Dietary plant stanol ester consumption improves immune function in asthma patients: results of a randomized, double-blind clinical trial

Abstract

In vitro and ex vivo studies have suggested that plant sterols and stanols can shift the T helper (Th) 1/Th2 balance toward a Th1-type immune response, which may be beneficial in Th2-dominant conditions such as asthma and allergies. We evaluated in vivo whether plant stanol esters affect the immune response in asthma patients. Fifty-eight asthma patients participated in a randomized, double-blind, placebo-controlled intervention study. All subjects started with a 2-wk run-in period in which they consumed 150 mL control soy-based yogurt without added plant stanol esters/d. Next, an 8-wk experimental period was started in which one-half of the participants received plant stanol enriched soy-based yogurts (4.0 g plant stanols/d), whereas the other one-half of subjects continued the consumption of control yogurts. After 4 wk of daily plant stanol consumption, all participants were vaccinated against hepatitis A virus (HAV), and the increase of antibody titres was monitored weekly until 4 wk after vaccination. Asthma patients in the plant stanol ester group showed higher antibody titres against HAV 3 and 4 wk after vaccination [19% (P = 0.037) and 22% (P = 0.030), respectively]. Also, substantial reductions in plasma total immunoglobulin E, interleukin (IL)-1β, and tumor necrosis factor-α were shown in the plant stanol ester group. The increase in serum plant stanol concentrations was correlated significantly with the decrease in IL-13 concentrations and the Th1 switch in the Th1/Th2 balance. However, no absolute differences in cytokine production between the plant stanol ester group and the control group were shown. To the best of our knowledge, we are among the first authors to show that plant stanol ester consumption improves the immune function in vivo in asthma patients. This trial was registered at clinicaltrials.gov as NCT01715675.