As if potential cataracts or macular degeneration weren't reason enough to make sure you get your vitamin C, it may also prevent and alleviate glaucoma. Studies have shown it to reduce pressure in the eyes of glaucoma patients. You should absolutely get the RDA every day. If you smoke, drink or have diabetes, you should try to take in extra vitamin C, because your levels will tend to be lower than average. The above values are for raw foods.
Cooking can change the values, as heat tends to decrease the vitamin C content.
Like vitamin A, C is better fresh than frozen or canned, as either process could deplete the amount of the vitamin. They're compounds that give certain foods their color and they often work as antioxidants. The good news is that almost any food that has vitamin C in it also has bioflavonoids, so there is no extra list of foods for you to eat. The white part in the center of citrus fruits is an excellent source of bioflavonoids, and you can also get them from red and purple fruits, such as cherries, grapes and plums. Buckwheat is another good source.