CAROTENOIDS are defined as organic pigments found in plants and other photosynthetic organisms like algae, some types of fungus and some bacteria. They are characterized by a large polyene chain usually consisting of 35 to 40 carbon atoms that end up in rings. More than 600 known carotenoids are split into two classes, xanthophylls and carotenes. Xanthophylls are carotenoids in which some of their double bonds are oxidized. Classified under this category are lutein and zeaxanthin. Meanwhile carotenes are un-oxidized carotenoids like alpha-carotene, beta-carotene and lycopene.
Carotene is probably the most well-known carotenoid in the group. Aside from giving the group its name, carotene is the ingredient that gives the orange color in carrots. Carotenoids are also said to cause the color pink in flamingos and salmon as well as the red colouring of lobsters. The color of carotenoids range from pale yellow through bright orange to deep red. It is directly linked to their structure since their double carbon-carbon bonds interact in a process called conjugation. The increase in the absorption of light by carotenoids results in an increase in wavelength and the number of double bonds, giving the compound a brighter red appearance.
Physical effects
Carotenoids assume an important role in the photo-synthetic reaction process of certain organisms either in the energy transfer process or in protecting the reaction center of organisms from auto-oxidation. The compound is also credited with the prevention of oxidation in non-photosynthetic organisms. They also assume many physiological functions given their structure. They are known as efficient free-radical scavengers by improving the vertebrate immune system. Studies also showed that people with high beta-carotene intake and high plasma levels of beta-carotene are less likely to incur lung cancer.
However other studies also showed that smokers who consume large doses of beta-carotene increased the likelihood of incurring lung cancer. This is due to the possibility that excessive beta-carotene results in breakdown products that reduce plasma Vitamin A and worsen the lung cell proliferation induced by smoke). Animals are incapable of synthesizing carotenoids and must obtain them through their diet.
Still carotenoids are found in animals through their ornamental traits. Due to their physioloigcal and chemical properties, they can be used as indicators of individual health and are thus used by animals in selecting potential mates.
Other by-products
When broken down the products produced by carotenoids include ionones, damascones and damascenones. These are said to be used as fragrance chemicals for the perfumes and fragrance industry. Both beta-Damascenone and beta-Ionone, while considered low in concentration in rose distillates are key contributing compounds to flowers. Carotenoid breakdown are said to be responsible for the sweet floral smells found in black tea, aged tobacco, grape, and many fruits. Still, crude palm oil is considered as the richest source of carotenoids in nature.
Health issues
Non-smokers may reduce their risk of developing diabetes by consuming high levels of carotenoids but as cited above, this is not seen in smokers. Carotenoids being antioxidants sourced from vegetables like carrots, tomatoes and spinach reduce the risk of diabetes by cutting oxidative stress. Though unconfirmed, high levels of carotenoids are cited by some as reducing the oxidative stress caused by cigarette smoking.
Previous reports have linked smoking with low levels of carotenoids. To further determine this analysts from the University of Minnesota School of Public Health in Minneapolis evaluated data from 4493 subjects, between 18 and 30 years of age, who took part in the Coronary Artery Risk Development in Young Adults (CARDIA) study. This study centered on 148 cases of diabetes covering the period of 1985 to 2001.
In nonsmokers, increasing carotenoid levels were linked with decreased risk of developing diabetes while smokers with high carotenoid levels were seen to have a slight increase in risk. These findings, according to experts, suggest that smoking may negate the protective effect of high carotenoid levels since antioxidant metabolism and oxidative defense system behave differently in smokers than in nonsmokers.
