Eat your fruits and veggies raw whenever possible. When you cook them, you strip the food of some of its vital nutrients. Cooking especially affects water soluble vitamins, such as vitamin C.
Keep a bowl of vitamin-C rich fruit in the house for snacking. A grapefruit for breakfast is not a bad idea. You may also consider eating more oranges, mangos and kiwifruit.
Have a light lunch with a side of crudité. Raw broccoli and red peppers are extremely high in this powerful antioxidant.
Eat more fermented vegetables. One serving of kimchi (a traditional Korean recipe made of fermented cabbage) provides about half of your recommended daily value of vitamin C. Sauerkraut is also a good option; just be sure to buy it in the refrigerated section. In addition to vitamin C and other vitamins, kimchi and sauerkraut also contain gut-strengthening probiotics.