The three gunas are Sattva, Rajas and Tamas gunas. These categories define and reflect our health, behaviour, thinking and diet.
Sattvic means purity, health, harmony and well-being.
Rajasic means stress, anger, activity and restlessness.
Tamasic means dullness, laziness and lethargy.

Sattvic foods are soothing, nourishing and promote and maintain a quiet, steady mind as well as help to sharpen your intellect. Sattvic foods are vegetarian and do not include foods derived from animals that have been harmed in any way and products which are free from animal rennet. It is important that foods are grown naturally and do not contain preservatives, artificial flavors, or additives. A sattvik food will become tamasic when over processed, kept for a longer period or deep-fried.

A sattvic diet generally consists of:

fresh, organic fruit and vegetables
whole grains and nuts
dairy products such as milk and ghee
beans and lentils
plant-based oils
mildly sweet foods (natural, unrefined sugars), honey, molasses
spices such as cinnamon, basil, coriander, ginger and turmeric.