We've all heard the saying "An apple a day keeps the doctor away." Presumably, the vitamin C content of apples is the easiest way to keep our immune systems functioning well. But the truth is that apples are not the best source of this key vitamin. Some say the greatest vitamin in the world is vitamin C.

Vitamin C can be found in a wide range of fruits and even vegetables. So there's no reason why everyone can't get their daily dose from something they enjoy eating. In fact, there are so many good sources that you could get yours from a different food every day of the month!

Some of the best foods for getting vitamin C may surprise you. Sure apples are fine with their 6 mg of vitamin C per 100 grams of fruit. But even the humble orange compares well with 53 mg, beating out grapefruits with their 34 mg What could be better than oranges?

How about a handful of fresh strawberries? They'll give you 57 mg of vitamin C per 100 grams. Sounds pretty good, doesn't it? But you can do even better than that. The humble kiwi fruit beats them all, packing in a whopping 98 mg of them per 100 grams.

If you're lucky enough to live in a spot where you can get your hands on some guava, you're in luck. This tasty, tropical fruit clocks in with a very impressive 180 mg of vitamin C per 100 grams.

Even if you can't find it fresh, you can get the same benefits from canned guava. Another super-rich source is the tiny black currant. 100 grams of these potent berries will supply about 200 mg of them. That's the full recommended daily dose!

The quest for the ultimate source of vitamin C has led nutritionists to discover the delights of some very tropical findings. The most impressive levels can be found in jujube, camu camu and acerola. If you haven't seen those in your local supermarket don't worry, there are plenty of other ways to get your vitamins.

Most of us aren't surprised to find them in fruit, but what is surprising is how easy it is to find in vegetables. Unlikely sources like cabbage, broccoli and cauliflower are great for people trying to cut down on their carbohydrates without letting their nutrition suffer.

Even using fresh herbs like coriander, parsley and thyme can boost your intake of them. But if you really want a vegetable that will provide a substantial dose of this important vitamin, look no further than sweet green or red peppers. Just 100 grams of green pepper will top up your vitamin C intake by 190 mg

So if you've been comparing apples to oranges all of these years, it's time to look at what else is available. There are so many wonderful foods that boost your vitamin C levels, your toughest decision may be which one to have first.