Nutrition Research Highlights 5|2012
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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!
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- Let's get moving and off the screen!
- Food for thought: the link to Alzheimer's disease
- Shaping the glass shapes drinking
The relation between nutrition and obesity is obvious but obesity is a complex issue and physical activity as well as sedentary behaviour also play an important role in its development. We refer to physical activity and sedentarism here because, in addition to nutrition, these behaviours, established at an early age, often go hand in hand!
Many of us have a gym membership card hanging around somewhere… surely, you have been running, jogging, played sports or attended pilates or kick-boxing classes even if it was only once because you thought it will help you be healthy. But sedentary behaviour which includes both screen time (the time spent watching TV, using the computer or playing video games) and sitting time (talking on the phone or reading) is also important, as reducing the time being sedentary helps us to stay healthy too. We highlight this point because increasing evidence is emerging on the influence of sedentary behaviour on health including obesity and chronic diseases (1, 2). Its importance has been discussed and portrayed in the front pages of many journals lately, so let's see why (3, 4).
The authors of a recently published review examined the associations between screen time, sitting time and risk of mortality from cardiovascular disease (CVD) (1). Increased risk was positively associated with screen and sitting time i.e., every 2 hours spent in front of the TV increased additionally the risk of CVD mortality. Along the same lines, another recent article looked at the association of sedentary time with diabetes, CVD and cardiovascular and all-cause mortality (2). The findings from the 18 studies analysed indicated that, again, the risk of being affected by chronic diseases increases dramatically with an increase in sedentary time. The strength of the association was most consistent for diabetes i.e., people with the greatest sedentary time were more than twice as likely to be diabetic, compared to those with the lowest sedentary time. As the analysed studies relied on people's self-reporting of their own sedentary time, it may well be that the link is even stronger. This was pointed out by the authors themselves that called for future prospective studies using more objective measures of sedentary behaviour (like accelerometers for example). These would provide more robust results that can help formulate public health guidelines to reduce the amount of sedentary behaviour in modern societies.
Finally, and not to end with grey scary numbers, do remember that family plays an important part when trying to improve your health profile. It is important to involve all the family when promoting healthier lifestyles (5). Children whose parents are active, participate in sports and organised activities and have fewer televisions at home are those that are most likely to be engaged in physical activities. A concluding message therefore is to get going and get moving, switch off the telly and take your family out and about! This will help you all to keep fit and healthy!!! (TM)
Image: Computer Keyboard (wikimedia commons)
Alzheimer's disease (AD) is a neurodegenerative disease that affects the brain and impairs cognition. It is a complex disease and its complexity has been puzzling researchers for many decades now. Slowly but steadily though, the past years have seen a new hypothesis take form that may explain further the origins of the disease. Based on recent evidence, science journalists (1) and the media in general have now brought this hypothesis to the spotlight. Several observations point to an increased AD risk in diabetic individuals (2) but the new twist is that like diabetes type II, also Alzheimer's disease appears to be linked to poor sensitivity to insulin, in this case insulin resistance in the brain. For this reason the proponents of this idea have dubbed Alzheimer's disease, type III diabetes (3).
While the use of the term type III diabetes has been challenged, evidence is mounting to support the concept that AD can be seen as a metabolic disease. For example, a recent study (4) showed that brains from Alzheimer's patients* are not responding effectively to insulin and that this impaired response correlates with cognitive decline. Many questions are still unanswered but there are still clear take-home messages from these findings. A first one, currently being investigated, is that diabetes drugs could be useful in the treatment of Alzheimer's disease (5, 6). A second one is that we have yet another reason to care for our diets and keep ourselves active; on the long run, intake of foods high in sugar and/or saturated fats affect the body's and brain's response to insulin. To help protecting against these effects – keep these at bay and move, since physical inactivity is linked to insulin resistance as well. (SC)
* in this case the patient brains studies are done post-mortem, brain slices derived from 'normal' adult brains react promptly to insulin while those from Alzheimer's patients do not.
Harmful and hazardous alcohol consumption is the third largest risk factor for ill health in the EU and young people (15-29 years) are particularly at risk of losing their lives from it (1, 2). In addition, there are growing concerns around increasing trends in heavy drinking episodes ("binge drinking") in this age group (2). That the size of a glass can influence how much we put in it and therefore how much we drink is a relatively straightforward concept. Interestingly though, researchers from the UK have now delved deeper in these sort of associations and propose that the glass shape can actually influence consumption rate from alcoholic beverages (3). In the study, the scientists report that adolescents and young adults drinking from a straight glass consumed alcoholic beverages slower (60% slower to be precise) that those drinking from a curved glass. They suggest that glass shapes that make it difficult to estimate when half of the beverage has been consumed, lead to faster drinking rates. Interestingly, this effect was only observed when a full glass was presented but not in the case of half a glass. This may be because curved glasses are relatively straight in the lower half. Importantly, in the curved glasses the individuals' perceptual point of the half-way point was lower than the real value so that they would effectively have consumed more than half of the beverage when reaching this point.
