MRC Elsie Widdowson Laboratory

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Findings from the Eating environment and meal satisfaction study

Study purpose

The environment in which food is eaten may affect how much we eat and the way we consume the food. An important environmental factor to this respect is the amount of food that is placed on our plate (portion size). This study looked at how being exposed to different portion sizes of the same food affects the way in which we eat a meal. The main purpose was to investigate the way in which small and large portion sizes affect how much food is loaded on the fork (known as bite size); how fast the food is eaten (known as eating speed); how the eating speed changes over the course of the meal (known as deceleration rate); and the overall duration of the meal. Because knowing this information beforehand can unconsciously affect the way in which we eat, the participants in our study were initially informed that the study was investigating the relationship between eating environment and meal satisfaction, but were debriefed of the true purpose of the study at the end of the last session.

Participants

A total of 37 overweight women took part and completed the study between June 2012 and February 2014 in Cambridge. The mean age of the group was 44 (± 11) years and the mean body mass index was 29 (± 3) kg/m2. The majority reported being of White ethnic background.

Method

eating stationParticipants attended a training session followed by five lunch sessions at the MRC Human Nutrition Research to consume a meal and complete a number of brief questionnaires. On arrival participants were asked to drink a glass of water and complete a questionnaire on the computer asking about their hunger and fullness levels. Participants were then served a lunch made of a single course of chilli-con-carne with rice while seated at the eating station (depicted right).
The portion size of the chilli-con-carne meal varied between 229 g (about 8 ounces) and 700 g (about 24 ounces) and provided between 300 and 900 calories (depicted below).

chilliAfter completing the meal participants filled in a third questionnaire asking about their enjoyment of the meal and their hunger and fullness levels again. On the last study visit participants filled in an additional questionnaire asking about their eating habits and were debriefed about the main purpose of the study.

Study findings

Participants ate differently when exposed to the larger compared with the smaller portions of the chilli-con-carne meal. Specifically, participants loaded more food on their fork, ate faster, and continued to eat at the same speed for longer, when served the larger portions, compared with the smaller ones. So compared with the smallest portion of 229 g, the average bite size increased by 0.22 g for every 100 g increase in portion size, and the change in speed of eating (deceleration rate) went down by 20%. In other words, participants continued to eat quicker for longer and put more on their fork at each bite with the larger portions. Participants also took longer in finishing the largest meal compared with the smallest one (11 vs. 4 min on average).

The smallest portion size corresponded to about half of a standard portion size (a standard portion size is what is normally included in a commercial ready meal); while the largest study portion represented 75% more than the standard portion. This study showed that varying the portion size within this range affects the way in which we eat the food, in particular the speed of eating. Related research[1] has shown that we tend to eat more energy when we eat faster. Taken together these results suggest that larger portion sizes have the potential to make us eat more by altering the amount of food we load on our fork and how fast we eat it. Interestingly we did not observe a marked increase in hunger after the smaller portion sizes, and we also know that reducing the speed of eating does not increase hunger necessarily1. We can conclude then that strategies leading to portion control via a reduction in eating rate could be sustainable and help individuals eat less in the face of large portions.

Conclusions

This study showed that being exposed to large portions makes us eat quicker and load more on our fork. The changes in the speed of eating and amount loaded on the fork may explain why large portion sizes lead to increased energy intakes. While excessive portion sizes persist in the environment, strategies to reduce how much we load on our fork and that reduce the speed of eating may provide individuals with coping strategies to reduce the risk of overeating.

Additional information:

The results of the study have been published in the journal Physiology and Behaviour and are accessible at:

http://www.sciencedirect.com/science/article/pii/S0031938414005599.

[1] Robinson E, Almiron-Roig E, Rutters F et al. A systematic review and meta-analysis examining the effect of eating rate on energy intake and hunger American Journal of Clinical Nutrition, 2014. 100: p. 123-151.

Estimated salt intake status for adults (19 to 64 years) in Northern Ireland now published

Today, Food Standards Agency in Northern Ireland have released the first Northern Ireland specific report with 24-hour urine estimated salt intake results; National Diet and Nutrition Survey: Assessment of dietary sodium Adults (19 to 64 years) in Northern Ireland, 2015. The report covers urinary sodium excretion and estimated salt intake results for 609 adults aged 19 to 64 years in Northern Ireland, based on analysis of 24-hour urine samples collected over seven months (February to August) in 2015. Similar surveys were run in England, published on the 22nd March 2016 and Scotland, published on the 23rd March 2016.

