Researchers Study Salad Nutrition

Researchers Study Salad Nutrition


Salad vegetables are chock full of important vitamins and nutirents. But according to a Purdue University study you won’t get much benefit without the right type and amount of salad dressing. So, in this study one of the targets for us was basically to look at salad vegetables as a primary source of carotenoids in the daily diet of Americans. So for our bodies to be able to absorb and utililize these nutriets we need fat to help solubilize them and extract them from the foods as we normally digest the food, but also to help the process, the natural process of fat absorption in the body which carries these fat soluble phytochemicals in. Carotenoids are compounds in nature that are believed to have health benefits beyond basic nutritional value. These benefits include lowering risks of several chronic and degenerative diseases, including: cancer, cardiovascular disease and macular degeneration. Salad vegetables is one of the main classes of vegetables which Americans seem to consume pretty regularly. This includes tomatoes, carrots, lettuce, spinach, fresh spinach. Our reason for using that was the fact that in some cases people will actually replace meals, especially lunch for example, with a salad. Researchers fed subjects salads topped off with saturated, mono-unsaturated and poly-unsaturated fat based dressings. Then tested their blood for absorption of these fat soluble carotenoids. These vegetable oil based dressings were chosen primarily because their common use in salad dressings. This being canola oil and soybean oil. Then we wanted to compare these vegetable oils to more saturated fat source such as butter. Our big question was not just related to how does fat influence absorption of carotenoids from these vegetables. Our question related more to the need to understand is there a logic to selection of a type and/or an amount of fat that’s going to be, let’s say optimal in the delivery of these carotenoids. What’s the best choice to make if you are a consumer or a food processer. So our primary findings were that in almost all instances amount was more critical to driving carotenoid absorption, amount of fat was more critical to driving carotenoid absorption than type. Fat soluble, health promoting carotenoids from widely consumed salad vegetables require fat for absorption. So you need to make sure that you have some fat in your salad dressing when you’re choosing healthy. Some fat is healthy. If you feel like choosing a heart healthy oil, such as canola oil or poly-unstaturated rich soybean oil over saturated fat you’ll get the same if not slighty better absorption depending on the individual carotenoids that are in the salad that you are consuming. It appears there’s priliminary evidence that suggests that low levels of heart healthy canola oil, mono-unsaturated rich, fatty acid rich canola oil, could be as potent as a facilitator for carotenoid absorbtion as higher levels of fat overall.

6 thoughts on “Researchers Study Salad Nutrition”

  1. Why didn't the study include one group who had no oil or fat on their salad and compare absorption levels to that group? The man in the video said it himself-the main point of the study was to compare different fats to each other. Is it possible that this guy is paid by big agriculture to promote the use of vegetable oils?

  2. A previous study from Iowa State in 2004 showed that carotenoids are fat-soluble. That study concluded that vegetables in salads needed to be paired with some fat to allow the body to absorb the carotenoids. Dr. Ferruzzi's study received no private funding. The U.S. Department of Agriculture funded his work.

  3. @Purdueagriculture I'm so glad you responded! It seems like you have a handle on what's going on around here. I've got some other questions that maybe you can answer. Do you know why fats from natural sources like nuts, seeds or avocado were not included in the study?

  4. More questions . . . Since the amount of fat needed to absorb the nutrients is really relatively little (maybe a teaspoon or even less?), do you know why the man in the video poured what looks like 1/4 cup of oil on the salad? Also, since salads are often accompanied by other food, wouldn't the fat in whatever else someone eats qualify as the fat necessary to absorb the nutrients? Why would someone need to dress the salad with fat at all?

  5. The guy in the video says salads are usually consumed as single meals when people want something light or do not have time to eat a full meal. In that case, an oil base dressing over a non-fat dressing makes sense.

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