Study: No-fat, low-fat dressings don't get most nutrients out of salads
The vegetables in salads are chock-full of important vitamins and nutrients, but you won't get much benefit without the right type and amount of salad dressing, a Purdue University study shows.
In a human trial, researchers fed subjects salads topped off with saturated, monounsaturated and polyunsaturated fat-based dressings and tested their blood for absorption of fat-soluble carotenoids ╨ compounds such as lutein, lycopene, beta-carotene and zeaxanthin. Those carotenoids are associated with reduced risk of several chronic and degenerative diseases such as cancer, cardiovascular disease and macular degeneration.
The study, published early online in the journal Molecular Nutrition & Food Research, 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.
This video is not supported by your browser at this time."If you want to utilize more from your fruits and vegetables, you have to pair them correctly with fat-based dressings," said Mario Ferruzzi, the study's lead author and a Purdue associate professor of food science. "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."
In the test, 29 people were fed salads dressed with butter as a saturated fat, canola oil as a monounsaturated fat and corn oil as a polyunsaturated fat. Each salad was served with 3 grams, 8 grams or 20 grams of fat from dressing.
The soybean oil rich in polyunsaturated fat was the most dependent on dose. The more fat on the salad, the more carotenoids the subjects absorbed. The saturated fat butter was also dose-dependent, but to a lesser extent.
Monounsaturated fat-rich dressings, such as canola and olive oil-based dressings, promoted the equivalent carotenoid absorption at 3 grams of fat as it did 20 grams, suggesting that this lipid source may be a good choice for those craving lower fat options but still wanting to optimize absorption of health-promoting carotenoids from fresh vegetables.
"Even at the lower fat level, you can absorb a significant amount of carotenoids with monounsaturated fat-rich canola oil," Ferruzzi said. "Overall, pairing with fat matters. 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."
The findings build on a 2004 Iowa State University study that determined carotenoids were more bioavailable ╨ absorbed by the intestines ╨ when paired with full-fat dressing as opposed to low-fat or fat-free versions. Ferruzzi; Wayne Campbell, a Purdue professor of nutrition science; Shellen Goltz, a Purdue graduate student in food science; and their collaborators, Chureeporn Chitchumroonchokchai and Mark L. Failla at Ohio State University, are the first to study different types of fats in differing amounts in human subjects.
Ferruzzi and colleagues will next work on understanding how meal patterning affects nutrient absorption. He is trying to determine whether people absorb more nutrients if they eat vegetables at one time or if consumption is spread throughout the day.
Meal Triacylglycerol Profile Modulates Postprandial Absorption of Carotenoids in Humans
Shellen R. Goltz, Wayne M. Campbell, Chureeporn Chitchumroonchokchai, Mark L. Failla, Mario G. Ferruzzi
Scope: Dietary lipids are considered to be primary potentiators of carotenoid absorption, yet the amount and source required to optimize bioavailability has not been systematically evaluated. The objective of this study was to examine the impact of both amount and source of triacylglycerols on postprandial absorption of carotenoids from vegetable salads.
Methods and results: Healthy subjects (n = 29) were randomized using a Latin square design (3x3) and consumed three identical salads with 3, 8 or 20 g of canola oil, soybean oil or butter. Blood was collected from 010 h and triacylglycerol-rich fractions (TRLs) were isolated by ultracentrifugation. Carotenoid contents of TRL fractions were analyzed by HPLC-DAD. Considering all lipid sources, 20 g of lipid promoted higher absorption compared to 3 and 8 g for all carotenoid species (p < 0.05), except for α-carotene (p = 0.07). The source of lipid had less impact on the absorption of carotenoids than amount of lipid. Pooling results from all lipid amounts, monounsaturated fatty acid rich canola oil trended toward enhancing absorption of lutein and α-carotene compared to saturated fatty acid rich butter (p = 0.06 and p = 0.08, respectively).
