Автор Тема:  Ново изследване открива намален риск от рак на черния дроб при хората пиещи кафе  (Прочетена 3406 пъти)

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Неактивен Радослав Русинов

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В статия, публикувана през август 2007 година, учени установяват намаляване на риска от развиване на рак на черния дроб при пациенти, които редовно употребяват кафе. Информацията беше публикувана на страницата на HCVAdvocate.org: Coffee and Liver Cancer

Тук публикувам цялата новина:
Цитат
Coffee and Liver Cancer
Alan Franciscus, Editor-in-Chief

 In the past couple of years there have been quite a few news stories on the health benefits of coffee particularly when it comes to the liver.  In the August 2007 issue of Hepatology, Francesca Bravi and colleagues reported on the association between coffee drinking and liver cancer in a paper titled “Coffee Drinking and Hepatocellular Risk:  A Meta-Analysis” (DOI 10.1002.hep.21708).  A meta-analysis is a review of previous studies using a variety of statistical methods to pool, combine, refine and come to a conclusion about an issue.

In this study a MEDLINE search was conducted on articles written between 1966 to February 2007 using terms such as “coffee,” and combinations of “hepatocellular” or “liver” and “carcinoma” or “neoplasm.”  A total of 10 studies were reviewed (2,260 patients with liver cancer) – 6 case-control studies from southern Europe and Japan (1551 cases of liver cancer) and 4 cohort studies from Japan (709 cases liver cancer).

It was found that there was a 41% reduction in the risk of liver cancer (HCC) among the coffee drinkers.  The authors pointed out that the favorable results were found in studies from Europe where coffee consumption is heavy as well as from Japan where coffee consumption is lighter, which lends credence to the findings.

The exact way in which coffee helps to reduce the risk of acquiring liver cancer is unknown, but the researchers offered up some theories including:
 • Certain chemicals in coffee (diterpenes, cafestol, and kahweol) may block the development of liver cancer.
 • Caffeine and antioxidant substances found in coffee may provide protective qualities against the development of liver cancer
 • Coffee may slow down liver disease progression which would protect against developing liver cancer

 The authors also noted that even though the association between coffee consumption and the decreased risk of developing liver cancer has not been proven they make a strong case for the association by building into their analysis other cofactors to counter the potential bias, such as hepatitis B and C, cirrhosis, other liver diseases, social class indicators, alcohol drinking and tobacco smoking.

The authors concluded that “the results of this meta-analysis provide quantitative evidence of an inverse relation between coffee drinking and liver cancer, the third-most common cause of cancer death worldwide after lung and stomach, with about 600,000 deaths in 2002.”  They also commented that “the interpretation of this association remains unclear, and the consequent inference of causality and worldwide public health implications remains open to discussion.”

Association is not Causation
Before we all start consuming massive amounts of coffee it is important to put this study in perspective.  Please see the coffee article in this month’s issue for more information about the potential risks and benefits from drinking coffee.  First and foremost it is really difficult to compare the studies because the definition of light, moderate and high consumption was different in the studies although the authors adjusted for the differences in their statistical analysis.   Also information was not available on the way the coffee was prepared (percolated, French press or drip), strength of the coffee (how much caffeine), if the coffee was black, used with cream and/or sugar and if it was taken with food.   Although it is doubtful, were the results misleading because people who started to develop cirrhosis stopped or reduced their coffee consumption because of gastrointestinal problems?

So the bottom line is that it is important to remember that when an association is found it doesn’t necessarily mean that the study factor actually causes the problem or benefits the problem.  In the above study the fact that a meta-analysis was performed leads us to believe that there is a likely association between coffee consumption and the reduced risk for liver cancer, but until science learns how coffee provides this benefit it is not a good idea to start drinking coffee – at least not as a primary reason to prevent liver cancer.


Тук публикувам превода на статията с малки съкращения:
В последните години беше публикувана съвсем малко информация, свързана с положителното влияние на кафето и по-специално по отношение на черния дроб. През август 2007 година в списанието "Hepatology", Francesca Bravi и екип от нейни колеги докладват за установена връзка между редовната употреба на кафе и рака на черния дроб в статия, наречена “Coffee Drinking and Hepatocellular Risk:  A Meta-Analysis”. Мета анализите всъщност представляват детайлен преглед и анализ на предишни научни изследвания, като се използват различни статистически методи за да се комбинират и анализират техните резултати и да се направи извод по изследвания проблем.

В това изследване са използвания научни статии, писани между 1966 до февруари 2007 и в които са използвани термини като "кафе", и комбинации от "чернодробни", "черен дроб" и "раково образувание". Проучени са общо 10 статии, в които са били включени резултатите от проведени изследвания върху общо 2260 пациента.

Изследването е установило, че рискът от достигане на рак на черния дроб е намален с 41% при хората, които употребяват редовно кафе. Авторите отбелязват това, че по-висок процент е открит при изследвания, проведени в Европа, където консумацията на кафе е традиционно по-голяма, а при изследванията проведени в Япония /където консумацията на кафе е по-малка/, процентът е по-нисък, което пък е допълнително доказателство, че заключенията на учените са верни.

