The six tastes in Ayurveda come from the five elements.  They are: Earth + Water = Sweet Earth + Fire = Sour Water + Fire = Salty Air + Space = Bitter Air + Fire = Pungent Air + Earth = Astringent

Because Vata is composed of Air and Space, Vatas stay in balance better when they favor foods that are sweet, sour and salty.

Pitta is composed of Fire and Water, so Pittas stay in balance when they favor foods that are sweet, bitter and astringent.

Kapha is made up of Water and Earth.  Kaphas are better balanced when they favor foods that have bitter, pungent and astringent tastes.