Do you see what I see from Vitamin C?

Hello there! I'd like to share something today. I've tried a couple of times to reply to a thread in a forum but to no avail. So before my frustration could reach its peek meter, I've decided to post it here instead.

But let's start first with a short introduction.

Vitamin C (Ascorbic acid) is a water soluble vitamin which is essential for the body. It has many benefits. Among these are for collagen formation and for strengthening the immune system. You can search in the Internet for more benefits of Vitamin C. And you can take it authentically or synthetically.

Natural foods such as oranges, papaya, lemon, red bell peppers, tomatoes, guava, etc. belongs to what I call authentic. Those supplements taken over the counter are what I call synthetic. I firmly believe that foods that we eat naturally is the best source of Vitamin C.

Now, there was this person who was asking why is he getting more sick though he was taking Vitamin C (whether regardless it was natural or supplemental) for 2 weeks. When he stop taking it, it made him feel better.
My supposed-to-be answer to him would go like this:

I've experienced it, too. Whenever I had bad colds, my mother would always scold me why I was not taking Vitamin C supplements everyday. I would just shrug it off and always tell her that I'm getting the amount of Vitamin C needed in my diet so there's no need for me to take more. In the past, I've had this notion that taking more tablets of Vitamin C would mean that I'll be more resistant to colds especially during rainy days.

Taking 2 tablets of vitamin C morning which are 500 milligrams each and 2 for the evening worked at first but later it just made it worst. So what did I do whenever I had a cold is this:

Sleep earlier than usual. Our body needs to recuperate more. It is one effective way of boosting your immune system.
Eat guava. I don't know if it is just me or it's only psychological but I remember my mother recommending this over oranges and dalandan. I guess, more Vitamin C? In my experience, guava helps me to recover faster and I pretty much like munching it too.
Frequent handwashing. Better to do it with soap and water. No need to say more.

I've read somewhere that Vitamin C will be much more effective if taken before catching a cold. I'm still confused whether there is really an overdose of Vitamin C since what I know is that it is a water soluble vitamin. Any excess would just go out in the the urine.