HNR provides the scientific lead for the UK NDNS Rolling Programme and country-specific sodium surveys These are government funded and are carried out in collaboration with NatCen Social Research.

This report provides the first Northern Ireland specific assessment of salt intake in adults (19 to 64 years) and includes a comparison between estimated salt intakes in Northern Ireland in 2015 and those in England and Scotland in 2014. Estimated salt intake was calculated using the equation 17.1mmol of sodium = 1g of salt and assumes all sodium was derived from salt. Results for estimated salt intake are compared with the Scientific Advisory Committee for Nutrition (SACN) threshold for the population salt intake to reduce to no more than 6g per day.

Key findings

2015 estimated salt intake in Northern Ireland

  • In 2015 the mean estimated salt intake for adults aged 19 to 64 years in Northern Ireland was 8.6g/day (on average 43% higher than the recommended maximum); 10.0g/day for men and 7.1g/day for women.

Comparison of estimated salt intake in Northern Ireland in 2015 with that in England and Scotland in 2014

  • There was no statistically significant difference between the geometric mean salt intake for all adults combined in the Northern Ireland 2015 sodium survey (7.7g/day) and the England 2014 sodium survey (7.2g/day). However, geometric mean salt intake was significantly higher in Northern Ireland (7.7g/day) than in the Scotland 2014 sodium survey (7.1g/day) for all adults combined.
  • Geometric mean salt intake was significantly higher for men in Northern Ireland in 2015 (9.3g/day) compared with men in England (8.5g/day) and Scotland (8.0g/day) in 2014. There were no statistically significant differences for women.

For more information and data, see the full report on the Food Standards Agency in Northern Ireland website.

See also

Estimated salt intake status for adults (19 to 64 years) in Scotland now published

Today, Food Standards Scotland published the latest 24-hour urine estimated salt intake results from the National Diet and Nutrition Survey: Assessment of dietary sodium Adults (19 to 64 years) in Scotland, 2014. The report covers urinary sodium excretion and estimated salt intake results for 663 adults aged 19 to 64 years in Scotland, based on analysis of 24-hour urine samples collected over five months (May to September) in 2014. An identical survey was run concurrently in England published on the 22nd March 2016. The report for a recent sodium survey in Northern Ireland was published on 28th July 2016.

HNR provides the scientific lead for the UK NDNS Rolling Programme and country-specific sodium surveys These are government funded and are carried out in collaboration with NatCen Social Research.

This report provides the latest assessment of salt intake in adults (19 to 64 years) in Scotland and includes an updated trend analysis, which supersedes that presented in previous reports. As part of the current report, work was undertaken to enable comparison of data from different time points which were obtained using different laboratory methods. Estimated salt intake was calculated using the equation 17.1mmol of sodium = 1g of salt and assumes all sodium was derived from salt. Results for estimated salt intake are compared with the Scientific Advisory Committee for Nutrition (SACN) threshold and long standing Scottish Dietary Goal for the population salt intake to reduce to no more than 6g per day.

Key findings

2014 estimated salt intake in Scotland

  • In 2014 the mean estimated salt intake for adults aged 19 to 64 years was 7.8g/day; 8.6g/day for men and 6.9g/day for women. On average 29% higher than the recommended maximum. 

Estimated salt intake in Scotland 2006 – 2014

  • The analysis which investigated both gradual trends and step-changes between the period 2006 and 2014 showed a statistically significant downward linear trend in the geometric mean salt intake from 2006 (8.2g/day) to 2014 (7.1g/day). This 1.1g difference equates to a relative reduction in mean estimated salt intake of approximately 13%.

Comparison of estimated salt intake in Scotland and England in 2014

  • There were no statistically significant differences between the salt intake for adults in Scotland and England for the 2014 surveys for all adults combined and when split by sex. The results showed that in 2014 the geometric mean salt intake in Scotland (7.1g/day) was similar to that in England (7.2g/day) for males and females combined.

For more information and data, see the full report on the Food Standards Scotland website.

