When it comes to hyperpigmentation, though, experience has proven that it is not as permanent a solution as laser treatments or stronger peels. In comparison, hydroquinone, which was once touted as the preferred skin lightener, has now been shown to promote cytotoxicity and irritation that can actually increase dark spots and discoloration over time. Old beauty regimens recommended rubbing whole lemons on rough, dark elbows and using lemon juice as a type of toner on a daily basis to combat age spots. These regimens did work if the person performing them did not mind the stinging and burning from rubbing lemons directly onto the skin too often.

HOW IT WORKS
Lemon juice derived directly from real lemons, not the processed versions often found in bottles, can be used as an effective skin bleaching ingredient. Lemons typically contain between five and eight percent citric acid and have a pH of around 2.3, making them highly acidic. These high levels of ascorbic acid are also known as vitamin C. Natural aging, excessive exposure to ultraviolet rays, and daily pollution can all cause a decline in vitamin C content in the dermis. Using lemon juice as a natural treatment can pack a triple punch of exfoliating, stimulating collagen, and reducing melanin production.

The production of melanin is the skin's response to protecting itself from sun damage. When people overindulge in sunbathing or forget to wear sun protection, the melanin production produced by the enzyme tyrosinase goes into overdrive, producing dark patches, sun spots, and other forms of hyperpigmentation. Vitamin C, or ascorbic acid, is a natural exfoliant that can help lighten the skin and improve skin tone.

The epidermis is exfoliated by the acid, gently sloughing old skin cells, including cells with dark pigmentation. Topically applying lemon juice, or vitamin C, will show mild skin-lightening effects caused by reductions in melanin production and melanin oxidation. Vitamin C also acts as a powerful antioxidant that can stimulate the production of skin collagen and protect the skin against free radicals. Vitamin C also limits the damage induced by ultraviolet light exposure.

A 2011 medical review at Oregon State University on vitamin C and skin health found that "the antioxidant properties of vitamin C (ascorbic acid) and its role in collagen synthesis make vitamin C a vital molecule for skin health. Dietary and topical ascorbic acid have beneficial effects on skin cells, and some studies have shown that vitamin C may help prevent and treat ultraviolet (UV)-induced photo-damage."1

Due to its high acidity, lemon juice should only be used in low concentrations, three-to-four times per week to avoid skin irritation and excess dryness. One solution is for clients to add a few drops of lemon juice to their daily moisturizer or toner to reap the benefits without the burn. Lemon juice will also make their skin photosensitive, so remind clients to limit their sun exposure and always use a broad spectrum sunscreen.

Skin care professionals continue to look for safer, more natural alternatives to chemically formulated skin lighteners. Vitamin C obtained from natural lemon juice can be a great alternative, as long as it is used sparingly or combined in lower concentrations with other topical carriers.

Reference
1. Michels, A. J. (2011, September). Vitamin C and skinhealth. Linus Pauling Institute. Oregon University.