The American Heart Association this week issued widely publicized recommendations about how Americans are drowning in sugar, and they suggest what to do about it. People (or is it just Americans?) should cut down from an average of 22 teaspoons a day to just 6 teaspoonfuls. Well, that's for the girls: guys get to have 9! This remarkably scientific precision is being reported widely in the media (e.g., CNN and the New York Times).
We wonder how long it will take some entrepreneurial marketer to develop a Sugarometer, that we can carry around to measure our daily dosages. Of course, there is a bit of a problem since most of the sugar we consume is already mixed into something else--like, almost anything else that we eat. So the Sugarometer will have to have some way to scan a product and work out the dose.
The caloric overdose problem in America, and in other wealthy countries, is a serious one. It is and will be a major burden on health care systems (even in countries like our own benighted land that are without universal health insurance). But the appearance of precision of this new dietary recommendation is rather silly. People are different in size, activity levels, genotypes, personal priorities (some still smoke!), and even self-image.
But we can't seem to shake our romance with technology, or its appearance. Things as simple and intuitive as dietary excess vs sedentary lives, with their heavily laden cultural and economic elements, have to be made precise. Even with a disclaimer that this is only a 'rough' estimate, how rough is it actually? Is it even meaningful? For example, do magazines and Hollywood determine the body shape that is considered OK? Are there really solid health data that are as specific as this report?
We regularly try to point out the problem of assuming a high predictability of phenotypes by genotypes. Here, it's somewhat the opposite, of assuming a high predictability of phenotypes by environments. It's the same kind of issue.
These studies give a misleading impression of human variation, first by standardizing what is probably not standard, and by assuming oversimplified ideas about causation. It would not surprise us to see GWAS done to find genetic effects per-teaspoonful-consumed.
While in a technical sense, such variation surely exists, and some of us are more vulnerable to a given level of health problem per teaspoon. However, the cost and patina of technical sophistication serves to distract from the real public health message, that has been known since Hippocrates: moderation in all things. You don't need million dollar grants(or professors) to know that!