The Science of Sugar

Three years ago, this YouTube video of a talk by Dr. Robert Lustig, a Professor of Pediatric Endocrinology at UC San Francisco, when viral (to date, the video has 2.7 million downloads).  His argument there, and subsequently in prestigious journals like Nature, is that sugar is toxic.   

I’m going to be honest, I haven’t invested the time to adequately evaluate the claims made about the biology, endocrinology, and metabology of sugar, but I suspect there is some truth to the argument that some foods are metabolized differently than others – in other words, it is more complicated than just “calories in, calories out” (although this adage is also almost certainly true on some level). 

What I do know is that the science of sugar is not nearly as certain as Lustig purports, a fact mentioned by Gary Taubes who is overall sympathetic to his claim (see also the citations in second paragraph of Lustig’s Wikipedia page).

Lustig is an accomplished and well-published scientist.  But, what bothers me is the all too common stance of many folks in the medical and public health communities failing to appreciate how little they know when they move to realms beyond their particular academic expertise.

The viral YouTube talk included a beginning slide with the words “Letting Science be the Guide” and Lustig personally began a speech in 2011 by asserting that “Ultimately science should drive policy.” Yet, I find it a bit ironic that neither of these talks seriously discusses the economic science behind the many sugar-recuing policies he supports. 

Economic study after study after study after study shows sugar policies (such as sweetened beverage taxes or bans on school vending machines) will only have very small effects on intake and weight.  When sodas are taxed (or banned), people can substitute toward other caloric drinks such as fruit juice or alcohol. Moreover, food taxes are regressive - meaning the burden is disproportionately borne by the poor.  It is also worth pointing to the economic research on farm policy and sugar production reveals a much more complicated situation than many pundits presume, with the authors showing that the “link between US sweetener consumption and farm policy is weak.” 

So the next time you hear someone pronounce that the “government has to get off its ass” because of sugar consumption, I suggest asking what economic science actually says about what will happen when the government moves it’s preverbal backside. 

Addendum:  One of my colleagues pointed out that the arguments used to claim sugar is addictive (primarily that our body becomes accustomed to a level of intake and requires more and more to achieve a given level of satisfaction) sounds remarkably like the psychologist’s notion of the hedonic treadmill – a phenomenon that is posited to hold for almost all aspects of life.