They do say that they controlled for class and physical activity: but the only thing open-access about the article is the abstract, so I can't tell how they controlled for those things.
"Other variables included in the analysis were age (35–44 years, 45–54 years, 55–64 years, 65–74 years and 75+ years), sex, smoking status (current smoker, ex-regular smoker, never smoked regularly) and social class of the head of household (manual, non-manual, other). Education (degree or equivalent qualification, other, no qualification), measured body mass index (BMI) (<20 kg/m2, 20–24.9 kg/m2, 25–29.9 kg/m2, ≥30 kg/m2), physical activity (as maximum activity intensity level in the past 4 weeks: inactive, light activity, moderate activity, vigorous activity) and alcohol consumption on heaviest drinking day in the previous week (non-drinker, drank within limits, drank above limits, drank more than twice the recommended daily limit) were also added to the models as indicated."
The most obvious thing missing from this list to me is all other dietary related variables. For example, people who like the taste of plants are probably far less likely to enjoy eating red meat, salty foods, and many other things that have been associated with increased mortality.
Which, incidentally, have really only been associated with increased mortality through flawed epidemiological studies such as this one.
Social class is manual/non-manual? What do retail and telemarketing count as?
edit: I'm being a bit pithy here, but what I want to know is if someone who went to DeVry and works in telemarketing ends up higher class than me, a six-figure college dropout with six-figure college (Northwestern/Northern Illinois) graduate parents.
Social class is almost fully determined by the wealth of people's parents, why don't we use it?
PDF: http://jech.bmj.com/content/early/2014/03/03/jech-2013-20350...