Nutrition Research Highlights 5 | 2 0 1 1
5 | 2 0 1 1
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 summarised as “News” items or presented as a “View”, comprising an analysis and expert opinion. Enjoy your reading!
Something is not right when children elect a potato chips brand as their most favourite. In an online survey made to 4000 UK children and teenagers (aged 7-15) that ranked 166 brands from 12 different categories including foods and drinks (Kids Brand Index 2011 report by Brand Republic and Harris Interactive 1), Walkers Crisps came 1st place overall. The third and 4th favourite brands are Coca-Cola and McDonalds respectively. Truth be said, there were not many 'healthy' food and drink brands to choose from in the survey but still it is revealing that children elect a potato chips brand over Wii Sports (10th place) or Lego (14th place). Based on this, can you guess how children would rank broccoli, carrots and apples when compared to chips, burgers and sweetened beverages? Probably not very high but such a ranking is important when discussing childhood obesity. In fact, regular consumption of energy-dense foods such as burgers or chips and sugar sweetened beverages is associated with obesity, both in adults and in children. And while these foods and beverages are certainly not the only contributors to the current obesity 'pandemic' they do have a place closer to children's hearts than 'healthier' fruits and vegetables, less energy dense and much richer in terms of essential micronutrients. To promote consumption of fruits and vegetables among children, Barbara Rolls and colleagues from the University on Pennsylvania have recently reported (2) an effective, albeit somewhat "sneaky", strategy. They have literally hidden vegetables in foods (incorporating pureed vegetables into bread, pasta sauce or chicken casserole), and showed that children (aged 3-6 year old) ate a consistent weight of food regardless of the amount of vegetables hidden (or not). This obviously resulted in an increase in vegetable intake over the day and also in a reduction of ingested calories (decreased energy) as children did not appear to compensate for the decreased energy content of the meals with an increase in snacking. While to covertly introduce pureed vegetables may be seen as "cheating", it is also simple enough to be included in foods served in crèches and schools as well as at home. If you are thinking of trying it with your own children you can ask for the recipes to the author of the study but keep in mind that, as the authors also discuss, this should not be the only way to present vegetables to children. In fact, Barbara's previous work has also shown that presenting a variety of colourful vegetables, especially at the start of the meal with no other 'competing' food is also another 'technique' to increase vegetable intake.
As covered in our previous issue, type 2 diabetes* is reaching alarming global dimensions. In this issue we follow up with a recent article (1) that re-visited the effects of red meat consumption on type 2 diabetes. The authors analysed red meat and processed red meat consumption from three long studies (16, 20 and 28yr long) that included roughly 200,000 health professionals (37.000 male doctors and 167.000 female nurses). According to the results of this study, consumption of red meat is positively associated with increased risk of type 2 diabetes. The authors looked both at unprocessed "red meat" consumption, i.e. beef, pork, sheep and goat, including chops, ribs and burgers from the same animals, and at "Processed red meat" such as sausages, hams, minced meat sauces, salami, bacon etc. The association with type 2 diabetes was observed for consumption of both processed and unprocessed meat, although the relative risk was higher for processed meat. Most importantly, the authors also evaluated whether substituting red meat with other sources of protein such as low-fat dairy products, nuts and whole grains, could lower diabetes risk. Indeed, when compared with one daily serving of red meat (e.g. 85g of unprocessed red meat), one daily serving of nuts (28 g), low-fat dairy products (240 ml milk, 28 g cheese, or 120 ml yogurt), and whole grains [32 g (1 slice) of bread or 200 g (1 cup) of cooked brown rice or cereals] was associated with a lower risk of T2D. These results do not imply that we should not enjoy red meat at all. Current guidelines in Europe however recommend around 500 g of meat per week which is probably much less than most of us consume. There is also evidence pointing out to an association between high levels of red meat consumption and risk of colon cancer (2) so reducing meat consumption to the recommended European levels could greatly benefit public health.
The end of September saw a new law being introduced in Denmark. What makes it different is that it is the first law in the EU which enforces taxation on any kind of food with high fat content. The outgoing Danish government introduced this across the board "fat tax" (1), hoping to steer the public into healthier diets. Denmark has also banned, on health grounds, the use of trans saturated* fats in cooking since 2004. This new fat tax is applied to all foods with a saturated fat** content higher than 2.3%, and is equal to 2.15 € per Kg of fat content. For example, a small 200g pack of standard butter, which contains about 100 g of saturated fats, would now cost 0.43 € more due to the newly introduced tax. Denmark is not the first EU country to introduce an "unhealthy" food tax, as it was preceded last July by Hungary, which introduced taxing of certain high salt, sugar, carbohydrate and caffeine on snacks, soft drinks and other pre-packaged foods that it considers unhealthy.
