INDEX

Lycopene

(Source: SaluGenecists, Inc.)

Lycopene, a member of the carotenoid family of phytonutrients, is the natural pigment responsible for the deep red color of several fruits, most notably tomatoes. While tomatoes have been consumed for centuries, it was not until the last part of the 20th century that research into their health benefits was initiated. Yet, in this short period of time, a significant body of research including laboratory, animal and population-based research has been amassed that supports the role of lycopene in human health. Its benefits have been specifically shown to be linked to prevention of cancers of the prostate, pancreas, stomach, breast, cervix and lung, as well as the prevention of cardiovascular disease, cataracts and age-related macular degeneration, the latter being a chronic eye condition in which light-sensing cells in the retinas center stop functioning.

Summary

Physiological functions of lycopene

  • Protect cells from the damaging effects of free radicals
  • Helps prevent the oxidation of cholesterol, thereby slowing the development of atherosclerosis

Physiological events that may signal a need for greater lycopene intake

  • Low intake of fruits and vegetables
  • Smoking
  • Regular alcohol consumption

Functions

Functions of lycopene

Protects cells from oxidative damage

None of the health benefits that lycopene conveys come from its relationship with vitamin A since it is one of the carotenoids that does not have any pro-vitamin A activity. It seems that many of its documented health benefits at this time are attributed primarily to its powerful antioxidant activity; in laboratory experiments lycopene has been shown to be an even more effective antioxidant than other carotenoids, including beta-carotene.

Lycopene is especially effective at quenching a free radical known as singlet oxygen, a highly reactive molecule formed during normal metabolic processes. Left unchecked, singlet oxygen reacts with and damages polyunsaturated fatty acids which comprise the major constituents of cell membranes. Yet, since lycopene is oftentimes located in the cell membrane it can protect against oxidative damage to these membrane lipids, helping to ensure the thickness, strength and fluidity of the membranes. Since cell membranes function as the gatekeepers of the cells – allowing nutrients in, keeping toxic compounds out and facilitating the removal of cellular waste – maintaining the integrity of cell membranes is a key factor for disease prevention and aging.

Since it inhibits LDL cholesterol oxidation that can be caused by free radicals, one of the first steps necessary in the deposition of cholesterol in the arteries, lycopene is believed to play a role in heart disease prevention.

Potential anticancer activities

In addition to having antioxidant activity, lycopene has been shown to be able to suppress the growth of tumors in both in vitro (test tube) and in vivo (animal) experiments. Lycopene is thought to be able to limit tumor growth through its ability to stimulate cell-to-cell communication, an important mechanism for maintaining the health of cells. Many researchers now believe that poor communication between cells is one of the causative factors of abnormal cell growth, a condition that can ultimately progress to the cancer tumor development.

Deficiency Factors

Causes and symptoms of lycopene deficiency

Fat malabsorption as well as extremely low fat diets can contribute to impaired lycopene status since lycopene is a fat-soluble substance. Pancreative enzyme deficiency, gallbladder disease, liver disease, Crohns disease, celiac disease, cystic fibrosis and surgical removal of part of all of the stomach are conditions that can cause fat malabsorption.

Research indicates that diets low in lycopene and other carotenoids can increase the bodys susceptibility to free radical damage. Therefore, over a period of many years, inadequate intake of lycopene and other carotenoids may increase tissue damage from free radical activity and set the stage for the development of several chronic diseases including heart disease and cancers.

Toxicity Factors

Causes and symptoms of lycopene toxicity

Although excessive consumption of lycopene can cause a deep orange discoloration of the skin, a harmless condition called lycopenodermia, a high intake of food containing lycopene is not known to cause any harmful adverse events.

There is some research that suggests that under certain conditions, such as cigarette smoke, lycopene as well as other carotenoids can become oxidized in the body, act like free radicals and cause cellular damage. This may explain, in part, why some research findings have suggested that cigarette smokers who took carotenoids supplements may be at increased risk for developing cancer or heart disease.

Although little in known about potential toxicity from high doses of supplemental lycopene, in 2000, when the Institute of Medicine at the National Academy of Sciences reviewed carotenoids they did not establish a Tolerable Upper Intake Level (UL) for these compounds.

Cooking, Storage and Processing

Effects of cooking, storage and processing on lycopene

There has been a significant amount of research attention focused upon the impact of food processing on the quality and bioavailability of lycopene. Although there is not absolute consensus, it is currently accepted that lycopenes availability in tomato products is increased when the foods are either processed at high temperatures or packaged with oil. Therefore, if this is correct, it suggests that the lycopene from oil-containing canned, pasteurized tomato juice and tomato products is more easily absorbed than that from a fresh, raw tomato. More research may be necessary in this arena.

Tomatoes that are vine-ripened have more lycopene than those that are ripened off the vine.

Drug & Nutrient Interactions

Interactions between medications and lycopene

Medications that may reduce lycopene status in the body:

  • Bile acid sequestrants such as Cholestyramine, Colestipol and Colestid
  • Olestra, a fat substitute
  • Plant sterols as found in Benecol and Take Control margarines

Nutrient Interactions

Interactions that occur between lycopene and other nutrients

Certain carotenoids have been suggested to compete with certain others for absorption as reflected in studies where beta-carotene supplements were shown to reduce blood levels of the carotenoid lutein. Yet, findings from a study that measured lycopene and beta-carotene absorption suggested that when these two nutrients were taken simultaneously, lycopene absorption was enhanced while beta-carotene absorption was not reduced. Additionally other research suggests that the lycopenes antioxidant potential is enhanced by the presence of other carotenoids, namely lutein. It seems that more studies are needed to clarify the relationship among carotenoids and their absorption.

Health Conditions

Health conditions that require special emphasis on lycopene

Individuals who have the following health conditions should pay special attention to their lycopene status:

  • Age-related macular degeneration
  • Cardiovascular disease
  • Cataracts
  • Breast cancer
  • Cervical cancer
  • Lung cancer
  • Ovarian cancer
  • Pancreatic cancer
  • Prostate cancer
  • Skin cancer
  • Stomach cancer

Forms in Dietary Supplements

Forms in which lycopene is found in dietary supplements.

Lycopene can be found in dietary supplements. either by itself or in a mixed carotenoid formula. Supplements with lycopene are often oil-based and sold in soft gels. Additionally, some supplements contain lycopene from tomato extracts..

Food Sources

Foods that are concentrated sources of lycopene

Lycopene is found in apricots, guava, papaya, pink grapefruit and tomatoes.