You need vitamin C for healing wounds, forming collagen and keeping your teeth and bones healthy. It also acts as an antioxidant, helping to limit cell damage from harmful substances called free radicals. Men need at least 90 milligrams per day, and women need at least 75 milligrams daily. Don't let concerns about acidity keep you from getting your recommended vitamin C -- this vitamin won't alter your body's acid levels.
Vitamin C and Acidity
Vitamin C is also known as ascorbic acid and is considered a weak acid. This doesn't mean it makes your body more acidic. In fact, vitamin C-rich foods, such as citrus fruits, are considered alkaline-forming foods, as the body burns the acids, leaving an alkaline end product. This doesn't mean that citrus fruits are a good idea for people trying to limit acidic foods because of acid reflux, however, as the acids in the food can still cause pain going down if your esophagus is damaged due to reflux.
Food and Blood Acidity
According to a classic article published in the American Journal of Public Health, foods won't change your blood acidity levels except perhaps in the case of a serious illness. Your body is designed to carefully regulate its acidity levels. One way it does this is by controlling your breathing rate. Should your blood start to be slightly acidic, you may start to breathe slightly faster to remove more carbon dioxide from your blood, which reduces the blood's acidity.
Food and Urine Acidity
While acid-producing foods don't make your blood more acidic, they can make your urine more acidic. Any excess acid formed from the food you eat gets eliminated by your kidneys into your urine, which is another way your body maintains the proper blood acidity level. The vitamin C you get from foods shouldn't have this effect, however, as most fruits and vegetables are alkaline-forming rather than acid-forming. As for supplements, you'd have to consume very large amounts for them to have an effect on your body's acidity levels.
Potential Health Effects
Check with your doctor before taking vitamin C supplements. Vitamin C isn't likely to make your body acidic, but it may have some other effects if you consume it in excessive amounts. The tolerable upper intake level is 2,000 milligrams per day. When consumed in amounts higher than this, vitamin C supplements might have a diuretic effect and cause an upset stomach, gas and diarrhea. Vitamin C supplements may also interact with certain medications, including nonsteroidal anti-inflammatory drugs, tetracycline, blood thinners, HIV medications, antacids, chemotherapy medications and birth control pills.