Malic acid is an acid found naturally in foods, especially unripe fruits. It was first isolated from fruit juice, and one of the best sources of this naturally-occurring acid is apples. It's malic acid that gives green apples their tart taste. Malic acid is also found in a number of other fruits and vegetables and wine. As fruits ripen, the malic acid they contain is converted to lactic acid, which makes the fruit less tart.
Because of its tartness, malic acid is used to flavor some food and confectionary products, particularly sour candies. Some candies that contain large amounts of malic acid have a warning label on their boxes since malic acid is so tart it can cause mouth irritation. Malic acid is also used to flavor a variety of other foods including yogurt, fruit-flavored drinks, jams, jellies and ice cream Because of malic acid's sour flavor, it's usually blended with other acids and sugar to reduce its tartness. Malic acid also helps to block the growth of bacteria in food products, giving them a longer shelf life.
Malic acid is also found inside cells where it's an important intermediate for the production of cellular energy. A combination of malic acid and magnesium is available as a treatment for the symptoms of fibromyalgia, a condition characterized by muscle pain and generalized fatigue. Because of its involvement in cellular energy production, it helps to boost the energy level of people with this condition. It also appears to have a blood pressure-lowering effect and the ability to bind to heavy metals and remove them from the body. Malic acid is also important for oral hygiene. It stimulates the production of saliva, helping to reduce the risk of dental caries and gum disease.
Malic acid is also an ingredient in a number of cosmetic and personal care products. Some products that contain malic acid include shampoos, hair conditioners, facial moisturizers, anti-aging treatments and nail products. One of its functions in these products is to adjust the pH or acid-base balance of products. Products work best when they're at a certain pH and adding malic acid helps to achieve this optimal acid-base balance.
This acid with the naturally tart taste is also classified as an alpha hydroxy acid. Alpha hydroxy acids are added to anti-aging skin care products and moisturizers because of their ability to improve skin texture and reduce the appearance of fine lines and wrinkles. Alpha hydroxy acids like malic acid promote shedding of the outer layer of cells of the epidermis by loosening the "glue" that holds them together. This helps to thin the epidermis, which improves skin texture and the ability of skin to reflect light.
Alpha hydroxy acids can also penetrate more deeply into the skin and boost collagen production in the dermis, the deeper layer of skin that lies beneath the epidermis. Collagen is a protein that supports skin and prevents wrinkling and skin laxity. Therefore, alpha hydroxy acids like malic acid have anti-aging benefits. They also help to lighten skin pigmentation and improve the symptoms of acne. Other alpha hydroxy acids include glycolic acid, lactic acid, citric acid, tartaric acid and mandaleic acid.
Like other alpha hydroxy acids, malic acid is used as a skin peeling agent to help rejuvenate skin. Malic acid peels help to remove dead skin cells in the outer layer of skin that make it look dull and less youthful. These peels are also beneficial for unclogging pores and treating acne, although they're not as effective as another class of acids called beta hydroxy acids.
Since malic acid is found naturally in fruits, it appears to be safe in the amounts found in cosmetic and personal care products. When used orally as a supplement, it can cause mild stomach upset and bloating. In cosmetics and skin care products where it's applied topically, malic acid may cause skin irritation and redness, especially for people with sensitive skin.
In summary, malic acid is a safe, naturally-occurring acid found in some cosmetic and anti-aging products that helps to improve skin texture, unclog pores and reduce the appearance of fine lines and wrinkles.