What is however the scientific evidence supporting such policy measures? A few years ago, researchers from the University of Berkeley in California used models to estimate what would be the effect of a dairy fat tax on consumer fat consumption (2). They concluded that although the fat tax would be efficient in raising revenue, the dairy fat consumption would not be affected by the tax, as people would not abandon dairy products. Specifically, a 10% tax on the value of the product (ad valorem) would only result in a 1% decrease of average fat consumption, and even a 50% tax would only lead to a 3% lower fat consumption. In addition, sensitive social groups such as the poor and the elderly would bear the brunt of the fat taxation and not benefit from an actual fat reduction (as seen above) The authors note that under certain conditions, very large fat taxes may, in the long run, benefit the consumers by increasing their lifespan and reducing healthcare costs, but that benefits from a more realistic, moderate tax on fat are unlikely to be seen even at the long run.
A similar study (3), performed by Brownell et al, was used to estimate the potential public health and economic benefits from introducing a sugar tax on sweetened beverages. The authors confirm the findings of the previous fat tax study concerning ad valorem taxes and explain that a percentage tax on the value of the sweetened drink would be ineffective because for example consumers could just switch to a similar lower priced brand and because they would only be aware of the added tax after deciding to buy a beverage. Instead, they propose a tax which is relative to the amount of sugar present in the drink (like the fat tax in Denmark), and show that a 1 cent (US $) tax per approx. 30 ml of soft drink would result in a 15-20% increase in the price of a 750 ml soft drink bottle. The authors go on and estimate that such a price increase would to a 10% reduction of calories ingested through soft drink consumption, which, they argue would be sufficient for weight loss. In addition, consumers could include switching to low sugar beverages, while the tax would greatly benefit those in high risk that consume great amounts of soft drinks etc. In addition, the revenue generated would be considerable and could be directed towards preventive measures against obesity.
Brownell et al conclude that the only way to truly test the effects of a tax on sugar sweetened beverages is to actually implement it, and perhaps this was also what Hungarian and Danish lawmakers had in mind when they designed and enforced such laws. Taxing as a "hard" policy approach to promote healthy eating is a complicated and quite controversial issue. Denmark has taken up the challenge with this flagship approach, and we look forward to see what the short and long term results will be.
* Trans fats can be found in many foods – but especially in snacks and fried foods like French fries and doughnuts, and baked goods including pastries, pie crusts, biscuits, pizza dough, cookies and crackers (Source: )
**Saturated fats occur naturally in many foods but mainly from animal sources, including meat and dairy products. Examples are fatty beef, lamb, pork, poultry with skin, beef fat (tallow), lard and cream, butter, cheese and other dairy products made from whole or reduced-fat. (Source: )
Photo: Butter (Wikipedia Commons)
Staring at the vegetable bench in the supermarket, do you hesitate between buying organic carrots or conventionally grown ones? It's only carrots after all, but choosing one over the other entails considering many factors if you carefully think it through. Some of us will choose the large, clean and nicely shaped orange carrots, others will simply choose the cheaper ones while others will choose the organic no matter what. The later group is steadily increasing as recent data point to a growth in the consumption of organic produce in Europe of roughly 30-50% per year (1). In the EU the production, control and labelling of organic products are closely regulated (2) and as of last year organic products can be easily recognised by the EU organic logo.
As far as fruits, vegetables and legumes are concerned, organic farming is characterised, among other points, by very strict limits on the use of chemical synthetic pesticides or synthetic fertilisers and is therefore seen by the consumer as healthier, safer and eco-friendlier alternative. Safety and environmental claims aside, as nutritionists, we asked ourselves one simple (or so we thought!) question: Does organic produce have a better nutritional profile when compared to conventionally produced foods? We took advantage of three recently published articles that asked this question using fruits and vegetables as examples (1, 3, 4).
