vegetables are best absorbed if they are cooked in oil
or eaten in a meal that contains at least some fat. (A
very tiny amount of fat is adequate).
The United States Institute of Medicine (IOM) of
the National Academy of Sciences develops values
calledDietary Reference Intakes(DRIs) forvitamins
and minerals. The DRIs define the amount of a
nutrient a person needs to consume daily and the largest
daily amount from food or dietary supplements that
can be taken without harm. The IOM has not devel-
oped any DRIs for carotenoids because not enough
scientific information is available and because no dis-
eases have been identified as being caused by inad-
equate intake of carotenoids. The IOM, the American
Cancer Society, and the American Heart Association
all recommend that people get all their antioxidants,
including carotenoids, from a diet high in fruits, vege-
tables, and whole grains rather than from dietary
supplements.Health claims for carotenoids
Many health claims for carotenoids are based on
laboratory and animal studies. Results from human
studies are often inconsistent and confusing. One diffi-
culty in evaluating these studies comes from the variety
of ways in which they are conducted. When increased
carotenoid intake comes from eating foods high in car-
otenoids, it is hard to separate the effects of the carote-
noids from the effects of other vitamins and minerals in
the food. When a dietary supplement is given to increase
the level of a specific carotenoid, the outcomes often
differ from those that occur in a diet of carotenoid-rich
vegetables. In addition, the fact that some carotenoids
are converted into vitamin A blurs the line between their
effects and that of vitamin A from other sources. More
controlled research needs to be done on these com-
pounds. Many clinical trials are underway to determine
safety and effectiveness of different carotenoids, both
alone and in combination with other drugs and
supplements.
BETA-CAROTENE.Beta-carotene is a yellow-orange
provitamin A carotenoid. Good sources of beta-carotene
include carrots, sweet potatoes, winter squash, pumpkin,
spinach, kale, and broccoli. When vitamin A stores are
low, the body can convert beta-carotene into vitamin A
to prevent symptoms of vitamin A deficiency. It takes 12
mcg of beta-carotene to make1 mcg of retinol, the active
form of vitamin A. Therefore, vitamin A deficiency is
usually more effectively treated by eating more foods
high in vitamin A and/or taking a vitamin A supplement
than by increasing beta-carotene intake.
The only use for beta-carotene dietary supplements
proven in well-controlled clinical trials is to treat a rare
genetic disorder called erythropoietic protoporphyria.
This disorder causes the skin to be painfully sensitive to
sunlight and causes the development ofgallstonesand
problems with liver function. Symptoms are relieved by
giving beta-carotene supplements under the supervision
of a physician.CarotenoidsCarotenoid Food sources
Alpha-carotene Carrots
Collard greens
Peas
Plantains
Pumpkin
Tangerines
Tomatoes, raw
Winter squash
Beta-carotene Broccoli
Cantaloupe
Carrot juice
Carrots
Dandelion greens
Kale
Pumpkin
Spinach
Turnip greens
Sweet potatoes
Winter squash
Beta-cryptoxanthin Carrots
Corn, yellow
Nectarines
Orange juice
Oranges
Papaya
Pumpkin
Red bell peppers
Tangerines
Watermelon
Lutein and zeaxanthin Broccoli
Brussels sprouts
Collard greens
Corn, yellow
Dandelion greens
Kale
Mustard greens
Peas
Pumpkin
Spinach
Summer squash
Turnip greens
Winter squash
Lycopene Baked beans, canned
Catsup
Grapefruit, pink
Marinara sauce
Sweet red peppers
Tomato juice
Tomato paste and puree
Tomato soup
Tomatoes, raw
Vegetable juice cocktail
Watermelon(Illustration by GGS Information Services/Thomson Gale.)
Carotenoids