OK, I'll help you to see the differences more clearly. Here is the NASB and KJV on Mark 7:19 in English and Greek with the same words in corresponding colors;
Mark 7:19 because it does not go into his heart, but into his stomach, and is eliminated?" (Thus He declared all foods clean.) NASB
Mark 7:19 Because it entereth not into his heart, but into the belly, and goeth out into the draught, purging all meats? KJV
‹19› ὅτι οὐκ εἰσπορεύεται αὐτοῦ εἰς τὴν καρδίαν ἀλλ’ εἰς τὴν κοιλίαν, καὶ εἰς τὸν ἀφεδρῶνα ἐκπορεύεται, καθαρίζων πάντα τὰ βρώµατα;
because it does not enter of him into the heart but into the stomach, and into the sewer goes out, cleansing all foods?”
As you can hopefully see, the words in purple are not in the Greek and the words in blue are in the Greek, but NOT in the NASB. All clean food eaten with dirty hands is cleansed out of the body into the toilet. How dare the NASB translators add "Thus He declared" and deceive millions of Bible readers like yourself.