Nutrition Research Highlights 5|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!
It has been almost three years since we last talked about nuts (1). A diet low in nuts and seeds is considered by many a risk factor for cardiovascular, circulatory and chronic disease (2).
A recent study by the PREDIMED* project highlights the connection between nut consumption and reduced risk of cardiovascular disease in a European population (3). Over seven thousand Spanish men and women aged 55 to 80 years with existing cardiovascular disease risk factors were assessed annually for their dietary habits for five years. Nut consumption was estimated with a semi quantitative food frequency questionnaire, which asked about general consumption and the consumption of walnuts in particular. Results from the study showed that consuming 1 to 2 servings of nuts per week (1 serving= 28 g) reduced the risk of cardiovascular and cancer mortality by 29% while those consuming more than 3 servings per week reduced this risk by 39%, compared to those who were non-consumers at baseline. Moreover, when the consumption was restricted to walnuts only (more than 3 servings per week), the total risk reduced by 45%.
Walnuts, almonds and hazelnuts are some examples of the large nuts family and they are excellent sources of dietary fibre, antioxidants, vitamins and mono-unsaturated fats. Nuts are not the "miracle solution" for our cardiovascular health, but by including some plain nuts as part of a healthy and well-balanced diet we might move one – if not two – steps away from heart disease. (AL)
* PREDIMED: PREvención con DIeta MEDiterránea (http://predimed.onmedic.net/Default.aspx?alias=predimed.onmedic.net/eng)
The adult human body is inhabited by a vast array of bacteria—most of which reside in the gut. These bacteria are so large in number that they exceed the number of body cells by a factor of 10*. Consequently, our gut bacteria can have a huge impact on our health. According to recent evidence (1, 2), what really seems to matter is not so much the total number of bacteria, but the diversity of bacterial species. A proxy for this diversity is the number of different bacterial genes; an analysis of the gut flora of 292 Danish (1) and 49 French (2) people revealed that low gut bacterial gene richness, or low gene count (LGC) for short, was found in 23-40% of the study populations**. At the same time, LGC was associated with higher levels of body fatness, low-grade inflammation as well as several other risk factors for metabolic disease, compared to subjects with a high gene count (HGC). Luckily, the composition of our gut flora is not carved in stone but can be shaped by environmental stressors*** such as high-fat or low-energy diets (3). When the French subjects, all overweight or obese****, were put on an energy-restricted high-protein weight loss diet for six weeks, those with LGC at the start shifted in gut bacterial gene richness close to levels seen in the HGC fraction (2). Over the subsequent six weeks of weight maintenance diet, gene richness remained above baseline, thus indicating that relatively persistent changes in the gut flora may be achieved with dietary intervention. The improvements in microbial gene richness in the LGC group were paralleled by significant decreases in body fatness and blood cholesterol, and a trend towards lower levels of inflammation. On the other hand, the HGC group began the study with an overall healthier metabolic profile but displayed more marked improvements in measures of inflammation.
The authors conclude that assessing gut microbial richness may help to identify people at higher risk of diseases linked to obesity, and that the methodology offers an avenue towards simple diagnostic tests (2). In the meantime, it appears prudent to follow recommendations for a varied diet rich in wholegrain, fruits and vegetables as this tended to coincide with higher gene richness (2). Think of all the bacteria you would be making happy with such a diet – and they would return the favour! (SSGB)
** The cut-off for falling into the LGC group was defined by the researchers as <480,000 different bacterial genes; people surpassing this threshold were categorised as having a high gene count (HGC). Gut bacterial gene count averages for the LGC and HGC group were 380,000 and 640,000, respectively.
Over the past 40 years, food consumption has changed both in quality and quantity. However, whilst caloric intake has increased continuously (1), this has not coincided with intakes of vital micronutrients, commonly referred to as vitamins and minerals (2). Micronutrients enable the body to produce and activate enzymes, hormones and other substances essential for proper growth and development (3).
A recent study mapped Europeans' dietary intake and deficiencies of minerals and vitamins across eight countries and found that vitamin D intakes were far below the Lower Reference Nutrient Intake (LRNI)* for children, men and women of all ages (2). This finding is consistent with a recent systematic review which measured 25-(OH)-D** values worldwide and identified institutionalised elderly as a group at particular risk (4). In addition to vitamin D, the intakes of several minerals were also below the Estimated Average Requirement (EAR)*** and LRNI (2). For example, high proportion of children with iodine intakes below average was seen in several countries and this was also observed in older adults in France and Germany. Selenium intakes were below average in almost all countries. Many adolescent girls had low magnesium intakes. For iron intakes, the same held true mainly for teenage girls and women up to age 50y. Notable was also low calcium intakes in most age groups in Poland.
These findings provide important information about inadequate micronutrient intakes across European countries, but the studies also emphasise the importance of clearly identifying subgroups at highest risk of deficiencies in order to plan and intervene effectively from the public health policy level. Currently, various recommendations for micronutrient intakes as well as reference values exist throughout Europe. This diversity makes it difficult to adequately study, compare and develop interventions at European level. Efforts are being made through initiatives such as the EURRECA project to align these various recommendations in order to develop evidence-based micronutrient and food-based dietary guidelines for European population groups (5).
Micronutrient deficiencies ought to be addressed using a multilevel approach that includes research and policy as well as the individual's own initiative. You can boost your intake of vitamins and minerals through a balanced diet! Fatty fish and fish liver oils are among the best sources of vitamin D, which is also being produced endogenously when ultraviolet rays from sunlight strike the skin and trigger vitamin D synthesis (6). In fact 30 minutes of skin exposure of the arms and face to sunlight can provide all the daily vitamin D needs of the body (7). As for the others, iodine and selenium are found in fish, shellfish and eggs; calcium in milk and cheese; iron in meat, fish and spinach; and magnesium in whole meal products and nuts (6). Voilà! Enjoy your meal! (TK)
* Lower Reference Nutrient Intake (LRNI) is an intake value below which it is unlikely that normal health can be maintained over longer periods, and it is used to evaluate the proportion with very low intakes in each country.
