The latest from the National Diet and Nutrition Survey

Last modified on 23/01/2019

Dr Frankie Phillips RD is a BDA Spokesperson, freelance dietitian and health writer. We asked Frankie to give her view on the latest NDNS results, published by Public Health England.

Today saw the publication of Public Health England’s latest installment from the National Diet and Nutrition Survey (NDNS) rolling programme for years 1-9, with data being collected from 2008 to 2017. This UK-wide survey provides the most comprehensive data on diet, nutrient intake and nutritional status for a range of ages and across the social strata. The new report assesses trends over time and across household income groups, highlighting some welcome progress, but also areas for significantly more improvement.

Having worked on the NDNS myself, I know from first hand experience what a massive task this is, and whilst it has its limitations, it is definitely as close as we can get to a reliable measure of what people in the UK are eating and drinking. In addition, blood and other physical measurements give an indication of the nutritional status of the population.

This review of the first nine years of the NDNS rolling programme is, I’m convinced, a reliable indicator of what dietary changes have come about in this time and provide an indicator of where action is still needed.

Food types

Fruit and vegetable intake hardly changed over the nine years covered, with mean intakes for all age groups falling below the recommended 5 A Day. Disappointing, but hardly surprising news.

Fruit juice counts towards the ‘5 A Day’, but the NDNS data showed a reduction in the proportion of children consuming fruit juice. Whilst the current recommendation states that a 150ml portion of fruit juice can ‘count’ as one portion, we need to be careful that the message to reduce free sugars doesn’t cause people to avoid fruit juice completely, falling even further from the ‘5 A Day’ recommendation.

Total meat intake also changed little, but there was a downward trend in intake of red and processed meat (not statistically significant in all groups). Current Department of Health advice recommends that people who eat a lot of red and processed meat (more than 90g cooked weight per day) should cut down to 70g.

The increased interest in plant-based eating may be having some impact here as the percentage of consumers of red and processed meat decreased for children aged 11 to 18 years, and most adult groups.

Total fish intake again showed hardly any change, but some good news in the percentage of oily fish consumers; for children aged 11 to 18 years there was a significant one percentage point increase in consumers of oily fish, but we’re still miles away from the recommended one portion of oily fish per week.

There was some welcome good news on the trends in consumption of sugar-sweetened soft drinks too. Bearing in mind that these data were collected before the sugar tax kicked in, there was a significant downward trend in the percentage of children consuming sugar-sweetened drinks – encouraging news that the public health messages about sugary drinks seem to be getting results.

Energy and Macronutrients

Looking at energy and macronutrients, the main news was an average decrease in total energy intakes for all age/sex groups over the nine year period. There was no consistent pattern of change in total fat, but the population average shows that targets of no more than 35% energy from fat are already being met by most age/sex groups. Unfortunately, the trend in saturated fatty acids shows rather less progress; despite public health campaigns to reduce saturates mean intakes continue to exceed the recommended 11% of food energy. Trans fatty acids intakes, however, continue to be below the target of 2% for all age / sex groups.

Children of all ages had a significant reduction in free sugars intake – between 2.4 and 3.5% reductions - again a welcome trend, but still, free sugars intake significantly exceeds the current recommendation of no more than 5% energy.

Fibre has been in the news recently with a focus on increasing the amount we eat. Unfortunately, the NDNS data showed that, for children, fibre intake actually decreased and for all age groups mean fibre intake is still too low; the recommendations are 30g/day for adults, 25g/day for children aged 11-16 years, 20g/day for children aged 5-11 and 15g/day for 2-5 year olds.

Micronutrients

Micronutrients warrant our attention, with a downward trend in intakes of most vitamins and minerals, according to the report. Whilst the news of a downward trend in total energy intake is welcome news in terms of obesity, there may be an unintended cost. It may be that we’re not only seeing a reduction in total energy intake across the population, but also losing valuable nutrients as well, rather than just so called ‘empty calories’.

In particular, all age / sex groups showed a significant reduction in vitamin A and folate. Of even more concern, blood folate concentrations decreased significantly for most groups. For women of childbearing age, the time trends showed an overall increase in the proportion with blood folate levels below the threshold of increased neural tube defects, from about two-thirds to almost 90%. Given the current advice to fortify flour with folic acid, such mandatory action needs to be put into place as soon as possible.

On a positive note, it would appear that the salt reduction measures by the food industry, as well as public health campaigns, have had some welcome impacts; sodium intake has shown a significant decrease over the nine years in all age / sex groups.

A particular focus of the report was vitamin D status. The NDNS collects data throughout the year, and so seasonal effects can be examined. For all age / sex groups, average 25-hydroxyvitamin D (25-OHD) were lowest in January to March, with 19% of children aged 4 to 10 years, 37% aged 11 to 18 years and 29% of adults had 25-OHD below the deficiency threshold. To my mind, these data confirm our concerns about vitamin D, and accentuate the need for seasonal vitamin D supplementation.

Inequalities

The NDNS nine year trends show some interesting results, and it’s obvious that there are some areas that are going in the right direction, while others have shown there is still some way to go.

However, the report reveals that there are stark contrasts between those of higher and lower incomes; those on higher incomes were closer to meeting some, although not all, recommendations, and there was an overall trend to better nutritional status with higher income.

I remember learning about inequalities in health outcomes during my dietetics degree course, nearly three decades ago, and still these equalities, and more, exist. 

In an era of increasing food poverty, food banks and widening gaps, the NDNS is yet another piece of evidence that many in the population are being denied the benefit of achieving dietary recommendations, and the health impacts that are aligned with these.

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