Studie: Vegetarier erkranken häufiger an Darmkrebs

Studie: Vegetarier erkranken häufiger an Darmkrebs

http://www.aerzteblatt.de/v4/news/news.asp?id=35819

Hintergründe? Fake? Infos?

Milch und Eikonsum könnte Einfluss haben:

Auf Basis der Evidenzkriterien der WHO/
FAO zeigt sich, dass ein risikosenkender Effekt eines
hohen Milch- und Milchprodukteverzehrs bei Tumoren des
Kolons und des Rektums möglich ist. Im Gegensatz dazu
steht der Verzehr von Milch und Milchprodukten im Ver-
dacht, das Risiko für Prostata- und Ovarialkarzinome zu
erhöhen. Die Evidenz hierfür wird ebenfalls als möglich
gewertet. Im Hinblick auf das Osteoporoserisiko ist kein
protektiver Effekt einer hohen Aufnahme an Milch und
Milchprodukten erkennbar. Die Evidenz für einen risiko-
senkenden Effekt wird deshalb als unzureichend gewer-
tet. Bei Eiern wird die Evidenz für einen risikosteigernden
Effekt sowohl in Bezug zu Tumoren des Kolons, des
Rektums und der Brust als auch bei kardiovaskulären
Erkrankungen als möglich bewertet.

Quelle:

Vegetarische Ernährung: Präventives Potenzial und mögliche Risiken
Teil 2: Lebensmittel tierischer Herkunft und Empfehlungen
Alexander Ströhle1, Annika Waldmann2, Maike Wolters1
und Andreas Hahn1
1Abteilung Ernährungsphysiologie und Humanernährung, Institut für Lebensmittelwissenschaft, Zentrum Angewandte Chemie
der Universität Hannover, Hannover, Deutschland
2 Institut für Krebsepidemiologie e.V. an der Universität zu Lübeck, Lübeck, Deutschland

Milch dürfte einen grossen Einfluss haben.

Siehe auch:

Psychonaut schrieb:In Beobachtungsstudien erkannte man eine Verbindung zwischen einer Aufnahme von Milchprodukten und einem erhöhten Risiko für Prostatakrebs.
Giovannucci et al. Calcium and fructose intake in relation to risk of prostate cancer. Cancer Res. 1998
Chan et al. Dairy products, calcium, phosphorus, vitamin D, and risk of prostate cancer. Cancer Causes Control. 1998
Chan et al. Dairy products, calcium, and prostate cancer risk in the Physician’s Health Study. Am J Clin Nutr. 2001

Psychonaut schrieb:
Konsum von Milch oder Milchprodukten bei Kindern erhöht das Darmkrebsrisiko um fast das Dreifache (unabhängig vom Konsum von Gemüse, Früchten, Fleisch oder sozioökonomischen Faktoren).
van der Pols et al. Childhood dairy intake and adult cancer risk: 65-y follow-up of the Boyd Orr cohort. Am J Clin Nutr. 2007

Hier die Studie

Cancer incidence in vegetarians: results from the European Prospective Investigation into Cancer and Nutrition (EPIC-Oxford)1,2,3,4

Timothy J Key, Paul N Appleby, Elizabeth A Spencer, Ruth C Travis, Andrew W Roddam and Naomi E Allen
1 From the Cancer Epidemiology Unit, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom.

2 Presented at the symposium, "Fifth International Congress on Vegetarian Nutrition," held in Loma Linda, CA, March 4–6, 2008.

3 Supported by Cancer Research UK, Medical Research Council.

4 Reprints not available. Address correspondence to TJ Key, Cancer Epidemiology Unit, University of Oxford, Richard Doll Building, Roosevelt Drive, Oxford OX3 7LF, United Kingdom. E-mail: tim.key @ ceu.ox.ac.uk.

ABSTRACT

Background: Few prospective studies have examined cancer incidence among vegetarians.

Objective: We report cancer incidence among vegetarians and nonvegetarians in the European Prospective Investigation into Cancer and Nutrition–Oxford (EPIC-Oxford) study.

