Green potatoes contain a larger amount of a toxin solanine. Potatoes naturally produce small amounts of solanine as a defense against insects, but the levels increase with prolonged exposure to light and warm temperatures. Solanine can cause nausea, headaches and neurological problems but for most people a large amount of green potatoes has to be eaten in order to experience these side effects. White potatoes and sweet potatoes have not been reported to have these same effects and may be a safer option. Try our Top 10 Ways to Enjoy Sweet Potatoes.