If you would have asked me this question few years ago I would jumped to answer Citrus fruits! It definitely has lots of Vitamin C but do not top the list!
Not so glamorous Bell Peppers tops the list! I did not believe it first time I heard it!
Next time you get some sniffles and think of chugging a glass of fresh orange juice add some orange bell pepper for a booster dose of Vitamin C. Also incorporate it in your daily diet by making an addition to your stir fry or salad or curry! I consider them innocent cause they blend in and can complement any dish without a fuss!
Papaya has even higher Vitamin C content then Bell Peppers but I am not putting it on the top of my list given most Papaya we import here in US are Hawaiian Papaya which is a GMO. (Might do more harm then good)
If you are a Non-GMO shopper like me bookmark this website: http://www.nongmoshoppingguide.com/ for tips and lessons to be a smart Non-GMO shopper!
Check out this table for produce with Vitamin C in ascending order:
|Food||Serving size||Calories||% DV||Nutrient Density|
|Bell Peppers||1 cup||28.5||157||98.9|
|Brussels Sprouts||1 cup||56.2||129||41.3|
Hope this helps and remember to give justice to all the produce in your daily meals!