I personally take the cheap stuff apart from my two doses a day of New Chapter. I take 3 grams a day of the cheap stuff and half a gram of the high quality New Chapter which compares to Mega Food C. I never get sick. I also take D-3 10,000 IU daily.
People in my apartment building are getting the flu all the time. My niece in her 30s got the flu twice last winter. But she is exposed to kids and at work. She does eat sugar by the 5 pound bag.