Date Published: August 13, 2019
Publisher: Public Library of Science
Author(s): Philip T. James, Ousubie Jawla, Nuredin I. Mohammed, Kabiru Ceesay, Fatai M. Akemokwe, Bakary Sonko, Ebrima A. Sise, Andrew M. Prentice, Matt J. Silver, Huixia Yang
Abstract: BackgroundInfant DNA methylation profiles are associated with their mother’s periconceptional nutritional status. DNA methylation relies on nutritional inputs for one-carbon metabolic pathways, including the efficient recycling of homocysteine. This randomised controlled trial in nonpregnant women in rural Gambia tests the efficacy of a novel nutritional supplement designed to improve one-carbon-related nutrient status by reducing plasma homocysteine, and assesses its potential future use in preconception trials.Methods and findingsWe designed a novel drink powder based on determinants of plasma homocysteine in the target population and tested it in a three-arm, randomised, controlled trial. Nonpregnant women aged between 18 and 45 from the West Kiang region of The Gambia were randomised in a 1:1:1 allocation to 12 weeks daily supplementation of either (a) a novel drink powder (4 g betaine, 800 μg folic acid, 5.2 μg vitamin B12, and 2.8 mg vitamin B2), (b) a widely used multiple micronutrient tablet (United Nations Multiple Micronutrient Preparation [UNIMMAP]) containing 15 micronutrients, or (c) no intervention. The trial was conducted between March and July 2018. Supplementation was observed daily. Fasted venepuncture samples were collected at baseline, midline (week 5), and endline (week 12) to measure plasma homocysteine. We used linear regression models to determine the difference in homocysteine between pairs of trial arms at midline and endline, adjusted for baseline homocysteine, age, and body mass index (BMI). Blood pressure and pulse were measured as secondary outcomes. Two hundred and ninety-eight eligible women were enrolled and randomised. Compliance was >97.8% for both interventions. At endline (our primary endpoint), the drink powder and UNIMMAP reduced mean plasma homocysteine by 23.6% (−29.5 to −17.1) and 15.5% (−21.2 to −9.4), respectively (both p < 0.001), compared with the controls. Compared with UNIMMAP, the drink powder reduced mean homocysteine by 8.8% (−15.8 to −1.2; p = 0.025). The effects were stronger at midline. There was no effect of either intervention on blood pressure or pulse compared with the control at endline. Self-reported adverse events (AEs) were similar in both intervention arms. There were two serious AEs reported over the trial duration, both in the drink powder arm, but judged to be unrelated to the intervention. Limitations of the study include the use of a single targeted metabolic outcome, homocysteine.ConclusionsThe trial confirms that dietary supplements can influence metabolic pathways that we have shown in previous studies to predict offspring DNA methylation. Both supplements reduced homocysteine effectively and remain potential candidates for future epigenetic trials in pregnancy in rural Gambia.Trial registrationClinicaltrials.gov Reference NCT03431597.
Partial Text: Parental nutritional status at the time of conception can influence the lifelong health and disease risk of the developing child [1,2]. Epigenetic modifications provide a plausible mechanism to explain some of these associations . Multiple maternal factors may affect the developing fetal epigenome in early gestation, with nutritional one-carbon-related metabolites being of particular interest [2,4,5]. One-carbon metabolism encompasses metabolic pathways crucial for the provision of methyl groups required for DNA methylation. These pathways involve folate, methionine, serine, glycine, choline, and betaine for methyl group donation, and vitamins B2, B12, and B6 as essential cofactors.
The participant flow diagram is shown in Fig 1. Of the 511 women initially approached for the trial, 100 were ineligible, 9 refused to start the study, and 104 did not attend the baseline visit. A total of 298 eligible women were therefore enrolled and randomised to the drink powder, UNIMMAP, and control arms. Although only 10 women officially withdrew over the study time frame (9 before midline and 1 before endline), on the days of the study visits, there were many absentees. At midline there were 16 absentees and 45 at endline, despite those in the supplement arms continuing with the intervention in their villages. There were 298, 273, and 243 plasma samples available for homocysteine analysis at baseline, midline, and endline, respectively. Of these, one (in the UNIMMAP arm at midline) had a homocysteine reading below the detection limit.
In this trial, both supplements were highly efficacious in reducing homocysteine after 12 weeks of daily supplementation, with the greatest effect sizes apparent after 5 weeks. There was evidence to suggest the drink powder was more efficacious than UNIMMAP at midline and that this advantage was maintained, although diminished, at endline. Trial compliance was high and self-reported AEs were low throughout the trial, and neither varied by intervention arm. The trial confirms an important proof of principle that dietary supplements can influence metabolic pathways that we have shown in previous observational studies to predict offspring methylation levels [10–12].