is needed to clarify the importance of Vit-A and B6 bioavailability in atherosclerotic CVD.

This trial was registered at clinicaltrials.gov as NCT00354081.