Some group/sects/cults claim you cannot eat meat or caffeine or tea (or whatever food or drink that they somehow decide is bad). However, the Lord declared all foods clean in the New Testament. Furthermore, the whole idea of “Kosher” food today is not supported by the New Testament. I am speaking here of foods consumed in the normal course of life, not the partaking of substances which may induce sinful behavior or vices (e.g. alcohol, tobacco, drugs, etc.), nor abstaining from certain foods due to medical reasons (e.g. food allergies). A discussion of such topics is beyond the scope of this book.
Even one verse that proves this teaching false is enough, so I present it here:
And He said to them, “Are you so lacking in understanding also? Do you not understand that whatever goes into the man from outside cannot defile him, because it does not go into his heart, but into his stomach, and is eliminated?” (Thus He declared all foods clean.) – Mark 7:18-19
Please note that the words in parenthesis were not added by me, they are in the inspired record (my underlines added for emphasis). See also Acts 10:9-16 where the Lord declared all foods/animals clean.
Why such crystal-clear literal words of the Bible are ignored or cannot be understood, especially by those who profess to be “Christian,” is truly mind boggling. The apostle Paul further warns that when a group/sect/cult makes artificial restrictions on foods, that act is itself a very sign of apostasy:
But the Spirit explicitly says that in later times some will fall away from the faith, paying attention to deceitful spirits and doctrines of demons, by means of the hypocrisy of liars seared in their own conscience as with a branding iron, men who forbid marriage and advocate abstaining from foods which God has created to be gratefully shared in by those who believe and know the truth. For everything created by God is good, and nothing is to be rejected if it is received with gratitude; for it is sanctified by means of the word of God and prayer. – 1 Timothy 4:1-4
Matthew Henry writes on the above verses: 
Having mentioned their hypocritical fastings, the apostle takes occasion to lay down the doctrine of the Christian liberty, which we enjoy under the gospel, of using God’s good creatures, – that, whereas under the law there was a distinction of meats between clean and unclean (such sorts of flesh they might eat, and such they might not eat), all this is now taken away; and we are to call nothing common or unclean, Act 10:15. Here observe,
- We are to look upon our food as that which God has created; we have it from him, and therefore must use it for him.
- God, in making those things, had a special regard to those who believe and know the truth, to good Christians, who have a covenant right to the creatures, whereas others have only a common right.
- What God has created is to be received with thanksgiving. We must not refuse the gifts of God’s bounty, nor be scrupulous in making differences where God has made none; but receive them, and be thankful, acknowledging the power of God the Maker of them, and the bounty of God the giver of them: Every creature of God is good, and nothing to be refused, 1Ti 4:4.
This plainly sets us at liberty from all the distinctions of meats appointed by the ceremonial law, as particularly that of swine’s flesh, which the Jews were forbidden to eat, but which is allowed to us Christians, by this rule, Every creature of God is good, etc. Observe, God’s good creatures are then good, and doubly sweet to us, when they are received with thanksgiving. – For it is sanctified by the word of God and prayer, 1Ti 4:5. It is a desirable thing to have a sanctified use of our creature-comforts. Now they are sanctified to us,
(1.) By the word of God; not only his permission, allowing us the liberty of the use of these things, but his promise to feed us with food convenient for us. This gives us a sanctified use of our creature-comforts.
(2.) By prayer, which blesses our meat to us. The word of God and prayer must be brought to our common actions and affairs, and then we do all in faith. Here observe,
[1.] Every creature is God’s, for he made all. Every beast in the forest is mine (says God), and the cattle upon a thousand hills. I know all the fowls of the mountains, and the wild beasts of the field are mine, Psa 50:10, Psa 50:11.
[2.] Every creature of God is good: when the blessed God took a survey of all his works, God saw all that was made, and, behold, it was very good, Gen 1:31.
[3.] The blessing of God makes every creature nourishing to us; man lives not by bread alone, but by every word that proceeds out of the mouth of God (Mat 4:4), and therefore nothing ought to be refused.
[4.] We ought therefore to ask his blessing by prayer, and so to sanctify the creatures we receive by prayer.
To summarize, the New Testament declares all foods clean and we may eat all things with thanksgiving and prayer. The only restriction is that we should restrain from partaking of certain foods at certain times in certain company if it might cause a weaker brother or sister in Christ to stumble, where their (more sensitive) conscience is troubled by a particular food (perhaps due to their upbringing, etc.) – see 1 Corinthians 8:1-8. As a side note, a Christian should not of course participate in any pagan (or other) idol ceremony (whether meat is used as a sacrifice in it or not, Acts 15:29). And, once again, where you find this false teaching, other false teachings will also be found!
 Henry, Matthew. Exposition of the Old and New Testaments, London. 1706-1710/1721.