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 |