Design: This was a prospective study of 63,550 men and women recruited throughout the United Kingdom in the 1990s. Cancer incidence was followed through nationwide cancer registries.

Results: The standardized incidence ratio for all malignant neoplasms for all participants was 72% (95% CI: 69%, 75%). The standardized incidence ratios for colorectal cancer were 84% (95% CI: 73%, 95%) among nonvegetarians and 102% (95% CI: 80%, 129%) among vegetarians. Comparing vegetarians with meat eaters and adjusting for age, sex, and smoking, the incidence rate ratio for all malignant neoplasms was 0.89 (95% CI: 0.80, 1.00). The incidence rate ratio for colorectal cancer in vegetarians compared with meat eaters was 1.39 (95% CI: 1.01, 1.91).

Conclusions: The overall cancer incidence rates of both the vegetarians and the nonvegetarians in this study are low compared with national rates. Within the study, the incidence of all cancers combined was lower among vegetarians than among meat eaters, but the incidence of colorectal cancer was higher in vegetarians than in meat eaters.



Ich fürchte, daß sogar Pescetarier (Verzehr von Fisch = Aufnahme von Quecksilber, polychlorierten Biphenyle und Dioxine) zur Gruppe "vegetarians" gezählt wurde.

Das genaue Gegenteil:

Colon Cancer

Vegetarians have lower rates of colon cancer than non-vegetarians (Phillips, 1980). Incidence of colon cancer has been strongly linked to the consumption of meat (Armstrong, 1975, Singh & fraser, 1998). Willett (1990) carried out a study of over 88 000 women aged 34 to 59 years. Women eating red meat daily ran over twice the risk of developing colon cancer than women eating red meat less than once a month.
Reduced incidence of colon cancer in vegetarians may be attributed to dietary differences which include increased fibre intake, increased consumption of fruit and vegetables, and decreased intake of total fat and saturated fat. The mechanism by which a vegetarian diet is protective against colon cancer is unclear and a great deal of research is being carried out in this area.

It has been suggested that secondary bile acids are carcinogens which may play an important role in colon cancer. These are derived by bacterial metabolism from primary bile acids made in the liver and secreted into the intestine. Vegetarians have lower levels of secondary bile acids than non-vegetarians (Turjiman, 1984). The differences in bacterial populations between the intestines of vegetarians and non-vegetarians may also be important. Bacterial flora in vegetarians has been shown to possess reduced ability to transform bile acids into potential carcinogens (Johansson, 1990).

The role of dietary fibre in prevention of colon cancer may also be important. This was first noted in 1971 when it was suggested the high incidence of colon cancer in Western countries was linked to low fibre diets. Other dietary components associated with high fibre foods, such as folate, have also been implicated as having protective effects.

Chen (2002) found that the risk of distal stomach adenocarcinoma was positively associated with red meat intake.

Kennt sich jemand mit Statistik aus? Wurde da was passend gerechnet?


Die standardisierte Inzidenzrate betrug 72 Prozent (95-Prozent-Konfidenzintervall 69-75 Prozent). Bei den Vegetariern gilt dies allerdings nicht für das Kolorektalkarzinom. Mit einer standardisierten Inzidenzrate von 102 Prozent erkrankten Vegetarier tendenziell häufiger an diesem Krebs als die Allgemeinbevölkerung.

Der direkte Vergleich von Fleischkonsumenten und Vegetariern in der Kohorte selbst bestätigt den Eindruck. Vegetarier erkranken tendenziell seltener als Fleischesser an Krebs: Der Unterschied war allerdings bei einer Inzidenzrate von 0,89 nicht sehr groß und er verfehlte mit einem 95-Prozent-Konfidenzintervall von 0,80 bis 1,00 auch das Signifikanzniveau. Wesentlich deutlicher war die Assoziation von vegetarischer Ernährung und Darmkrebs: Die Inzidenzrate betrug 1,39. Der Fleischverzicht erhöht das Risiko um mehr als ein Drittel, und mit einem 95-Prozent-Konfidenzintervall von 1,01 bis 1,91 war der Zusammenhang auch statistisch signifikant.


