The term vitamin A bases for two chief groups of compounds ; the pre-formed vitamin A ( vitamin A1, retinaldehyde, retinoic acid ) and the vitamin A precursors, which include the hydrocarbons or provitamin As ( ?-carotene, ?-carotene, lycopene ) and oxygen-containing carotenoids or luteins ( cantaxanthin, zeaxanthin, astaxanthin, xanthophyll ) . All signifiers of vitamin A are fat-soluble molecules that are absorbed with lipoids in the little bowel forming micelles and are transported to the liver utilizing chylomicrons. About 80 % of dietetic pre-formed vitamin A is absorbed, whereas the soaking up of provitamin As depends on the nature and emanation of the nutrient and can be up to 60 % . Some provitamin As can be converted into vitamin A1, a chemical reaction catalyzed by provitamin A dioxygenase ( Bender 2008 ) . Natural beginnings of all vitamin A signifiers are shown in Table 1. Retinol and its compounds are chiefly found in nutrients of carnal beginning, such as liver, oily fish and milk. On the contrary, ruddy and orange-colored fruit and veggies every bit good as green leafy veggies are chief beginnings of carotenoids. ( Krinsky et al. 2005 ) .

Vitamin A is involved in vision and in protein synthesis from the DNA, which leads to cellular and tissular distinction and, hence, growing, development and reproduction. Provitamin as may demo an extra action as antioxidants, particularly in tissues where there is low concentration of O ( Bender 2008 ) . The uninterrupted survey of vitamin A focuses on its function on assorted cellular procedures. A batch of research has been conducted to demo possible effects of vitamin A on cardiovascular diseases and different signifiers of malignant neoplastic disease.

Prostate and prostate malignant neoplastic disease

Prostate is an organelle following to the urethra and it weighs 20 – 30 gms in an grownup adult male. It acts as a secretory organ, let go ofing ions, enzymes and organic molecules such as spermine to forestall pathogens from come ining the generative system of work forces. The prostate epithelial tissue consists of three types of cells, each of which has a specific function. The secretory cells produce the prostate – specific androgen ( PSA ) and show the androgen receptor ( AR ) , the basal cells produce secretory cells when needed, and the neuroendocrine cells excrete a scope of different molecules ( Steers 2011 ) .

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Table 1: Food merchandises rich in different signifiers of vitamin A ( Krinsky et al. 2005 ) .

Forms of vitamin Angstrom

Food merchandises

Retinol and compounds

liver

oily angle

milk and dairy merchandises

butter

fortified oleo

?-carotene

carrots ( natural and cooked )

Mangifera indica

sweet murphy ( cooked )

Spinacia oleracea

chou

winter squash ( Cucurbita pepo )

boodle

tomato

Brassica oleracea italica

apricot

cantaloup vine

melon

orange

Lycopene

tomato ( natural, cooked, canned, paste, puree, sauce, juice, soup )

Watermelon

ruddy ( bell ) Piper nigrums

pink or ruddy Citrus paradisi

pink-fleshed Psidium littorale

persimmons

Lutein, zeaxanthin

Spinacia oleracea

chou

boodle

Brassica oleracea italica

Prostate malignant neoplastic disease is an glandular cancer ( chief type of malignant neoplastic disease for glandular tissues ) , stand foring 12 % of all malignant neoplastic diseases among work forces worldwide and 19 % of all malignant neoplastic diseases in developing states. It is the 2nd most common malignant neoplastic disease among work forces, in a rate of 25.3 incidences per 100,000 people, and 76 % of them occurred in work forces populating in developed states ( Baade et al. 2009 ) . The chief hazard factor for prostate malignant neoplastic disease is age, as incidence rises aggressively after 40 old ages of age ( Table 2 ) . Other established hazard factors include race and geographics, whereas environmental factors such as smoke, fleshiness, intoxicant and dietetic fat consumption have been proposed but non yet proven. The function of nutrition in prostate malignant neoplastic disease development remains controversial and research focal points on antioxidant compounds, such as vitamin A ( Willis et al. 2003 ) . The chief hypothesis is that vitamin A may has a protective function against prostate malignant neoplastic disease, as it inhibits cell proliferation and induces cell programmed cell death in many variety meats and tissues such as the prostate ( World Cancer Research Fund / American Institute for Cancer Research 2007 ) .

