- Nonprovitamin A carotenoid
For Patients & Caregivers
Bottom Line: Diets that contain many fruits and vegetables rich in carotenoids like lycopene can help prevent some types of cancers and heart problems. However, not enough research has been done to say whether lycopene supplements have the same effect.
Lycopene is a natural pigment that is produced by plants and microorganisms. Laboratory experiments with lycopene confirm that it acts as an antioxidant and affects the way cells grow and communicate with each other, although it is not as potent as beta-carotene. Scientists have proposed several different mechanisms by which lycopene might fight cancer. These include stopping cancer cell growth, preventing DNA damage, and enhancing enzymes that break down cancer-causing products. Studies in healthy elderly patients suggest that consumption of lycopene or tomato juice does not stimulate the immune system. In general, diets rich in carotenoids like lycopene have been associated with decreased risk of macular degeneration, cataracts, some types of cancers, and some heart problems.
- To prevent and treat cancer
Lycopene is an antioxidant. One clinical trial suggested that preventative use of lycopene supplements reduces the spread of localized prostate cancer, but there is no other proof from clinical trials that lycopene can treat cancer. Diets rich in carotenoids like lycopene are generally associated with a decreased risk of certain types of cancers.
- To treat asthma
One clinical trial showed that daily lycopene supplementation protected against exercise-induced asthma, but no additional studies have been performed to confirm this.
- As an antioxidant
Laboratory studies support this use.
- To treat heart disease
Diets rich in carotenoids like lycopene are generally associated with a decreased risk of some cardiovascular events. However, there is no proof that lycopene supplements have the same effect.
- To prevent and treat macular degeneration
Diets rich in carotenoids like lycopene are generally associated with a decreased risk of macular degeneration. However, there is no proof that lycopene supplements have the same effect.
Benign prostatic hyperplasia (BPH):
Forty participants with BPH received lycopene or placebo for 6 months. Symptoms of BPH including prostate specific antigen (PSA) levels and prostate enlargement were measured. Patients who took lycopene had decreased PSA levels and no further prostate enlargement. Patients given placebo had no changes in their PSA levels and further prostate enlargement. Larger, long-term studies needed to validate whether lycopene supplementation is useful for BPH treatment.
For Healthcare Professionals
A natural pigment synthesized by plants and microorganisms, lycopene is used primarily as an antioxidant and also to prevent and treat cancer, heart disease, and macular degeneration. Lycopene has antioxidant activity and is classified as a nonprovitamin A carotenoid, other examples being lutein and zeaxanthin. Alpha-carotene, beta-carotene, and beta-cryptoxanthin are classified as provitamin A carotenoids because they can be converted into retinol. Small clinical trials suggest possible benefit against exercise-induced asthma (1), benign prostatic hyperplasia (BPH) (2), and cancer, but no optimal dosage has been established.
Lycopene enhanced antitumor efficacy of docetaxel against prostate cancer in animal studies (22). Epidemiologic studies suggest an inverse relationship between lycopene consumption and risk of cancer (3), particularly lung (4), stomach (5), prostate (6), estrogen receptor (ER) and progesterone receptor (PR)-positive breast cancers (7). However a consistent association between lycopene consumption and endometrial cancer risk has not been detected (8)(9).
Low intake of tomato sauce may be associated with advanced prostate cancer in patients with low-grade cancer at diagnosis (10) although data from other studies indicate that lycopene or tomato-based regimens do not prevent prostate cancer (11). Variable results were reported for lycopene supplementation in prostate cancer patients (12). A recent study did not find any association between levels of serum lycopene and risk of prostate cancer (23).
An analysis of six commercially available brands revealed that lycopene content varied from the labeled dosage by as much as 43% (14).
Lycopene is a natural pigment synthesized by plants and microorganisms. Referred to as a nonprovitamin A carotenoid, it is not known to have any vitamin A activity. Biological actions include antioxidant activity via singlet oxygen quenching and peroxyl radical scavenging, induction of cell to cell communication, and growth control, although less efficiently than beta-carotene (15). Proposed mechanisms of action in cancer prevention include inhibition of cancer growth, induction of differentiation by modulation of cell cycle regulatory proteins, alterations in insulin-like growth factor-1 (16) or vascular endothelial growth factor (17) levels, prevention of oxidative DNA damage, and possible enhancement of carcinogen metabolizing enzymes (18).
Other possible actions for all carotenoids include immunoenhancement, inhibition of mutagenesis and transformation, and inhibition of premalignant lesions.
Carotenoids have also been associated with decreased risk of macular degeneration and cataracts, decreased risk for some types of cancers, and decreased risk of some cardiovascular events (19).
Intestinal absorption of carotenoids, including lycopene, is facilitated by the formation of bile acid micelles containing carotenoids. The presence of fat in the small intestine stimulates the secretion of bile acids from the gall bladder and improves the absorption of carotenoids by increasing the size and stability of the micelles, thus allowing more carotenoids to be solubilized. Bioavailability of lycopene is affected by the dose and presence of other carotenoids such as Beta carotene (20).
Concentrations of lycopene in serum and body tissues are highly variable and are dependent on food source, efficiency of absorption, and amount of fat in the diet. The serum concentration after a single dose peaks at 24 to 48 hours post dose (21). Lycopene is primarily stored in adipose and liver. In both serum and tissue storage, lycopene cis-isomers constitute greater than 50 percent of the total lycopene present.
It is assumed that lycopene is excreted through the bile and kidneys (20).
Schwarz S, et al. Lycopene inhibits disease progression in patients with benign prostate hyperplasia. J Nutr. Jan 2008;138(1):49-53.
Because epidemiological studies suggest that dietary intake of lycopene is associated with decreased prostate cancer risk, this study sought to determine if lycopene supplementation improved benign prostatic hyperplasia (BPH), which may be a risk factor for prostate cancer development. Forty participants with BPH received lycopene (15 mg/day) or placebo for 6 months after which prostate specific antigen (PSA) levels and prostate enlargement was assessed. Decreased PSA levels were detected in the intervention group whereas there were no changes in the placebo group. Furthermore, although prostate enlargement was detected in the placebo group, no changes from baseline measurements were seen in the lycopene group.
Larger, long-term studies are necessary to determine if lycopene supplementation could influence prostate cancer in men with BPH.