A Little Fat Helps the Vegetables Go Down
Eating salads with fat-free dressings may rob the body of nutrients
July 27, 2004 -- Eating your salad or carrot sticks with a little fatty
salad dressing may actually be better for your health than pouring on the
A new study shows that eating fresh vegetables with a little fat, such as
oil-based salad dressings or cheese, helps the body absorb valuable nutrients
found in vegetables, such as lycopene and beta-carotene, which have been shown
to help prevent heart disease and cancer.
In contrast, eating a salad without any fat in it may deprive your body of
these healthy nutrients, which are known as carotenoids.
"We're certainly not advocating a high-fat diet, or one filled with
full-fat salad dressing," says researcher Wendy White, associate professor
of food science and nutrition at Iowa State University, in a news release.
"Our findings are actually consistent with U.S. dietary guidelines, which
support a moderate diet, rather than one very low, in fat."
"But what we found compelling was that some of our more popular
healthful snacks, like baby carrots, really need to be eaten with a source of
fat for us to absorb the beta carotene," says White. "If you'd like to
stick with fat-free dressing, the addition of small amounts of avocado or
cheese in a salad may help along the absorption."
Researchers say that the popularity of fat-free and low-fat salad dressings
has grown in the last 10 years, and 20% of men and 33% of women say they always
choose low-calorie rather than full-calorie salad dressings.
Fat Helps the Body Absorb Nutrients
Vegetables commonly found in salads are essentially fat-free and are a rich
source of healthy carotenoids. In order for these carotenoids to be absorbed by
the human digestive system, fat is needed. But researchers say exactly how much
fat is needed to provide optimal absorption of these nutrients is not clearly
In the study, which appears in the August issue of the American Journal
of Clinical Nutrition, researchers compared nutrient absorption after
eating salads with varying levels of fat.
Seven healthy men and women ate salads of spinach, romaine lettuce, cherry
tomatoes, and carrots topped with Italian dressings containing 0, 6 (0.2
ounces), or 28 grams (almost 1 ounce) of canola oil on different occasions
during a 12-week period. Hourly blood samples were taken for 11 hours after the
meal and tested for nutrient absorption.
The study found that only negligible amounts of alpha- and beta-carotene and
lycopene were detected in the blood after eating a salad with fat-free
dressing. Significantly more of these substances, known as carotenoids, were
detected in the blood after eating salads with reduced-fat dressing or full-fat
Researchers say this study shows that the minimum amount of fat required for
optimal absorption of these nutrients from the salads is more than 6 grams of
added fat. But because salads are often consumed with other items that contain
fat, the use of a reduced-fat salad dressing may still allow the body to reap
the maximum nutritional benefits of fresh vegetables.