The consumption of soy-based products, such as tofu and miso soup, has been repeatedly associated with a reduction in the risk of breast cancer.
However, information found in laboratory studies has suggested that women afflicted by this cancer should avoid this types of food.
So how does one act when facing these contradictory results?
ISOFLAVONES IN SOY
Soy-based products are exemplary, and their full potential has yet to be achieved in our society. In addition to being rich in protein, essential fatty acids and vitamins and minerals, soy is one of the only food items to contain a group of polyphenols called isoflavones.
An interesting characteristic of isoflavones is their striking similarity to estrogen, the female sexual hormone, which is why they are known as phytoestrogen. These hormones play a central role in the formation of breast cancer: in fact, when the levels of these hormones is too high, an excessive stimulation of mammary gland growth occurs which in turn increases the risk of cancer. Because phytoestrogens resemble estrogen so much, they prevent the hormones from properly interacting with the breasts' cells, resulting in a reduced cancer risk.
Because of this, studies have suggested that regular consumption of soy-based foods, like edamame, tofu or miso soup will reduce the risk of being afflicted by breast cancer. This preventative effect is more pronounced if the products are consumed regularly after puberty, which
is accompanied by a marked increase in estrogen levels.
CONTROVERSY
Despite these positive observations, certain studies conducted on cells from mammary tumours or by using lab animals has contrarily shown that the isoflavones could in fact stimulate the growth of these cells. This information suggests that soy would not have the same benefits for woman already hit with breast cancer and could even have a negative impact by stimulating the growth of cancer cells that have survived treatment.
It is thus recommended to breast cancer survivors to consume these foods in extreme moderation and in some cases, avoid them altogether. That said, this still needs to be clearly proved through studies of the effects of soy products on women having been touched by breast cancer.
REASSURING STUDIES
Two studies conducted in 2009 have suggested that the dangers attributed to soy products were not justified and that these food items could
actually reduce the risk of recurrence in breast cancer survivors.
For example, a study conducted using 2,000 women who had fought breast cancer and were treated with tamoxifen showed that soy consumption resulted in a 60 % decrease in the risk of recurrence. These encouraging results were confirmed by a larger scale Chinese study that used more than 5,000 breast cancer survivors.
In this study, researchers observed that women who consumed moderate amounts of soy (about 10 g of protein per day) saw their recurrence risk and mortality rate associated with breast cancer reduced by 30 %, whether or not they were treated by tamoxifen. That is a very
significant reduction.
Therefore, it appears that the consumption of soy is of no danger for breast cancer survivors and that it could even have extremely positive
effects on the survival of these women by reducing the risk of recurrence.
ANTICANCER RECIPE:
DARK CHOCOLATE AND SILK TOFU PUDDING
2 1/2 cup (375 g) silky almond tofu
10 oz (300 g) 70% dark chocolate
Field berries, to taste
Blend tofu for 30 seconds, until smooth. Melt chocolate in a bain marie or by placing it in a container over large shallow pan of warm water. Using a mixer, beat tofu and chocolate together at low speed. Pour pudding into 4 small dishes and serve with berries.
- Source: Eric Harvey, teacher at Ecole Hoteliere de la Capitale, in Quebec City
