Lycopene

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Lycopene

• Pennington Biomedical Research Center
• Division of Education
• Heli J. Roy, PhD, RDShanna Lundy, BS
• Phillip Brantley, PhD, Director

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Lycopene Information

• Belongs to a class referred to as carotenoids
• Carotenoids are yellow, orange, and red pigments
  synthesized by plants
• In plants, their function is to absorb light in
  photosynthesis, protecting plants against
  photosensitization
• The five principal carotenoids found in human
  plasma, as the result of ingesting plants,
  include alpha and beta-carotene,
  beta-cryptoxanthin, lutein, and lycopene, but
  over 600 have been identified to date

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Lycopene Information

• Lycopene is what gives tomatoes, pink grapefruit,
  watermelon, and guava
  their red color
• It has been estimated that 80 of the lycopene in
  the US diet comes from tomatoes and tomato
  products like tomato sauce, tomato paste, and
  catsup
• Unlike Alpha-carotene, Beta-carotene, and
  Beta-cryptoxanthin, lycopene is not a provitamin
  A carotenoid, meaning that the body cannot
  convert lycopene into Vitamin A

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Lycopene Information

• Tomatoes and tomato products are the single best
  source of lycopene, with only a short list of
  other foods containing much lower amounts
• In tomatoes, lycopene content is affected by
  specific variety and ripening stage
• Deep red varieties contain up to 50 mg/kg, while
  yellow types may be as low as 5 mg/kg

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Lycopene Information

• American lycopene intake averages 3.1 to 3.7
  mg/d, closely matching
  beta-carotene
• In contrast, British intake averages 1.1 mg/d and
  that for Finns is even lower at 0.7 mg/d

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Lycopene Information

• Was largely ignored for decades because of its
  lack of provitamin A activity, long thought
  to be the distinguishing characteristic among
  carotenoids
• In the 1960s, during a case study which first
  documented lycopenemia, an accumulation of
  lycopene in the body tissues, the following was
  stated
• So far as is known, lycopene is neither toxic
  nor beneficial, but is only an adventitious
  visitor to the body. Its failure to form Vitamin
  A may account for its accumulation in the liver

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Lycopene Function

• Far from being inert, by virtue of its unique
  chemical properties, studies have shown lycopene
  to possess superior antioxidant abilities in
  comparison to other carotenoids
• It has the ability to quench singlet oxygen and
  prevent oxidative damage to other molecules and
  cellular structures because of its unique
  structure of 11 conjugated double bonds and no
  cyclic groups
• Because of this role, many researchers now
  believe that lycopene may profoundly influence
  the evolution of several chronic diseases in a
  tissue-specific manner

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Lycopene Information

• Recent studies of lycopene bioavailability have
  shown that cooking tomato products significantly
  increases lycopene bioavailability compared to
  raw products, as does the presence of a small
  amount of oil or fat
• This is because the absorption of carotenoids
  depends on the
  presence of fat in the intestine
• As little as 3-5 grams of fat in a meal appears
  sufficient to ensure carotenoid absorption

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Lycopene Content of Selected Foods
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Food Serving Lycopene (micrograms)
Tomato Paste, canned 1 c 75,362
Tomato puree, canned 1 c 54,385
Marinara sauce 1 c 39,975
Tomato soup, canned 1 c 25,615
Vegetable juice cocktail, canned 1 c 23,337
Tomato juice, canned 1 c 21,960
Watermelon, raw 1 wedge 12,962
Tomatoes, raw 1 c 4,631
Ketchup 1 tablespoon 2,551
Pink grapefruit, raw ½ grapefruit 1,745
Baked beans, canned 1 c 1,298
Sweet red peppers, raw 1 c 459
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Absorption

