lycopene

Foods Richest in lycopene

No food chart data available.

About lycopene

Description

Lycopene is a carotenoid pigment responsible for the deep red color of tomatoes, watermelon, pink grapefruit, and guava. Research into its biological effects began in the late 20th century and has since generated a substantial body of laboratory, animal, and population-based evidence. Epidemiological studies have associated higher lycopene intake with reduced risk of cancers of the prostate, pancreas, stomach, breast, cervix, and lung, as well as lower incidence of cardiovascular disease, cataracts, and age-related macular degeneration (progressive loss of function in the light-sensing cells at the center of the retina).

How it functions

Unlike beta-carotene or alpha-carotene, lycopene has no pro-vitamin A activity; the body does not convert it into retinol. Its biological effects stem primarily from antioxidant activity. In laboratory comparisons, lycopene quenches singlet oxygen (a reactive oxygen species generated during normal metabolism) more efficiently than other carotenoids, including beta-carotene. Singlet oxygen reacts readily with polyunsaturated fatty acids in cell membranes. Because lycopene concentrates in these lipid bilayers, it helps protect membrane structure, preserving the thickness, fluidity, and selective permeability that cells require for nutrient uptake, waste removal, and intercellular signaling.

Beyond antioxidant activity, lycopene suppresses tumor growth in in vitro and in vivo experiments. One proposed mechanism involves gap junction communication between cells; lycopene upregulates connexin 43, a gap junction protein, and impaired intercellular communication is considered an early event in carcinogenesis.

Lycopene may contribute to cardiovascular protection by reducing oxidation of LDL cholesterol. LDL particles must undergo oxidative modification before they can be incorporated into arterial plaques, and lycopene’s singlet oxygen quenching capacity may limit this initial oxidation step.

A small clinical trial (n=30) found that lycopene supplementation improved both sperm concentration and motility in infertile men, with six pregnancies resulting from the trial period. Larger studies are needed to confirm this finding.

Deficiency symptoms

Inadequate intake of lycopene, and other carotenoids, over a period of many years may set the stage for the development of several chronic diseases, including heart disease and various cancers. One important mechanism for this relationship appears to involve free radicals. Research indicates that diets low in carotenoids can increase the body’s susceptibility to damage from free radicals. As a result, over the long term, carotenoid-deficient diets may increase tissue damage from free radical activity, and increase risk of chronic diseases like heart disease and cancers.

Toxicity symptoms

A high intake of foods containing lycopene is not known to cause any harmful side effects. However, excessive consumption of lycopene can cause a deep orange discoloration of the skin, a harmless condition called lycopenodermia. Although very little is known about the potential for adverse effects from high doses of supplemental lycopene, the Institute of Medicine at the National Academy of Sciences did not establish a Tolerable Upper Intake Level (UL) for carotenoids (including lycopene) when it reviewed these compounds in 2000.

Some research indicates that under certain circumstances, lycopene (and other carotenoids) can become oxidized in the body, and may subsequently behave like free radicals and cause cellular damage. Cigarette smoke, for example, may cause lycopene to become oxidized. This may explain, at least in part, the research findings that cigarette smokers who take carotenoid supplements may have an increased risk of cancer or heart disease.

Impact of cooking, storage and processing

The bioavailability of lycopene from tomato products appears to increase with heat processing and the presence of dietary fat. Thermal processing disrupts cell walls and converts lycopene from its trans- to cis-isomer form, which is more readily absorbed. Tomato products cooked with oil (sauces, for example) may therefore deliver more bioavailable lycopene than raw tomatoes, though this remains an active area of investigation.

Vine-ripened tomatoes have a higher lycopene content than tomatoes ripened off the vine.

Factors that affect function

Lycopene is fat-soluble and requires dietary fat for intestinal absorption. Extremely low-fat diets or conditions that impair fat absorption (pancreatic enzyme deficiency, Crohn’s disease, celiac disease, cystic fibrosis, gastric surgery, gallbladder disease, liver disease) can reduce lycopene status.

Nutrient interactions

Some research indicates that the various members of the carotenoid family compete with one another for absorption. The example most often cited of this interaction is the reduction in blood levels of lutein that occurs with beta-carotene supplementation. However, one study that measured the absorption of beta-carotene and lycopene found that, when taken at the same time, beta-carotene absorption was not reduced and lycopene absorption was actually enhanced.

Other conflicting research suggests that carotenoids actually work synergistically, and that the antioxidant activity of lycopene is enhanced by the presence of other carotenoids, specifically lutein. More studies are needed to clarify these relationships.

Health conditions

Lycopene may play a role in the prevention and/or treatment of the following health conditions:

Food sources

Foods highest in lycopene include tomatoes, pink grapefruit, watermelon, and guava. Other foods containing small amounts of lycopene include persimmon and apricots.

 

Food Source Analysis not Available for this Nutrient

Public health recommendations

To date, no recommended dietary intake levels have been established for carotenoids, including lycopene. However, the National Academy of Sciences supports the recommendations of various health agencies, which encourage individuals to increase their consumption of carotenoid-rich fruits and vegetables.

Related Articles

References

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