Carotenoids are natural pigments which are synthesized by plants and are responsible for the bright colors of different vegetables and fruits. The carotenoids absorb light energy of specific frequencies and transfer it to chlorophyll for use in photosynthesis. In addition, act as antioxidants for chlorophyll, protecting it from damage by oxidation in the presence of sunlight. They are split into two classes, xanthophylls (beta-cryptoxanthin, lutein, and zeaxanthin) and carotenes ((alpha-carotene, beta-carotene, and lycopene).
Beta carotene, alpha-carotene, and beta-cryptoxanthin are carotenes that are converted into vitamin A or retinol in the body. Lycopene, zeaxanthin, and lutein have no vitamin A activity.
Food sources of carotenoids include carrots , tomatoes, tomato paste, tomato sauce, tomato soup, beets, pink grapefruit, watermelon, pomegranate, guava, papaya, bell peppers, spinach.
Carotenoids are thought to provide positive effects in decreasing the risk of disease, especially certain cancers and eye illness.
• Beta Carotene
Beta carotene, along with alpha-carotene and beta-cryptoxanthin, can be converted to retinol and is classified as a provitamin A carotenoid. Free radicals can damage the basic structure of cells and so lead to chronic diseases and accelerate the aging process. Beta carotene and others carotenoids have antioxidant features in vitro and in animal models. Beta carotene has strong antioxidant effects, helps the body scavenge free radicals, therefore limiting the damage to cell membranes, DNA and protein structures in the cell.
Beta-carotene may enhance macrophage function and natural killer cell cytotoxicity and increase T-helper lymphocyte counts. Findings from a number of studies suggest that beta-carotene containing foods avoid the initiation and progression of different cancers. Beta carotene stimulates a molecule that helps the immune system target and destroy cancer cells. It increases the number of receptors on white blood cells for a molecule known as major histocompatibility complex II. MHC II is integral in helping monocytes, a type of white blood cell, direct killer T cells to cancerous cells.
Epidemiological studies have demonstrated an inverse relationship between presence of different cancers and dietary carotenoids or blood carotenoid levels. In a study showed that 44 % of patient with colon cancer who were given 30 mg daily beta-carotene had cancer inhibition after only 2 weeks. Researchers showed beta-carotene, additionally using 30 mgs per day for pre-cancerous mouth lesions, caused total or partial regression in 71% of tumours.
In the study, 2 groups of men participating in the Physicians Health Study for 12 years were given either beta carotene (50 mg) or placebo throughout the course of the study. When looking at natural killer cell activity, the elderly men on beta carotene had 59% higher natural killer cell activity than the placebo group. Was seen in the middle-age group with beta-carotene supplementation, with the placebo group having 53% higher natural killer cell activity compared to the placebo group.
Beta carotene, along with zinc,copper, vitamin C, and vitamin E may help treat advanced age-related macular degeneration, an eye disease. A clinical trial, the “Age Related Eye Disease Study“, found that individuals who had macular degeneration could slow its progression by taking beta-carotene (15 mg), vitamin C (500 mg), vitamin E (400 mg), copper (2 mg) and zinc (80 mg).
Lycopene is the natural substance responsible for the deep red color in many foods, most particularly in tomatoes. Lycopene is more plentiful in cooked and processed tomato products such as tomato paste, and tomato sauce. The absorption of lycopene from cooked tomato paste was shown to be 3.8 times that from fresh tomato.
Lycopene has powerful antioxidant properties and researches indicate that it can help avoid certain cancers, macular degeneration and heart disease. 10 to 30 milligrams per day has been found to be effective in combating free radicals. In addition to preventing oxidative damage to cell membranes, lycopene can avoid oxidation of proteins and DNA.
Some researches have demonstrated that lycopene concentrations, found in foods, can fight this immortal cancer cells that had disrupted the programmed sequence of apoptosis or cell death in normal tissues. Lab experiments with lycopene confirm that it acts as an antioxidant and affects the way cells grow and communicate with each other. In a Harvard study conducted with 47,894 men, scientists found that eating 10 or more servings a week of tomato products was linked with a reduced risk of prostate cancer by as much a 34% .
A study on heart illness found that men with high levels of lycopene in their fatty tissues had a 50 % reduced risk of heart disease. In the EURAMIC study, the risk for acute heart attack at the highest level of lycopene in adipose tissue was reduced by 65 %, compared to adipose lycopene at the lowest level.
Lutein and Zeaxanthin
The only carotenoids found in the retina are zeaxanthin and lutein. Lutein is used by the body as an antioxidant, and for blue light absorption.
Lutein and zeaxanthin, form the yellow pigment of the retina and absorb blue light, a harmful component of sunlight. Lutein works by means of its antioxidant effects which protect the cells of the retina against free radicals. A Harvard research in 1994, demonstrated that 6 milligrams of lutein may reduce your risk for developing macular degeneration. According to a 2007 study reported in the Archives of Opthamology, people with an increased intake as zeaxanthin and lutein, had a decreased risk of developing age related macular degeneration.
Epidemiological studies have long suggested an association between carotenoid intake and decreased risk of cardiovascular disease. In a study (University of Southern California) demonstrated that lutein may help protect against clogging of the carotid arteries in the neck, an indication of atherosclerosis, the disease that leads to most heart attacks. Found that participants with the highest levels of lutein in the blood at the outset had no increase in plaque in the arteries throughout the 18 months of the study.
A epidemiological study from “Harvard School of Public Health“, reported in the Journal of the National Cancer Institute, found an inverse ratio between zeaxanthin and lutein intake and breast cancer in a group of more than 83000 women. Korean scientists have found algae-extraction carotenoids such as zeaxanthin and lutein can reduce colon cancer growths. Other recent study demonstrated lutein could inhibit growth in mouse mammary tumors by regulating angiogenesis and apoptosis.