Horizon Sugar vs. Fat - bad science!

On BBC 2 Wednesday 29th January 2014 at 9pm Horizon: Sugar vs. Fat aired for the viewing public. I normally don't blog too much about TV programmes, but the more I watched this particular documentary the more I felt that something had to be said! In fact it got me in the right mood for a proper rant! Horizon is a well respected programme that explores many important issues on numerous subjects. The presenters of the show, twins Chris and Xand Tullenken, are no doubt respected doctors in their specific fields of study, which are infectious disease and tropical medicine. However, I think the combination of the two together for this programme provided a documentary that may provide some entertaining TV, but to be honest it catastrophically failed to deliver in the realms of accurate and correctly controlled scientific understanding!

The basic premise of the documentary was to compare an extremely high dietary fat intake to an extremely high intake of sugar and processed carbohydrates in a pair of identical twins - the doctors van Tullenken themselves! The programme introduced the idea that there are apparently polar views between Britain and the USA stating that Britain has been locked into the dogma that fat is bad for us, whereas in the USA the prevalent view is that sugar is bad for us. This is somewhat confusing from the start! Indeed in the 1960's and 70's it was an American, Ancel Keyes, who dogmatically championed the theory that dietary fat, especially saturated fat, was the underlying cause of heart disease. Meanwhile in the UK during the same time period a prominent British nutritional scientist, John Yudkin, provided strong counter evidence that sugar was the real health challenge to the heart that should become the focus of public health guidelines. The dietary fat - heart hypothesis theory won out and the all too familiar low fat dogma has gone on to become the prevailing public dietary advice since 1980 in the USA and since 1984 in Britain. Whilst it is likely that in both countries there are opposing camps on this issue of fat or sugar as public enemy number one it seems strange that they would make this issue a division of opinion across nations. If anything the programme actually raises further questions regarding the chronic health problems associated with obesity and diabetes in the Western world.

Doctor Chris opted to go on the high sugar diet and Xand the high fat diet to experiment upon themselves to see if these foods have any differing effects on their identical genetic makeup. In theory this sounds intriguing, but in scientific terms it has little relevance to the wider population as their own specific genetic code may already be geared to succeed better on a diet with more glucose or alternatively more fat or even somewhere between the two extremes, which is most likely. A much more useful experiment that would be more scientifically sound would have been to recruit 40 or 50 sets of twins of different ages, genders and social status and run a well considered dietary experiment for 3 months with every pair and to pool all the data together to determine if any dominant trends could be observed in the resulting health outcomes. This would have cost more but would have been a much more valid experiment and provided significantly more meaningful results in relation to the population at large. There should have also been some individuals on a control diet to serve as a central or normal comparison point. It is much more scientifically valid to view the results of a high fat or high sugar diet in comparison to a typical British diet, rather than compare them to an opposing extreme diet without a central reference point. This is simply one of the basic principles of science.

They involved a nutritionist to provide the rules for their opposing diets. She had set up a visual display of different foods to demonstrate for the viewing public the diets that had to be followed. On first glance this all seemed to make sense. But on closer inspection there was some seriously big holes in the dietary methodology. Chris on the high sugar diet was told to eat lots of processed sugary foods and refined starchy foods like white pasta, white rice, white bread and potatoes as these ultimately get digested and become glucose once they enter the blood stream. This seems to make sense, except that sugar is 50:50 glucose and fructose which are dealt with differently by the body and wheat, rice and potatoes will digest down into mostly glucose. They are not the same! They will affect the body differently. Chris was also allowed to drink plenty of soft drinks which use mainly high fructose syrups to sweeten - again more fructose than glucose - which will be metabolised differently by the body! One of the strangest bits of advice was that he was also allowed unlimited fruit and vegetables. This choice in itself would have had considerable ramifications. Important nutrients, such as vitamins and antioxidants, provided by the fruit and vegetables will absolutely have helped counteract the potentially damaging effects of the high sugar on Chris’s health.

Xand's diet restricted fruit and only allowed a very limited amount of vegetables, reducing his access to a valuable source of antioxidant nutrients that would help to protect his body against free radical damage. As the camera panned over the food choices allowed on the 'high fat' diet (see image above) it quickly became apparent that this was also a diet very high in protein from a broad selection of meat, poultry, eggs and nuts he was allowed to eat. Leaving the skin on a chicken breast does not turn a lean high protein piece of chicken into a high fat food! 100g of roast chicken breast typically has 31g of protein and 5g of fat, whereas the same chicken breast cooked with skin on increases this to a staggering 8g of fat! Hardly a high fat food to be fair. It should be noted that the scientific literature is full of plenty of studies that have warned against high protein diets as they have their own set of problems associated with health and blood sugar control and the stress they place on the body to convert and produce glucose from protein when glucose is lacking.

Astonishingly both doctors were also both allowed to eat as much as they liked with no calorie control whatsoever. This created a problem in itself as demonstrated later in the programme that Chris was always hungry without much fat and protein in his diet and was eating all the time, whereas Xand was almost never hungry and ate much less as a result of the powerful satiating effects of the high protein diet. This was demonstrated when in one meal Xand managed an impressive 825 calories of fat and protein before feeling totally overwhelmed and satiated, whereas Chris was able to keep easily eating until he had consumed 1250 calories primarily from carbohydrates and still did not feel satiated. These different calorie intakes would have created vastly differing internal biochemistry alone even without the differences in what composed the calories. It is blatantly clear that the two diets imposed simply had too many uncontrolled variables for the results to truly be meaningful, fair and comparative. From a scientific standpoint this really was poor to be honest and did not follow even some of the most basic principles of scientific investigation to provide worthy, valid results - namely control all the variables except the one difference to be investigated i.e. fat and sugar!

