Whole grain intake, diet quality and cardio-metabolic health in two UK cohorts

Abstract

Processed grains that retain all three component parts - bran, germ and endosperm are known as whole grains. Epidemiological evidence suggests an inverse association between whole grain (WG) consumption and the risk of non-communicable diseases, such as cardio-vascular disease, type 2 diabetes, obesity and some cancers. The USA and Denmark have quantityspecific WG dietary recommendations, but other countries, including the UK, do not. Despite recognition that WG is an important component of a healthy diet, monitoring of WG intake in the UK is poor. Thus, there is a need to assess WG intake and its consequences in the UK population. The purpose of this work was to calculate WG intake and investigate potential associations with cardio-metabolic measures, nutrient intakes and intakes of other foods in the most recent UK National Diet and Nutrition Survey (NDNS) data and in the Newcastle Thousand Families Study (NTFS), a birth cohort from Newcastle upon Tyne. The estimated WG content of whole-grain foods identified in 3073 four-day food diaries was used to calculate WG intake of adults and children from the NDNS 2008-2011. A cereal food frequency questionnaire was developed with estimated portion sizes to estimate WG intake. WG intake was also calculated in the NTFS at 50- and 60-year follow-up. WG intake, which came mainly from breads and breakfast cereals, was low with an average of 20g/d in adults and 13 g/d in children of the NDNS and 19, 21 and 33g/d in the NTFS at ages 50, 60 and 67 years, respectively. In both studies WG was inversely associated with some, but not all, cardio-metabolic measures, after adjustment for confounding factors. Associations were small, but significant, suggesting that WG may have an important role in disease prevention. For example, a significant decrease in NDNS white blood cell counts were seen across tertiles of increasing WG intake, after adjustment for age, sex and total energy intake. In the NTFS members at 50-year follow-up, each 10g/d increase in WG intake was associated with a 0.1mmol/L reduction in total and LDL cholesterol concentrations, after adjustment for confounders such as sex, SES, medication use and smoking status. WG consumers also had overall better dietary profiles, with higher intakes of fibre, iron and magnesium and lower intakes of fats. iv The recent UK recommendation to increase dietary fibre intake will require a greater emphasis on consuming more WG. Specific recommendations on WG intake in the UK are warranted as is the development of a public health policy to promote the consumption of these important foods.