  Recently there has been a proposal for modified gravitational f(R) actions
which include a direct coupling between the matter action and the Ricci scalar,
R. Of particular interest is the specific case where both the action and the
coupling are linear in R. It is shown that such an action leads to a theory of
gravity which includes higher order derivatives of the matter fields without
introducing more dynamics in the gravity sector and, therefore, cannot be a
viable theory for gravitation.
