For alkalizing with a genuine improvement in health, I suggest have an alkalizing diet. You can take baking soda to make your body more alkaline in the short term, but an alkalizing diet would be much better in the long term.
Also
Synthetic vitamin C is acidic, and can make the body acidic. Lemon juice, is also rich in vitamin C and acidic, but makes the body more alkaline.
Nutrition from living plants is much more beneficial than synthetic substances.