Hey, There's a Lycopene in My Ketchup!
by Dana Denis, MSPH., RD (topic expert: nutrition)

Have you read your ketchup bottle lately? The label probably states that it is a good source of lycopene. But what is lycopene and why is it important?

What is it?

Lycopene is a carotenoid. Much like carotene provides the orange color to carrots, lycopene provides the red color to tomatoes. The redder the tomato, the more lycopene it contains. Lycopene can also be found in watermelon, pink grapefruit, pink guava, and papaya. Approximately 85% of the lycopene consumed in North America comes from tomatoes and tomato products like ketchup, tomato juice, tomato paste, tomato soup and tomato sauce.

Processing of the tomatoes actually makes the lycopene we eat more available for use in our bodies. In other words, there is more lycopene absorbed when eating tomato sauce than fresh tomatoes. In addition, because lycopene is lipophillic (likes fats) it may also be better absorbed when eaten with a little bit of fat in the meal.

In our bodies, lycopene can be found largely in liver, adrenal, testes and prostate tissues. It is the most abundant carotenoid found circulating in our bloodstream. The amount found in our bodies, both circulating in our blood and stored in our tissues, changes with the amount of lycopene we consume in our diet.

Lycopene and Cancer

Lycopene is a strong antioxidant, thought to be more potent than beta-carotene in laboratory testing. Antioxidants help to eliminate free radicals, which can damage cells and lead to chronic disease. Initial studies showed a strong association between lycopene and reduced cancer cell growth.

Prostate cancer has been a major area of study, probably due to the high levels of lycopene in prostate tissue. Several studies have shown that an increase in the dietary intake of tomato products and/or blood lycopene levels corresponded with a decreased incidence of prostate cancer. Other studies have found reductions in risk; however, the effect was not large enough to be called "statistically significant." Yet other studies did not find the same association between lycopene and reduced prostate cancer risk.

One intervention study gave tomato sauce entrees to men diagnosed with prostate cancer for 3 weeks prior to their surgeries and compared them to control prostate surgery patients. The tomato sauce supplemented patients had reduced levels of PSA (prostate specific antigen - a marker for prostate cancer) resulting from increased cancer cell death. This was a small study and much larger studies are necessary to confirm this effect [6].

There have been studies that have observed the beneficial effect of lycopene in reduced risk of lung, breast, stomach, and colorectal cancers. Again, there are many studies that have found lycopene to have a protective effect; however, the evidence is not conclusive due to other studies finding little or no effect.

Lycopene and Cardiovascular Disease

A recent area of study has been the effect of lycopene on cardiovascular disease. Initial studies suggest an inverse association between dietary lycopene and CVD; however, more recent studies could not show improvement in blood lipid levels (for example, cholesterol levels).

Why are there conflicting results?

The reasons are usually due to differences in study design. One example is that the techniques and questionnaires for obtaining diet history from participants vary between studies.

In addition, many of the studies looked at the dietary intake of lycopene while others evaluated the plasma or tissue content of lycopene and the risk of developing cancer. Studies also look at patients with different types of tumors, so they are difficult to compare.

Another major difference among studies was the amount of lycopene the participants consumed, some as low as 2 to 3 mg per day (about the amount in 1 tablespoon of ketchup) and others provided 30 mg per day (� cup pasta sauce).

As stated earlier, the bioavailability of lycopene could be different based on the product used and how it is consumed. For instance, spaghetti sauce with a little fat may increase the ability of the body to utilize dietary lycopene. You can also imagine how difficult it is to isolate the effect of one carotenoid against all other potential factors that could play a role in cancer.

What are the recommendations?

The benefits of eating a diet high in fruits and vegetables are well documented. The conclusion from the International Nutrition and Health Conference Report: Lycopene and the Prevention of Chronic Diseases states a recommendation of five servings of tomato products per week, approximately 5 to 10 mg per day.4

Source: USDA National Nutrient Database for Standard References. Release 16-1.

One finding was consistent in all studies: no adverse effect was found from consuming lycopene.

References:

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