What is immediately apparent from these articles and much of the literature in the field is that the question does not have an easy answer. Comparisons between foods derived from these two different systems are not straight forward as they should take in consideration not only the type of farming (organic versus conventional) but also other factors like the quality of the soils, the age of the plants, the cultivar they are derived from as well as several harvest and post harvest parameters such as time between harvest and consumption (an exhaustive list is presented in (1). The fact that so many variables must be considered –and often are not - is probably at the heart of inconsistent and conflicting results reported in different studies that aim to compare organic versus conventional produce. Nevertheless, there seems to be a general consensus in what regards a higher content of Vitamin C and phenolic compounds in organic plants but also lower levels of carotenes when compared to conventional produce (1, 3). In one recent article, Hunter and colleagues (4) have performed a more restrictive analysis of previous literature including only studies that controlled for many of the confounding variables. Taking these selected studies in consideration, their analysis shows that organic plant foods have a slightly (5.7%) higher content of vitamins and minerals than their conventionally grown counterparts. This is particularly true for minerals present in the vegetables or legume food groups.
Interestingly, all these articles discuss how agricultural methods may influence micronutrient and the phytochemical composition of plant foods. For example, in the absence of protection given by synthetic pesticides, increased biological and ecological stresses appears to promote the production of ascorbic acid (i.e. Vitamin C) in organic plants. Interestingly, similar responses against pathogen stresses have also been hypothesized to contribute to a higher content of phytochemicals (some with beneficial anti-oxidant properties, for example) in organic plant produce. There may be some drawbacks too though. Higher levels of endogenously produced compounds could have negative implications depending on their biological effects. In terms of sensory quality, the levels of phytochemicals such as citric acid or glycoalkaloids can affect the taste of the organically grown produce; Lester and Saftner discuss in their article two sensory studies in which organic potatoes or grapefruit juice were considered more bitter or acidic by a panel of consumers probably due to the higher production of these naturally occurring self-defence chemicals (1). Additional trade-offs between organic and conventional food agrosystems also stem from differences in the amount and source of nitrogen available in both systems. As Brandt et al (3) discuss a decrease in nitrogen availability to the organic plants will result in increased phenolic compounds defense compounds, which increases the resistance of the plants to pests and diseases, although at the cost of lower growth rate thereby limiting the yield of the crop.
The discussion above stresses the complexity of the multiple interactions between soil, climate, ecological niche and so many other factors that affect plant composition and growth, in addition to all other harvest and post-harvest factors that impart on the properties of the plant foods.
There is clearly a need for further well-controlled investigations in this fascinating topic as solid knowledge in these areas will satisfy the information needs of the consumer and importantly, guide further improvements to both organic and conventional farming practices. Another equally essential and unfortunately equally challenging question follows: are differences found in the nutritional/chemical composition of organic versus conventional plant foods associated with human health benefits? There are so far a limited number of studies addressing this question. Brandt et al speculate in their article that based on their results and previous estimates on general fruit and vegetable intake, switching to organic fruits and vegetables would correspond to an increase in life expectancy of, on average 17 days for women and 25d for men. These theoretical values are an interesting exercise but quite simplified estimate as they do not take in consideration any of the synergies, antagonisms, bioavailability or human variation issues that must be weighted carefully when addressing such a complex question.
As it turned out, answering our question was not straight forward. One would argue that, based on these recent articles there appear to be differences in the composition of organic versus conventional plant produce and that, according to Hunter et al (4), these are more pronounced for certain minerals (like phosphorous) and in particular plant groups like legumes and vegetables. But the complexity of the question – that we hope to have conveyed – and the uncertainty about the beneficial health effects that these would have in humans leave the question only partially answered. Importantly too, there are many other points to equate while staring at the vegetable bench in the supermarket and finally choosing which carrots to buy. Our article did not consider any environmental benefits of organic farming or delved into possible direct consequences of pesticide and synthetic fertilisers' usage but these are obvious issues that may influence your choice. So much to be said about choosing carrots after all...
Photos: EU organic logo, Carrots (Wikipedia Commons)
Nutrition Research Highlights is a bi-monthly publication prepared by the Nutrition & Health Group of the DG-Joint Research Centre, Institute for Health and Consumer Protection. The Nutrition team is comprised of Sandra Caldeira, Petros Maragkoudakis & Jan Wollgast.
The views expressed here do not necessarily reflect the opinion of the European Commission.
© European Union, 2011. Reproduction of articles (excluding photographs) is authorised, except for commercial purposes, provided that the source is mentioned.