Baseline self-reported supplement category use and two-visit difference in lipoprotein(a): an observational analysis...

Circulating Lp(a) is largely genetically determined, but repeated measurements indicate that Lp(a) concentrations may differ within individuals over time. It remains unclear whether self-reported use of common supplement categories is associated with differences between repeated Lp(a) measurements. We aimed to investigate associations between baseline self-reported supplement-category use and two-visit difference in Lp(a), and to explore whether these associations differed by Lp(a) genetic risk.

We included 12,109 UK Biobank participants with Lp(a) measured at baseline and at the first repeat assessment. Self-reported use of common supplement categories (vitamins A, B, C, D, E, folate, and multi-vitamins) was assessed by questionnaire. The primary outcome was the continuous two-visit difference in log10[Lp(a)], defined as log10[repeat-assessment Lp(a)] minus log10[baseline Lp(a)]. The primary analysis used core behavioral/sociodemographic-adjusted multivariable linear regression. Threshold-category and genetic-risk analyses were secondary and exploratory.

Among 12,109 participants with repeated Lp(a) measurements over a median 4.4 years, estimates in the primary core behavioral/sociodemographic-adjusted continuous log-scale model were small and centered near the null, ranging from β = -0.014 to 0.005 log10 units, corresponding to approximately - 3.18% to 1.22% relative difference in the conditional repeat-to-baseline Lp(a) ratio. None met the Bonferroni-corrected threshold. Expanded clinical/genetic adjustment and secondary descriptive screens did not alter the null interpretation.

In this selected repeat-assessment sample, baseline self-reported use of common supplement categories was not associated with two-visit difference in log10[Lp(a)]. Because supplement use was measured only as broad baseline self-reported categories, these findings should not be interpreted as evidence about dose-specific, sustained, or biological effects of vitamin supplementation on Lp(a).