Nutrition Research Highlights 1|2013
1 | 2 0 1 3
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!
While high obesity levels are no news to most of us, obesity is still often on the news, a reminder of its dimension and consequences. In fact, at the start of the new year, two top medical scientific journals published inspiring articles on the problem. The first one is an interesting read on popular myths, presumptions and facts about obesity (1). We will not discuss them here, there are 13 myths and presumptions and 9 facts listed but it is worthwhile reflecting on the first fact "…calculations show that moderate environmental changes can promote as much weight loss as the most efficacious pharmaceutical agents available". Identifying these successful environmental changes and putting them in practice is of course more complex than it reads. Acknowledging this complexity, the second article (2) on global obesity trends, risk factors and policy implications calls for obesity prevention strategies and policies across multiple levels.
Coordinated efforts at the levels listed in Figure 1 are key (2). The European Commission's EU strategy on nutrition, overweight and obesity-related health (3) is an excellent example of an approach that incorporates and coordinates efforts at these levels with targets for obesity prevention. The strategy is now being evaluated to report on the degree of achievement of actions by the Commission and the Member states and how far they contributed to promote health in Europe. We are confident that much has been achieved. Given its dimension however, the obesity problem is still far from being solved in Europe as the latest OECD report states that more than half (52%) of the adult population in the European Union is overweight or obese (4). Scientific articles such as the two we describe highlight the need to continue supporting and giving priority to such multi-layered actions – perhaps adding new instruments or players – but keeping obesity high on the political agenda and involving as many relevant stakeholders as possible. (SC)
Figure (at the right): Summary of levels of policy strategies for obesity prevention. Reproduced from (2) with permission.
Cholesterol is known to everyone but its functions and transport in the human body are so complex that it is likely that not everyone really knows cholesterol and its different forms. Cholesterol is a lipid produced by the body or ingested in foods and is transported in the bloodstream in the form of lipoproteins. As the name says, these particles are composed of lipids and proteins. Particles that carry cholesterol can be High-Density Lipoproteins (HDL-C) or Low-Density Lipoproteins (LDL-C). HDL is often referred to as the 'good' cholesterol and LDL is in turn the 'bad' cholesterol as it causes build-up of plaques inside the arteries eventually leading to coronary artery disease (CAD), the leading cause of death in the EU (1). But there is a less known form of cholesterol particles… The media have called them 'ugly' cholesterol (2) (as in the popular movie 'The Good, the Bad and the Ugly') but scientists refer to these as 'remnant' cholesterol or remnant lipoproteins cholesterol (RLP-C) (3). RLP-Cs carry 5 to 20 times more cholesterol than LDL-C particles (4) but are not regularly screened for in blood tests. There have been discussions of an association between these remnant particles and an increased risk of CAD (5, 6) but this hypothesis has now gained more support. A recent Danish study (3) involving more than 73.000 individuals showed that in the population studied, high levels of cholesterol remnants were also associated with an increased risk of CAD, independently of the levels of HDL- C (the good cholesterol). The study also considered the genetic make-up of the participants and how it affects blood lipid levels. Importantly, the authors point out that in their study, remnant cholesterol was determined in the nonfasting state*. By using samples from nonfasting individuals, the levels of remnant cholesterol can be easily calculated from a standard lipid profile** at hardly any extra cost so it seems reasonable to consider further the usefulness of assessing remnant cholesterol levels for better prevention of CAD and also in developing new treatments. (SE)
*Blood lipid tests are often made after fasting for a period of time but there is debate on whether fasting or non-fasting tests are more useful for the assessment of cardiovascular risk.
**In nonfasting conditions, remnant cholesterol can be calculated as nonfasting total cholesterol minus HDL cholesterol minus LDL cholesterol.
Energy drinks and their consumption are hardly a consensual issue. The potential adverse effects of these beverages, for example, increased heart rate, blood pressure or sleep disturbances are discussed in two articles recently published in the Journal of the American Medical Association (1, 2). Energy drinks, characterised by varying amounts of caffeine (range: 50–505 mg caffeine per can or bottle), started by being marketed to sportsmen but they are now sold as products claiming to improve physical or cognitive performance amongst others (3). They are very popular especially among adolescents, young adults and athletes (4). In fact, a recent EFSA (European Food Safety Authority) survey (5) indicates that in the 16 European countries assessed approximately 68% of adolescents reported energy drink consumption. The contribution of energy drinks to total caffeine exposure was approximately 8% for adults, 13% for adolescents and 43% for children.
