Have you seen advertisements for products such as coral calcium or alkaline water that are supposed to neutralize acid in your bloodstream? Taking calcium or drinking alkaline water does not affect blood acidity. Anyone who tells you that certain foods or supplements make your stomach or blood acidic does not understand nutrition.
You should not believe that it matters whether foods are acidic or alkaline, because no foods change the acidity of anything in your body except your urine. Your stomach is so acidic that no food can change its acidity. Citrus fruits, vinegar, and vitamins such as ascorbic acid or folic acid do not change the acidity of your stomach or your bloodstream. An entire bottle of calcium pills or antacids would not change the acidity of your stomach for more than a few minutes.
All foods that leave your stomach are acidic. Then they enter your intestines where secretions from your pancreas neutralize the stomach acids. So no matter what you eat, the food in stomach is acidic and the food in the intestines is alkaline.