Table 2: Incidence rate of prostate malignant neoplastic disease harmonizing to age ( Baade, Youlden et Al. 2009 ) .

Age ( old ages )

Incidence rate ( per 100,000 population )

15-44

0.2

45-54

10.6

55-64

72.9

& A ; gt ; 65

259.6

Retinol ( retinoids ) and prostatic malignant neoplastic disease

Retinol is a compound of retinoids and one of the functional signifiers of vitamin A in the human organic structure ( Bender 2008 ) . A few surveies have been conducted to analyze possible associations of serum or plasma vitamin A1 and the hazard of developing prostatic malignant neoplastic disease, both localised and aggressive. Main values of gauging vitamin A1 position were serum vitamin A1, which is proven to be the most accurate step of vitamin A1 position, and retinol dietetic consumption. Consequences from retinol surveies are controversial and most of them show no association of high serum vitamin A1 and prostate malignant neoplastic disease. The most recent published survey refering plasma vitamin A1 and prostate malignant neoplastic disease was a big nested instance – control survey from the Prostate Testing for Cancer and Treatment ( ProtecT ) test. No association or tendency of plasma vitamin A1 degrees and overall [ Odds Ratio OR: 0.95, 95 % Confidence Interval ( 0.74, 1.22 ) , P for tendency = 0.19 ] or aggressive prostate malignant neoplastic disease hazard was found ( Gilbert et al. 2012 ) . These consequences are besides supported by other surveies ( Key et al. 2007, Goodman et al. 2003, Huang et Al. 2003, Beilby et Al. 2010, Gill et al. 2009, Karppi et Al. 2012 ) , where no statistically important associations were found in either localized or aggressive prostate malignant neoplastic diseases.

However, some surveies show important, but assorted consequences. A big cohort survey associated high vitamin A1 degrees with 20 % higher hazard of developing any phase of prostate malignant neoplastic disease in the follow-up period ( 5th quintile of vitamin A1 degrees against 1st quintile Oregon: 1.18, 95 % CI 1.01, 1.38, P for tendency = 0.02 ) . After follow-up, work forces at the 5th quintile both at baseline and the followup had the greatest hazard of prostate malignant neoplastic disease ( Mondul et al. 2011 ) . This survey included merely tobacco users, proposing a possible smoke – vitamin A1 opposite association. On the other manus, two surveies ( Beydoun et al. 2011, Schenk et Al. 2009 ) presented an reverse correlativity between high plasma vitamin A1 and the hazard of prostate malignant neoplastic disease and one of them pointed out a important decrease in aggressive prostate malignant neoplastic disease ( Schenk et al. 2009 ) .

Apart from serum vitamin A1, serum retinyl palmitate esters were measured in a survey ( Huang et al. 2003, Beilby et Al. 2010 ) which showed reverse associations with prostate malignant neoplastic disease hazard, proposing vitamin A1 ‘s antiproliferative value. What is more, one survey used vitamin A1 and ?-carotene – which converts to retinol in some extent in human organic structure – addendums to increase retinol consumption and showed increased prostate malignant neoplastic disease hazard on utmost high serum vitamin A1 ( Neuhouser et al. 2009 ) . Consequently, it is hard to gauge whether vitamin A1 or retinol compounds have a important consequence on prostate malignant neoplastic disease hazard. Furthermore, most of the surveies had certain bounds such as little sample ( Beilby et al. 2010, Karppi et Al. 2012 ) and inability to govern out confusing factors ( Karppi et al. 2012, Neuhouser et Al. 2009 ) .

?-carotene and prostatic malignant neoplastic disease

B-carotene is the chief signifier of vitamin A derivation from the workss and a compound with powerful antioxidative value. However, consequences from surveies are conflicting and no appraisal can be made on prostate malignant neoplastic disease hazard. Most surveies show no association between serum ?-carotene degrees and the hazard of developing prostatic malignant neoplastic disease ( Key et al. 2007, Goodman et al. 2003, Huang et Al. 2003, Gill et al. 2009, Beydoun et Al. 2011, Lu et Al. 2001 ) and few nowadays either a negative ( Karppi et al. 2012, Neuhouser et Al. 2009, Vogt et Al. 2002, Zhang et Al. 2007 ) or a protective consequence ( Wu et al. 2004, Chang et Al. 2005, Bosetti et Al. 2004 ) .

