Nothing tastes more like summer, to this inveterate gardener, than a home-grown, vine-ripened tomato. As a child, on a sweltering August afternoon, I used to swipe one from our garden to nibble slowly in the backyard. Or Id share a bright red Beefsteak with mom. Slathered with mayonnaise and nestled on a bed of lettuce between slices of bread, it made a great summer sandwich.
But never in my wildest dreams could I have imagined that tomatoes might offer summertime health benefits to a sunburn-prone towhead like me. Yet thats just what a European research team reports this month in the Journal of Nutrition. The catch: Such benefits depend on cooking the tomatoes or their juice before eating them.
Tomatoes derive their rich color from carotenoids–beta-carotene, lutein, and especially lycopene. The last of these is an especially potent antioxidant, able to quench biologically damaging free radicals. These molecular fragments are spawned by natural processes, disease, and a number of environmental insults–including overexposure to the sun.
There is, however, a trick to absorbing potentially therapeutic concentrations of lycopene, according to work by Wilhelm Stahl, a nutritional biochemist, and his colleagues at Heinrich Heine University in Düsseldorf, Germany. Four years ago, they demonstrated that tomatoes really need first to be cooked, then eaten along with something fatty, such as vegetable oil.
And thats just what Stahl and his colleagues prescribed for their recent 10-week trial. The scientists recruited 22 men and women with fair complexions–all with blue eyes, blonde or light-brown hair, and a tendency to burn, not tan. Half the group were directed to add 10 grams of olive oil to their diet daily. The rest were prescribed this oil plus another daily 40 grams of tomato paste. Thats about half of a small can of paste, which the participants typically spread on a few slices of bread.
Why use paste? Earlier work by the Düsseldorf biochemists suggested that something in cooking appears to liberate carotenoids from the plant cells. Though eating them along with the oil facilitates their uptake by the body, Stahl notes that they become most effective when they actually enter the oil–as will occur, for instance, if tomato products are simmered with oil to make a tomato sauce.
In their trial, the researchers used sun-simulating ultraviolet light to irradiate a coin-size patch of skin on the back of each volunteer. In earlier testing, they had established how long the sun lamp had to be shined on each individual to trigger a reddening. During the feeding trial, Stahls group periodically exposed each participants skin to 125 percent the ultraviolet light of that minimum reddening dose.
The skin of people who ate their normal diet plus oil remained similarly sensitive to sunlight throughout the 10 weeks. But the skin resisted burning in those who downed the tomato/oil duo. By 10 weeks, the sun lamp had created 35 percent less reddening than it had during the first 4 weeks.
Stahl cautions that the sunburn protection afforded by downing this extra lycopene is not very impressive. It would appear to be comparable to a tanning lotion with a sun-protection factor (SPF) of only 2 or 3, he told Science News Online. Still, his group notes that most sun exposures occur during activities when our skin is totally unprotected–such as going to and from the car, walking a few blocks to lunch or to mail a letter at midday, or perhaps chatting with a chance acquaintance outside the bank.
Because these exposures can contribute substantially to our cumulative ultraviolet exposures, the researchers contend, dietary factors with sun-protecting properties might have a substantial beneficial effect. Stahl says his team is now investigating what other carotenoids or antioxidant compounds–such as the flavonoids in cherries (SN: 4/17/99, p. 247) or other plant products–might be combined with lycopene-rich tomatoes to boost their SPF.
For now, however, he recommends that people focus on getting their dietary sun protection by eating paste.
This may sound like justification to pig out on pizza all summer. In fact, tomato paste can be incorporated into a broad range of other meals, from soybean casseroles and chicken cacciatore to crostini with brie and roasted garlic. Recipes for such offerings can be downloaded from sites all over the Internet.
The following, a quick meal for overworked parents to whip up, comes from the chefs at Contadina (http://www.contadina.com/RecipeSearch.htm), a division of Del Monte Foods.
1 pkg. (10 oz.) dry radiatore or other cut pasta
1 Tbs. olive oil
1-1/2 cups chopped onion
2 cloves garlic, minced
14.5 oz. can of diced tomatoes with Italian seasonings
2 cans (6 oz. each) of tomato paste with roasted garlic
1 cup chicken broth
2 Tbs. chopped fresh basil
1 plus 1/2 cup (6 oz.) shredded mozzarella cheese, divided
1/2 cup (2 oz.) grated Parmesan cheese
Cook pasta according to package directions; drain.
Heat oil in a large skillet over medium-high heat. Add onion and garlic; cook 2 minutes. Stir in undrained tomatoes, tomato paste, broth, and basil. Season with salt and pepper, if desired. Bring to boil. Then, reduce heat to low; cover and simmer for 10 minutes.
Combine pasta, sauce, 1 cup mozzarella cheese and Parmesan cheese in a large bowl; pour into 13 x 9-inch baking dish. Sprinkle with remaining mozzarella cheese.
Bake in preheated 375F oven for 10 minutes–or until cheese is melted.
Institüt fur Physiologische Chemie I and Biologisch-Medizinisches Forschungszentrum
Heinrich-Heine Universität Düsseldorf
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