Nutrition myths exposed - Sugar, Part 1

Sugar

For decades, fat was the enemy; today, there’s a new scapegoat: sugar. Where did this myth even come from? Well, It all started with a book published by professor John Yadkin in 1972, titled "Pure, White and Deadly". The book talks about how sugar is killing us and what we can do to stop it. Even though the book is currently often quoted by fitness and health professionals, it didn't gain as much acclaim initially. The reason was that just two years earlier iconic "The seven countries study" was published by Ancel Keys. The study shifted public attention away from sugar on to dietary fat and that shift lasted for decades. 

Sugar recently has caught more spotlight in 2003, when American Journal of Clinical Nutrition published a review article where they talked about similarities between the trend in high fructose corn syrup availability and the trends in the prevalence of obesity in the United States. The authors also noted that fructose and glucose have different metabolic effects, especially with the regard to insulin release. so, they singled out fructose as the main evil. There are many more systematic reviews that didn't adjust for total energy intake and found a strong correlation between sugar intake and obesity.

If we add some documentaries to all the above, It makes it more than enough to boost this myth. It is quite understandable that a large majority of the public has come to accept this idea as scientific truth.

The main issue with the aforementioned conclusions about the sugar is that they make the unjustified jump from correlation to causation. And those two terms are not the same. Such correlations are the weakest form of evidence available.

Now, for some stronger evidence. 2005 paper titled "Sugars and Health Controversies: What Does the Science Say" concluded that " Sugar doesn't make a unique contribution to obesity. Moreover, in a condition as complicated as obesity it is highly unlikely that one single nutrient would uniquely cause this condition. It is more likely the totality of the diet including increased caloric consumption from all sources, exerts a significant impact on the likelihood of obesity. There is much more direct evidence showing that sugar clearly is not to blame for weight gain. One is a massive systemic review from 2013, looking at 68 studies which found that if you replace dietary sugar with other macro-nutrients and control for caloric content, you don't see any change in body weight. 

So, the burning question is if the evidence for sugar being detrimental to our health is so weak how is that so many people believe it is the truth. I think it comes down to a few factors. First, the anti-sugar advocates will often use "emotion raising language". Throughout the usage of words like "deadly, evil, dangerous, plague" to describe sugar, they make us fear it. Secondly, the disfigurement of scientific information. This mostly takes the form of weak epidemiological or observational research which gets more attention that it deserves. They usually mix up correlations with causation. Lastly, the exposure effect. This simply means that the more frequently you hear something, whether true or false, the more likely you are to accept it as true

Concluding all the above, even though there are no strong links in scientific evidence suggesting that sugar plays a central role in either the cause of obesity or type 2 diabetes, it doesn't mean you should all the sugar in the world. The WHO recommended an upper limit of 10% of total calories, basing this recommendation on the well-established relationship between added sugars and dental care. The 2010 article by Alan Aragon "The bitter truth" suggest about 50 grams as a ballpark safe upper limit for fructose intake.  You have to remember though, that any recommendation will be highly dependant on your lifestyle, total calorie intake and your goals. The point is not to stress about reducing your sugar intake if your overall diet is within a reason. Just enjoy it!

References:

https://www.sevencountriesstudy.com/study-findings/publications/

https://academic.oup.com/advances/article/6/4/493S/4568634

http://www.alanaragonblog.com/2010/01/29/the-bitter-truth-about-fructose-alarmism/

https://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0051979/

https://www.ncbi.nlm.nih.gov/pubmed/23742715

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4496733/

https://www.ncbi.nlm.nih.gov/pubmed/22723585