According to one of the articles that discusses caffeine related adverse effects (1), caffeine can indeed be toxic and a ceiling of less than 500mg per day is generally considered a safe dose for a healthy adult. The ceiling is 100mg of caffeine per day for adolescents and 0 mg for children (6). The latest EU food information regulation states that drinks containing more than 150 mg/l of caffeine must state ‘Not recommended for children or pregnant or breast-feeding women’ in addition to ‘High caffeine content’ (7).
Aside caffeine, these drinks can also contain taurine, glucuronolactone, glucose, vitamins or herbal supplements ingredients often in undisclosed amounts and their benefits are subject to debate (3, 8). In 2009, EFSA issued an opinion on the safety of taurine and D-glucurono-γ-lactone as individual ingredients. The Panel was careful to note that it did not evaluate the safety of energy drinks as such and concluded that ‘the exposure to taurine and D-glucurono-γ-lactone at the levels presently used in “energy” drinks is not of safety concern’ (9). Adding to the concerns of energy drinks consumption is the fact that these are often mixed with alcoholic beverages (2). The mix is then linked to distorted perceptions of intoxication, increased alcohol consumption and impairment of judgment towards risky behaviors (like drunken driving) as compared to alcohol consumption alone (2). Recent adverse events reports allegedly related to energy drinks or shots consumption have once again prompted doubts and questions (10, 11) regarding their safety and the US Food and Drug Administration (FDA) is currently investigating these. In Europe too, the Parliament has asked the European Commission about its intentions to carry out an assessment report on energy drinks and consumer safety (12).
The recent EFSA survey provides important exposure data. Parallel to these, improved toxicity surveillance has been called for (13) and there is a need for additional research on the health and behavioural effects of these drinks. This is an important point as clear data is needed not only to demonstrate their safety but also potential effects on physical and cognitive performance. These could inform gaps in safety policy and promote informed consumers choice (13). Nonetheless, several recommendations emerge. Caffeinated drinks should not be seen as alternatives to sleep or rest and young adults and adolescents in particular, should be very alert to the levels of caffeine they ingest and the effects the energy drinks and alcohol mix causes. In addition, as also stated by the FDA and the International Society of Sports Nutrition (4, 10) individuals should consult with a health care provider before taking these beverages to ensure that they do not have an underlying or undiagnosed medical condition (for example diabetes, liver or heart disease) that could worsen as a result of their use. (TM)
9. Scientific Opinion of the Panel on Food Additives and Nutrient Sources added to Food on a request from the Commission on the use of taurine and D-glucurono-γ-lactone as constituents of the so called “energy” drinks
Image: Energy drinks (Wikimedia commons)
Scientific progress often comes through debate, controversies, alternative hypothesis and challenging conventional wisdom. Nutritional sciences are certainly not an exception. However, the recent attributes given to sugar and to the molecule fructose, which together with glucose constitutes sugar, in particular such as "toxic"(1, 2), "addictive substance" (3), "pure, white and deadly" (4) are exceptionally alarming as they refer to a widespread nutritive, albeit non-essential, food components. Both public and scientific debates on the topic are lively and controversial (5). We aim here to shed some light on these as a recent series of scientific articles (6, 7, 8) may help addressing some parts of the controversy.
Throughout most of the human history, intakes of fructose had predominantly come from the consumption of fruits and had remained relatively low. However, over the last century, the intake has increased several folds mainly through the addition of sugars to foods and beverages (9, 10). Some investigators have linked sugar intake, and in particular intake of sugar-sweetened beverages, to increased risk of obesity, metabolic syndrome and related health issues (5). Indeed, a recent article presents a large body of evidence on the association of free sugars and sugar-sweetened beverages and weight gain in ad libitum* diets, apparently due to increased overall energy intake (6). As we hinted above, the fructose part of added sugars has received particular attention due to the distinct physiologic effects of fructose, a non-essential nutrient, compared to glucose, the only component of the most important dietary carbohydrate starch and delivering energy to all body cells including being the almost exclusive source of energy for the brain (10). Briefly, while glucose metabolism is under strict hormonal control to match energy requirements, the metabolism of fructose is not adjusted to energy needs and the molecule is rapidly and almost completely metabolised in the liver to generate glucose, glycogen, lactate and fat (9, 10). Moreover, fructose in contrast to glucose only weakly stimulates insulin and satiety signals and causes higher activation of brain regions that regulate appetite, motivation, and reward processing (8).
