Time-of-day and nutrient composition of eating occasions: prospective association with the metabolic syndrome in the 1946 British birth cohort

BACKGROUND: Diet is a key modifiable factor in the prevention and treatment of the metabolic syndrome. However, few studies have examined the prospective association between time-of-day of nutrient intake and the metabolic syndrome. OBJECTIVE: To examine the association between time-of-day and nutrient composition of eating occasions and the long-term development of metabolic syndrome in the Medical Research Council (MRC) National Survey of Health and Development (NSHD; 1946 British birth cohort). METHODS: The analysis comprised 1488 survey members who completed at least 3 days of estimated diet records at age 43 years (1989) and for whom data on metabolic syndrome at age 53 years (1999) were available. Dietary records were divided into seven meal slots: breakfast, mid-morning, lunch, mid-afternoon, dinner, late evening and extras. Metabolic syndrome was defined by the criteria of the adult treatment panel (ATPIII8), and was modified to include glycosylated haemoglobin instead of fasting glucose. Associations between time-of-day of nutrient intake at age 43 years and prevalence of metabolic syndrome at age 53 years were assessed using multivariate nutrient density logistic models after adjustment for sex, social class, smoking status, region, alcohol intake and recreational physical activity. RESULTS: There were 390 cases of metabolic syndrome at age 53 years. Substituting 5% of energy from carbohydrate for a similar amount of energy from fat at breakfast (odds ratio=0.93; 95% confidence interval=0.89–0.98; P=0.002) and mid-morning at age 43 years (odds ratio=0.96; 95% confidence interval=0.93–0.99; P=0.011) was associated with lower odds of the metabolic syndrome at age 53 years. Carbohydrate intake at breakfast or mid-morning was particularly protective against abdominal obesity (P⩽0.001). Increasing carbohydrate intake at breakfast while simultaneously decreasing fat intake was also negatively related to triacylglycerols (P⩽0.001). CONCLUSIONS: Increasing carbohydrate intake in the morning while simultaneously reducing fat intake could be protective against long-term development of the metabolic syndrome and its components.