Supplement Use and Diet Quality Among U.S. Adults by Eligibility for Lipid-Lowering Therapy

Background: The 2026 American Heart Association/ American College of Cardiology (AHA/ACC) dyslipidemia guideline advises against supplements for lipid lowering. Whether supplement use reflects broader engagement in cardiovascular prevention, including healthy eating, remains uncertain. We examined supplement use and selected dietary characteristics across lipid-lowering therapy (LLT) treatment and eligibility groups. Methods: We conducted a cross-sectional analysis of National Health and Nutrition Examination Survey data (2015-2020) from adults aged 30-75 years. Participants were classified as current LLT users or untreated adults. Untreated adults were further classified as recommended, reasonable/selectively consider, or not routinely recommended for LLT, using the 2026 AHA/ACC guideline. Outcomes were self-reported heart health or cholesterol supplement use and dietary misalignment burden, defined as the number of unmet benchmarks across nine selected recall-day indicators informed by 2026 AHA dietary guidance. Analyses incorporated the complex survey design and fasting subsample weights to generate national estimates and compare supplement use across burden categories. Results: We analyzed 3,743 participants, representing 147.3 million US adults; 49.0% were female, and 25.0% were receiving LLT. Overall, 11.3% [9.4-13.6] reported supplement use. Supplement use was highest among adults receiving LLT (19.5% [14.9-25.1]) and lowest among untreated adults for whom LLT was not routinely recommended (3.6% [2.6-5.1]). Among untreated adults for whom LLT was recommended, 4.2 million (12.8% [10.5-15.4]) used supplements. Dietary inadequacies were common across measured domains and LLT eligibility strata; the weighted median misalignment burden was 7 (IQR 6-8). Supplement use did not differ significantly across dietary misalignment burden categories. Conclusions: Millions of US adults recommended for LLT were untreated while using heart health or cholesterol supplements, and supplement use did not differ significantly across selected dietary misalignment burden categories. Proactive assessment of supplement use may help redirect prevention counseling toward guideline-directed LLT and heart-healthy dietary patterns.