Function

• Citric acid is often confused with ascorbic acid, or vitamin C. While they have a similar chemical makeup, they are different. Citric acid's primary role is as part of the Krebs cycle, in which the body produces ATP, the main source of cellular energy.
  
  

Citric Acid in Fruits

• While citric acid is detectable in most plants, the primary fruit source is citrus fruits, such as lemons, grapefruits, oranges and limes, but it also occurs in pineapples and gooseberries. Of the citrus fruits, lemons and limes generally have the highest levels. Often, but not always, the tartness of a fruit can be an indication of the presence of citric acid. The table in the "Resources" section below lists the citric acid levels of various fruits and juices.
  
  

Commercial Uses

• A weak acid, citric acid is often used as a preservative. If you've ever eaten a food or sipped a beverage that has a tart taste, that taste is likely due to added or naturally occurring citric acid. Citric acid is also used in the manufacture of certain cleaning products, especially those that are more environmentally sensitive.
  
  

Other Uses

• In addition to its internal antioxidant properties, citric acid is sometimes applied topically in creams to help rejuvenate the skin. Through chelation, a type of chemical bonding, it also helps your body absorb certain minerals, such as calcium, and it often will be included in the production of mineral supplements. It is also used to acidify and preserve in home canning.
  
  

Considerations

• While citric acid is generally very safe, it is an acid and may irritate some people's skin. It can also cause stomach irritation. You should speak with your doctor if you take supplements with citric acid or eat a lot of fruits containing it, as it may have an effect on the effectiveness of medications that you take.