• The absorption of carotenoids is limited to a
  range of 10-30
• Of this amount, the majority is excreted in the
  feces
• The low absorption and high excretion rate is
  partly due to the fact that the carotenoids are
  tightly bound to large molecules, forming protein
  complexes in foods
• Separation of carotenoids from protein complexes
  or dispersion of carotenoid aggregates occurs
  upon heating these food items, which, as
  previously mentioned, increases their
  bioavailability

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Factors that Affect Absorption
Rate of Carotenoids

• Level of dietary fat intake
• Studies comparing carotenoid absorption rate with
  a 40 fat diet to a 20 showed a significant
  reduction in absorption
• Level of carotenoids ingested
• Intestinal absorption decreases significantly as
  carotenoid intake increases

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Pathway of Carotenoids

• Absorption pathway is similar to that of dietary
  fat
• Carotenoids are believed to passively diffuse
  from the micelles across
  the intestinal cell membrane into the mucosal
  cell
• Once inside the intestinal cell, carotenoids may
  be converted to vitamin A, those that are
  provitamin A carotenoids, or taken up by
  chylomicrons which transport them to the
  bloodstream via the lymphatic system to the liver
• From the liver, carotenoids reenter circulation
  carried by lipoproteins, in similar proportions
  as cholesterol among the various fractions

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• Lycopene, which is more lipophilic because of its
  non-polar chemical
  structure, appears to be carried exclusively by
  LDL, residing deep within the core of the
  lipoprotein, lipid layer
• Beta-carotene probably protrudes into the aqueous
  interface of the lipoprotein
• The location of the carotenoid within the
  lipoprotein molecule may influence tissue uptake

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Tissue Distribution Of Lycopene

• Because of its lipophilic nature, lycopene tends
  to accumulate in body tissues
• It predominates in prostate, liver, adrenal
  glands, and testes, with lycopene
  accounting for up to 80 of total carotenoid in
  these latter two tissues
• Lycopene concentration in the testes and adrenals
  is up to 9Xs higher than in the tissue with the
  second highest amount, the liver

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Several factors can influence lycopene tissue
concentrations

• Higher carotenoid concentrations tend to occur in
  tissues with a large number of LDL-receptors and
  high uptake of lipoproteins? the liver, adrenals,
  and testes
• Other factors include body mass index and waist
  circumference, with both exhibiting an inverse
  relationship with lycopene concentration in
  adipose tissue
• Gender- this same study reported up to 50 lower
  carotenoid adipose levels in men compared to women

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Biological Activity

• The general mechanism by which carotenoids are
  thought to influence the development of chronic
  disease is by preventing oxidative damage in
  biological systems, which includes damage to the
  cell membrane and other structures, DNA
  molecules, lipids, and proteins
• This damage arises from exposure to free radicals
• Free radicals are molecules with an unpaired
  electron in their outer atomic orbital, causing
  the molecule to be extremely reactive

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Free Radicals

• Environmental sources of free radicals include
• Environmental toxins and air pollutants-
  
  such as ozone and nitrogen dioxide
• Sunlight
• Ionizing radiation
• Certain drugs
• Cigarette smoke

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Free Radicals

• The body can also produce free radicals during
  normal aerobic respiration, the metabolism of
  fatty acids, and from an acute or chronic immune
  responses
• From the usage of superoxide dismutase,
  glutathione peroxidase, and dietary intake of the
  antioxidant nutrients, Vitamins E and C,
  selenium, and the carotenoids, the body can help
  fight off oxidative damage

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Lycopene and Chronic DiseasesResearch Findings

• Overview
• Digestive Tract Cancers
• Prostate Cancer
• Bladder, Cervical, Breast, Lung Cancers
• Cardiovascular Disease
• Other Diseases

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Digestive Tract CancersEsophageal and Gastric
cancers

• As early as 1979, researchers in Iran reported
  that weekly tomato consumption was associated
  with a 40 reduction in risk for esophageal
  cancer
• In 1989, a case controlled study of 2,175
  participants was conducted in Italy in high and
  low risk areas in order to assess the geographic
  variation in mortality rates from gastric cancer
• Tomato products showed a significant inverse
  relationship with the
  occurrence of gastric cancer