Key et Al. ( 2007 ) examined the association of plasma carotenoids and prostate malignant neoplastic disease hazard in the European Prospective Investigation into Cancer and nutrition ( EPIC ) survey, and found no important associations in either localised or aggressive phase. However, the higher the serum degrees of entire carotenoids, the lower the incidence of aggressive prostate hazard ( highest quintile against lowest quintile: Oregon: 0.35, 95 % CI 0.21, 0.98, P for tendency = 0,04 ) , proposing a likely interactive action of all carotenoids in the prostate tissue. On the other manus, Neuhouser et Al. ( 2009 ) had opposite consequences, utilizing a addendum of ?-carotene and retinyl palmitate. However, there can be no appraisal whether ?-carotene, retinyl palmitate, or farther supplementation were responsible for this consequence. Furthermore, two surveies separated their instance and control samples harmonizing to their race and one of them found important addition in prostatic malignant neoplastic disease hazard among Blacks ( OR: 2.43, 95 % CI non presented, P & A ; lt ; 0.05 ) ( Vogt et al. 2002 ) , while the other did non ( Zhang et al. 2007 ) . However, low engagement was the major restriction of both surveies.

The rating of dietetic ?-carotene, apart from serum ?-carotene merely, may hold more important consequences. A big survey which evaluated serum and dietetic carotenoids showed an reverse correlativity of serum ?-carotene and prostatic malignant neoplastic disease hazard in all participants, but statistically important merely in work forces under 65 old ages old ( highest quintile against lowest quintile Oregon: 0.36, 95 % CI 0.14, 0.91, P for tendency = 0.03 ) . Besides, when entire ?-carotene was evaluated ( blood and dietary ) , work forces in the highest quintile of plasma/dietary tonss had a 77 % reduced hazard of developing prostatic malignant neoplastic disease, compared to the lowest quintile, but the sample was excessively little to measure a statistical significance ( P for tendency = 0,15 ) ( Wu et al. 2004 ) .

Lycopene and prostate malignant neoplastic disease

Lycopene is a carotenoid compound that does non change over to vitamin A, therefore it does non hold any vitamin A activity. However, several surveies have been conducted on lycopene consumption and different signifiers of malignant neoplastic disease, due to its antioxidant belongingss. Interest is increased, as lycopene is present on prostate tissue and is shown to hold specific effects on prostate malignant neoplastic disease development ( Krinsky et al. 2005 ) . There has been more thorough research on lycopene instead than retinol and ?-carotene harmonizing to prostate malignant neoplastic disease and different survey designs have been used.

Two clinical tests used 30 mg lycopene supplementation in the intercession group and observed differences from a control group. Merely one survey presented significantly lower prostate – specific antigen consequences ( biomarker of prostate malignant neoplastic disease ) because of lycopene supplementation ( Schwarz, et Al. 2008 ) whereas the other two showed no effects on PSA degrees before and after the test ( Van Breemen et Al. 2011, Bunker et al. 2007 ) , although serum lycopene degrees were significantly higher in all intercession groups. The tests were either excessively little or excessively short to measure the long term effects of lycopene supplementation. Serum lycopene degrees were besides the marker of lycopene position in nine instance – control surveies. Five cohort and one retrospective surveies did non associate lycopene to overall prostate malignant neoplastic disease hazard or showed non-significant tendencies whereas one cohort and three retrospective surveies showed a strong reverse relation of high lycopene ingestion and prostate malignant neoplastic disease hazard, particularly for advanced phases ( Tables 3 and 4 ) .

Table 3: Prospective surveies of plasma/serum lycopene and overall prostate malignant neoplastic disease risk* : Odds Ratios ( OR ) and 95 % Assurance Intervals ( 95 % CI ) for the highest compared with the lowest lycopene concentration in each survey.

