Carotenoids have two important functions in plants. First, they can contribute to photosynthesis. They do this by transferring some of the light energy they absorb to chlorophylls, which then use this energy to drive photosynthesis.
Second, they can protect plants which are over-exposed to sunlight. They do this by harmlessly dissipating excess light energy which they absorb as heat. In the absence of carotenoids, this excess light energy could destroy proteins , membranes, and other molecules. Some plant physiologists believe that carotenoids may have an additional function as regulators of certain developmental responses in plants.
It can be a source of vitamin A, but it produces half as much as beta-carotene. Premkumar listed papaya, mango and oranges as good sources of it. Beta-cryptoxanthin is typically found in yellow foods, such as corn and bell peppers, and is present in yellow-colored dairy products, such as egg yolks and butter. Some studies have shown that beta-cryptoxanthin may be effective in preventing lung cancer. In an analysis of several studies from North America and Europe, published in Cancer Epidemiology, Biomarkers and Prevention , researchers found that participants who consumed the most beta-cryptoxanthin had a 24 percent lower chance of developing lung cancer than those with the lowest consumption.
In a large-scale study conducted in the Netherlands and also published in Cancer Epidemiology, Biomarkers and Prevention , researchers found that though all carotenoids were measured for their relationship to lung cancer risk, only beta-cryptoxanthin, lutein and zeaxanthin were associated with reduced cancer risk. Beta-cryptoxanthin may be helpful in reducing the risk of inflammatory polyarthritis, which includes rheumatoid arthritis. Scientists suspect this is because its antioxidant abilities can reduce chronic inflammation.
In a large-scale European study published in the American Journal of Clinical Nutrition , researchers found that participants who developed inflammatory polyarthritis had 40 percent less beta-crytpxanthin than those who did not. Participants who consumed the most beta-cryptoxanthin were significantly less likely to develop inflammatory polyarthritis.
The researchers advised that a modest increase in beta-cryptoxanthin, such as a glass of orange juice a day, could be helpful in preventing arthritis. Of the provitamin A carotenoids, beta-carotene is the most powerful when it comes to turning into vitamin A; twice as much beta-carotene becomes vitamin A than does alpha-carotene or beta-cryptoxanthin.
Beta-carotene was the first and is the most widely studied of the carotenoids. It seems to be capable of both positive and negative effects, especially for smokers taking it as a supplement. Two studies of showed that smokers and former asbestos workers who took beta- carotene supplements increased their risk of lung cancer, according to the Linus Pauling Institute.
Doctors currently advise smokers not to take beta-carotene supplements. Large amounts of beta-carotene from food, however, do not seem to carry this risk; the worst they can do is temporarily turn your skin orange, according to the National Institutes of Health. Cantaloupe, mangoes, papaya, carrots, sweet potatoes, spinach, kale and pumpkin are good sources of beta-carotene, said Premkumar. Beta-carotene gives orange foods their color; in fact, the word carotene comes from the Latin word for carrot.
Beta-carotene may help protect against sunburn, according to a meta-analysis published in Photochemistry and Photobiology. The researchers looked at several studies and found that participants who took beta-carotene supplements for 10 weeks had lower rates of sunburn. For each month of additional supplementation, the protection level increased.
Beta-carotene may help lower the risk of metabolic syndrome, at least in middle-age and elderly men, a study published in the Journal of Nutrition found. Metabolic syndrome is characterized by high blood pressure, high blood sugar, abnormal cholesterol levels and excess fat around the waist.
The men with the most beta-carotene intake had the lowest risk of metabolic syndrome, as well as reduced waist circumference. Early studies suggested that beta-carotene was associated with a reduced risk of lung cancer, according to a review published in the Journal of Nutrition. More recent studies have shown that relationship to be unreliable, although other carotenoids like alpha-carotene, lycopene and beta-cryptoxanthin have shown promise. Alpha-carotene produces half the vitamin A that beta-carotene does.
Alpha-carotene is found in similar foods to beta-carotene and is often studied in conjunction with that carotenoid, though it is rarer and less well-understood. Recently, scientists have been paying more attention to alpha-carotene, and have found some potential longevity benefits, in addition to the vitamin A goodness alpha-carotene can provide. Anthocyanins are water-soluble pigments produced via the flavonoid pathway in the cytoplasm of the colored plant cell.
The attachment of the sugar molecule makes them particularly soluble in the sap of the vacuole, where these molecules are stored….. These are responsible for the pink-red colors of most flower petals, of most red fruits like apples and almost all red leaves during the autumn. Anthocyanins absorb light in the blue-green wavelengths, allowing the red wavelengths to be scattered by the plant tissues to make these organs visible to us as red. Learn More about Our funders.
All rights reserved. Jump to Navigation. Harvard Forest. Search form Search. Leaf Pigments Plants make an amazing variety of pigment molecules, far more than animals.
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