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Lycopene

Lycopene is the main carotenoid in tomato fruit (Lycopersicon esculentum). The carotenoid content and composition are highly dependent on the tomato variety and on the ripeness of the fruit. It is also present in guava, rosehip, watermelon and pink grapefruit as well as several other plant species.

structure of lycopene

Presence of lycopene in some products:

Source : www.lycopene.org

Lycopene has a greater property than being the colour of tomatoes. It is a strong antioxidant, which can help to combat degenerative diseases such as heart disease. It was found that increased concentration of lycopene gave an increased protective effect, so the most concentrated food sources, like tomato puree and ketchup, are better protectors against these diseases. However the human body cannot produce this molecule and needs to obtain it from tomatoes in our diet. High lycopene foods like soup have been found to be the most effective against degenerative diseases.

Lycopene helps prevent degenerative diseases by donating its electrons to oxygen free radicals thus quenching and neutralising them before they can damage cells. Free radicals are molecules that have at least one unpaired electron. By donating an electron lycopene can stabilise the free molecule. There have been many recent studies into lycopene so that it can be used to its fullest potential in fighting these diseases. A heart study measuring lycopene in fatty tissue of 1,374 men showed that it could reduce the risk of a heart attack by 50%.

Lycopene also has other ailing effects. It has been seen that lycopene can be used as an anti-carcinogen, greatly reducing the risk of some cancers. In a six-year study of 47,000 male health professionals Harvard Medical School found that eating tomato products more than twice a week was associated with 21-34% reduced risk of prostate cancer. In 1995 Harvard School of Public Health studied further into this and found that those men who ate more than 10 servings of tomato foods a week were 45% less at risk to prostate cancer; those with only 4-7 servings were 20% less at risk. The University of Illinois found that comparing woman with the highest levels of lycopene and those with the lowest showed that the highest levels were five times less likely to have cervical cancer.

Tomatoes are therefore a very important part of our diet and if tests are conclusive then this could be a serious step towards combating other cancers. However there are some that do not believe that lycopene can improve cancer protection. In January 1996 the US National Cancer Institute issued a press release declaring beta-carotene to be useless and harmful. They claimed that it might increase the risk of lung cancer in long-term smokers. This implies that the case would be the same for lycopene. Lycopene and beta-carotene are very similar and so they are implying that lycopene is harmful. The research though was not published and so other antioxidant researchers are not convinced by the argument.

There is also some evidence that lycopene reduces LDL (low-density lipoprotein) oxidation and helps reduce cholesterol levels in the blood.

Lycopene is the most predominant carotenoid in human plasma, present naturally in greater amounts than beta-carotene and other dietary carotenoids. This perhaps indicates its greater biological significance in the human defence system. Its level is affected by several biological and lifestyle factors. Because of its lipophilic (fat-loving) nature, lycopene concentrates in low-density and very-low-density lipoprotein fractions of the serum. Lycopene is also found to concentrate in the adrenal, liver, testes, and prostate. However, unlike other carotenoids, lycopene levels in serum or tissues do not correlate well with overall intake of fruits and vegetables.

Research shows that lycopene can be absorbed more efficiently by the body after it has been processed into juice, sauce, paste, or ketchup. In fresh fruit, lycopene is enclosed in the fruit tissue. Therefore, only a portion of the lycopene that is present in fresh fruit is absorbed. Processing fruit makes the lycopene more bioavailable by increasing the surface area available for digestion. More significantly, the chemical form of lycopene is altered by the temperature changes involved in processing to make it more easily absorbed by the body. Also, because lycopene is fat-soluble (as are vitamins, A, D, E, and beta-carotene), absorption into tissues is improved when oil is added to the diet. Although lycopene is available in supplement form, it is likely there is a synergistic effect when it is obtained from the whole fruit instead, where other components of the fruit enhance lycopene's effectiveness.

Sources :

• www.lycopene.org;
• http://www.chem.ox.ac.uk/mom/lycopene/lycopene.htm;
• http://chemistry.about.com/library/weekly/aa050401a.htm;
• http://www.cce.cornell.edu/food/fdharchives/030499/tomatoes.html