Lemon Juice: The Benefits of Citric Acid - The Dermatology Review

Lemon Juice: The Benefits of Citric Acid

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09.09.20 AD DISCLOSURE

What is Citric Acid?

Citric acid may be an ingredient that you are familiar with but may not be a skincare ingredient that you’re particularly familiar with the benefits of. Citric acid is a source of alpha hydroxy acid or AHA. AHAs are used to help improve the texture and overall appearance of the skin and are a cult ingredient used by both skincare fans and dermatologists alike. 

Citric acid is a weak acid that is widely found in both plants and animals, particularly in citrus fruits, which is what gives these fruits their characteristic acidic taste. One example is lemon juice, which contains about 5 to 8 percent citric acid. 

Interestingly, more than a million tons of citric acid are manufactured each year. There are many uses of this ingredient, including as an acidifier, as a flavoring, and a skincare ingredient. Because it is one of the stronger edible acids, the dominant use of citric acid is as a flavoring and preservative in food and beverages, especially soft drinks and candies. As Healthline discussed in their article on citric acid, it is often used in cheese and winemaking as well as in sauces and bread. 

Citric acid is also well known for its use in cosmetics and personal care products. According to the 2016 U.S. Food and Drug Administration’s Voluntary Cosmetic Registration Program, citric acid was used in almost every category of cosmetic product, with over 10,000 reported uses. However, it is essential to remember that these products are formulated by chemists with sensitivity and safety in mind. To get the benefits from citric acid, it is always best to use a product formulated with citric acid, as lemon juice by itself is often too harsh for the skin. 

Citric Acid

the good:Citric acid helps improve the texture and appearance of the skin by mildly exfoliating the skin and helping support skin cell turnover.  

the not so good:Citric acid and other AHAs can be too harsh for some sensitive skin types.

Who is it for?All skin types except those that have an identified allergy to it.

Synergetic ingredients:Works well with most ingredients

Keep an eye on:Keep an eye on the source of citric acid as most brands will use a natural identical or synthetically made citric acid. This is due to the environmental impact and expense of sourcing it from naturally occurring sources such as fruits.

Why Is Citric Acid In My Skincare?

Citric acid functions as an alpha-hydroxy acid or AHA, in skincare and cosmetic formulations. AHAs are a class of chemical compounds that consist of a carboxylic acid (-COOH) substituted with a hydroxyl group (-OH) on the adjacent carbon. AHAs can be naturally derived from fruit, like citric acid from citrus fruits, or they can be synthetically produced.

AHAs are well known for their use in the skincare industry as they have been used to reduce signs of aging, such as wrinkles, lines, and pigmentation. AHAs are also widely used for their potential to support the stimulation of collagen production. A study published in the Journal of Dermatologic Surgery determined that AHA treatments increase the production of collagen and fibroblast proliferation both in vivo and in vitro. Collagen is found within the dermal layer of skin, and it is responsible for keeping the skin smooth and firm. When the skin is stimulated to produce more collagen, fine lines and wrinkles may be visibly reduced.

Citric acid is also used in formulations to adjust the pH of formulations to prevent them from being too alkaline. The pH of cosmetics and skincare products is essential because the skin’s normal pH is slightly acidic, between 4.5 and 5.75. On the one hand, if a product is too acidic, it may irritate the skin or cause a stinging sensation. On the other hand, a product that is too alkaline is detrimental because it depletes your skin of vital, natural fats or lipids.

Citric acid treatments, when formulated correctly, can help brighten skin, reduce the appearance of pores, support the healing of mild acne, minimize the visible pigment associated with dark spots and help improve the appearance of fine lines. When applied to the skin, citric acid exfoliates the top layers of skin and sloughs off dead skin cells. Additionally, the speed of new cell turnover increases, which promotes new skin growth that can help alleviate the appearance of age spots, acne scars, small wrinkles, and areas of uneven tone and texture. 

What Are the Side Effects of Citric Acid?

Despite the benefits of citric acid, there are some side effects to using AHAs. A 2018 article published in the scholarly journal Molecules outlined that as a class, AHAs can cause swelling, burning, and itching after topical use. Another common side effect of AHAs is photosensitivity. Since AHAs remove dead skin and some of the upper layers of skin, you may sunburn easily from very little sun exposure or from using a tanning bed.

Irritation is the most common side effect of citric acid. As an acid, citric acid has a low pH of 2. This low pH is often responsible for irritation as the skin’s natural pH is 4.5-5.75. Using products with an acidic pH can disrupt the skin mantle barrier, which helps to protect the skin from moisture loss, allergens, and bacteria. This is why products that are formulated with citric acid use it sparingly to prevent irritation with prolonged use. However, if you have sensitive skin or skin with barrier issues such as dermatitis, it may be best to avoid products with this ingredient and look for gentler exfoliating options.

Who Should Use Citric Acid?

Citric acid products are generally suitable for most skin types when formulated with sensitivity in mind. However, if you have sensitive or irritated skin, you may want to avoid products with high concentrations of citric acid. 

What Should You Know About Using Citric Acid?

Research on the ability of citric acid to exfoliate the skin looked into the effects of much higher concentrations than are used in skincare products. This is important to note as results may not be as immediate as studies suggest at the concentrations that are generally used in skincare formulations. If you are looking for a higher concentration of citric acid in your product, be mindful that it may cause some sensitivity. If sensitivity occurs, reduce the frequency or discontinue the product and speak to your doctor or dermatologist. 

Is Citric Acid Safe?

The Cosmetic Ingredient Review Expert Panel reviewed scientific literature and data on the safety of citric acid and its salts and ester in 2014. This data revealed that at concentrations used in cosmetics and personal care products, citric acid and its salts and esters were not eye irritants, nor did they cause skin irritation or allergic skin reactions. Thus, CIR concluded that the available scientific data showed that citric acid, its salts, and esters were safe under current conditions of use in cosmetics and personal care products.

References:
Tang, S, & Yang, J, 2018. ‘Dual Effects of Alpha-Hydroxy Acids on the Skin’ Molecules, vol. 23, is.4.
Fiume, M et al., 2014. ‘Safety Assessment of Citric Acid, Inorganic Citrate Salts, and Alkyl Citrate Esters as Used in Cosmetics’, International Journal of Toxiciology.
Bernstein, E, et al., 1997. ‘Citric Acid Increases Viable Epidermal Thickness and Glycosaminoglycan Content of Sundamaged Skin, Dermatologic Surgery, vol. 23, is. 8, pp. 689-694.
Babilas, P, Knie, U & Abels, C, 2012. ‘Cosmetic and dermatologic use of alpha hydroxy acids’, Journal of the German Society of Dermatology, vol. 10, is. 7, pp. 488-491.

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