August 2012 Issue

“Edible” Plants as Sunscreen

Some plant foods, including tomatoes and soy, contain powerful compounds that may help protect your skin from the damaging effects of UV radiation. So, this summer, take a bite of edible sunscreens.

In nature, living plants need to protect themselves from harmful ultraviolet (UV) rays, just as humans do. The color pigments and nutrients that naturally protect plants from harmful rays can also provide sun-protection to humans. Going back hundreds of years, plants such as olives and aloe vera, can be found in dozens of lotions, creams and topical ointments because of the many skin benefits attributed to their use. Now, more than ever, compelling research indicates that your consumption of a variety of colorful plant foods can play a vital role in protecting your skin—from the inside-out.

Plant compounds that fight sun damage. Skin-protective plant compounds (phytochemicals) include carotenoids, polyphenols, and isoflavones, among many others. Phytochemicals and nutrients work in a variety of ways to offer skin protection. Some absorb damaging UV rays and decrease sunburn, while others provide antioxidant and/or anti-inflammatory compounds that protect the skin cells from free radicals that damage DNA and may lead to skin cancer. Human skin naturally contains antioxidants that protect the skin; however, it’s important to maintain optimal dietary antioxidant intake to fortify the skin’s defenses over an extended period of time. Here’s a look at some of the most promising skin-protective nutrients.

• Carotenoids. These naturally occurring pigments protect the plant against excess light—and it looks like they offer similar effects for us. According to a 2007 study published in Molecular Biotechnology, carotenoid-rich diets have been shown to protect the skin by decreasing sensitivity to UV radiation-induced erythema (redness of the skin caused by sunburn.) Studies suggest the benefits of including the carotenoid beta-carotene in the diet, as it provides an immune defense against free radicals and the development of skin cancers. Beta-carotene is found in orange-colored fruits and vegetables including carrots, cantaloupe, sweet potatoes, mango and dark-green leafy vegetables including spinach and kale. Aim for 30 milligrams of beta-carotene per day by eating one to two servings of orange and/or green produce.

Lycopene, a carotenoid found abundantly in red-colored produce including tomatoes, watermelon and red bell peppers, has been shown to have even greater impacts than beta-carotene in protecting the skin against sunburn by decreasing the skin’s sensitivity to UV light and reducing the likelihood of sunburn. A 2011 study in the British Journal of Dermatology found that lycopene intake through daily servings (55 grams each) of tomato paste had a protective effect against UV-induced sunburn. A study in 2001 reported in the Journal of Nutrition demonstrated that a lycopene-rich diet from daily servings of tomato paste (40 grams) served with 10 grams of olive oil over 10 weeks resulted in a 40 percent reduction in sunburn. So, try to include lycopene-rich foods in your diet every day for maximum protection. 

• Antioxidant vitamins C and E. It is well known that antioxidant vitamins C and E, naturally found in the skin, play an important role in maintaining the integrity of skin. Berries, citrus fruit, and kiwi are abundant sources of vitamin C in the diet. Vitamin E is found in vegetable oils and nuts. Studies indicate that vitamins C and E are depleted in UV-light exposed areas of the skin. Further investigation illustrates that these antioxidants can both protect us and reduce the severity of sunburn. The latest evidence reported in a 2010 study in Nutrients indicates that sun protection is maximized when vitamin C and E are supplemented in combination, rather than taken individually. Increase your servings of fruits and vegetables and include a handful of nuts and seeds every day for maximum vitamin C and E intake.

• Polyphenols. Consuming a plant-rich diet that includes tea, cocoa, grape seeds, onions, apples and soy foods is an easy way to ensure optimal intake of polyphenols—plant compounds that provide protection against the development of skin cancers. A 2010 review in the Archives of Dermatology Research concluded that polyphenols protect the skin from adverse effects of UV radiation by suppressing, retarding or reversing the process of carcinogenesis. For example, the polyphenol epigallocatechin 3-gallate from green tea (Camellia sinensis) has been shown in animal studies to protect against the development of non-melanoma skin cancer, and reduce and possibly reverse tumor growth. Similar results were found in most of the polyphenols studied. A 2000 study conducted in southeastern Arizona showed that hot tea drinkers had significantly lower risk of skin cancer, compared with non-drinkers. Drinking one to two cups of brewed tea regularly may maximize benefits.

• Isoflavones. Genistein, an isoflavone and antioxidant found primarily in soybeans, shows activity in preventing tumor development and sun damage. Evidence suggests that the high soy intake of Asians is responsible for the fact that wrinkling is not noticeable until about age 50 in this ethnic group. In addition to consuming isoflavone-rich soyfoods (aim for two or three servings per day,) topical application of genistein prior to and after sun exposure appears to offer protection against UV radiation-induced sun damage.

The best sun protection. Protect yourself from the inside out by eating and drinking plenty of plant foods and beverages, limiting exposure to UV rays, and wearing sunscreen and sun protection. It’s important to note that some of the studies on skin protection used isolated and concentrated forms of nutrients. However, your best bet is to focus on eating nutrients in their whole plant food form so that you can gain the synergistic effects from all the nutrients working together. So, enjoy the great outdoors and stock up on nature’s bounty on your next trip to your grocery store or farmers market. 

—Barbara Ruhs, M.S., R.D., L.D.N.