The good news is that with all the research being done, we now have a much clearer picture of the soy/breast cancer relationship.
Before we proceed: the topic of soy and breast cancer is extensive and cannot be covered completely in one single blog post. My goal in this article is to cover a few key points.
Why All the Confusion?
Interestingly, soy was first studied for its protective role against breast cancer. In these early studies, Asian women who traditionally consumed higher amounts of soy were seen to have lower rates of breast cancer.
The controversy began when researchers brought the study of soy out of people and into the laboratory. Studies done in lab animals and test tubes showed that soy actually promoted the growth of breast cancer cells.
So what gives? Why did the studies in people show a protective effect and the lab studies show a harmful effect?
We now believe it has to do with the type of soy being used in research. In the human studies, most of the women were eating traditional whole soy foods. In the lab studies, highly concentrated soy products were used in amounts much greater than women would traditionally eat. From this knowledge researchers determined that consuming processed soy or soy supplements may be harmful for women, especially women at high risk of breast cancer or those with breast cancer.
It is best to consume whole (minimally processed) soy foods and avoid processed soy foods and supplements. Studies done in large populations of people continue to assure us of the safety of consuming whole soy foods.
Examples of Whole Soy Foods
- whole soybeans
- roasted soybeans
- soy milk
Examples of Processed Soy Foods
- soy shakes
- soy chips
- soy bars
- soy supplements
- soy powders
- fake meat products
If the product is questionable, read the label. If the ingredient list has any of the follow words “soy protein concentrate”, “soy isolate”, or “isolated soy protein”, avoid the product.
How Much is Safe to Eat?
The active compounds in soy are called isoflavones. Isoflavones have a structure similar to human estrogen and can act like a weak form of human estrogen. It is still unclear whether or not this is a good thing. In some cases it appears to be good and in others it appears to be bad. This is why it is a good idea to be conservative with your soy intake.
Small amounts of whole soy foods appear to be completely safe – maybe even protective against breast cancer, but too much may be harmful.
1 to 2 servings of whole soyfoods per day are safe and healthy for most women to consume.
Soy Serving Sizes
- 8 oz soymilk
- 3.5 ounces of tofu or tempeh (about the size of the palm of your hand or a deck of cards)
- ¼ cup roasted soybeans
- ½ cup cooked soybeans or edamame
You don’t need to consume soy to be healthy, but know that it can be safely included in your breast cancer prevention plan if you want to eat it. Just make sure you choose whole, minimally processed soy foods and keep it to 1 or 2 servings each day.
I would love to hear what you think! In the comments below, tell me:
1. If you have ever felt confused by the soy/breast cancer relationship.
2. What would help make the confusion go away?
photo by: the 10 cent designer on Flickr