All over the news today I've read about some research that was presented by some Harvard professors purporting to show that sugary beverages lead to 180,000 deaths worldwide and 25,000 deaths in the US (here is Time, ABC, Forbes, or a press release by the American Heart Association).
I haven't yet been able to get my hands on a copy of the actual paper (which isn't yet published) but from all accounts, this is not hypothesis-testing-science sort of research but rather assumption-driven-simulation sort of research. I've done some of that kind of work myself and it can produce some useful insights, but the results are only as good as the assumptions, and I suspect (though don't know) the simulation is assuming causality where there is only correlation.
While we are looking at correlations, we might as well have some fun with it. About two weeks ago, I blogged about (and reanalyzed data from) some research by anti-sugar crusader Robert Lustig that was published in PLoS ONE. In short, they showed a positive correlation between countries that eat a lot of sugar and prevalence of diabetes in the country. The correlation was widely interpreted as proving a causal link between sugar and diabetes. So, let's apply that same logic to the topic of death and sugar consumption.
I took the same sugar consumption data as I talked about in my previous post. Then, I merged it with life expectancy by country as compiled by the UN (you can download the data from Wikipedia). Here is the relationship between average life expectancy in a country (in years) and per capita availability of sugar (in kcal).
We've clearly got a positive correlation here. In fact if I run a population-weighted regression, I find that for every 100 kcal increase in sugar availability, life expectancy increases 1.9 years! The p-value is even less than 0.001! Drink more sugar and you'll live longer!
Now, do I actually think increased sugar consumption increases life expectancy? Probably not. Richer countries can probably afford to buy lots of things (like more sugar) and richer countries are also likely to have higher life expectancies (because they can also buy more health care). But, it does make you wonder what's going on if the Harvard researchers are right and all that sugar is causing so many deaths.
I rather suspect, a lot of deaths due to other problems are being attributed to sugar from sodas. I'm reminded of this passage from Eric Oliver's book Fat Politics as it relates to attributing deaths (or medical costs) to obesity.
The researchers who estimated that obesity costs us 100 million dollars a year did so by calculating all the expenses associated with treating type 2 diabetes, coronary heart disease, hypertension, gallbladder disease, and cancer . . . Once again, they simply assumed that if you got heart disease or breast-cancer it was because you were fat.