Точният механизъм, по който кафето помага за намаляване на риска от рак на черния дроб, е неясен, но учените предлагат няколко теории по този въпрос:
 • Точно определени химикали, които се срещат в кафето /diterpenes, cafestol, и kahweol/ може би блокират развитието на рака на черния дроб
 • Кофеина и съставките на кафето, имащи антиоксидиращо действие може би имат защитни качества по отношение на развитието на рака на черния дроб
 • Кафето може би забавя прогресирането на чернодробните болести, което пък може да бъде защита срещу развитието на рак на черния дроб

Авторите на статията също заключават, че "резултатите от тези мета-анализи предоставят качествено доказателство в полза на обратнопропорционалната зависимост между пиенето на кафе и рака на черния дроб, третата най-срещана причина за смъртните случаи вследствие на заболяване от рак, след рака на белия дроб и рака на стомаха, с регистрирани 600 000 смъртни случая през 2002 година". Те също коментират и това, че "интерпретацията на тази асоциация все още няма ясно обяснение, и те са отворени за дискусия по отношение на установяване на причината за връзката между пиенето на кафе и рака на черния дроб".

Асоциацията не е причина
Преди всички да започнат да консумират огромни количества кафе, важно е това изследване да се погледне под различен ъгъл. Първо и най-важното, много е трудно да се сравнят проучванията заради различните дефиници на "малка", "средна" и "голяма" консумация на кафе в различните изследвания, въпреки че учените са отчели тези разлики в проучването си и изчисленията си. Още повече, че няма достатъчно информация за това как точно е приготвяно кафето, колко силно е било, дали кафето е било черно, дали е било със сметана или не, дали е било със захар, както и дали е било пито с вода. Също не е ясно и дали резултатите не са подвеждащи заради това, че най-вероятно болните които са започнали да развиват цироза, са спрели или намалили консумацията на кафе заради стомашно-чревни проблеми.

В това изследване, факта че са направени мета-анализи ни кара да вярваме, че съществува директна връзка между консумацията на кафе и рака на черния дроб, но докато науката не научи как точно става това, не е препоръчително да се започне нарочната консумация на кафе - поне това не трябва да е главния метод, с който човек трябва да се опитва да се бори с рака на черния дроб.


И още малко информация в цифри оттук: Coffee Reduces Liver Cancer Risk

Цитат
Coffee Reduces Liver Cancer Risk

Drinking coffee may reduce the risk of liver cancer, according to a meta-analysis published in the August 2007 issue of Hepatology. F. Bravi and colleagues searched the MEDLINE database and identified four cohort studies and five case-control studies that assessed the relationship between coffee consumption and primary liver cancer. In total, these studies included 2,260 patients with liver cancer and 239,146 control subjects without cancer. All studies found that people who drank more coffee were less likely to develop liver cancer; this association was statistically significant in six studies. Overall, coffee consumption was associated with about a 40% decrease in the risk of liver cancer, and the reduction was even greater for heavy coffee drinkers (55%). Each additional daily cup of coffee was associated with a 23% lower risk of liver cancer – though the results do not necessarily imply that coffee caused the risk reduction. For more discussion of this study, see the September 2007 HCV Advocate

Превода и по-специално частта с конкретните цифри:
Всички проучени изследвания включват 2260 пациенти с рак на черния дроб и 239 416 хора, които нямат рак на черния дроб. Всички изследвания откриват, че хората които пият често кафе, по-рядко развиват рак на черния дроб, като тази връзка е била ясно изразена в 6 от проучванията. Като цяло, консумацията на кафе е била асоциирана с 40% намаляване на риска от развитието на рак на черния дроб, като при хората, които пият големи количества кафе, този риск дори достига до 55%. Всяка допълнителна чаша кафе на ден, е асоциирана с 23% намаляване на риска от рак на черния дроб, въпреки че тези резултати не могат да докажат, че точно кафето е предизвикало намаляването на случаите на развиване на рак на черния дроб.
« Последна редакция: Декември 03, 2007, 22:53:17 от Radoslav Rusinov »
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Неактивен Радослав Русинов

  • Администратор на форума - немедицинско лице
  • Степен на активност - Професор
  • *******
  • Публикации: 5569
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    • Профил
    • My Home Page
  • Вид лечение: Пегилиран интерферон + рибавирин
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  • Статус: Хроничен хепатит C
Любопитна информация за любителите на кафето
« Отговор #1 -: Декември 03, 2007, 22:33:03 »
Тук публикувам малко интересна информация за кафето, малко история и любопитни факти.
Информацията е от тази новина Coffee, написана след проучване направено от Alan Franciscus, един от редакторите на HCVAdvocate.org

Цитат
Coffee
Alan Franciscus, Editor-in-Chief

 In the process of researching the lead article on the potential benefits of coffee in regards to liver cancer, I came across a lot of interesting information about coffee that I thought I would share with our readers.  Just so you know, I have been a coffee drinker for many, many years and my love of coffee can be viewed by some as creating a certain bias when writing about the potential health benefits of coffee. 

