"Meat contains proteins."
Translation:La carne contiene proteínas.
You may be right, but why literally translate my suggestion? Obviously I am not discussing literal translations. In addition, I know of several counter examples in which the subject does take the definite article in a general statement, such as "Estudio la historia", "I study history".
This was a year ago, but maybe it will help somebody else. In the case of "Estudio la historia" for "I study history" history is not the subject, I am, but the pronoun is dropped. History is the object.
I think "Estudio la historia" would be closer to I study the story than I study history which I think would be "Estudio historia". Not sure though.