Adding a low-fat dressing to your salad may seem like a healthy choice. But new research has found the opposite is actually true: Full-fat dressings help the body absorb the most vitamins and nutrients from vegetables in salads.
In fact, Purdue University food scientists found a low-fat or fat-free dressing may neutralize some of the health benefits of eating a salad.
"If you want to utilize more from your fruits and vegetables, you have to pair them correctly with fat-based dressings," said Mario Ferruzzi, lead author of the study published in the journal Molecular Nutrition & Food Research. "If you have a salad with a fat-free dressing, there is a reduction in calories, but you lose some of the benefits of the vegetables."
For the study, Ferruzzi and his colleagues fed 29 people salads topped off with saturated, monounsaturated and polyunsaturated fat-based dressings. They tested their blood for absorption of beneficial fat-soluble carotenoids - such as lutein, lycopene, beta-carotene and zeaxanthin. Those compounds are believed to reduce the risk of several chronic and degenerative diseases such as cancer, cardiovascular disease and macular degeneration.
Each salad was served with 3 grams, 8 grams or 20 grams of fat from dressing.
Researchers found that monounsaturated fat-rich dressings required the least amount of fat to get the most carotenoid absorption, while saturated fat and polyunsaturated fat dressings required higher amounts of fat to get the same benefit.
The bottom line: The more fat on the salad, the more carotenoids the subjects absorbed.
The U.S. Department of Agriculture funded the research.