Lycopene

At the outset, there is no RDA for lycopene. It is not an essential nutrient; however, this post discusses the benefits of lycopene found naturally in certain foods (I am not talking about wasting our money on buying lycopene supplements — too many studies show that taking supplements does more harm than good even though there are benefits when eating natural whole plants to get such) and the benefits for our health even though there is no RDA. (As an aside, there are studies showing that we should avoid taking vitamin  pills and other supplements, and just get all the vitamins, minerals, etc., needed from natural, whole plant foods; e.g., http://www.drmcdougall.com/misc/2010nl/may/vitamins.htm.)

The name of lycopene is derived from the tomato’s species classification: lycopersicon esculentum. Therefore, visually, lycopene is a carotenoid responsible for the red color of the tomato, watermelon and pink grapefruit. Interestingly, the highest natural concentrations of lycopene in food are found not in tomatoes, but in watermelon. So this summer, let’s eat lots of watermelon! 🙂 (Importantly, however, of 46 fruits and vegetables evaluated, only tomato products showed a measurable relationship with reduced prostate cancer risk!)

Watermelon contains 15 to 20 milligrams (15,000 to 20,000 mcg) of lycopene per 2-cup serving; however, most all dietary lycopene is derived from tomato products. Lycopene content of tomatoes can vary significantly, depending on type of tomato and ripening. The redder the tomato, the more lycopene is present. However, as an example, one 6 oz can of tomato paste has about 48 mg (48,000 mcg) of lycopene.

Lycopene is also found in apricots, papaya, pink grapefruit, and guava.

In plants, lycopene is similar to other carotenoids, serving as a light-absorbing pigment during photosynthesis and protecting cells against photosensitization. It has a unique long chain molecular structure containing 13 double bonds, more than any other carotenoid. This configuration is responsible for lycopene’s special ability to neutralize free radicals. Among the carotenoids, it is the most efficient quencher of singlet oxygen free radicals.

Lycopene has been linked with reduced risk of prostate and cervical cancers, as well as supporting cardiovascular health.

Recent findings indicate that lycopene is an important part of the human organism’s natural defense mechanism that protects us from harmful oxidizing agents.

Lycopene is an acyclic isomer of beta-carotene. Beta-carotene, which contains beta-ionone rings at each end of the molecule, is formed in plants, including tomatoes, via the action of the enzyme lycopene beta-cyclase. Lycopene is a 40 carbon atom, open chain polyisoprenoid with 11 conjugated double bonds.

Lycopene tends to concentrate in bodily tissues at higher amounts than all other carotenoids, especially in the testes and adrenal glands.

The health benefits of lycopene are attributed to its ability to protect cells against oxidative damage. Lycopene has the ability to quench singlet oxygen (more so than beta-carotene), to trap peroxyl radicals, to inhibit the oxidation of DNA, to inhibit lipid peroxidation, and in some studies, to inhibit the oxidation of low-density lipoprotein (“LDL”).

Daily consumption of tomato products providing at least 40 mg (40,000 mcg) of lycopene substantially reduces LDL oxidation. High LDL oxidation is associated with increased risk of atherosclerosis and coronary heart disease.

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.

Because lycopene is a potent antioxidant and seems to inhibit growth of cancer cells, it is logical that a higher intake of this carotenoid may indeed be associated with reduced incidence of cancer.

Several studies suggest that eating vegetables rich in lycopene, such as tomatoes or tomato-based products, may reduce the risk of getting :

• breast cancer;
• cervical cancer;
• gastrointestinal cancer;
• colorectal cancer;
• lung cancer; and,
• prostate cancer.

Carotenoids work to protect against cancer and aging-related diseases by acting as an antioxidant to counteract damaging effects of free radicals in tissues.

Lycopene is one of the major carotenoids found in human blood and tissues, and is found primarily in the testis, adrenal glands, liver, prostate, breast, colon, and lung.

Also, lycopene is found to:

• prevent oxidation of lipids and low density lipoprotein cholesterol (“LDL”);
• reduce the risk of a person developing atherosclerosis;
• reduce coronary heart disease;
• inhibit cholesterol synthesis;
• inhibit HMG-CoA (hydroxymethylglutaryl coenzyme A) reductase activity; and,
• upregulate LDL receptor activity in macrophages.

Lycopene helps prevent heart disease through this same antioxidant mechanism via an inhibition of oxidative damage to LDL cholesterol. The strong lipid antioxidant properties of lycopene make it particularly effective in blocking LDL oxidation and protecting against free radical activity on the arterial wall.

• Human studies conducted at the University of Toronto on dietary lycopene confirmed that it acts as an antioxidant. As lycopene levels in the blood go up, the levels of oxidized lipoprotein, protein and DNA compounds go down.

• A study of 48,000 men by Harvard Medical School estimated that consuming tomato products twice a week, as opposed to never, was associated with a reduced risk of prostate cancer of up to 34%.

• Research conducted into breast, lung and endometrial cancer at Ben Gurion University and Soroka Medical Center in Israel shows that lycopene is even more effective than its cousins, alpha- and beta-carotene, in causing a delay in the cell cycle progression from one growth phase to the next.

• A study, conducted by the University of North Carolina, compared fat samples from 1,379 American and European men who had suffered a heart attack with those of healthy men. It found that those with high levels of lycopene were half as likely to have an attack as those with low levels.

Age-related macular degeneration (“ARMD”) is the most common form of blindness for elderly people in the western world. Lycopene is the only micro-nutrient whose serum level is shown to be inversely related to the risk of ARMD.

For sun-worshipers and seekers of the perfect tan but having a paranoia of getting skin cancer (melanoma), lycopene may help reduce the damage to the skin caused by ultraviolet light during and after sun exposure. Skin exposure to ultraviolet radiation is responsible for sunburn, tanning, premature aging and skin cancer. These effects are partly due to the formation of oxygen free radicals. Lycopene has the ability to quench free radicals, which are highly reactive compounds that are formed in the body from normal metabolism, as well as from environmental pollutants and radiation.

Exposure to certain types of UV radiation can cause damage to DNA (the genetic material of the body) and increase the risks of skin cancer. The powerful antioxidant action of lycopene helps to prevent the oxidation of serum lipids, thus promoting arterial health.

In conclusion, major epidemiological studies show that those who eat at least 10 servings of tomato products per week, averaging about 6.5 mg (65,000 mcg) of lycopene per day (that is a lot of pizza btw!!), had the greatest reduction in cancer risk. Additional research shows that drinking two cups (about 540 ml) of tomato juice per day provides about 40 mg (40,000 mcg) of lycopene. This is the amount recommended to significantly reduce the oxidation of LDL cholesterol, according to one human dietary intervention study.

Eat well, live long, and prosper!