Saturday, February 25, 2012

Berries do not decrease cancer risk


Background: berries are said to decrease cancer risk. If we google for "berries cancer" we see that pretty much all titles suggest this to be true. These ideas are based on the assumption that berries include several nutrients thought to be healthy, such as vitamins, minerals and polyphenols. But if we take a closer look at the evidence, we see that articles are consistently based on either:
-Animal research.
-Studies in cell lines.
-Nothing. No references are given to back up the claim.

If berries are to decrease cancer risk in humans, it would be logical that humans with higher intake of berries have lower cancer risk than humans with lower intake of berries.


 
Methods: I searched the Pubmed database for prospective (= cohort) studies relating berry consumption to cancer risk for 7 major types of cancer. Details of the search term and inclusion criteria can be found on my other internetsite (1).

Results.
A) Breast cancer:
Study:
Subjects:
Type of berries:
Effect:
2) Adebamowo CA (2005)
90,630 women
Blueberries
RR = 1.25 (0.86-1.80; P = 0.84)
One study was found. Blueberries did not protect against breast cancer risk.

B) Colorectal cancer:
Study:
Subjects:
Type of berries:
Effect:
3) Michels KB (2000)
88,764 women
Blueberries
No significant association with colon or rectal cancer
3) Michels KB (2000)
47,325 men
Blueberries
No significant association with colon or rectal cancer
4) Lin J (2005)
36,976 women
Blueberries
No significant association with colorectal cancer
Two studies were found, including three cohorts. Blueberries did not protect against colorectal cancer risk. No relative risks were provided in the articles referred to.

C) Lung cancer:
Study:
Subjects:
Type of berries:
Effect:
5) Knekt P (1997)
9,959 men and women
Total berries (lingonberries, blueberries, black currants, raspberries and gooseberries)
RR = 1.80 (1.11-2.93)
6) Cutler GJ (2008)
34,708 women
Total berries (mostly blueberries and strawberries)
No association was found
7) Feskanich D (2000)
77,283 women
Blueberries
No association was found
7) Feskanich D (2000)
47,778 men
Blueberries
No association was found
8) Hirvonen T (2001)
27,110 men
Total berries
A nonsignificant protective effect.
Four studies were found, including five cohorts. Only one study (Knekt P. 1997) provided a relative risk which showed a significant 80% increased risk of lung cancer. No other significant associations were found.

D) Pancreatic cancer risk:
Study:
Subjects:
Type of berries:
Effect:
9) Bobe G (2008)
27,111 men
Total berries
HR = 0.88 (0.63-1.24; P = 0.94)
10) Vrieling A (2009)
478,400 men and women
Total berries (e.g., strawberries and raspberries
HR = 0.90 (0.66-1.23; P = 0.61)
Two studies were found. No associations were found.

E) No prospective studies were found examining berry consumption in relation to esophageal, ovarian, or prostate cancer risk.

Conclusion: prospective cohort studies consistently show that subjects with higher intakes of berries do not have lower cancer risk.

Limitations: results presented here were limited to only 7 types of cancer. However, these include major types of cancer: breast, colorectal, esophageal, lung, ovarian, pancreatic and prostate cancer risk. And no protective effects were found in 2 studies examining total cancer risk (1).



References:
1) Hoenselaar R. Cancer and diet. A systematic review. http://canceranddiet.nl/
2) Adebamowo CA et al. Dietary flavonols and flavonol-rich foods intake and the risk of breast cancer. Int J Cancer. 2005 Apr 20;114(4):628-33. Int J Cancer. 2005 Apr 20;114(4):628-33. http://www.ncbi.nlm.nih.gov/pubmed/15609322
3) Michels KB et al. Prospective study of fruit and vegetable consumption and incidence of colon and rectal cancers. J Natl Cancer Inst. 2000 Nov 1;92(21):1740-52.  http://jnci.oxfordjournals.org/content/92/21/1740.full
4) Lin J et al. Dietary intakes of fruit, vegetables, and fiber, and risk of colorectal cancer in a prospective cohort of women (United States). Cancer Causes Control. 2005 Apr;16(3):225-33. http://www.ncbi.nlm.nih.gov/pubmed/15947874
5) Knekt P et al. Dietary flavonoids and the risk of lung cancer and other malignant neoplasms. Am J Epidemiol. 1997 Aug 1;146(3):223-30. http://aje.oxfordjournals.org/content/146/3/223.full.pdf
6) Cutler GJ et al. Dietary flavonoid intake and risk of cancer in postmenopausal women: the Iowa Women's Health Study. Int J Cancer. 2008 Aug 1;123(3):664-71. http://www.ncbi.nlm.nih.gov/pubmed/18491403
7) Feskanich D et al. Prospective study of fruit and vegetable consumption and risk of lung cancer among men and women. J Natl Cancer Inst. 2000 Nov 15;92(22):1812-23. http://jnci.oxfordjournals.org/content/92/22/1812.full
8) Hirvonen T et al. Flavonol and flavone intake and the risk of cancer in male smokers (Finland). Cancer Causes Control. 2001 Nov;12(9):789-96. http://www.ncbi.nlm.nih.gov/pubmed/11714106
9) Bobe G et al. Flavonoid intake and risk of pancreatic cancer in male smokers (Finland). Cancer Epidemiol Biomarkers Prev. 2008 Mar;17(3):553-62. http://cebp.aacrjournals.org/content/17/3/553.long
10) Vrieling A et al. Fruit and vegetable consumption and pancreatic cancer risk in the European Prospective Investigation into Cancer and Nutrition. Int J Cancer. 2009 Apr 15;124(8):1926-34. http://www.ncbi.nlm.nih.gov/pubmed/19107929

Reacties:

2 reacties:

Kostas said...

Two studies made on actual humans that show cacner protective effects of berries:
http://nutritionfacts.org/video/best-fruits-for-cancer-prevention/
http://nutritionfacts.org/video/strawberries-versus-esophageal-cancer/

Bella Edward said...

Hatts off to you Dear! You have done a great job by sharing this with us. I have also read alot about on cancer. read here all facts about cancer

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