When you select food in your character's inventory in Atlas, you will see colored arrows in the corner of the food icon. These are vitamins that this product contains, and they come in different colors. Cooked meat will help raise pink vitamins, and fish is linked to blue vitamins.
There are four types of vitamins available in the game - A, B, C and D. Their level decreases as you go hunting, fishing, exploring the world, etc. To replenish your vitamin supply, eat the following foods:
Vitamin A
Vitamin B
Vitamin C
Vitamin D
Be sure to check what vitamin a particular food offers in order not to get vitamin poisoning.