Oxalate is a substance found in some plants. It causes kidney stones in some people, so a low oxalate diet is necessary.e of the foods to avoid are strawberries, rhubarb, spinach, beets,hocolate, tea and coffee. Dietary vegetarian meals are low fat, well-balanced and high fibre. Grains, seeds, nuts, fruits, legumes, eggs, yogurt are some healthy alternatives to meat & fish.