By Lin Yan
Tomato is actually the fruit of the tomato plant, but is popularly used as a vegetable in cooking. The tasty tomato is one of the most commonly consumed foods in America. Tomato also has attracted public attention because of its potential health benefits in reducing some cancer and heart disease.
The tomato is native to South America. Many historians believe that Spanish explorers may have been the first to transfer the tomato to Europe, others believe that Italians are the first to take back the tomato.
Tomato was not introduced to North America until the early 1800s. Mass immigrants from Europe to America, particularly Italians, ate tomatoes and brought that food with them. Because of tomato's long-growing season, the Sun Belt states of the United States today are major tomato-producers, particularly Florida and California.
The United States is the second largest tomato producers in the world, only after China. For the plum tomato or paste tomato, California accounts for 90 percent of U.S. production and 35 percent of world production.
Tomato's red hue comes mainly from a phytochemical called lycopene, a compound appearing to act as an anti-oxidant and neutralizing free radicals that damage cells of our body. Studies revealed that eating tomato may reduce the risk of cancer. In a study of over 40,000 health professionals, Harvard investigators reported that men who ate more than 10 servings of tomato-based foods daily could cut the risk of developing prostate cancer by 35 percent compared to those who ate the least amount of these foods.
The benefits of lycopene were even more pronounced with advanced stages of prostate cancer. In another study of prostate cancer, researchers analyzed blood levels of lycopene and found that the risk of developing prostate cancer decreased with increased blood lycopene levels. The high level of lycopene in the blood was associated with low blood levels of prostate specific antigen, a biomarker of prostate health. Furthermore, studies indicated that tomato consumption may reduce the risk of colorectal, stomach and lung cancers.
A greater intake of lycopene-rich tomato may benefit heart health by lowering the risk of cardiovascular disease. Studies showed that tomato lycopene prevented the oxidation of LDL "bad" cholesterol. In the process known as atherosclerosis, LDL cholesterol, fat and other substances are deposited in the arteries as plaque. When plaque builds up over time, it narrows the inner artery making it harder for blood to flow. Low levels of lycopene in blood are associated with increased mortality from heart disease (compared with higher levels?). A clinical study showed that eight weeks of daily intake of a tomato extract was related to a significant drop in both systolic and diastolic blood pressure in patients with mild to moderate hypertension. The investigators assumed that this antihypertensive effect is a result of the antioxidative activity of the tomato extract.
Tomatoes are the second richest dietary source of lycopene, only after gac. Gac has the highest content of lycopene comparing with any known fruits or vegetables, approximately 50 times more than tomatoes. However, it is rare outside Southeast Asia. Tomatoes, particularly processed tomato products such as sauces, juices and ketchup account for more than 85% of the dietary intake of lycopene for most people, and the lycopene content of tomatoes depends on species and it increases as the fruit ripens.
When choosing tomatoes, be sure to pick those with the most brilliant shades of red, which indicate the highest amounts of lycopene. Unlike most of the fruits and vegetables, where cooking may reduce the contents of certain nutrients such vitamin C, processing of tomatoes increases the content of bioavailable lycopene-the quantity of lycopene that can be utilized by our body. The processed tomato products, such as pasteurized tomato juice, soup, sauce and ketchup, contain the highest contents of bioavailable lycopene than fresh, raw tomatoes. For this reason, the processed tomato products are a preferable source comparing to raw tomatoes.
The other important aspect about lycopene is that it is insoluble in water. Cooking and crushing tomatoes (as in the canning process) or serving in oil-rich dishes such as spaghetti sauce greatly increases assimilation from the digestive tract into the bloodstream. Lycopene is fat-soluble, so oil can help absorption, and thus it increases its bioavailability.
Let us enjoy the benefits of lycopene by eating more tomatoes and processed tomato products.