A new study claims that while low-fat salad dressings contain less calories, they also have fewer health benefits.
Researchers from Iowa State University fed 29 people salads dressed with butter, high in saturated fat, canola oil for monounsaturated fat, and corn oil for polyunsaturated fat.
Each salad was dished up with three grams, eight grams or 20 grams of fat from dressings to see if fat dosage made a difference to the overall results.
The participants had their blood tested for absorption of fat-soluble carotenoids, which are compounds associated with a reduced risk of several chronic and degenerative diseases such as cancer and cardiovascular disease.
With all but the canola oil, made from genetically modified rapeseed, the more fat that was used the more carotenoids were absorbed, says the study in the journal Molecular Nutrition & Food Research.
Canola oil and olive-oil based dressings promoted the same carotenoid absorption at three grams of fat, as they did at 20 grams – suggesting this would be a good choice of dressing for people watching their weight but wanting to remain healthy.
Results showed corn oil was the most dependent on dose, with the more fat on the salad, the more carotenoids the participants absorbed.
butter rich in saturated fat was also dependent on dose when drizzled on the salads, but not to a lesser extent.
Professor Mario Ferruzzi of Purdue University in the US said: ‘If you want to utilise more from your fruits and vegetables, you have to pair them correctly with fat-based dressings.
‘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.’
The researchers are taking the study further by trying to understand how meal patterns affect nutrient absorption, determining whether people absorb more nutrients if they eat vegetables at one time or spread throughout the day.
Professor Ferruzzi added: ‘You can absorb significant amounts of carotenoids with saturated or polyunsaturated fats at low levels, but you would see more carotenoid absorption as you increase the amounts of those fats on a salad.’
‘Overall, pairing with fat matters,’ he concluded.