Nutrition Research Highlights 4|2013
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This newsletter is published by the Nutrition & Health Group of the JRC’s Institute for Health and Consumer Protection. Regularly surveying the top nutrition and medical journals, we select the most recent news on nutrition research, relevant to current societal debates or policies. These are then summarized as “News” items or presented as a “View”, comprising an analysis and expert opinion. Enjoy your reading!
Both our attitude and our behaviour regarding sleep have changed over the past century even though the need for sleep from the biological point of view has remained the same. Analysis of a real-world database* on sleep behaviour shows that on average individuals are sleeping 38 minutes less now than they did 10 years ago (1). Many of us these days experience social jetlag, defined as the mismatch between our biological need for sleep and our everyday demanding lives, leading to loss of sleep on workdays and to oversleeping on weekends. Social jetlag has important consequences and increased risk of obesity appears to be one of them (2). Several studies have suggested the existence of a link between short sleep duration and development of overweight/obesity, especially in children and adolescents (3).
A recent study investigated further the consequences of short sleep duration in terms of energy intake and expenditure (4). The authors compared energy intake and expenditure of 16 healthy adults; half slept 5h for 5 consecutive days while the other half was allowed 9h of sleep every day for 5 days. Participants with a sleep deficit had higher energy expenditure (5%) but they also consumed 6% calories more, coming mainly from carbohydrates, protein and fibre in the form of after-dinner snacks. The authors suggest that the increased energy expenditure is a physiological adaptation to provide the energy needed for increased wakefulness. However, this is coupled to an increased energy intake and in a world where food is constantly available it is likely that this increased intake will surpass the real needs for energy.
This report and others point to the role of metabolism and hormones such as leptin (satiety hormone) and ghrelin (appetite hormone) (4, 5) in the response to insufficient sleep and weight gain but additional studies are needed to fully elucidate their effects. Sleep research is gaining momentum and researchers are now actively calling for a “human sleep project” bringing a different multi-disciplinary approach to sleep research, away from animal models and laboratory studies and more focused on systematic and quantitative in situ** data-collection relying on simpler sleep tracking and monitoring devices (1). While waiting for more data to come, be sure to get sufficient sleep. (SE)
* The Munich Chronotype Questionnaire (MCTQ) database (2002 – present) includes personal entries of over 150000 individuals worldwide ( http://www.thewep.org/en/index.php)
“Your decisions are what you eat” is the catchy title of a recent article in EMBO reports (1) that describes how some metabolic factors can lead to decision-making biases. That our brain plays a role in what and when we eat is well established but that what and when we eat also plays a role in brain’s decision-making is a different story! In the animal world, hungry animals display riskier food choice behaviours than well-fed animals. But researchers are now showing that also in ‘rational’ human beings, metabolic states can affect risk attitudes or economic decision-making. In one study, the same person's risk decision-making preferences were tested using lottery games across 3 different metabolic states: fasting, immediately after a meal or one hour after a meal (2). The results showed that people risked least in the 3rd state, i.e. 1 hour after eating. This correlated with a decrease in the circulating levels of ghrelin, a hormone that stimulates appetite and whose levels decrease after nutrient intake. So, if you are the type that likes to play safe, these results suggest that you should consider making risky decisions after a good meal only. The field is in its infancy; there are studies that point to a much more complex nature of the interaction between metabolic state and decision making than the one depicted here (3) but the implications of these findings are important. There are other studies, for example looking at judges' parole’s decisions and how they might be affected by the lack of a snack pause (4) or that relate low blood glucose levels with lower self-control (5). These examples raise the hypothesis that eating disorders or obesity could also affect decision-making in ways not yet considered. Which type of decisions can be affected and to what extent? Do the findings apply to real economic and financial decisions and to more mundane day-to-day choices? The field is broad and seems to promise a great deal of exciting results! (SC)
Some 30% of the world's population, or two billion people, are deficient in iodine (1). Although the most severe cases occur in developing countries, Europeans are affected too, with about half of continental Europe being mildly iodine deficient* (2). Iodine is a critical nutrient particularly for the developing foetus and infant because of its vital role in brain development, and the World Health Organization describes iodine deficiency as "the single most important preventable cause of brain damage" (3).
