I take Vit c with bioflavonoids, usually 4-5000mgs a day with no ill effects. I'm also taking a powder called Camu Camu which is from the Amazonian rainforest. It is a light orange coloured fruit about the size of a lemon and contains the highest recorded amount of natural vit c known on the planet. I take a teaspoon a day and mix it with water. It tastes like sherbert!