Pizza for Prostate Cancer Prevention?
It sounds more than a little unlikely, but scientists at the National Institutes of Health and three major universities have found that the lycopene in fresh tomatoes does little or nothing to prevent prostate cancer, while spaghetti sauce, pizza sauce, and lasagna do.
Scientists have known for a number of years that consumption of tomato products seems to be associated with a reduced risk of prostate cancer, but the findings are not consistent. Sometimes tomatoes seem to help, and sometimes they don't, although overall the studies hint at a reduction of prostate cancer risk of as much as 20 per cent in men who consume the most of this commonly consumed vegetable. The National Institutes of Health took a closer look at just which forms of the vegetable are most effective.
The National Institutes of Health followed over 30,000 men in the Prostate, Lung, Colorectal, and Ovarian Trial. Cancer-free men aged 55 to 74 were given PSA tests when they entered the study and then follow-up blood work and digital (finger) examinations every year for four years. They were also queried about all the foods they ate on a daily, weekly, and monthly basis.
The scientists learned that the most lycopene was to be found in:
- Tomato juice, and
- Tomato sauce.
And the men in the study consumed more sauce than any other product.
The greatest protection against prostate cancer, however, was found with consumption of:
- Pizza,
- Lasagna, and
- Spaghetti,
But more was not necessarily better. In fact, about one serving a week seemed to offer the most protection against cancer. Why would this be?
Lycopene dissolves in fat, not water. Oils and fats carry this important plant compound to the lining of the colon where it can be absorbed, but watery foods simply pass through without entering the body.
Lycopene in raw tomatoes is a trans- isomer. Basically, this means there is just one point on the molecule where a human cell can "grab" it and move it inside.
But the same molecule in cooked tomatoes is a cis- isomer. This means there are two points on the molecule where it can be attracted to a cell. It is easier for the body to absorb lycopene if the tomato has been cooked a long time (as in sauce) or at high temperature (as in pizza). Additionally, mashing and cooking the tomato bursts the cell walls of the tomato so that it is more thoroughly released. Cooking makes the healing plant compound easier for the body to take in.
There are limits, of course, to how much spaghetti, lasagna, and pizza are really cancer-preventive, especially since they are usually prepared with high amounts of saturated fat. In the National Institutes of Health study, this was about once a week.
Other studies have found little or no benefit for lycopene supplements in preventing prostate cancer. The protection comes from real tomatoes, cooked, but consumed in moderation. And the reduction in risk is 10 to 20 per cent.