Habe in der Vorlesung gepennt, wer kennt sich mit Konfidenzintervallen und Inzidenzraten aus?

Noch ein paar Studien zum Thema Krebs und Fleischkonsum:

Psychonaut schrieb:Eine Analyse aus der Studie zum Gesundheitszustand der Adventisten, kam zu dem Ergebnis, dass Nichtvegetarier ein um 54% höheres Risiko hatten, an Prostatakrebs zu erkranken, und ein 88% erhöhtes Risiko für Dick- und Mastdarmkrebs. Sowohl rotes als auch weißes Fleisch waren unabhängig voneinander mit einem erhöhten Darmkrebsrisiko verbunden.
Fraser GE. Associations between diet and cancer, ischemic heart disease, and all-cause mortality in non-Hispanic white California Seventh-day Adventists. Am J Clin Nutr. 1999

Es wurden geringere Werte für die Kolonzellproliferation bei Vegetariern im Vergleich zu Nichtvegetariern ermittelt.
Lipkin et al. Seventh-day Adventist vegetarians have a quiescent proliferative activity in colonic mucosa. Cancer Lett. 1985

Psychonaut schrieb:
Brustkrebs:
Eine hohe lebenslange Östrogenexposition ist mit einem erhöhten Brustkrebsrisiko in Verbindung gebracht worden. Einige Forschungsergebnisse dokumentieren geringere Östrogenwerte in Serum und Urin von Vegetarierinnen.
Barbosa et al. The relationship among adiposity, diet, and hormone concentrations in vegetarian and nonvegetarian postmenopausal women. Am J Clin Nutr. 1990

Es gibt auch einige Nachweise für einen späteren Eintritt der Menstruation bei vegetarisch ernährten Mädchen, was das Brustkrebsrisiko durch geringere lebenslange Östrogenexposition reduzieren könnte.
Sanchez et al. A hypothesis on the etiological role of diet on age of menarch. Med Hypotheses. 1981
Kissinger, Sanchez. The association of dietary factors with the age of menarche. Nutr Res. 1987

Psychonaut schrieb:Darmmilieu:
Das Darmmilieu von Vegetariern unterscheidet sich auffällig von demjenigen von Nichtvegetariern. Vegetarier haben eine geringere Konzentration an potenziell karzinogenen Gallensäuren (siehe van Faassen) und weniger intestinale Bakterien, die die primären Gallensäuren in karzinogene sekundäre Gallensäuren umwandeln (siehe Finegold). Häufigere Stuhlentleerung und der Grad bestimmter Enzyme im Darm verbessern die Elimination potenzieller Kolonkarzinogene (siehe van Faassen und Davies). Die meisten Forschungsergebnisse zeigen auf, dass bei Vegetariern in geringerem Maße fäkale Mutagene vorliegen (siehe Nader).
van Faassen et al. Bile acids and pH values in total feces and in fecal water from habitually omnivorous and vegetarian subjects. Am J Clin Nutr. 1993
Finegold et al. Fecal microbial flora in Seventh Day Adventist populations and control subjects. Am J Clin Nutr. 1977
Davies et al. Bowel function measurements of individuals with different eating patterns. Gut. 1986
Nader et al. Diet and DNA-modifying activity in human fecal extracts. Nutr Rep Int. 1981

Weitere Faktoren:
Vegetarier konsumieren kein Hämeisen, für welches gezeigt werden konnte, dass es zur Bildung hoch zytotoxischer Faktoren im Darm führt, die das Darmkrebsrisiko erhöhen.
Sesink et al. Red meat and colon cancer: The cytotoxic and hyperproliferative effects of dietary heme. Cancer Res. 1999
Sesink et al. Red meat and colon cancer: dietary haem, but not fat, has cytotoxic and hyperproliferative effects on rat colonic epithelium. Carcinogenesis. 2000

