One week soup of the day science says coffee will kill you and the next week it says it is highly beneficial.
Most science now days is a type of "Look and See Science" I call "soup of the day science".
Look and see Science is always wrong even when it's right. Real science can only be based on proper experiment and not the opinion of Peers.
It's sad, but unsurprising, that you would believe that different studies coming to different conclusions is an indication of science contradicting itself.
It's sad, but unsurprising, that you don't understand that some fields of study can only be done by trying to evaluate effects on trees or monkeys or humans. It's sad, but unsurprising, that you can't understand why these kinds of studies would produce differing results.
It's sad, but unsurprising, that you believe this affects all branches of science and all manner of scientific study.
Is science contradicting itself by stating the earth is a sphere?
Is science contradicting itself by stating the sun is just one of a few billion stars in a grouping called the Milky Way?
Is science contradicting itself when newer and better tools for analysis find newer and different things than were known previously?