In normal digestion, food and fluid pass from the stomach to the small intestine, where nutrients are absorbed and wastes are passed. Your digestive system needs vitamin C to complete this process.

Vitamin C is a water-soluble vitamin that dissolves in the blood and leaves the body through urine. It also acts as an antioxidant, helping to block some of the damage caused by free radicals.

Side Effects

The recommended daily amount of vitamin C is 75 to 90 milligrams, which is easily attainable by eating a diet rich in fruits and vegetables like citrus, broccoli, strawberries, and peppers. Many people take high doses of vitamin C in supplement form, however, in hopes of improving their overall health or bolstering their immune system during illness. In some cases, this increased intake of vitamin C can lead to side effects such as diarrhea.

When vitamin C is taken orally, it enters the intestines where it gets converted to a water-soluble form called dehydroascorbic acid. This vitamin is then absorbed by cells, where it is reduced to ascorbic acid. Unlike other vitamins, our bodies don’t store vitamin C, which means that any excess amounts are eliminated from the body through urine. Because the body does not hold onto vitamin C, it’s important to consume it regularly to avoid a deficiency.

IV vitamin C enters the bloodstream directly, bypassing the stomach and intestines, which may minimize the risk of adverse reactions. Each person has a unique tolerance and sensitivity to substances, so it’s important to communicate any pre-existing digestive issues with a healthcare professional before receiving an IV treatment.

Dosage Tips

Although vitamin C is generally safe at high doses, it can still cause diarrhea when it exceeds bowel tolerance levels. The condition usually subsides within a day or two once you stop taking excessive amounts of the supplement.

Since vitamin C is water-soluble, it doesn't get stored in the body and any excess gets excreted through the urine. You can get enough of the nutrient in your diet by eating five varied servings of fruits and vegetables per day. Vitamin C also improves the absorption of non-heme iron (from plant foods) in your digestive tract and helps the body absorb copper from food or supplements (1).

Antioxidants are like invisible superheroes in your body, protecting you against the free radicals that can damage cells, promote aging and contribute to chronic health conditions such as cancer, heart disease and arthritis. Vitamin C is one of the most potent antioxidants available and has been shown to reduce oxidative stress in the colon and enhance mucosal health.

If you want to add more vitamin C to your diet, be sure to choose a natural or synthetic supplement with no added sugar. Also, look for buffered ascorbate powder or effervescent tablets, which may be easier on the stomach if you are prone to gas and bloating.

Health Facts

As a powerful antioxidant, vitamin C helps protect cells from damage. It also plays a role in building and strengthening tissues, healing wounds and supporting the immune system. Registered dietitian Devon Peart says that most people get enough vitamin C through their diet, but those who eat little or no fresh fruits and vegetables can become deficient in vitamin C. Getting too little of this essential nutrient can lead to scurvy, which is most common among malnourished adults. Vitamin C has low toxicity, and high intakes from supplements are unlikely to cause problems because the body does not store this water-soluble vitamin. However, too much vitamin C can lead to diarrhea and gastrointestinal upset because of the osmotic effect of unabsorbed supplement in the digestive tract.

Foods that are rich sources of vitamin C include oranges, red and green peppers, cantaloupe, apricots, papaya, strawberries and raw leafy vegetables such as turnip greens and spinach. You can find supplemental vitamin C in tablets, capsules and chewables or in powdered crystalline or effervescent forms. It's also available as an esterified form that may be easier on the stomach than ascorbic acid. Ask your doctor about adding this nutrient to your diet, or talk to a dietitian who can help you determine the best dosage of supplements for your needs.