Golden Apple

Golden Apples are the most difficult to obtain, but most beneficial Food item. They are extremely rarely found in dungeon and abandoned mine shaft chests, though they can also be obtained by crafting a red apple and eight gold blocks together. Eating one heals, and grants enhanced regeneration for 30 seconds, regardless of hunger level. Due to their rarity, they are most often obtained using an inventory editor.

Advantages

 * Golden apples are the only food that can completely refill the player's health, without a full hunger bar.
 * They are also the only food items that cause temporary constant health regeneration that is not dependent on the player's hunger. This is indicated by the line of hearts bobbing up and down in a wave pattern, with each full wave restoring half a heart.

Disadvantages

 * Red apples can only be found in Strongholds or by killing Notch in SMP.
 * Golden apples have an extremely slim chance of appearing in dungeon chests (0.9%).
 * Since each golden apple requires 8 gold blocks, or 72 ingots to craft, they are neither time nor resource efficient to craft as the equivalent amount of gold could yield 18 clocks or 72 powered rails, excluding other ingredients.

Pre-Release
As of Minecraft's 1.9 pre-release 2, Golden Apples now have a purple-ish glow when viewed from the player's inventory. Note: The glow effect is not shown when the apple is in the player's hotkey bar, but rather only when they are viewing their inventory, a chest or furnace.

Trivia

 * Golden Apples would weigh 387,000 pounds and be worth $8,938,496,000 in real life, based on the price of gold, how much is needed to create it, and it's density.