Recently, reports from the UK (4), Belgium (5, 6), and Germany (7) have flagged declining or persistently inadequate iodine intakes in school-aged children and/or their mothers. In the UK study (1), children born to mild-to-moderately iodine-deficient mothers performed measurably poorer on various cognitive skill tests such as verbal IQ, reading accuracy and reading comprehension at age 8-9 years than children of iodine-sufficient mothers. The findings from Belgium and Germany showed suboptimal iodine levels in school-age children (5-7) and their mothers (5, 6). Approaches to combat iodine deficiency include: the iodisation of salt, which can then be used in the household as well as in food processing (e.g. bread, cured meat); the use of iodine-enriched feed in animal food production; and iodine supplementation of e.g. pregnant women. Of note, bread made with iodised salt helped improve iodine status in the Belgian school children (but not their mothers) (6).
We need only tiny amounts of iodine daily for good health: from 90 micrograms for children aged 0-6 years to 250 micrograms – the weight of two grains of table salt – for pregnant and lactating women (2). However, food iodine content largely depends on the level of iodine in the soil the food is produced from, which in various parts of Europe is too low to ensure dietary adequacy. Several researchers (4-7) are calling for increased use of iodised salt in food processing to achieve optimal iodine nutrition in Europeans. Enriching table salt with iodine is the most widespread and successful measure to combat iodine deficiency worldwide, but concerns about excessive iodine intakes in at-risk populations may prompt policy makers to be cautious extending this measure to all processed foods. Especially the elderly and people with pre-existing iodine deficiency can be sensitive to excess iodine, broadly defined as daily intakes above 500-600 micrograms. In this context, it may be reassuring to learn that iodine fortification levels for salt are calculated so that there is no overdose even if all foods were to be manufactured with iodised table salt. However, in light of on-going efforts to reduce dietary salt intake – most of which comes from processed foods – salt iodisation levels may need to be adjusted. Careful monitoring of food iodine levels and population iodine status is advisable to assess effectiveness of this public health strategy. (SSGB)
* Iodine status is assessed by the median concentration of iodine in urine (UIC) and is graded as follows (2): severely deficient (UIC < 20 µg/L), moderately deficient (20-49 µg/L), mildly deficient (50-99 µg/L), adequate (100-199 µg/L), risk of more than adequate intake in the overall population (200-299 µg/L), risk of adverse health consequences (≥ 300 µg/L). For pregnant women, the UIC ranges are somewhat higher at: insufficient (< 150 µg/L), adequate (150-249 µg/L), above requirements (250-499 µg/L), and excessive (≥ 500 µg/L).
In the last years, it has become clear that advertising and promotional marketing of ‘unhealthy’ foods and beverages to children has enough of an effect on their diets to be considered a risk factor for obesity (1-6). Many public health actors have therefore called for measures to reduce the impact of the promotion of energy-dense foods and beverages to children (see for example the European Commission’s White Paper "A strategy on nutrition, overweight and obesity-related health issues" (7), the WHO’s European Charter on Counteracting Obesity (8) or more recently the Vienna Declaration on Nutrition and Noncommunicable Diseases in the Context of Health 2020 (9)). At the EU level, the EU Pledge is a response to some of these calls: several leading food and beverage companies pledge not to advertise food and beverage products to children under twelve on TV, print and internet in the European Union, or only to advertise those products that meet specific nutrition criteria. Also, the 2010 Audiovisual Media Services Directive (10) encourages " media service providers to develop codes of conduct regarding inappropriate audiovisual commercial communications, accompanying or included in children’s programmes, of foods and beverages containing nutrients and substances with a nutritional or physiological effect, in particular those such as fat, trans-fatty acids, salt/sodium and sugars, excessive intakes of which in the overall diet are not recommended."
In Europe, the majority of governments have opted for promoting self-regulatory measures in this regard. The question is now – are they working? During the last months, a few studies have addressed this question of marketing practices to children worldwide. Three main channels were examined: food packaging, internet and TV.