Survey

Year

Sample ( cases/controls )

OR ( 95 % CI )

Peters et Al.

2007

692/844

1.14 ( 0.82-1.58 )

0.99 ( 0.62-1.57 ) aggressive

Kristal et Al.

2011

1809/1809

0.99 ( 0.94-1.04 ) Gleason score 2-6

1.01 ( 0.94-1.08 ) Gleason score 7-10

Huang et Al.

2002

184/364 ( CLUE I )

142/284 ( CLUE II )

0.83 ( 0.46-1.48 )

0.79 ( 0.41-1.54 )

Beilby et Al.

2010

96/226

0.77 ( 0.40-1.47 )

Wu et Al.

2004

450/450

0.66 ( 0.38-1.13 )

Key et Al.

2007

966/1064

0.97 ( 0.70-1.34 )

0.40 ( 0.19-0.88 ) ** aggressive

* Aggressive prostate malignant neoplastic disease hazard or Gleason mark is besides referred in some surveies

** P & A ; lt ; 0.05

Dietary lycopene is consumed chiefly through tomatoes and tomato merchandises. Several surveies investigated the relation of tomato and tomato merchandises ingestion and prostate malignant neoplastic disease hazard. Three instance control surveies from Iran, Auckland and Italy showed no important association between high tomato ingestion and prostate malignant neoplastic disease hazard

Table 4: Retrospective surveies of plasma/serum lycopene and overall prostate malignant neoplastic disease risk* : Odds Ratios ( OR ) and 95 % Assurance Intervals ( 95 % CI ) for the highest compared with the lowest lycopene concentration in each survey.

Survey

Year

Sample ( cases/controls )

OR ( 95 % CI )

Chang et Al.

2009

118/52

1.30 ( 0.63-2.71 )

Zhang et Al.

2007

193/197

0.46** ( 0.22-0.94 )

Vogt et Al.

2002

209/228

0.65 ( non presented, P for tendency = 0.09 )

0.37** ( non presented, P for tendency = 0.04 ) aggressive

Lu et Al.

2001

65/132

0.17** ( 0.04-0.78 )

* Aggressive prostate malignant neoplastic disease hazard is besides referred in a survey

** P & A ; lt ; 0.05

( Bosetti et al. 2004, Pourmand et al. 2007, Norrish et Al. 2000 ) , but they contained little samples and evaluated lycopene ingestion from a individual Food Frequency Questionnaire ( FFQ ) . On the other manus, Giovannucci et Al. ( 2002 ) conducted a prospective dietary survey that used multiple dietetic appraisals to gauge lycopene consumption and found a protective consequence of high lycopene ingestion ( OR: 0.84, 95 % CI 0.73, 0.96, P for tendency = 0.003 ) and particularly tomato sauce ingestion ( OR: 0.77, 95 % CI 0.66, 0.90, P for tendency & A ; lt ; 0.001 ) on prostate malignant neoplastic disease hazard, largely in older work forces. On the contrary, two prospective dietetic surveies showed void consequences ( Kristal et al. 2010, Kirsh, et Al. 2006 ) . Factors that may lend to inconsistent consequences in lycopene surveies include low tomato ingestion in some populations, uncomplete Food Frequency Questionnaires and low effectivity of a individual dietetic appraisal, as prostate malignant neoplastic disease patterned advance is really low.

Other carotenoids and prostate

Other carotenoids include ?-carotene, ?-carotene and ?-cryptoxanthin, which convert in vitamin A every bit good as xanthophyll and zeaxanthin that, as lycopene, do non hold vitamin A activity. Surveies examine several types of carotenoids and entire prostate malignant neoplastic disease hazard, but consequences lack significance. Lutein and zeaxanthin are normally measured as one carotenoid and merely two surveies found a statistically important protective function against prostate malignant neoplastic disease ( Lu et al. 2001, Chang et Al. 2005 ) . However, samples in these surveies were really little and examined specific populations. On the other manus, other surveies did non associate any carotenoid with prostate malignant neoplastic disease ( Gill et al. 2009, Beydoun et Al. 2011 ) . Furthermore, consequences on high serum ?-carotene degrees suggest either a lessening ( Beydoun et al. 2011 ) or an addition ( Karppi et al. 2012 ) in entire prostate malignant neoplastic disease hazard, but most of them show void association ( Huang et al. 2003, Vogt et Al. 2002 ) . Merely one survey showed a possible benefit of high serum ?-cryptoxanthin degrees ( Lu et al. 2001 ) . Finally, ?-carotene is estimated merely in Goodman et Al. survey ( 2003 ) and no important consequences were found. Overall, there seems to be no consequence of other carotenoids in the development of prostate malignant neoplastic disease, although deficiency of associations may be due to hapless survey designs.

