BCS70: key findings

The majority of diet-related analyses in BCS70 were cross-sectional and conducted in the 1990s using the sweep 4 (age 16 years) diet diaries [69, 76-82].

Teenager’s intakes of fats and extrinsic sugars exceed the 1991 Department of Health recommendations and intakes of milk sugars, starch and non-starch polysaccharides were lower than recommended [69].

Regular breakfast consumption at 16 years was associated with lower intakes of fat while non-consumers had lower micronutrient intakes [82]. Higher fibre breakfast cereals were more likely to be consumed in London and the Southeast than in Scotland and the North and less likely to be consumed as the socioeconomic position declined [82].

When looking at regional differences, dietary intake of Scottish teenagers was different compared to the rest of Great Britain even after accounting for smoking, alcohol, family size and family tenure [76]. These teenagers had lower intakes of fibre, some micronutrients, non-processed vegetables, and polyunsaturated fat spread and higher intakes of soft drinks, chips and white bread [76].

Two studies examining the dietary intakes of dieting teenagers found that their total energy and micronutrient intake were lower than non-dieters but their protein intake as a percentage of energy was higher [77, 78]. Teenagers whose parents smoked had diets that were lower in fibre, vitamin C, folate and magnesium with lower intakes of fruit juices, wholemeal bread and vegetables compared to those with non-smoking parents [80].

In a similar study among teenage smokers, the authors found they consumed less fibre and vitamin C, as well as fewer puddings, biscuits, wholemeal bread, fruit juices [81]. Eating takeaway meals twice or more per week, consuming two or more soft drinks per day and a history of dieting to lose weight at 16 years was associated with an increase in BMI z-scores between 16 and 30 years [83].

In a study that compared dietary intake between NCDS and the 1970 British birth cohort, the authors identified and compared clusters of health behaviours, including diet, smoking, alcohol and physical activity among participants in their thirties.

The authors used principal component analyses to summarise dietary intake into three variables; fruit and vegetable, chips and fried food, sweets, chocolate and biscuits.

They identified three clusters that were similar among men and women:

• a risky group
• a moderate smokers group
• a mainstream group.

The mainstream group included not smoking, frequent fruit and vegetable consumption, less frequent consumption of chips and fried food and being more physically active [84]. Consumption of sweet foods, however, was also common in the mainstream cluster.

Cluster patterns were similar between men and women and across cohorts. More people in the BCS70 fell into the mainstream group and tended to have healthier behaviours (except alcohol) than NCDS.