Soy or No Soy

Soy or no soy?

Many cancer patients are fearful of eating soy. This is particularly common among breast cancer patients. Because soy contains estrogen-like compounds, there is a fear that soy may raise the risks of hormone-related cancers like breast cancer.

However, latest evidence shows that this is not true.

Tofu, tempeh, soymilk and miso are instances of soy foods that many, especially Asians, enjoy much. Soy is one of the few plant foods which could provide high-quality proteins our body needs.

Soy foods contain several key nutrients and phytochemicals which have been studied for their correlation with cancer occurrence. Yet overall, studies on human subjects show that soy foods do not increase cancer risks. In some cases, soy may even lower cancer risks.

Studies in Asia link soy consumption with lower breast cancer risks. Asian women consume moderate amounts of soy throughout their life. There is a protective effect of soy against breast cancer, but it relates to soy consumption since childhood, adolescence, and throughout puberty.

So, how much of soy is considered moderate?

A moderate amount is approximately 1 to 2 servings a day. Examples of 1 serving¹ are:

  • Tofu, 100 g (about ½ block)
  • Tempeh, 50 g (about 1 piece)
  • Unsweetened soy milk, 200 g (about 1 glass)

We can still enjoy soy foods within the moderate amount. Soy supplements, on the other hand, are not recommended at this time as studies on safety issues remain inconclusive.

Don’t think taking soy can “cure” cancer. It won’t.

As soy foods are good sources of protein, we may include soy foods in the menu for cancer patients. Replacement of milk protein with soy protein is not necessary, unless you are advised by the doctor and the dietitian.


¹ Malaysian Food Composition Database. Institute for Medical Research, Kuala Lumpur, 1997.

Further reading:

AICR’s Foods That Fight Cancer™.  American Institute for Cancer Research, 2016.

Marcus Lee, Dietitian