Conclusion: While both amount and source of co-consumed lipid affect carotenoid bioavailability from vegetables, amount appears to exert a stronger effect.
Journal reference: Molecular Nutrition & Food Research
Provided by Purdue University
- Can a Mediterranean diet help prevent colon cancer? Jun 13, 2007 | not rated yet | 0
- Macadamia nuts can be included in heart healthy diet Apr 11, 2008 | not rated yet | 0
- With fat: What's good or bad for the heart, may be the same for the brain May 18, 2012 | not rated yet | 0
- Intake of the right fatty acids can help to prevent heart attacks Jun 30, 2011 | not rated yet | 0
- Can our genes be making us fat? Mar 22, 2012 | not rated yet | 0
- Motion perception revisited: High Phi effect challenges established motion perception assumptions Apr 23, 2013 | 3 / 5 (2) | 2
- Anything you can do I can do better: Neuromolecular foundations of the superiority illusion (Update) Apr 02, 2013 | 4.5 / 5 (11) | 5
- The visual system as economist: Neural resource allocation in visual adaptation Mar 30, 2013 | 5 / 5 (2) | 9
- Separate lives: Neuronal and organismal lifespans decoupled Mar 27, 2013 | 4.9 / 5 (8) | 0
- Sizing things up: The evolutionary neurobiology of scale invariance Feb 28, 2013 | 4.8 / 5 (10) | 14
Classical and Quantum Mechanics via Lie algebras
Apr 15, 2011 I'd like to open a discussion thread for version 2 of the draft of my book ''Classical and Quantum Mechanics via Lie algebras'', available online at http://lanl.arxiv.org/abs/0810.1019 , and for the...
- More from Physics Forums - Independent Research
More news stories
(Medical Xpress)—Health care spending is much higher for older Americans than for younger adults and children, on average, and analysts have said that increasing spending leads to longer life expectancy.
Health 1 hour ago | not rated yet | 0
(Medical Xpress)—High blood pressure is something that has traditionally been a problem in Scotland, but might there be a link to our climate?
Health 1 hour ago | not rated yet | 0
(Medical Xpress)—A report published today shows a 2.6% decrease in the amount of alcohol sold per adult in Scotland in the year following the introduction of the Alcohol etc. (Scotland) Act in October 2011.
Health 1 hour ago | not rated yet | 0
New mothers throughout Australia are needed to help QUT sleep researchers investigate whether the disrupted sleep experienced by mothers when caring for their new baby raises the risk of injury while driving.
Health 3 hours ago | not rated yet | 0
Research presented today shows that high-fructose corn syrup can cause behavioural reactions in rats similar to those produced by drugs of abuse such as cocaine. These results, presented by addiction expert Francesco Leri, ...
43 minutes ago | not rated yet | 0
On May 22, JoVE will publish details of a technique to measure the health of human genetic material in relation to a patient's age. The method is demonstrated by the laboratory of Dr. Gil Atzmon at New York's Albert Einste ...
42 minutes ago | not rated yet | 0
New research shows that craving drugs such as nicotine can be visualized in specific regions of the brain that are implicated in determining the value of actions, in planning actions and in motivation. Dr. Alain Dagher, from ...
41 minutes ago | not rated yet | 0
(Medical Xpress)—Scientists supported by the National Institutes of Health have a new theory as to why a woman's fertility declines after her mid-30s. They also suggest an approach that might help slow ...
2 hours ago | not rated yet | 0 |
Is it permissible to harm one to save many? Those who tend to say "yes" when faced with this classic dilemma are likely to be deficient in a specific kind of empathy, according to a report published in the scientific journal ...
5 hours ago | not rated yet | 0 |
Medical researchers discover new ways to target, develop and design drugs to prevent and treat viral infection
Researchers at the University of Alberta have discovered a new drug target, developed a new drug and identified a new way to design drugs—all of which could be a winning combination in the battle against viruses.
2 hours ago | 4 / 5 (1) | 0 |