Poor-quality diets promote ischemic stroke. Red blood cell fatty acids (RBC-FAs) are objective, long-term biomarkers of diet. In a case-control study nested in the European Prospective Investigation into Cancer and Nutrition (EPIC)-Spain, we developed a blood-based lipidomic fat quality (LFQ) score considering pre-defined RBC-FA diet-related biomarkers, and examined whether LFQ score relates to the risk of ischemic stroke.

We determined the RBC-FAs (n = 438 cases of incident ischemic stroke, n = 438 matched controls). For each participant, we scored 1 for each beneficial metric (C15:0+C17:0; C18:2n-6; C18:3n-3; C20:5n-3; C22:6n-3) ⩾the median of the control group; and 1 for each detrimental metric (C16:0; C16:1n-7; C18:0) n = 2468 participants from the Framingham Offspring Study without ischemic stroke at baseline, 12-year median follow-up, n = 121 cases).

In a fully adjusted model, the Odds Ratio (OR) for ischemic stroke was 0.86 (95% confidence interval [CI] = 0.77–0.95) for each 1-unit increase of the LFQ score. Compared to individuals at the lowest category of LFQ score (0–3 points), those at the top category (5–8 points) had lower odds (OR = 0.64, 95% CI = 0.44–0.94). The findings were similar in the Framingham Offspring Study (Hazard Ratio [HR] for each 1-unit increase = 0.83; 95% CI = 0.70–0.99; HR for those at top category = 0.49; 95% CI = 0.29–0.84, compared to those at the lowest category).

Low blood-based LFQ scores relate to a high risk of ischemic stroke.