Critics of the study may argue that the underlying mechanisms leading to the effect are speculative and that these findings need to be further confirmed in different settings and across other population groups and beverages. Nevertheless, based on their findings and the fact that there are so many branded drinking glasses, many of which have specific shapes as a differentiating feature, the authors propose that serving alcoholic beverages in glasses with a clearly labelled midpoint may be a soft policy approach to reduce drinking rate. We have already highlighted that many individuals struggle to make choices in their best self-interest regarding long term health and that at times a small nudge in the right direction can have a beneficial effect. Nevertheless, there is clearly not yet enough evidence to demonstrate that marking the half-point of glasses or glass shape in general would significantly affect drinking behaviour and by no means are we suggesting that such a measure should be at the core of addressing this major public health issue. Still, the simplicity of such measures make them worth a second thought. (JW)
Image: Different Glasses (Wikimedia Commons)
"Breakfast is the most important meal of the day". This should surely not be a surprise to anyone, since we have probably both been told of this as kids and then said it to our own children in turn. Equally, we all know that "we should not skip breakfast" and some researchers (1) recently even suggest that skipping breakfast may actually drive us to seek high caloric foods later in the day. Our hectic lifestyles however often lead us to choose between sleeping longer or having breakfast, so let's have a look at the evidence behind these 'well known breakfast advices' and find out if we should keep on giving them.
Breakfast has been defined as "the first meal of the day, eaten before the start of the daily activities…within 2hrs of waking, typically no later than 10:00 am and of a calorie level between 25% and 35% of total daily energy needs" (2). There are various types of breakfasts, depending on geographical location and cultural background, and as such there is no universal recipe on what constitutes a correct breakfast. As a general guideline however, a balanced breakfast should contain little fat or added sugar and foods from these product groups (3): dairy products, whole grains reach in fibre and fruits (fresh or natural juices).
The importance of eating breakfast is related with benefits in body weight and cognitive performance. Although larger and better controlled studies are still needed to reaffirm these findings, the available literature (2, 4, 5, 6, 7) concludes that there is good evidence that breakfast consumption is associated with reduced risk of overweight and obesity as well as better nutrient intake in children and adolescents, and that breakfast skippers have a higher BMI compared to those who eat breakfast regularly. The above studies were performed in Western societies like the US and Europe, but a recent review looking into breakfast skipping in the Asian and Pacific regions came to the same conclusions (8). The US department of Agriculture (USDA) recommends eating a nutrient dense* breakfast as skipping breakfast has been associated with overweight, especially in children and adolescents, while on the other hand eating breakfast has been associated with weight loss, weight loss maintenance as well as improved nutrient intakes (9).
Many people might wonder at the logic of it all: Why would removing a daily meal lead to an increased risk of being overweight? The exact mechanisms are still not clear. Breakfast eating may prevent overweight and obesity via biological and behavioural mechanisms (see Figure) that include appetite control and reduction of energy intake, effects in glucose metabolism, as well as promotion of better dietary choices (4, 6, 7, 10).
Breakfast consumption is also influencing mental functions; it has been linked with stronger memory, better learning and academic performance in general in schoolchildren (4, 6, 7). In demanding academic settings such as those of medical students, skipping breakfast has been suggested to lead to increased fatigue and poorer university performance (11).
Knowing the importance of breakfast, it is alarming to look at data on its consumption among the young, on both parts of the Atlantic. Europeans on average skip breakfast 20% of the time (13), while approximately only half of 11-15 yr olds eat breakfast every school day, with large variations observed between different EU countries (14). Recent data from some European countries shows that 7% of adolescents do not consume breakfast at all, and that the majority of those that do, eat a low quality breakfast (15). Although there is variation in the numbers reported by various studies (16), the US sees a similar trend with breakfast skipping ranging from 10-30% in children and adolescents (4, 5, 17).
Gender, age, socio-economic status and geographic location appear to have a significant impact in breakfast eating habits. In Europe some age and population groups are more likely to skip breakfast: girls, older adolescents, adolescents from families with low socio-economic status or adolescents from Southern Europe for example (12, 14, 15). Family structure and parental breakfast habits also appear to have serious implications on adolescent breakfast consumption (18, 19). Skipping breakfast is also associated with several health-compromising behaviours such as higher levels of smoking, alcohol and drug use, as well as more sedentary lifestyles and increased consumptions of snacks (12).
Nutrition is a major component of our daily lives, one that is highly interlinked with our well-being and one were all people can relate to and even form strong opinions about, independently of social, educational or economic background. As such, the field of nutrition is ripe with "common knowledge" which may or may not be true. In the case of breakfast however, common knowledge and scientific knowledge seem to go hand in hand. So, to answer our initial question, yes, we should take the extra time to regularly consume breakfast…like a king. And yes, we can keep giving this advice. (PM)
* Nutrient dense foods are foods that contain vitamins, minerals, fiber or other beneficial substances but have low calories. Vegetables, fruits, whole grains, seafood, eggs, beans, fat free or low fat dairy as well as fat free meat and poultry are all nutrient dense foods. Adapted from (9)
Image: Breakfast (wikimedia commons)
Figure: Theoretical model of how breakfast may influence the development of obesity - Used with permission from Nutr Rev (2007) 65: 268-281
September - October 2012
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. The Nutrition team is comprised of Sandra Caldeira, Petros Maragkoudakis, Theodora Mouratidou & Jan Wollgast.
The views expressed here do not necessarily reflect the opinion of the European Commission.
© European Union, 2012. Reproduction of articles (excluding photographs) is authorised, except for commercial purposes, provided that the source is mentioned.