How are phytochemicals organized?
Scientists group phytochemicals according to their chemical structure. This often means that
phytochemicals in a group act in the human body in a similar way. Two broad classes of
phytochemicals are carotenoids and flavonoids.
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Does the color of a fruit or vegetable indicate what phytochemicals it contains?
Color is a good, but not exclusive, indicator of phytochemical content. Many, but not all,
phytochemicals are pigments that give plants color. Some phytochemicals are colorless. Some
phytochemicals are responsible for taste. Sometimes one color may mask another color. Products
in a color group will have varying amounts of the same phytochemical.
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What is the connection between 5 A Day The Color Way and phytochemicals?
Most people tend to eat the same fruits and vegetables. 5 A Day The Color Way is a campaign
that gives consumers a system for choosing a variety of fruits and vegetables every day. Each
fruit or vegetable has a unique mixture of nutrients and phytochemicals. Eating across and within
the color groups is a great way to get the health benefits fruits and vegetables can provide.
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What part of a fruit or vegetable contains the phytochemicals?
Phytochemicals are found in all edible portions of a fruit or vegetable, although
they are frequently concentrated in the skin. So eating them with their peels
on is a plus.
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What affects the amount of phytochemicals in foods?
Both genes and the environment affect the amount of phytochemicals in foods.
Genes - some varieties have far higher amounts than others
Environment
- soil and fertilization methods
- sunlight exposure
- altitude, climate, and temperature
- maturity of plant
- the presence of predators (e.g., molds, bacteria, insects, or animals that attack a
plant can greatly increase its phytochemical content as it tries to fight off the predator)
- storage, processing, preparation methods
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Do fresh fruits and vegetables have more phytochemicals than canned or frozen?
Not necessarily. For example, the carotenoids in vegetables and fruit can be absorbed more efficiently
in processed form (juice, sauce, paste, ketchup). Temperature changes that occur when tomatoes are
processed, in addition to pureeing or blenderizing, make the carotenoids more easily absorbed by the
body. However broccoli steamed for more than 3 or 4 minutes loses isothiocyanates.
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How do phytochemicals work in the body?
We still have much to learn about the bioavailability of phytochemicals in our bodies, but scientists have
identified several ways that phytochemicals work. Many phytochemicals are strong
antioxidants that help moderate the damage
to cells resulting from oxidation, which is a normal process the body uses
to produce energy. Phytochemicals are also involved in
many of the metabolic pathways that regulate the body's functions. Some seem to work by preventing bacteria
from sticking to places they should not be or preventing blood cells from sticking together and flowing freely.
Also, some phytochemicals may reduce inflammation that occurs in the walls of arteries. Phytochemicals may
also enhance the body's ability to detoxify chemicals, slow or stop growth of
cancer cells and even kill
cancer cells.
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Are phytochemicals stored in the body?
Carotenoids are fat-soluble compounds, like vitamins A, D, E, and K, and they can get stored in body fat
the same way. Also like vitamins, one is very much less likely to accumulate toxic levels from whole foods
than from concentrated supplements.
Flavonoids are more water-soluble, like B-vitamins and vitamin C. They get washed out of the body and are
rarely stored, so food sources of flavonoids may have to be eaten more frequently than foods containing
fat-soluble carotenoids, in order to get their benefits.
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Do phytochemicals work with traditional nutrients to promote health?
There are still many unanswered questions in this area, but studies show the greatest health benefits seem
to come from eating fruits and vegetables as opposed to taking the isolated nutrients. It appears that the
nutrients and some phytochemicals from food might work together to produce a greater effect than they may
have produced in isolation.
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How much is enough?
The amount of fruits and vegetables recommended in new Dietary Guidelines for Americans
(http://www.healthierus.gov/dietaryguidelines/)
has gone up for every age and gender. For most people (consuming 2200 calories), the new guidelines
suggest 5 cups of fruits and vegetables a day. This translates into about half of your plate or half
of what you eat each day. Currently, there are no national recommendations for the amounts of
phytochemicals needed to prevent disease. The Institute of Medicine has just finished updating
the guidelines (Dietary Reference Intakes) on traditional nutrients, but more research is needed
before decisions can be made on effective amounts for phytochemicals. By eating a variety of fruits
and vegetables of all colors, you will get a good mix of phytochemicals in your diet.
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If I increase my fruits and vegetables to 5-13 servings per day to reap the health
benefits of phytochemicals, should I be concerned about the amount of pesticides to which I am exposed?
Click below for the answer...
http://www.niehs.nih.gov/external/faq/pest.htm
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For more information on PBH Research, please contact PBH's Elizabeth Pivonka.
Other Phytochemical Info Center Topics
Phytochemical List
About the Phytochemical Info Center
Glossary
References
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