It was almost four decades ago when childhood obesity was proposed as “the most important nutritional disease in the affluent countries of the world” (1). Despite this early warning, it still remains as a considerable public health problem not only in the wealthy countries but globally (2). Importantly, childhood obesity entails a range of other complications (see figure) (3,4). The challenge is not limited to childhood but it is passed onwards into adulthood and creates a growing social, economic and health burden for the future generations (5). Numerous scientific studies, reports and political statements have been issued regarding the problem of childhood obesity and this article attempts to grasp some of their most recent messages.
Puzzling numbers on child obesity prevalence – levelling off, decreasing or still increasing?
Care is needed for interpreting differences in childhood obesity rates between countries. In particular, the use of different standards and cut off points to define overweight and obesity in children have made international comparisons difficult. Nevertheless, developments within the same country usually show only one thing: childhood obesity has been increasing dramatically over the last 30 to 40 years. For example, prevalence of childhood obesity in the United States has multiplied from around 5% in the 1960s and 70s to approximately 17% in children aged 2 to 19 years (6-8). The figures for Europe are somewhat lower than the U.S, with current rates between 5% and 15% in 6-10 year olds. However, alarming numbers are reported for boys in both Italy and Greece where more than 1 in four were found to be obese (9, 10).
Some very recent analyses on the other hand, suggest childhood obesity rates have stabilised or even on a slow decline in certain populations. For example, new data from the US suggest that although the latest figures for 2010 show an increase with respect to the years 1998-2000, most of this increase happened until the middle of the 2000s and since then, childhood obesity rates have remained stable or even slightly decreased (7, 11-13). Similar trends have also been reported in some European countries (14). However, experts warn against too much optimism since childhood obesity rates are still increasing in various other countries in Europe and previously stable phases have been followed by further increases in rates (15).
It is noteworthy that where childhood obesity rates have stabilised, these rates are still high and concern more than 10 million children in Europe, and similarly in the US. Also, the observed decreases, although statistically significant, are relatively small in magnitude and may hide worsening trends in subgroups, such as children with severe obesity, which is associated with even more serious and more immediate health consequences (16). Nevertheless, some experts see signs that change is possible and that predicted trends of obesity for 2030 and beyond can be avoided if the necessary actions are undertaken (17, 18).
What has caused the childhood obesity epidemic, what public measures are effective against it and who is in charge to act?
"As a consequence, significant progress in combating childhood obesity can only result from changes at multiple levels, including the individual, the family, the community and the population."
Looking at populations in which childhood obesity has decreased, it is tempting to ask: is it possible to identify the key public interventions that have led to the reduction of childhood obesity, so that more of those best practices can be implemented in other countries as well? Apparently, this is not so straightforward. Because of the differences in the various national or regional settings e.g. physical, social, cultural and political environments, which contribute to the differences in their local public health policies, educational programmes, and individuals' nutrition and exercise habits; it is very difficult to pinpoint the key features and measures that bring about these declining rates (19). Nevertheless, the causes for the obesity epidemic have been studied and debated extensively. It is increasingly recognised that obesity is the result of individuals responding to a complex system in which they live (18, 20, 21). A freely accessible interactive obesity system map developed for a landmark study on obesity (18) illustrates the complexity of the obesity challenge. As a consequence, significant progress in combating childhood obesity can only result from changes at multiple levels, including the individual, the family, the community and the population (18, 20, 23, 24). Having said this, it should be stressed that although single interventions may not produce big results against childhood obesity when assessed in isolation, they may still constitute important elements of an overall strategy or part of a stepwise approach to obesity prevention (23, 24). In particular, school-based interventions have been studied extensively and evidence supports their effectiveness on improving children's diet and physical activity habits, especially through multicomponent interventions, including food and beverages offered to children, education, school curricula, teacher training and involving a home or community component (25, 26). In contrast, other settings such as home, primary care or childcare have been studied less. Available evidence on their effectiveness is lacking and this should receive more attention in future research (25).
It is becoming increasingly evident that even adults have less control over their bodyweight than previously suggested (18, 20). This is certainly also true for children as they have even less control on the food provided and their eating behaviour than adults. This insight puts civil society and in particular policy makers more in charge of acting. Both children and adults need effective prevention and treatment measures. However, those measures alone will not suffice to return to "pre-epidemic" childhood obesity levels of 5%* or less if the surrounding environment remains obesogenic**. As a recent report summaries, "a meaningful change on a societal level is needed if individuals’ attempts to change their physical activity and eating behaviours are to be effective" (20). (JW)
* Remarkably, decreasing childhood obesity back to 5% was the goal for 2010 set in 2000 in the US, a target which was missed as we know today. In 2010 the goal was reset for 2020 and more modestly targets now 10% lower than 2005-2008 levels, i.e. close to 15%, a level three times higher than the 2010 target (27). For comparison, in 2006 the European Charter on counteracting obesity (5) stated: "Visible progress, especially relating to children and adolescents, should be achievable in most countries in the next 4–5 years and it should be possible to reverse the trend by 2015 at the latest."
** Obesogenic environments refer to those environments which promote high energy intake and sedentary behaviour. The obesogenicity of an environment has been defined in the scientific literature as ‘the sum of influences that the surroundings, opportunities, or conditions of life have on promoting obesity in individuals or populations’ (28).
September - October 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, Therese Kardakis, 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.