Vegetarier haben eine höhere Aufnahme an Phytochemikalien, von denen für viele bekannt ist, dass sie der Krebsentwicklung entgegenwirken. Für Isoflavone in Sojaprodukten konnten krebswidrige Effekte nachgewiesen werden, insbesondere in Bezug auf Brust- und Prostatakrebs.
Griffiths K. Estrogens and prostatic disease. International Prostate Health Council Study Group. Prostate. 2000
Messina, Loprinzi. Soy for breast cancer survivors: A critical review of the literature. J Nutr. 2001

Psychonaut schrieb:Milch, Milchprodukte, Fleisch und Brustkrebs, Eierstockkrebs, Gebärmutterkrebs:

The continued increase in incidence of some hormone-related cancers worldwide is of great concern. Although estrogen-like substances in the environment were blamed for this increase, the possible role of endogenous estrogens from food has not been widely discussed. We are particularly concerned about cows' milk, which contains a considerable quantity of estrogens. When we name cows' milk as one of the important routes of human exposure to estrogens, the general response of Western people is that "man has been drinking cows' milk for around 2000 years without apparent harm." However, the milk that we are now consuming is quite different from that consumed 100 years ago. Unlike their pasture-fed counterparts of 100 years ago, modern dairy cows are usually pregnant and continue to lactate during the latter half of pregnancy, when the concentration of estrogens in blood, and hence in milk, increases. The correlation of incidence and mortality rates with environmental variables in worldwide countries provides useful clues to the etiology of cancer. In this study, we correlated incidence rates for breast, ovarian, and corpus uteri cancers (1993-97 from Cancer Incidence in Five Continents) with food intake (1961-97 from FAOSTAT) in 40 countries. Meat was most closely correlated with the breast cancer incidence (r=0.827), followed by milk (0.817) and cheese (0.751). Stepwise multiple-regression analysis (SMRA) identified meat as the factor contributing most greatly to the incidence of breast cancer ([R]=0.862). Milk was most closely correlated with the incidence of ovarian cancer (r=0.779), followed by animal fats (0.717) and cheese (0.697). SMRA revealed that milk plus cheese make the greatest contribution to the incidence of ovarian cancer ([R]=0.767). Milk was most closely correlated with corpus uteri cancer (r=0.814), followed by cheese (0.787). SMRA revealed that milk plus cheese make the most significant contribution to the incidence of corpus uteri cancer ([R]=0.861). In conclusion, increased consumption of animal-derived food may have adverse effects on the development of hormone-dependent cancers. Among dietary risk factors, we are most concerned with milk and dairy products, because the milk we drink today is produced from pregnant cows, in which estrogen and progesterone levels are markedly elevated.

Quelle:
Ganmaa et al. The possible role of female sex hormones in milk from pregnant cows in the develop ment of breast, ovarian and corpus uteri cancers. Med Hypotheses. 2005

Ich tippe auf Eikonsum, siehe Studie:

Bei Eiern wird die Evidenz für einen risikosteigernden
Effekt sowohl in Bezug zu Tumoren des Kolons, des
Rektums und der Brust als auch bei kardiovaskulären
Erkrankungen als möglich bewertet.

Mal mehr Input:

Cancer and Vegetarianism
On March 11, a study was released that measured the cancer incidence among British vegetarians. The study was part of European Prospective Investigation into Cancer and Nutrition–Oxford (EPIC-Oxford). I have updated the VeganHealth.org article Cancer, Vegetarianism, and Diet with the new findings.

(For this article to make sense you should take a minute to read this quick explanation of disease rate statistics if you are not already familiar with them.)

The participants in EPIC-Oxford were recruited from 1993 to 1999 and were followed through 2005. Previously, they had their overall cancer mortality through 2002 reported: Vegetarians had an 11% higher rate of death from cancer, but it was not statistically significant (1.11, .82 – 1.51).

