The essential dietary nutrient and food additive, ascorbic acid, the chemical name for vitamin C, helps keep you healthy when taken in recommended amounts. If you consume more than 2,000 milligrams daily, the safe upper limit of vitamin C, you may experience uncomfortable side effects that do not usually pose a threat to your long-term health.
Dietary sources alone usually do not cause excessive intake of ascorbic acid, because your body gets rid of what it does not use. If you take supplementary vitamin C in large doses, however, you may experience digestive symptoms, including diarrhea. Large amounts of ascorbic acid can overwhelm the capacity of your intestines to absorb this nutrient. Unabsorbed, excess ascorbic acid leads to increased water in your bowels and diarrhea. If you experience diarrhea because of excessive ascorbic acid supplementation, reduce your dosage.
If you consume too much ascorbic acid, you may develop abdominal cramps. As water accumulates in your bowels because of ascorbic acid overload, spasms and painful cramps often occur. Abdominal cramps associated with ascorbic acid overload typically happen before diarrhea develops. Once the excess ascorbic acid passes in your stool, the abdominal cramps go away -- unless you continue to overload your system.
Increased Kidney Stone Risk
Consuming excess ascorbic acid may increase your risk of forming a kidney stone. How people metabolize excess ascorbic acid varies. In a July 2005 study published in the "Journal of Clinical Nutrition," registered dietitian Linda Massey and colleagues reported that approximately 40 percent of study subjects given 2,000 milligrams of ascorbic acid daily produced high levels of urinary oxalate, a breakdown product of ascorbic acid. High concentrations of urinary oxalate can lead to the formation of a kidney stone. If you have had a kidney stone, talk with your doctor before taking a vitamin C supplement.
Sources of Ascorbic Acid
Ascorbic acid occurs naturally in high concentrations in a variety of fruits and vegetables, including oranges, grapefruit, sweet peppers, papayas, strawberries, broccoli, Brussels sprouts, peas and kiwis. As a food additive, ascorbic acid helps preserve the color and flavor of food. Foods that may contain added ascorbic acid include cured meats, ready-to-eat cereals, rolled oats, fruit drinks, powdered milk, cheese, sherbet, sorbet, vinegar, mustard, canned fruit and wine. High-dose vitamin C supplements typically cause ascorbic acid overload, which rarely occurs from dietary sources alone.
- Institute of Medicine of the National Academies, Food and Nutrition Board: Dietary Reference Intakes (DRIs): Recommended Intakes for Individuals
- University of Maryland Medical Center: Vitamin C
- National Institutes of Health, Office of Dietary Supplements: Vitamin C
- Oregon State University Linus Pauling Institute: Vitamin C
- The Journal of Clinical Nutrition: Ascorbate Increases Human Oxaluria and Kidney Stone Risk