Polyphenols are natural or synthetic molecules, soluble in water with a molecular weight of 500 to 4000 Da, with more than 12 phenolic hydroxyls, and 5 to 7 aromatic rings for every 1000 Da. They are capable of combating excess free radicals responsible for the onset of diseases and premature skin aging. They can be found mainly in natural foods such as fruits, vegetables, and greens.
One type of situation that leads to the formation of free radicals is skin exposure to UV solar radiation, which can result in consequences such as wrinkling, peeling, dryness, hyper or hypo-pigmentation, and skin cancer. The skin has an efficient antioxidant protection that gradually decreases over the years.
It has long been known that the intake of certain types of foods with antioxidant power can help combat free radicals. Some examples of such foods are: onion, cocoa, grape seeds, green tea, apple, and red wine, citrus fruits, cherries, and soy. However, only more recently have studies begun to emerge related to the protective power of these compounds against the harmful effects of UV radiation on the skin.
Polyphenols are known to have a chemoprotective effect in tumor protection, and the increasing knowledge of molecular and cellular techniques makes them potential candidates for cancer prevention. More recently, polyphenols are also being studied as topical protectors against UV radiation from the sun. Most natural polyphenols are pigments, usually yellow, red, or purple in color, capable of absorbing part of the UV radiation, reducing its effects on the skin. The absorption spectrum of polyphenols includes the wavelengths of UVB, and part of UVC and UVA.
An example recently studied by a group from the dermatology department at the University of Alabama in Birmingham (USA) in 2009 was the effect of polyphenols from green tea (image on the side ©leojmelsrub) when added to drinking water and administered to hairless mice. The result indicated a decrease in skin edema induced by UV radiation and also the inhibition of the expression of the COX-2 enzyme and the formation of prostaglandins, which are typical biomolecular markers of keratinocytes when exposed acutely or chronically to UVB radiation. The COX-2 enzyme and prostaglandins are also indicators of carcinogenesis and the appearance of skin tumors.
Despite many evidences in the medical literature indicating the benefits of using polyphenols as protective molecules against the onset of skin cancer, and also in the prevention of issues such as inflammation and premature aging, such compounds can be used daily only as adjuncts in the prevention of these problems and not as substitutes. However, it is still very early to say that we will soon have any pill or cream based on polyphenols that will be able to guarantee 100% prevention of skin cancer and other issues related to UV radiation exposure.
The best remedy for maintaining healthy skin and health is still good nutrition, healthy lifestyle habits, and living without stress. Is it possible? With effort, yes. The reward: a peaceful old age with much well-being.
Photo credits for the table: ©FotoosVanRobin, ©Hekay and ©Wikimedia
Source:
Joi A. Nichols, Santosh K. Katiyar. Skin photoprotection by natural polyphenols: anti-inflammatory, antioxidant and DNA repair mechanisms Arch Dermatol Res (2010) 302:71–83.
Phenolic Compounds
Where to find
Phenolic Acids
Coffee and Blueberry
Anthocyanin
Grapes
Flavonols
Onion, Apple, red wine, broccoli
Isoflavones
Soy
Lignans
Whole grains
Resveratrol
Skin of dark grapes