The new findings reported the rates in two different ways:

1. Comparing vegetarians (including vegans) to all the meat-eaters.

2. Breaking the meat-eaters into two groups: regular and fish-eaters (no meat except fish).

The only statistically significant findings were:

Vegetarians had higher rates of colorectal cancer than all meat-eaters (1.49, 1.09-2.03).
Vegetarians had higher rates of colorectal cancer than the regular meat-eaters (1.39, 1.01-1.91).
Fish-eaters had lower rates of all cancer than regular meat-eaters (.83, .71-.96).
Vegetarians had borderline-significant, lower rates of all cancer than regular meat-eaters (.89, .80-1.00).
Rates for breast, prostate, lung, and ovarian cancer did not differ between groups.

When comparing this study population (including vegetarians and all meat eaters), their cancer rates were 28% lower than the overall population, their smoking rates were about half, and the meat-eating among the meat-eaters was “only moderate.” The authors hypothesized that, “Consumption of vegetables and fruit was higher among vegetarians than among nonvegetarians, but the differences were not large (< 20%). Thus, if high intakes of meat had an adverse effect and high intakes of fruit and vegetables had a beneficial effect, the relatively low meat intake and high fruit and vegetable intake of the nonvegetarians in this cohort could reduce the chance of observing lower cancer rates in the vegetarians than in the nonvegetarians."

Although we consider cancer rates of 1.49 (1.09-2.03) and .83 (.71-.96) as being statistically significant, I'm starting to wonder how relevant measurements of this magnitude actually are. The studies on vegetarians that have shown statistical significance are pretty inconsistent, and most studies have not found statistical significance. On the other hand, if you look at how the smoking rates affected lung cancer in this study, heavy smokers had 87 times the amount of lung cancer (87.3, 37.8 – 202). Now that is statistical significance. Even light smokers (27.1, 11.1-66.4) and former smokers (6.54, 2.89-14. had many times the rates of lung cancer as nonsmokers.

If we include these latest findings of vegetarian cancer rates with the others that have been measured (listed in Cancer, Vegetarianism, and Diet), I think we start to get a fairly consistent picture:

Among vegetarians and people who eat moderate amounts of meat and don’t smoke, cancer rates are about the same, but lower than for people who do smoke and eat large amounts of meat. In other words, you can reduce your risk of cancer by not smoking, by limiting meat to moderate amounts (or abstaining entirely), and by eating plenty of fruits and vegetables. The evidence for stronger claims doesn’t seem to be there.

Similarly, the combined colon cancer rates to date seems to indicate that, in comparison to eating moderate amounts of meat, being vegetarian neither increases nor decreases your risk of colon cancer.

http://jacknorrisrd.com/?p=379

Many people commented on yesterday’s post, Cancer and Vegetarianism, saying they wished the researchers had separated vegans from vegetarians.

In the paper, the authors stated, “…because of the small number of cancers among vegans, in this article the vegans are included in the vegetarian category.”

All we really know from that statement is that vegans didn’t have an unusually large number of cancers – so much that they would have reached some sort of statistical significance. It could also be that vegans have less cancer, or even a lot less cancer, but there was not enough data to create any sort of statistical significance.

I think it’s reasonable to hold out some hope that vegans will eventually be shown to have less cancer than meat-eaters or lacto-ovo vegetarians.

It could also be that except for in cases of very high amounts of animal products and very low amounts of fruits and vegetables, diet might not affect cancer that much. In the more moderate amounts of these foods, your body may be getting enough antioxidants, or have enough other mechanisms, to deal with carcinogens introduced by food.

I didn’t include a citation to the study in the original post:

Key TJ, Appleby PN, Spencer EA, Travis RC, Roddam AW, Allen NE. Cancer incidence in vegetarians: results from the European Prospective Investigation into Cancer and Nutrition (EPIC-Oxford). Am J Clin Nutr 2009;89(suppl):1S-7S.

http://jacknorrisrd.com/?cat=19

GO VEGAN!