There is evidence that high fructose intakes in humans can cause dyslipidemia and impaired hepatic insulin sensitivity (9). It is now generally accepted that every dietary form of fructose, whether free, such as in fruits, honey and 'high-fructose corn syrup' widely used by the US food industry, or bound to glucose, such as in sucrose used in most European countries, exerts essentially the same metabolic effect (5,10). The controversy lies on whether the small amount of fatty acids generated from fructose in the liver through a process called "de-novo lipogenesis" is negligible in real-life situations or whether these small amounts of fat are indeed responsible for the adverse metabolic effects of fructose. Critics of the hypothesis of adverse metabolic effects of fructose argue that most studies showing the adverse effects of fructose are based on animal model studies with limited value due to the difference in carbohydrate metabolism between mice and men. Moreover, when human studies are performed they often used unrealistically high amounts of fructose, administered in pure form rather than associated with glucose and other dietary compounds and those effects would not be seen in studies where moderate amounts of fructose were given together with a mixed diet (5). However, a new study has shown impaired hepatic insulin sensitivity and changes in lipid profiles in healthy, young, normal weight men following the intakes of moderate amount of fructose and sucrose in a mixed diet (7). These results may counter the latter argument, in particular if the results are repeated and shown in longer-term and larger trials.
Nevertheless, regardless of the effects of moderate amounts of fructose, a small but still significant proportion of the population may be exposed to worrying and potentially deleterious intakes of fructose, mainly from added sugars (10). For instance, in the United States 13% of people, or one person in eight, aged 4 and above consume more than 25%** of their energy intake from added sugars, and for those individuals the main source is beverages (11). In addition, physical activity, gender and ethnic or genetic differences could modulate the health effects of fructose (10). In contrast, other people may have enhanced responsiveness and increased risk of developing metabolic disease, such as children of subjects with diabetes, overweight and insulin resistant subjects or ethnic groups with a high risk for metabolic diseases (7, 10)
In this context it is noteworthy that adverse effects of high fructose intake as part of a diet have been shown repeatedly in hypercaloric situations (4). However, whether the effects are due to fructose or the excess of calories still needs to be determined (12). In any case however, we note that the adverse effects of moderate fructose intake in the study described above (7) appear to have occurred without overeating. Also, a hypercaloric situation is likely to be a common reality given the rise in obesity prevalence. Added sugar and/or fructose may contribute to excess eating due to increased palatability as well as through specific effects on neurobiological pathways involved in appetite, satiety and reward (8, 10) so in real life situations it may be difficult to disentangle fructose and overeating effects. It will be important to understand better the role of realistic amounts of fructose within a mixed diet in controlling food intake and also clarify the mechanism(s) involved in addiction that may lead to increased energy intake (10, 13).
Finally, if the addition of fructose and sugar is confirmed as an important determinant of excess calorie intake through enhancing appetite then it may be of little practical relevance whether the adverse metabolic effects are caused by fructose under hypercaloric conditions directly or indirectly. At the end of the day, the remedy may remain eating less, but the targets will be reducing free sugar and fructose intake (13). (JW)
* Latin: at ones pleasure, referring to nutrition it means free access to food and water.
** Neither the European Food Safety Authority EFSA nor the US Institute of Medicine (IoM) have established upper limits of intakes for added sugars. Nevertheless, 25% of energy (E%) is suggested by IoM as the maximum level partly based on considerations linked to deficient micronutrient intakes (11) while EFSA acknowledges some evidence that high intakes (>20 E%) of sugars may impair blood lipids and more than 20 to 25 E% of sugars may adversely affect glucose and insulin response (14). Finally, it is noteworthy that some EU countries and the WHO recommend less than 10 E% from added sugars (14).
Image: An heroic sacrifice (Wikimedia commons)
January – February 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, Theodora Mouratidou, Tsz Ning Mak and Jan Wollgast contributed to this issue.
The views expressed here do not necessarily reflect the opinion of the European Commission.