Many studies about food and health are based
on links researchers make between people’s
health and what they say they eat. But that
doesn’t prove one causes the other. If a thin
person loves cereal and eats it nearly every day,
for instance, that doesn’t mean cereal is the
reason they’re thin.
Health experts who defend advice to cut
back meat say the researchers were applying
an unreasonable standard — evaluating the
strength of the meat studies with a method
intended for medical studies, where a specific
dose of drug can be tested under controlled
conditions.
With nutrition, they say it’s impossible to
conduct studies where people’s diets and
lifestyles are controlled and monitored over long
periods. They say the statistical signals they see
in nutrition studies are meaningful, and that
people should be given guidance on the best
available data.
THE PERSON VS. THE POPULATION
If it’s true that there would be seven fewer
cancer deaths for every 1,000 people who cut
back on red meat, then it is also true that 993 of
those people would not see that benefit even if
they ate fewer burgers.
For many public health experts, the potential
for those seven fewer deaths is worth making a
broad recommendation to limit meat. Across an
entire population, the numbers could add up to
many lives saved.
But the question is where to draw the line, and at
what point the potential benefit is too small and
uncertain to ask people to change their behavior.