Development and piloting of a food-based intervention to increase vitamin E intake in pregnant women in a randomised controlled trial

Low maternal vitamin E intake during pregnancy is associated with childhood asthma and a trial is required to test whether increasing maternal vitamin E intake reduces childhood asthma. This study investigated whether such a trial is possible using food to increase vitamin E intake. Three soup varieties with enhanced vitamin E content (16–19 mg/can) from food ingredients were developed. Near identical retail versions (vitamin E 1–4 mg/can) acted as placebo. In a pilot double-blind randomized controlled trial, pregnant women were randomized 1:1 to enhanced or placebo soups (three tins/week) from 12 weeks gestation to delivery. Vitamin E intake was quantified at 12, 20, and 34 weeks gestation. Qualitative interviews were conducted. 59 women were randomized (29 enhanced, 30 placebo), 28 completed the trial, (15 enhanced, 13 placebo). In women completing the trial, vitamin E intake of the placebo group remained unchanged; 7.09 mg/d (95% CI 5.41–8.77) at 12 weeks, 6.41 mg/d (5.07–7.75) at 20 weeks, and 6.67 mg/d (5.38–7.96) at 34 weeks gestation; vitamin E intake of the enhanced group increased from 6.50 mg/d (5.21–7.79) at 12 weeks to 14.9 mg/d (13.3–16.4) at 20 weeks and 15.2 mg/d (12.9–17.5) at 34 weeks, P < 0.001. Qualitative interviewing provided clear guidance on improving adherence. Although 31 women withdrew at median 19 weeks gestation (interquartile range 16–25), the intervention was consumed by women for 80% of weeks between 12 and 34 weeks gestation and for 63% of weeks between 12 weeks gestation and delivery. In a pilot double-blind randomized controlled trial (RCT) it is possible to increase maternal vitamin E intake using food ingredients, a further food product is required to improve adherence.