Tomatoes and lycopene

For many years tomatoes have been known for their health benefits. The tomato has been the subject of many studies since the 1980’s. These studies, as expected, have revealed some interesting facts related to why the tomato is of benefit in our diet. Tomatoes contain many beneficial nutrients including vitamin C, vitamin B complex, iron, potassium and calcium. They also contain a phytochemical called lycopene. This is an anti-oxidant carotenoid related to beta-carotene. It is what gives the tomato its red colour. Other sources include red oranges, pink grapefruit, watermelon, guava and rosehips. The tomato is by far the richest source of lycopene.

Anti-oxidant properties

Lycopene is deposited in many organs of the body including the liver, lungs, prostate, colon, skin, testes and adrenal glands. The body concentration of lycopene is higher than that of any other carotenoid. Although a relative of beta-carotene it differs slightly and it may be these differences that hold the reason as to why it is so beneficial. It is the longest caroteniod found and unlike beta-carotene it is not converted into vitamin A. It is the conversion to vitamin A that weakens the anti-oxidant properties. This may be why lycopene is thought to be a more potent anti-oxidant.
Anti-oxidants work in the body to scavenge and disarm free radicals. Free radicals are imbalanced molecules that react with cell components and cause irreversible damage. They are involved in the destruction of healthy molecules and are thought to be carcinogenic (cancer forming). Free radicals are a result of many normal cellular activities and are released when frying food, smoking and are also a result of pollution.
Lycopene inactivates these free radicals and it has been shown to have an ability twice that of beta-carotene and nearly ten times that of alpha tocopherol (vitamin E)

Lycopene availability

The lycopene content within tomatoes varies depending on how much sunlight the tomato was exposed to. Sun ripened tomatoes have the highest content of lycopene. The lycopene is enclosed within the flesh of the fruit and so processing increases its bio-availability. This is because the flesh is broken down increasing the surface area for digestion. The chemical form of lycopene is altered by temperature, therefore heating increases absorption. As it is fat soluble absorption into tissues is greatly enhanced by cooking tomatoes with a little oil.

Historical uses

In the past tomatoes have been used for a variety of reasons. It was initially thought that tomatoes were inedible and poisonous as they are a member of the deadly nightshade family. Once it was established that they are actually edible many health benefits were discovered. They have been used to treat diarrhoea when combined with apple. Cleansing and rejuvenation of the skin by including them in face peels and masks. They have also been used to treat sunburn and as a poultice to aid wound healing.
More recently it is the anti-oxidant properties that have been of interest. As lycopene is a potent anti-oxidant it reduces the amount of free radicals within the body. Free radicals have been linked to many degenerative conditions such as cancer, arthritis, heart disease, cataracts and the ageing process.

Cancer risk reduction

Lycopene has been linked with the reduction in the risk of several cancers including cancers of the lung, skin, stomach, pancreas, oral cavity, oesophagus, stomach, colo-rectum, bladder and cervix..
Lycopene is most widely known for its association with prostate cancer. Numerous studies conducted have shown a link between increased intake of tomato and tomato based products and a reduced risk of prostate cancer. Studies have also shown that lycopene may also be more effective with aggressive tumours and may actually reduce the size of an existing tumour. Researchers have also observed that in a lycopene treated group a significant percentage had tumours that were confined to the organ. In other words the tumour did not spread to other parts of the body as readily. Many Mediterranean countries such as Italy or Greece that have a high tomato consumption have a low incidence of prostate cancer.

Other properties

Lycopene has also been linked to the reduction of heart disease risk. It is thought that the anti-oxidant reduces the risk of atherosclerosis formation. As it is fat soluble it binds to the LDL cholesterol receptors and therefore reduces the LDL cholesterol levels in the blood, further lowering the risk of heart disease.

It is also thought that lycopene is involved in the reduction of age related macular degeneration which leads to blindness.

Although many studies have been carried out on the health benefits of tomatoes and there seems to be a strong link with tomato consumption and the reduced risk of several cancers, no direct relationship has yet been proven. This may be due to the fact that lycopene is not the sole nutrient and other nutrients within tomatoes may also play a role.
Therefore a recommended daily intake has not yet been established. Some studies have indicated that for optimum health 7-10 servings a week are beneficial.. Some recommend 3-6 mgs daily. One medium tomato provides around 4mg of lycopene.