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Digestive Tract CancersPancreatic cancer

• In one case-controlled study of 44 matched
  control subjects and 22 diagnosed cases of
  pancreatic cancer, it was found that the greatest
  difference between controls and cancer cases was
  in serum lycopene concentrations
• In the second of two studies, researchers found
  that low serum lycopene was significantly
  correlated with pancreatic cancer

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Prostate Cancers

• Strongest known link between lycopene and chronic
  disease
• From the Health Professionals Follow-Up Study
  (HPFS) conducted from 1986 through January 31,
  1992, it was suggested that frequent intake of
  tomato products or lycopene, is
  associated with reduced risk of prostate cancer

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Prostate CancersGiovannucci et al.

• Evaluated additional data from the HPFS to
  determine if the association between lycopene and
  prostate cancer would persist
• They gathered prostate cancer cases from 1986
  through January 31, 1998,
  among 47,365 HPFS participants who
  completed dietary questionnaires in 1986, 1990,
  and 1994
• From 1986 to 1998, 2,481 men in the study
  developed prostate cancer

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Their Findings Giovannucci et al.

• For the entire period of 1986 through 1998, using
  the cumulative average of the three dietary
  questionnaires used in the study, lycopene intake
  was associated with reduced risk of prostate
  cancer
• Intake of tomato sauce, the primary source of
  bioavailable lycopene, was associated with an
  even greater reduction in prostate cancer risk

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Bladder, Cervical, Breast, Lung Cancers

• Researchers at the John Hopkins University School
  of Hygiene and Public Health reported on a study
  of 25,802 participants
• 35 cases of bladder cancer were diagnosed after
  the 12-year study period, with the risk
  increasing with decreasing serum levels of both
  lycopene and selenium
• Most studies show that lung and breast cancer are
  not related to serum lycopene levels, although
  there is a recent study by the Harvard School of
  Public Health linking breast cancer with lycopene

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Bladder, Cervical, Breast, Lung Cancers

• Study results have been mixed for cervical
  cancers
• Although, there has been a recent investigation
  showing a slight link between lycopene and
  cervical cancer

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Cardiovascular Disease

• Oxidative damage is believed to be the underlying
  mechanism in the etiology of cardiovascular
  disease (CVD)
• More recently, the multifaceted role of
  oxidatively modified LDL has been proposed as
  being instrumental in atherogenesis
• It is believed that, along with Vitamin E,
  carotenoids may function as a network to protect
  LDL against oxidation
• Its believed that once Vitamin E is depleted, the
  carotenoids may become involved as a second
  barrier, with LDL succumbing to oxidation only
  when the carotenoids are destroyed

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Cardiovascular DiseaseIn Smokers

• Because of reactive oxygen species found in smoke
  which increase LDL oxidation, smokers are at
  higher risk for development of CVD
• A recent study of smokers indicated that
  increased plasma concentrations of lycopene,
  Vitamin C, and beta-carotene were significantly
  inversely associated with several parameters
  indicative of oxidative stress, including
  oxidation of LDL

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Other Diseases

• Animal and laboratory studies have shown that
  carotenoids exert immunomodulatory effects by
  influencing T and B lymphocytes, natural-killer
  cells, and macrophages
• In patients with HIV infection, even with
  adequate dietary intake, several have
  specifically identified carotenoid deficiencies
• Relationships between lycopene and functional
  capacity in the elderly exist, indicating that
  deficiencies may significantly decrease self-care
  ability

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References

• http//sun.science.wayne.edu/nfs/dietetics/lyco.h
  tm
• http//lpi.oregonstate.edu/infocenter/phytochemica
  ls/carotenoids/index.html
• Giovannucci et al. A Prospective Study of Tomato
  Products, Lycopene, and Prostate Cancer Risk.
  JNCI. 2002. 945 391-398