Update on Lycopene
Dr. Michael Murray’s
Natural Facts Newsletter
The carotenes are a highly colored (red to yellow) group of fat-soluble plant pigments. All organisms whether bacteria or plants, that rely on the sun for energy, contain carotene molecules. These compounds via their antioxidant effects play a crucial role in protecting the organism against damage during the process of photosynthesis – the process of converting the sunlight into chemical energy.
In humans, carotenes play two primary roles. Some are converted into vitamin A, and all exert antioxidant activity. Of the 600 carotenes that have been identified, about 30-50 are believed to have vitamin A activity. Carotenes that the body is able to convert to vitamin A are referred to as “provitamin A” carotenes. The most well known of this group are beta-carotene and alpha-carotene. Some of the better known carotenes without provitamin A activity, but with very high antioxidant activity, are lutein, lycopene, and zeaxanthin.
Historically, while beta-carotene has been termed the most active of the carotenes due to its higher provitamin A activity, recent research suggests that this function of carotenes has been overemphasized. Several carotenes, most notably lycopene and lutein, have been found to exhibit more important physiological activities than beta-carotene. While beta-carotene gets the most attention, it is important to point out that it comprises only 20–25% of the total serum carotene level.
So, what is the most predominant carotene in the blood? Surprising to many it is lycopene which accounts for more than 50% of the carotenes in human serum. Owing to its fat-loving nature, lycopene is found to concentrate in LDL and VLDL fractions and not in HDL fraction of the serum cholesterol. Studies have shown lycopene to exhibit the highest overall singlet oxygen quenching of the carotenes thus far studied. Its activity is roughly double that of beta-carotene. Furthermore, lycopene exert even more impressive anti-cancer effects.
Lycopene in the prevention and treatment of prostate cancer
In one of the more detailed studies of lycopene protection against cancer, Harvard researchers discovered that men who consumed the highest levels of lycopene (6.5 mg per day) in their diet showed a 21 percent decreased risk of prostate cancer compared with those eating the lowest levels. When the researchers looked at only advanced prostate cancer, the high lycopene eaters had an 86% decreased risk. Similar results were seen in lycopene protection against cancers of the gastrointestinal tract, cervical cancer, and breast cancer.
In addition to a protective effect, lycopene may exert a therapeutic effect as well. In a study of patients with existing prostate cancer, lycopene supplementation (15 mg per day) was shown to slow tumor growth, shrink the tumor, and lower the level of PSA (prostate specific antigen, a marker of cancer activity) by 18%.