Regarding food packaging, Mehta and colleagues (11) looked at marketing techniques used on the packages of children-oriented products sold through one big supermarket chain in Australia. Of the 157 products that the authors considered children-oriented products, 118 (75.2%) were classified as products high in fat and sugar (HFS products). This is despite the existence of a Code adopted by the AANA (Australian Association of National Advertisers) to develop and maintain a high sense of social responsibility in advertising and marketing to children (12). There was a high use of marketing techniques that appeal to children in these such as graphics, cartoons and celebrities. More than half of these HFS products even carried claims about health and nutrition. These results prompted the authors to warn policy makers about the marketing of high sugar and high fat foods to children via product packaging in supermarkets. Special attention should be given to health or nutrition-related claims on HFS foods which can potentially mislead and confuse child, children's parents and adult consumers.
The web is another source of food marketing to children. Ustjanauskas and colleagues (13) analysed popular children's web sites in the United States and quantified display advertising on those sites, classifying the adds according to whether they promote a food, beverage, and restaurant or non-food product . The objective was also to assess the proportion of advertising covered by CFBAI self-regulatory pledges, an initiative to advertise only healthier dietary choices to children, including in display advertising on child-directed web sites*. Popular children's web sites were identified (from July 2009 through June 2010) that met three criteria:
• Were visited by more than 100 000 different children (2–11 years) on average per month
• Had an average monthly child-audience share higher than 20%
• Contained child-targeted features
Food ads were further classified and their nutritional quality was evaluated using IWG (Interagency Working Group on Food Marketed to Children) nutrition standards** including serving size and calories, sugar, saturated fat, trans fat and sodium per serving. The results of the study show that, 84% of products advertised on web sites for children were high in fat, sugar and/or sodium. These foods did not meet the IWG nutrition standards and, these authors, like Mehta et al recommend that further attention should be given to this topic by policy makers.
Finally, Boyland and colleagues (14) reviewed the existing evidence on the effects of television advertising on children’s food choice, consumption and obesity, pointing out that, despite self-regulation, children in the UK are exposed to a considerable number of food adverts on TV, predominantly for foods high in fat, salt and sugar. These foods are marketed to children using promotional characters and fun themes as mentioned above. The study concludes that these adverts have been shown to increase the intake and enhance preference for high-carbohydrate and high-fat foods in children, particularly in overweight and obese individuals.
These three studies (11,13,14) and a recent report by WHO Europe on “Marketing of foods high in fat, salt and sugar to children: update 2012–2013” (15) show that further attention and high priority needs to be given to this issue as childhood obesity levels remain stubbornly high. Zsuzsanna Jakab’s*** words summarise this need quite forcefully:
"Policy simply must catch up and address the reality of an obese childhood in the 21st century. Children are surrounded by adverts urging them to consume foods high in fat, sugar and salt, even when they are in places where they should be protected, such as schools and sports facilities." (CMS)
Trans fat: 0 g (<0.5 g) per reference amount customarily consumed (RACC) or per 50 g for foods with small RACC for individual foods (per serving for main dishes and meals).
Added sugar: No more than 13 g of added sugar per RACC or per 50 g for foods with small RACC for individual foods (per serving for main dishes and meals).
Sodium (interim limit): No more than 210 mg per serving for individual foods (450 mg per serving for main dishes and meals)
Saturated fat: 1 g or less per RACC per eating occasion or per 50 g for foods with small RACC and 15% or less of calories for individual foods (per 100 g and less than 10% of calories for main dishes and meals).
July - August 2013
Nutrition Research Highlights is a bi-monthly publication prepared by the Nutrition Team of the DG-Joint Research Centre, Institute for Health and Consumer Protection. Sandra Caldeira, Sandra Eisenwagen, Anastasia Livaniou, Tsz Ning Mak, Theodora Mouratidou, Carlos Martin Saborido, Stefan Storcksdieck genannt Bonsmann and Jan Wollgast contributed to this issue.
The views expressed here do not necessarily reflect the opinion of the European Commission.