In plants, phytochemicals confer characteristics like color, which can help the plant by providing an attractive beacon to passing bees to help in pollination. Or they offer a protective effect to the plant to prevent insects from harming it, or repel grazing animals. But they have often been found to have benefits for human health when analyzed in laboratories. It is these chemicals in plants that make fruit and vegetables so much more valuable than simply the macro nutrients like vitamin C.
Antioxidants are one class of phytonutrients, though there are many. Antioxidants work by supplying an extra oxygen molecule to those molecules that are missing one, called free radicals. If antioxidants don't supply the missing oxygen molecule to free radicals, the free radicals will take an oxygen molecule from another compound in the body, making one that was previously healthy and intact itself a free radical. Free radicals are not 'baddies', simply unstable chemical molecules, but the effect they have on the body is negative, as they can damage cells. Free radicals are produced as a normal by product of the metabolic processes of our cells, as well as by our immune system as it counteracts the effects of pathogens and the environment.
The trick is to keep the balance in the body where there is enough of a supply of antioxidants to cope with the body's production of free radicals.
Free radicals affect the skin in three main ways. They can alter the fatty layers in your cellular membranes. These fatty layers provide structure to the cell, and control which nutrients and other agents can pass in and out. They can alter the DNA within cells, which aside from the potential to develop into serious illnesses, can make your skin inclined to wrinkles and sagging before its natural biological time. Altered DNA creates a blueprint for collagen and elastin fibers that don't function as healthy, normal ones would. And to compound matters, the skin's pores need healthy collagen and elastin fibers to stay tight and small. So another undesired result is open, large pores.
Free radicals also lead to a process called the cross-linking of collagen fibers. This occurs in the skin's dermis, as a result of collagen and elastin fibers becoming hard, thick, and then binding together. Cross-linked fibers create wrinkles, skin sag, and cause your regular expression lines to become etched in your face as a permanent fixture. With healthy collagen and elastin fibers these expression lines would simply disappear once you moved your facial muscles in a different way. And enzymes that metabolize collagen are encouraged by free radicals, which, given the importance of collagen in youthful looking skin, is best minimized.
Other phytonutrients in plants that are of importance to skin beauty are carotenoids and flavanoids. Flavanoids are great for the health of blood vessels. They strengthen the capillaries that supply important nutrients to the skin's cells, as well as supporting cellular membranes. Healthy cell membranes regenerate quickly, and slow the aging process. Carotenoids also strengthen cell membranes. It seems carrots are not just good for eyesight! And flavanoids help reduce inflammation, as well as increasing levels of glutathione, which is an antioxidant.
References: Erica Angyal, Gorgeous Skin In 30 Days (Lothian Books, 2005)
