A second study shows that lycopene from tomato paste is better absorbed by the body than lycopene from fresh tomatoes, suggesting that processed tomato productssuch as tomato paste, tomato sauce and ketchupare a better source of this antioxidant.
The study by Gärtner et al, published in the July 1997 issue of the American Journal of Clinical Nutrition, suggests that lycopene from tomato paste is 2.5 times more bioavailable in humans than lycopene from fresh tomatoes.
It has been suggested that lycopene helps prevent the development of some cancers, such as prostate cancer. A 1995 epidemiologic study by Giovannucci et al linked diets rich in tomato products to a reduced risk of prostate cancer. These authors hypothesized better bioavailability of lycopene from processed tomato products than from fresh tomatoes; the new study addressed this hypothesis.
The study establishes that processed tomato products such as tomato paste provide the most readily absorbed source of lycopene, according to co-researcher Helmut Sies, MD, Institute of Physiological Chemistry, Heinrich Heine University, Dusseldorf.
Gärtner et al compared subjects lycopene response based on a single dose of lycopene from fresh tomatoes or from tomato paste. The study was conducted on two experimental days 2 weeks apart. Five participants consumed a diet low in carotenoids 3 days before the study days. On the study days, subjects fasted overnight and then consumed either 400 g of fresh tomatoes or 40 g of tomato paste, which contained the same amount of lycopene (23 mg), plus 15 g of corn oil and 100 g of bread. The fresh tomatoes were sliced and served as a salad together with the corn oil. For the tomato paste meal, the corn oil was stirred into the tomato paste.
Blood samples were drawn before and after the consumption of the tomato meals. Ingestion of tomato paste yielded 2.5 times the amount of lycopene in subjects than fresh tomatoes.
These results are significant in light of the mounting evidence showing health benefits of lycopene, said Dr. Sies. It is important for us to study how lycopene is metabolized and distributed, and how people can optimize both intake and absorption.
Fresh or Processed TomatoesWhy the Difference?
Researchers believe that processing or cooking the tomatoes breaks down cell walls, making the lycopene more accessible to the body when ingested. Absorption of lycopene is further enhanced when it is consumed with a small amount of fat, which is present in cooking oils used in preparing most tomato products.
Lycopene has been shown to exhibit the highest antioxidant activity of all dietary carotenoids. At the March 1997 International Symposium on the Role of Lycopene and Tomato Products in Disease Prevention, numerous studies investigating the potential health benefits of lycopene were presented, further propelling interest in the study of this relatively unknown phytochemical.