See also

Estimated salt intake status for adults (19 to 64 years) in England now published

Today, Public Health England published the latest 24-hour urine estimated salt intake results from the National Diet and Nutrition Survey: Assessment of dietary sodium Adults (19 to 64 years) in England, 2014. The report covers urinary sodium excretion and estimated salt intake results for 689 adults aged 19 to 64 years in England, based on analysis of 24-hour urine samples collected over five months (May to September) in 2014. An identical survey was run concurrently in Scotland and results were published on the 23rd March 2016.The report for a recent sodium survey in Northern Ireland was published on 28th July 2016.

HNR provides the scientific lead for the UK NDNS Rolling Programme and country-specific sodium surveys are carried out in collaboration with NatCen Social Research.

There is an established relationship between salt intake and risk of high blood pressure (BP). High blood pressure (hypertension) is a risk factor for cardiovascular disease (CVD) and scientific evidence shows that a high salt intake can contribute to the development of elevated blood pressure. CVD is a major cause of morbidity and mortality in the UK and worldwide. The British Heart Foundation (BHF) in 2015 estimated that CVD causes 155,000 deaths in the UK and costs the UK economy £19 billion annually. Dietary modification is a major component in the preventative strategy to reduce the risk of CVD. Targeted public awareness campaigns by the Food Standards Agency (FSA) have aimed to inform the population about health risks associated with high salt consumption. More recently the national Change 4 Life campaign has focused on healthy lifestyles, including salt reduction. These campaigns have advised individuals to decrease their salt intake to no more than 6g/day (less for children). For more information about salt intake and effects on health, please visit the NHS website and Change 4 Life website.

This report provides the latest assessment of salt intake in adults (19 to 64 years) in England and includes an updated trend analysis, which supersedes that presented in the previous England 2011 report. As part of the current report, work was undertaken to enable comparison of data from different time points which were obtained using different laboratory methods. Estimated salt intake was calculated using the equation 17.1mmol of sodium = 1g of salt and assumes all sodium was derived from salt. Results for estimated salt intake are compared with the Scientific Advisory Committee for Nutrition (SACN) threshold for population salt intake to reduce to no more than 6g per day.

Key findings

Estimated salt intake in England in 2014

  • In 2014, mean estimated salt intake for adults aged 19 to 64 years was 8.0g/day (33% higher than the SACN recommended maximum); 9.1g/day for men and 6.8g/day for women. Median estimated salt intake was 7.6g/day (27% above the SACN recommended maximum); 8.6g/day for men, 6.2g/day for women.
  • As in the past, the distribution of sodium excretion/estimated salt intake among the adult population aged 19 to 64 years was wide, ranging from 0.8g/day to 24.2g/day. The estimated salt intake of adult men aged 19 to 64 years was on average higher than women of the same age.

Estimated salt intake in England 2005/06 – 2014

  • The revised trend analysis, which investigated both gradual trends and step-changes between 2005/06 and 2014, used log-transformed data and geometric means due to the skewed nature of the data. The results showed a downward linear trend in the geometric mean salt intake from 2005/06 (8.1g/day) to 2014 (7.2g/day). This 0.9g difference equates to a relative reduction in mean estimated salt intake of approximately 11%.
  • This is a smaller difference than found in the earlier trend analysis published with the 2011 survey, due to (a) adjustments of data from previous analytical surveys to take account of changes in laboratory analytical methods for sodium over time (b) a focus on England only urinary sodium data (rather than UK data as used in the previously published trend analysis) and (c) exclusion of data from the 2000/01 NDNS of adults aged 19 to 64 years from this analysis (this was included in the previous trend analysis).
  • There was a statistically significant downward step-change in salt intake between 2005/06 and 2008/09. The change in mean estimated salt intake between 2005/06 and 2008/09 was 0.5g/day. This difference equates to a relative reduction in mean estimated salt intake of approximately 6%. Whilst the data suggest further gradual decline in subsequent years, there was no statistically significant downward linear trend or further significant step-change between the remaining neighbouring years from 2008/09 to 2014.

For more information and data, see the full report on the UK government website.

