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Sunday, November 6, 2011

Taxing the fat and sweet

Taxing the fat and sweet

There is at present a considerable media interest in the taxation of both fat and sugar in an attempt to control the epidemic of obesity. In a typical Western diet, fat and sugar combine to contribute about 55% to 65% of our total caloric intake. To contemplate putting a tax on more than half our energy intake is palpably absurd so the target is then moved toward specific foods which merit taxation based on (a) their fat and sugar levels and or (b) their putative contribution to obesity. The problem regarding the latter is a total lack of any evidence linking very specific food groups to obesity.  Across time  (decades of research) and space (all continents) there is no universal single pattern of food choice uniquely associated with obesity. Consider a solid example of how this works. Across time and space, every study that has sought to examine the link between dental caries and diet has found that it is the frequency of sugar consumption, which is important.   When, time after time, in all corners of the globe and under all sorts of different circumstances an observation is found to be simply constant, then it ends up in the “no-brainer” category of knowledge. Not so with obesity. There is no consistent pattern of food intake. Some eat excessively and never eat chips, others eat chips but don’t eat excessively and you can substitute “chips” in that phrase with any food you like. If there were a pattern that every researcher saw every time they looked we’d have done something about it long ago. However, there simply is no consistent pattern of food choice that is uniquely linked to obesity.

Of course that is a great disappointment to those who hold the belief that obesity is directly related to the intake of fast food or to foods with empty calories, high in sugar or fat. Having an identifiable corporate whipping boy makes life easy. Bashing McDonalds might make some concerned citizens feel good but since McDonalds are responsible for the sale of maybe just 10% of all chips consumed, ignoring the main purveyors of chips (ethnic restaurants, fish and chip shops, pubs, works canteens, mobile food vendors etc) means that the real “villains” are getting away “Scot free”. And of course when it comes to the practicality of imposing a fat tax on chips (and other fast foods), the taxing of bars, fish and chip shops and the other suppliers of the nation’s chips poses quite a logistical problem.

In the absence of hard data to identify foods, which are uniquely involved in the development of obesity, the next step is to use the nutritional composition of foods to sort out those that are high in those nutrients for which we should reduce our intake. This is referred to as “nutritional profiling”.  The theory here is that a mathematical formula can be devised into which the nutritional properties of individual foods are entered allowing an output which marks foods into “good”, “bad” and “ok but not great” categories. In the UK the dream is to then assign a colour code to this as per traffic lights. Interestingly, when the mathematical construct gets things wrong, that is to say when it disagrees with the a priori opinion of the users, the formula is changed to make sure that the output meets the opinions of the particular experts who are adherents to this process. In principle, anything that helps consumers to make better choices must be welcome but the problem here in the EU is that the process is doomed to poor science for the simple reason that we do not use portion sizes here but rather units of 100g or 100 ml. The argument is that across the EU, portion sizes differ. For example, it is argued that in Italy, the average intake of pasta is 3 to 4 times higher than in Northern EU. However, this difference is not due to portion size but to the frequency of consumption. A plate of pasta in Rome is the same as a similar plate in any Italian restaurant across the entire EU. Mixing up frequency of consumption (higher for pasta in Italy) with portion size is nonsense but that is at the heart of the EU thinking as regards EU food legislation. In the US there is an agreed RACC (Recognised Amount Commonly Consumed) value for each food. To understand how daft this is, consider the comparison of water biscuits (usually served with cheese) and pizza. A typical 100-gram of pizza will provide about 7 grams of fat while 100 grams of water biscuits provide up to 23 grams of fat. However, a typical serving size of pizza would yield about 20+ grams of fat while a typical serving of water biscuits would contain about 4 grams of fat. Ignoring portion size can penalise foods, which have typically small servings Per 100g, mustard has twice as much fat as full fat milk!!!!!

 Trying to find a single all embracing formula to assign a general nutritional quality index to every food is difficult and will be constantly bothered by obviously “wrong” decisions. An approach used successfully in Scandinavia, uses an agreed compositional target per food category. If there is a move toward a reduction of a given nutrient, then the regulators and the manufacturers of a particular category of food can agree a target that all can work towards. In Scandinavia, foods that reach that target get to display an emblem which consumers can recognise as having met a given standard.

One of the first lessons to be learned in nutrition is that there are no such things as “good foods” or “bad foods” but rather “good diets” and “bad diets”. Sadly, it is a lesson quickly forgotten by those who regard diet and obesity as a simple problem linking certain naughty foods with weight gain. 

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