Intake of fat and carotenoids can promote the absorption of lycopene
"Heating is the key to this process, but adding some fat is also important," Schwartz said. In previous studies, he and colleagues determined that simultaneous intake of fat and carotenoids can promote the absorption of lycopene and other compounds, but scientists are unsure of the exact reason.
When humans ingest fat or lipids, the body produces tiny droplets of fat called lipid micelles during digestion, which easily enter the bloodstream through the intestinal wall.
Continued research led Schwartz to hypothesize that linear forms of lycopene tend to accumulate and crystallize, which reduces but does not eliminate their absorption potential. However, the curved form of lycopene is more likely to enter lipid micelles during digestion, and this form of antioxidant is more likely to increase as fat is transported into the bloodstream.
Considering all these factors, the researchers processed red tomatoes into two sauces: one rich in cis lycopene, which is in the curved form, and the other mainly contains trans lycopene, which is in the linear form. The taste of the two sauces is similar, and the initial heating method is also the same. Corn oil was added to both sauces. However, to produce the curved molecular form of lycopene, the sauce was heated for a second time at 260 degrees Fahrenheit for 40 minutes. The content of cis isomers in this sauce is 9 times higher than that in conventional processed sauces.
Twelve people participated in a study on sauces, during which all people ate two types of sauces. After each meal, the researchers took seven samples of the participants' blood over the next nine and a half hours to measure lycopene levels. The scientists used a special test method to analyze lycopene levels in the blood that are only related to tomato sauce meals, avoiding any other possible sources of these compounds in the blood.
The total absorption rate of lycopene in the blood of study participants after consuming a special sauce increased by 55% compared to the level of lycopene in the blood after consuming a normal sauce. Schwartz said the finding reinforced expectations that the curved form of lycopene is more easily absorbed by the body's blood.
The details of the study were first published in the British Journal of Nutrition in 2007. More clinical trials are underway.
Schwartz said that most commercially available products currently do not contain the curved form of lycopene molecules. However, he pointed out that some home cooking methods may produce the same results as the special processing methods designed by him and colleagues.
"Some people like to cook tomato sauce for a long time, sometimes reheating it day after day because it tastes better on the second and third days. They add fat by using oil or meat, and if fat is present and continue cooking, this will start inducing cis isomers of lycopene," Schwartz said. "Therefore, it is also possible for people to induce this process through conventional food preparation processes and increase lycopene absorption."
The majority of this research was supported by the Ohio Center for Agricultural Research and Development Competitive Grant Program, the National Research Resource Center of the National Institutes of Health, the National Cancer Institute, and the U.S. Department of Agriculture's Future Agriculture and Food Systems Program.
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