See also

Blood folate status for the UK now published as part of NDNS

Today, Public Health England published the latest blood folate results from the National Diet and Nutrition Survey (NDNS) rolling programme for the UK. The report covers folate results for the UK as a whole and separately for Scotland, Northern Ireland and Wales, based on analysis of blood samples collected over four years 2008/09-2011/12 (2009/10-2012/13 for Wales).

HNR provides the scientific lead for the NDNS; the survey is carried out in collaboration with NatCen Social Research and, for this period, the University College London Medical School.

chard nitrates

Leafy green vegetables are high in folate. Credit: Samantha Forsberg Flickr

Folate in the diet comes from naturally occurring folates in foods, such as green leafy vegetables and brown rice, and folic acid from fortified foods, such as some breakfast cereals, and from dietary supplements. Folic acid is important for pregnancy, as it can help to prevent birth defects known as neural tube defects, including spina bifida. For more information about folic acid and pregnancy, please visit the NHS website.

Two measures of blood folate are reported: serum total folate, which reflects recent dietary intake, and red blood cell folate, which reflects longer term body stores and is generally considered the better measure of long term status. Results for both red blood cell and serum total folate are compared with the World Health Organization (WHO) thresholds indicating biochemical folate deficiency.

Key findings

Women of child-bearing age

  • For women of childbearing age (16 to 49 years) in the UK as a whole, 11.3% had a red blood cell folate concentration below the WHO threshold indicating biochemical deficiency while 16.5% had a serum total folate concentration below the threshold indicating biochemical deficiency.
  • Mean red blood cell folate concentrations were significantly lower in younger women (16 to 24 years) than older women of child-bearing age (35 to 49 years). In the 16 to 24 year age group, 15.6% of women aged 16 to 24 years had a red blood cell folate concentration below the WHO threshold and 22.1% had a serum total folate concentration below the WHO threshold, both higher than for the group as a whole.

Other adults

  • The proportion of other adults with a red blood cell folate concentration below the WHO threshold was 6.8% of men and 8.6% of women aged 19 to 64 years and 7.3% of men and 10.8% of women aged 65 years and over.
  • For serum total folate 15.5% of men and 13.9% of women aged 19 to 64 years and 8.5% of men and 12.4% of women aged 65 years and over fell below the WHO threshold indicating biochemical deficiency.

Children

  • In the 4 to 10 years age group, 1.6% of boys and 5.9% of girls had a red blood cell folate concentration below the WHO threshold and 2.6% had a serum total folate concentration below the WHO threshold.
  • In the 11 to 18 years age group, 9.3% of boys and 19.7% of girls had a red blood cell folate concentration below the WHO threshold and 16.9% of boys and 21.8% of girls had a serum total folate concentration below the WHO threshold.

Scotland

  • Mean red blood cell folate concentration was significantly lower in Scotland than in the UK as a whole for women aged 19 to 64 years and men and women combined aged 65 years and over. 13.9% and 16.5% of these age groups respectively had concentrations below the WHO thresholds, compared with 8.6% and 9.3% in the UK as a whole. 14.8% of women of child-bearing age (16 to 49 years) in Scotland had a red blood cell folate concentration below the WHO threshold.
  • Mean serum total folate concentration was significantly lower in Scotland than in the UK as a whole for women of child-bearing age (16 to 49 years), women aged 19 to 64 years and men and women combined aged 19 to 64 years. 24.4% of women of child-bearing age in Scotland had a serum total folate concentration below the WHO threshold, a higher proportion than for the UK as a whole (16.5%).

Northern Ireland

  • Mean red blood cell folate and serum total folate concentrations were significantly lower in Northern Ireland than in the UK as a whole for women of child-bearing age (16 to 49 years), women aged 19 to 64 years and men and women combined aged 19 to 64 years. The proportion of women of child-bearing age in Northern Ireland with red blood cell and serum total folate levels below the WHO threshold indicating biochemical deficiency was 20.2% and 30.6% respectively, higher than in the UK as a whole (11.3% and 16.5% respectively).

Wales

  • There were no significant differences between mean red blood cell and serum folate levels in Wales and those in the UK as a whole, except for adults aged 65 years and over in Wales who had a significantly lower mean serum total folate than in the UK as a whole. The percentages of people below WHO thresholds for biochemical folate deficiency in Wales were similar to the UK as a whole.

For more information and data, see the full report on the UK government website.