We find that God placed a tree of life in the midst of the Garden of Eden.
And out of the ground the Lord God made every tree grow that is pleasant to the sight and good for food. The tree of life was also in the midst of the garden and the tree of the knowledge of good and evil (Genesis 2:9).
Actual Trees
The Scripture makes it clear that the trees in the Garden of Eden were actual trees, there is no hint in the Bible that they were meant to be taken symbolically. It is not possible for us to determine anything of the nature of the trees in Eden. God would have somehow made it clear which tree was the tree of life, and which was the tree of the knowledge of good and evil.
Nothing Magical
We must note that the Bible does not emphasize there was anything magical about the fruit on the tree of life. The life humankind experienced would be due to their obedience to God rather than any physical results from eating from the tree.
Stopped The Decline
On the other hand, some commentators believe that eating the fruit stopped the physical decline of their bodies and safeguarded them against disease. But this we cannot know for certain. We can safely conclude that in some manner eating from the tree preserved the life Adam and Eve had in their perfect state.
Lived Forever Without Sin
The tree of life represented the perfect state where man and woman were placed. Had they obeyed God, they would have lived forever without sin and pain. Sin and death would have not entered the world. They would have voluntarily chosen God over the temptation of the devil. Thus they would have lived in this perfect environment by exercising their own choice to serve God rather than the devil. However, by their own choice, this was not to be.
Why Not Prohibit Eating?
According to Scripture, God did not prohibit Adam and Eve to eat the tree before the Fall. God did not prohibit eating that tree, as well as the tree of the knowledge of good and evil, because it represented the choice of humanity. By making both of the trees, God provided humanity with a legitimate choice between good and evil. If humankind would have chosen God rather than eating from the forbidden tree, then they would have lived forever in a perfect state. By giving humankind the choice, God gave humankind the chance to serve Him.
Another Tree Of Life
The tree of life and the tree of the knowledge of good and evil were both in the midst of the Garden of Eden. When God creates a new heaven and new earth there will be another tree of life.
And he showed me a pure river of water of life, clear as crystal, proceeding from the throne of God and of the Lamb. In the middle of its street, and on either side of the river, was the tree of life, which bore twelve fruits, each tree yielding its fruit every month. And the leaves of the tree were for the healing of the nations (Revelation 22:1,2).
God promised that those who trust Him would eat of this tree of life.
To him who overcomes I will give to eat from the tree of life, which is in the midst of the Paradise of God (Revelation 2:7).
Believers Only
Those, however, who do not trust the Lord will not be permitted to eat from this tree.
Blessed are those who do His commandments, that they may have the right to the tree of life . . . But outside are dogs and sorcerers and sexually immoral and murderers and idolaters, and whoever loves and practices a lie (Revelation 22:14,15).
Summary
The tree of life in the midst of the garden represented the life humankind would continue to have as long as they obeyed God. Eating of the tree represented their continual obedience to the Lord. In some manner, eating from the tree perpetuated their eternal life.
In the future, those who obey God will be able to eat eternally from a new tree of life in the midst of His new heaven and earth.