A better choice would have been to have each twin consume exactly the same diet every day, but in each meal they would add a specific number of calories of fat or sugar e.g. 100 kcals of sugar to each meal for Chris and 100 kcal of fat added to Xand's. This would have been a much more accurate reflection of the impact the inclusion of one additional ingredient in extreme amounts could have on health and measurable health markers.

The two doctor’s were asked to keep daily video diaries which clearly showed that neither extreme diet was palatable for very long and had they been able to choose they would have stopped following the regimen long before the 1 month objective was up. Such a prescriptive, unpalatable diet is even more unlikely to be commonly followed by the general public as food enjoyment, appetite and cravings are by far the most persuasive drivers of human dietary behaviour.

Part of the programme was to test both mental and physical performance whilst on the dietary regime's. A computer based trading task was undertaken as part of the mental test. Again some really poor science here. They simply compared both individuals performance by who made the most profit on the day. This is a ridiculous test as we are not given any indication of how they could have performed on such a mental test if they had been eating a regular diet. There is no control for which to compare performance change in each individual. Xand may have still performed much worse than Chris as Chris may simply have had better business and trading aptitude. This is a flagrant failing in scientific terms. The physical test involved a cycling performance test  with 2 parts, a 1 hour endurance cycle to drive blood glucose down followed by a tough hill climb up the notorious Olympic route, Box Hill. Interestingly on the longer flat cycle where intensity levels were more consistent, Xand on the high fat diet faired much better with only a 31% drop in blood sugar during the hour, whereas Chris dropped 43% in the same time period. This is because we can adapt to the diet we eat. High carbohydrate intake increases the muscle reliance on glucose and high fat intake shifts the muscles capacity to utilise fats creating a glucose sparing effect as experienced in the endurance cycle by Xand who maintained better blood sugar overall. They then consumed a pat of butter and a sugar gel prior to the hill climb where the high intensity and the large sugar boost played into Chris's hands. What was scary was he started with a blood sugar of 2.7 prior to the gel intake then climbed Box Hill and even after all that intense exercise Chris's blood glucose was still 7.1! Enough to be diagnosed as diabetic. I wonder how high his blood glucose would have become if he didn't do the hill climb. Avoid those sugary gels for sure! The cycle was a poor test also as it has long been know that glucose is needed for high intensity exercise and fats do a great job in sustaining better endurance exercise. This only really highlighted the normals needs for different intensity exercise, it did not prove which diet worked best to fuel performance. The programme also did not have a control exercise test performed prior to the start of the extreme diets to determine what their performance would have been like on a regular diet. It would have been a better indicator to see how the extreme diet changed their respective performances rather than how they compared to one another on a single test. Again basic scientific principles ignored. Come on Horizon?

It was also disappointing to hear the doctors refer to LDL as 'bad' cholesterol and HDL as 'good' cholesterol. I appreciate that this is what many people, including doctors have been taught, but it is too simplistic. Science has already moved way beyond this concept. LDL cholesterol has different sizes or types. One being large and fluffy and the other small and dense. Saturated fat has been found to increase the amount of large fluffy LDL cholesterol. These are not implicated in heart disease as they cannot get into the lining of the artery when it is damaged and inflamed. Refined carbohydrates produce the small, dense type of LDL which combined with damage and inflammation get into the lining of the arteries and increase heart disease risk. This is not a heart disease blog, but there is much more to be said on this topic. Needless to say the science they were basing their cholesterol views on is from the 1980's and we have moved a long way forward in our understanding of cholesterol since then.For more information on this line of thinking about cholesterol look into the work of Uffe Ravnskov, Dr Malcolm Kendrick, Anthony Colpo or Jimmy Moore.

The documentary did finally make the conclusion that it is actually a combination of fat and sugar in foods that is the problem as when they are together it provides the most hedonic or pleasurable response and increases our brain activity and endorphins the most. This was demonstrated by the desire of people to scoff the glazed doughnut ring! This is not really a revelation either. Sorry docs. This tidbit of information has long been known in food science circles and amongst the major food processing and manufacturing giants and is the primary reason that so many processed food products have both sugar and fats in abundance. Perhaps one of the biggest mistakes that mankind has made took place years ago which was to seek out and find ways to extract and refine sugars from cane and beets in a mission to sweeten our food. Once the crippling taxes were removed from sugar in the late 1870’s and it became a highly affordable food stuff it has steadily increased in the human diet with average consumption now reaching 42kg per person per year in the UK and 65kg per person in the USA. On the flip side there has always been a plentiful supply of fats in the diet, even in a natural diet, one only needs study the Eskimo, Native Americans or the Masai to find this out. However, naturally occurring sources of sugar in any long standing traditional diet is more difficult to find outside of seasonal fruit consumption and hard to obtain honey.

Most of the major sources of modern food that drive blood glucose up come from processed foods such as wheat flour, pasta, refined rice, cakes, ice cream, biscuits, pastries, crisps, pizza, chips, chocolate, confectionery, soft drinks, fruit juices etc. It is mankind and the food processing giants who have refined carbohydrate ingredients and mixed them with cheap vegetable fats like soy, corn and rapeseed oil to provide foods with high pleasure and hedonic response. The drive to make money out of food by business is responsible for our obesogenic environment. Nature is not to blame! Food is not to blame! Food processing on the other hand and those that service the food processing giants have a lot to answer for.

Can we have some better science in these influential programmes please Horizon? Let's be sure we teach the public the right message based on sound scientific reasoning and principles.

Rant over. Thank you for sticking with me to the end!