Vitamin C taken orally is not effective enough?

Absorbed about 70% of vitamin C taken by mouth. When the amount of nutrition or as a supplement high absorption rate is reduced. For this reason, small amounts needed to be taken by mouth is more accurate. Moreover, vitamin C, heat, light, and quickly lose their effectiveness is found in contact with air, caution should be exercised in this regard. Parenteral (intravenous) route taken will not decrease the effectiveness of 100%, and much more effective than blood may get involve