POTENTIAL MECHANISMS

All signifiers of vitamin A are proposed to hold belongingss that protect the tissues from unmanageable cell proliferation that leads to tumours. The chief signifier of vitamin A that circulates in the human organic structure is retinol, because ?-carotene and several other carotenoids convert to this vitamin A signifier. Although vitamin A1 is known to hold anticarcinogenic action, high intraprostatic degrees of vitamin A1 are shown to increase cell proliferation. However, it is non known whether high serum vitamin A1 degrees are related to high intraprostatic degrees. By and large, vitamin A1 has the ability of bring oning cell programmed cell death and modulating cell proliferation. A possible mechanism is retinol ‘s action on the written text of by suppressing the activity of DNA polymerase in the G1 stage of the cell rhythm. What is more, vitamin A has no antioxidant effects ; alternatively it promotes the action of other vitamins, such as vitamin E and minerals, such as Se, known for their ability to donate an negatron and to destruct free groups ( Willis 2003 ) .

Lycopene is one of the few carotenoids that can non change over to retinol, proposing a different function from vitamin A. It is one of the most active antioxidants, modulating cell proliferation, low-density lipoprotein cholesterin, immune system and redness. The function of lycopene in prostate malignant neoplastic disease is found on the ordinance of serum insulin-like growing factor-1 ( IGF-1 ) , which is one of the possible factors that promote prostatic malignant neoplastic disease ( Willis 2003 ) .

Decision

Great involvement has arisen in the association of nutrition factors and the hazard of different types of malignant neoplastic disease. Prostate malignant neoplastic disease is the 2nd most common malignant neoplastic disease and represents about 7 % of all cancer-related deceases among males worldwide ( 2002 ) . Potential benefits from the ingestion of antioxidants such as different signifiers of vitamin A have examined. All compounds except for lycopene have yet failed to turn out their antioxidant effects on prostate malignant neoplastic disease hazard. Most surveies have presented inconsistent or ono-significant consequences. Uncertainty of possible benefits of several carotenoids and retinol ingestion leads to farther research on the field of prostatic malignant neoplastic disease bar.

On the other manus, several surveies have shown that high lycopene ingestion chiefly from nutrient merchandises may cut down prostate malignant neoplastic disease hazard, although in some of them the consequences are non important. A recent reappraisal from Wei et Al. ( 2012 ) failed to demo a decrease in entire prostate malignant neoplastic disease hazard due to high lycopene consumption. In the reappraisal, it is stated that earlier surveies have presented promising consequences but it was due to a limited involvement on lycopene research. As involvement grew, recent surveies were better organised and did non back up old findings. Furthermore, surveies published before Prostate – Specific Antigen showing was established may hold linked the positive effects of lycopene intake peculiarly with aggressive types of prostate malignant neoplastic disease, whereas most recent surveies show inconsistent consequences on non-aggressive types of prostate malignant neoplastic disease.

Vitamin A is an indispensable vitamin for vision, cistron look and cell distinction. Consequently, it acts on a assortment of tissues apart from the prostate tissue. Prostate malignant neoplastic disease is one of the most common types of malignant neoplastic disease and it is a great issue of public wellness, taking to lower quality of life and increased financess on medical attention and medical specialties. Further research on the Fieldss of vitamin A compounds and prostate malignant neoplastic disease hazard is required, so as to uncover possible protective action of antioxidants in the prostate tissue and be used as constituents in preventative medical specialty or factors that alter the development of prostate malignant neoplastic disease into aggressive phases.

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