History
Coffee consumption can be traced back to the ninth century in Ethiopia and its use spread to Egypt, Yemen and reached Persia, Turkey, and northern Africa by the fifteenth century.

It eventually spread to Italy where it was revered by the wealthy in Venice.  From there coffee consumption spread to the rest of Europe and eventually the seeds of the coffee bean were obtained and planted by the European colonialists in other parts of the world.  In the U.S. coffee was not widely consumed until the Revolutionary War.  The switch from coffee to tea was a necessity because the U.S. was at war with England – the largest supplier of tea to the colonies.  In some circles switching from tea to coffee was considered patriotic.  Today, coffee is one of the most widely consumed beverages in the U. S. and around the world.  Starbucks is probably the most well-known of the coffee store chains.  In the near future, Starbucks will have as many stores as there are McDonalds in the U.S. If you want to get an idea of the popularity of Starbucks and coffee go to www.starbucks.com and enter your zip code into the store locator for a list of stores within a 5 mile radius.  Probably the highest density of Starbucks of any city in the U.S. is in New York City.  When I typed the NYC zip code 10036 the store locator listed a staggering 203 stores in a 5 mile radius.

Coffee
The coffee plant is a member of the group of flowering plants called the Rubiaceae.  A coffee plant can grow up to more than 16 feet tall.  It has glossy green leaves and fragrant white flowers.  The coffee beans are actually green berries that are processed and roasted before they are consumed.

There are two main types of coffee – coffea robusta and coffea arabica.   The most popular type and the one considered to have the best flavor is arabica which accounts for about 75% of cultivated coffee.  Robusta tends to have more of a bitter taste compared to the Arabica.  Robusta is easier to grow because it is more disease resistant and also contains more caffeine than Arabica.  For these reasons and because it is cheaper to grow, it is the type that is usually used in more inexpensive forms of coffee.

Once the coffee beans are picked by hand, the seeds are processed to remove the pulp,  dried and sorted.  At this stage the seeds are green in color.  The next step in the process is roasting the green coffee beans.  This is the step that dictates the appearance and taste of the brewed coffee.  The darker the color of the roasted bean the smoother the flavor.  However, the lighter roasts contain the most caffeine. 

Caffeine
Caffeine is a substance that is found in certain plants such as coffee.  When a person drinks a cup of brewed coffee it is quickly absorbed into the blood stream and passes into the brain.  Caffeine is used for quick “pick me ups” but, because it is not stored in the body, the effects are short term.  However, caffeine is a sti-mulant so there is a potential for addiction, although it is considered a mild addiction in most people.  Withdrawal from caffeine usually produces mild symptoms such as headache, drowsiness, nausea, and irritability.  If possible slowly reduce the intake of caffeine to reduce any withdrawal symptoms.

The side effects of consuming excessive amounts of coffee can include nervousness, excessive urination, nausea, vomiting, anxiety, depression, upset stomach, appetite suppression, and difficulty sleeping.

Decaffeinated coffee
Decaffeinated coffee is processed in two ways – the European Process and the Swiss Water Process.  The European Process involves soaking the beans in water and then washing them in methylene chloride to absorb the caffeine.  After the beans are soaked they are rinsed off to remove the chemicals, and the beans are dried.  The Swiss Water Process involves using hot water and steam to remove the caffeine from the coffee.  The next step involves putting the water solution through activated charcoal filters to remove the caffeine.  Once the caffeine has been removed, the beans are soaked in the decaffeinated solution which allows for the re-absorption of the fluid into the coffee beans and restores most of the flavor.  It is interesting to note that the caffeine used in various products such as energy drinks, diet drinks, over the counter stimulants, and medications is the by or end-product of the decaffeination process. 

Preparing Coffee
Coffee is purchased in whole beans or already ground up.  Whole beans must be ground up before making a cup of coffee.  Coffee purists will swear that the only way to truly make a good cup of coffee is to grind up the coffee just before brewing.  The grind (course, medium, fine) will also influence the taste and texture of the brewed coffee.

Once the coffee is ground it can than be brewed by boiling (Turkish), percolation (an old American standard), pressing (French press), espresso (forcing hot water under pressure through finely ground coffee), and, the most popular in this country, the drip process.

You will note that this article does not mention instant coffee – this is my bias because the thought of drinking instant coffee is abhorrent to me.

Health Claims
There have been many studies that have found various health benefits from consuming coffee.  But many of these benefits have been refuted by other studies.  Similarly, the health risks of drinking coffee have been widely studied, but there is also data that refutes the claims.  However, the number of studies on the benefits of coffee on the liver suggests that there might be some truth in the notion that light to moderate coffee consumption may be healthy for the liver.

Safe Levels
It is recommended that healthy adults can consume up to 3 cups (8 oz) a day without any health risks.  It is also generally recommended that pregnant women and people with coronary heart disease or ulcers refrain from consuming caffeinated beverages.  Children should be closely monitored so that they don’t consume too much caffeine. It is important to remember that caffeine can be in other food and drinks including sodas, teas, and chocolate as well as some medications; so always check the product label.   Check in with your medical provider to find out if there are any potential interactions between any medications you are taking and caffeine.
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