Vitamin C, also known as ascorbic acid, is a powerful antioxidant that plays a vital role in maintaining a healthy immune system, skin, and tissue repair. It also helps the body absorb iron from plant-based foods. 

Here are some foods that are rich in vitamin C:

1. Citrus fruits: Oranges, lemons, limes, grapefruits, and tangerines are excellent sources of vitamin C. One medium orange provides about 70 milligrams (mg) of vitamin C.

2. Kiwi: Kiwi fruit is another great source of vitamin C. One medium-sized kiwi provides about 64 mg of vitamin C.

3. Red bell peppers: Red bell peppers are one of the best sources of vitamin C. One medium-sized red bell pepper provides about 152 mg of vitamin C.

4. Strawberries: Strawberries are rich in vitamin C. One cup of sliced strawberries provides about 98 mg of vitamin C.

5. Broccoli: Broccoli is a cruciferous vegetable that is rich in vitamin C. One cup of cooked broccoli provides about 81 mg of vitamin C.

6. Tomatoes: Tomatoes are a good source of vitamin C. One medium-sized tomato provides about 24 mg of vitamin C.

7. Brussels sprouts: Brussels sprouts are another cruciferous vegetable that is rich in vitamin C. One cup of cooked Brussels sprouts provides about 97 mg of vitamin C.

By including these vitamin C-rich foods in your diet, you can help boost your immune system and support overall health. Aim to consume at least 75-90 mg of vitamin C daily, which can easily be achieved by eating a varied diet that includes fruits and vegetables.