Lycopene is one of many popular nutrients that occur abundantly in nature. Often thought of as the tomato (Lycopersicon esculentum) vitamin, lycopene is largely linked to fruits and vegetables with a red coloring, with tomatoes having the richest content of this nutrient.1

Lycopene is a potent antioxidant with an oxygen radical absorbance capacity (ORAC) rating of 6,000 micromoles TE/g.2 Like many antioxidants, lycopene is synthesized only in plants, not animals. Surveys of typical U.S. diets indicate that approximately 85% of lycopene consumption in the United States is from tomatoes and tomato products.3

Background


In its role as an antioxidant, lycopene’s oxidative protection has been targeted as a potential anticarcinogen.4 The secret to the tomato is the presence of an enzyme, lycopene cyclase, that converts lycopene into beta carotene, which is also a potent antioxidant.5

Lycopene is extremely attractive as a nutritional substance for a variety of other reasons as well. In addition to its antioxidant activity and its ready availability, lycopene is also being studied for its antiproliferative effect.6 The antioxidant is thought to prevent cell damage by protecting other critical biomarkers, including DNA, proteins and lipids.3

Science


Research has been focused on lycopene and its potential as a mitigating agent for cardiovascular disease (CVD) and cancer (especially prostate cancer). Researchers project that at least 30% of cancer mortality in the United States could be avoided with dietary modifications.7

The overall mechanisms of action for lycopene are that it decreases oxidative stress and cellular apoptosis. Physiologically, these actions reduce, or block, harmful mechanisms such as intimal inflammation in arterial walls, oxidative cell damage in lungs, and neoplastic cell formation.5

Lycopene is frequently studied as an agent for reducing prostate cancer incidence and slowing prostate cancer growth. In prostate cells, lycopene inhibits androgen receptor expression, which then leads to a reduction of prostate cancer cell proliferation.8

A review of 20 clinical trials evaluated the impact of tomato/lycopene dietary intake on the incidence of prostate cancer. Data supported a 25% to 30% decrease in the occurrence of the disease.9 However, there are always conflicting or equivocal findings, and the lycopene-prostate cancer link is not exempt from such ambiguity. In the past 10 years, multiple clinical trials have failed to show a significant impact of the amount of dietary lycopene intake on the incidence of prostate cancer.10

Lycopene also holds promise in preventing CVD and cerebrovascular disease attributable to atherosclerotic damage. A study of more than 1,000 middle-aged men followed for more than 10 years examined the association between serum lycopene levels and end-point occurrence of ischemic stroke.11 The results indicated an average risk reduction of more than 55% in the cohort.11

As part of a larger clinical trial, researchers focused on the impact of dietary lycopene on CVD in women.6 Nearly 29,000 middle-aged and elderly women from the ongoing Women’s Health Study, were followed for approximately five years until death or diagnosis of cancer or CVD.6 Women with serum lycopene levels in the upper three quartiles experienced a 50% cardiovascular risk reduction compared with women with low lycopene levels.6

In another study, investigators monitored the thickness of the carotid intimal layers of more than 1,000 middle-aged men for more than four years.12 The initial research hypothesis stating the assumption that high serum lycopene levels correlated with a reduction in intimal-wall thickening was supported. Across all levels of serum lycopene measurements, a linear reduction in carotid intimal-wall thickening correlated with an equivalent decrease in risk of cardiovascular events.12

Safety, how supplied, cost, and dose


Allergy to tomatoes or tomato products poses a safety risk for lycopene use. Depending on the level of hypersensitivity, reactions range from a mild response to severe anaphylaxis.

Aside from being present in natural food products, lycopene is available in supplement form—usually tablets or capsules. Depending on the brand, manufacturer, and strength, lycopene cost $20 to $30 for a one-month supply. The suggested dose for an adult ranges from 2 mg to 30 mg per day.2

Summary


Health-care professionals can recommend lycopene supplement (or lycopene-rich food) without reservation. A daily diet abundant in this compound will contribute toward a healthy lifestyle. So, feel free to write your next prescription for the tomato vitamin.

Sherril Sego, FNP-C, DNP, is a staff clinician at the VA Hospital in Kansas City, Mo., where she practices adult medicine and women’s health. She also teaches at the nursing schools of the University of Missouri and the University of Kansas.

References


  1. Rao AV, Rao LG. Carotenoids and human health. Pharmacol Res. 2007;55:207-216.

  2. Agricultural research page. United States 
Department of Agriculture website. 
  3. Basu A, Imrhan V. Tomatoes versus lycopene in oxidative stress and carcinogenesis: conclusions from clinical trials. Eur J Clin Nutr. 2007;61:295-303.
  4. Mayo Clinic. Lycopene. 
  5. Heber D, Lu QY. Overview of mechanisms of action of lycopene. Exp Biol Med. 2002;227:920-923. 
  6. Sesso HD, Buring JE, Norkus EP, Gaziano JM. Plasma lycopene, other carotenoids, and retinol and the risk of cardiovascular disease in women. Am J Clin Nutr. 2004;79:47-53.
  7. Khan N, Afaq F, Muktar H. Cancer chemoprevention through dietary antioxidants: progress and promise. Antioxid Redox Signal. 2008;10:475-510.

  8. National Cancer Institute. Prostate cancer, nutrition, and dietary supplements.
  9. Kirsh VA, Mayne ST, Peters U, et al. A prospective study of lycopene and tomato product intake and risk of prostate cancer. Cancer Epidemiol Biomarkers Prev. 2006;15:92-98.
  10. American Cancer Society. Lycopene.
  11. Karppi J, Laukkanen JA, Sivenius J, et al. Serum lycopene decreases the risk of stroke in men: a population-based follow-up study. Neurology. 2012;79:1540-1547.

  12. Rissanen TH, Voutilainen S, Nyyssönen K, et al. Serum lycopene concentrations and carotid atherosclerosis: The Kuopio Ischemic Heart Disease Risk Factor Study. Am J Clin Nutr. 2003;77:133-138.
  13. All electronic documents accessed on April 2, 2013