Women eating increasing amounts of soy have a higher risk of breast cancer

This study was published in the British Journal of Cancer 2003 Oct 6;89(7):1255-9

 

Study title and authors:

Flavonoid intake and breast cancer risk: a case--control study in Greece.

Peterson J, Lagiou P, Samoli E, Lagiou A, Katsouyanni K, La Vecchia C, Dwyer J, Trichopoulos D.

Schools of Nutrition and Medicine, Boston, MA 02111, USA.

 

This study can be accessed at: http://www.ncbi.nlm.nih.gov/pubmed/14520456

The study investigated the association between flavonoids and the risk of breast cancer. The study included 820 women with breast cancer and 1,548 control women without breast cancer.

Regarding isoflavones, (the overwhelming dietary source of isoflavones are from soy products, see table below), the study found that for every 0.8 mg per day increase in isoflavones there was a 7% increase in breast cancer.

Isoflavones contents of food

Below are isoflavones contents (total isoflavones, daidzein and genistein) of foods taken from the USDA database. Values of isoflavones are expressed in mg per 100g.

Food product	Total isoflavones	Daidzein	Genistein
Soy flour, full-fat	177,89	71,19	96,83
Soy flour, textured	148,61	59,62	78,90
Soy flour, defatted	131,19	57,47	71,21
Soybeans	128,34	46,46	73,76
Soy protein concentrate, aqueous washed	102,07	43,04	55,59
Soy protein isolate	97,43	33,59	59,62
Natto	58,93	21,85	29,04
Soybean chips	54,16	26,71	27,45
Tofu, fried	48,35	17,83	28,00
Tempeh	43,52	17,59	24,85
Miso	42,55	16,13	24,56
Soybean sprouts	40,71	19,12	21,60
Tofu, soft	29,24	8,59	20,65
Tofu, silken	27,91	11,13	15,58
Soy infant formula, powder	25,00	7,23	14,75
Tofu, firm	22,70	8,00	12,75
Soy hot dog	15,00	3,40	8,20
Okara	13,51	5,39	6,48
Soy protein concentrate, alcohol extracted	12,47	6,83	5,33
Bacon, meatless	12,10	2,80	6,90
Soy milk	9,65	4,45	6,06
Vegetarian burger	9,30	2,95	5,28
Soy cheese, Mozzarella	7,70	1,10	3,60
Soy cheese, Cheddar	7,15	1,80	2,25
Soy drink	7,01	2,41	4,60
Split peas	2,42	2,42	0,00
Shoyu	1,64	0,93	0,82
Pigeon peas	0,56	0,02	0,54
Clover sprouts	0,35	0,00	0,35
Peanuts	0,26	0,03	0,24
Navy beans	0,21	0,01	0,20
Mung beans	0,19	0,01	0,18
Granola bars	0,13	0,05	0,08
Chickpeas	0,10	0,04	0,06
Green tea	0,05	0,01	0,04
Broadbeans	0,03	0,02	0,00
Cowpeas	0,03	0,01	0,02
Lima beans	0,03	0,02	0,01
Lentils	0,01	0,00	0,00
Alfalaval seeds, sprouted	0,00	0,00	0,00
Black beans	0,00	0,00	0,00
Flax seed	0,00	0,00	0,00
Rye bread	0,00	0,00	0,00