Effects of phytosterol-enriched corn–wheat germ blended oil on immune markers and T-cell subsets in Chinese adults with dyslipidaemia: a secondary analysis of a randomised controlled trial

Abstract Dyslipidaemia is associated with chronic low-grade inflammation and immune dysfunction, but the immunological effects of dietary phytosterols in humans remain unclear. We conducted a secondary analysis of an outcome-assessor-blinded, randomised controlled feeding trial to evaluate the effects of a high-phytosterol (HPS) diet, using phytosterol-enriched corn–wheat germ blended oil (CWGO), compared with a low-phytosterol (LPS) diet using peanut oil, on systemic inflammatory markers, humoural immune markers and peripheral blood lymphocyte subsets in Chinese adults with dyslipidaemia. After a 2-week run-in period, 104 participants were randomised to the HPS group ( n 52) or the LPS group ( n 52) for 12 weeks. In intention-to-treat analyses, the HPS group had a higher CD4 + :CD8 + ratio at 12 weeks than the LPS group (adjusted mean difference: 0·561; 95 % CI 0·060, 1·063; P = 0·03) and a lower CD8 + T-cell count (adjusted mean difference: −116·315 cells/μl; 95 % CI −215·781, –16·849; P = 0·02). No significant between-group differences were observed for systemic inflammatory markers, humoral immune markers or most other lymphocyte subset outcomes. In per-protocol analyses, the difference in CD4 + :CD8 + ratio remained significant, whereas the reduction in CD8 + T-cell count was attenuated. These exploratory findings suggest that a 12-week phytosterol-enriched CWGO intervention may be associated with changes in T-cell subset balance in adults with dyslipidaemia, although the results should be interpreted cautiously given the exploratory nature of this secondary analysis.