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30 Apr 2024

What’s the story with soy?

Food & Fluids

Humans have been growing soybeans for at least 3,000 years. But for the past 25 of those, there have been lots of debate about how this legume might affect our health. NZ Nutrition Foundation shows how soy and other plant-based proteins stack up against animal sources of protein. 

Soy milk is a healthy, plant-based milk that can fit into just about any diet. It's naturally lower in fat and calories than dairy milk but offers more protein than other popular plant-based milks, such as almond and oat.

Here’s the gist of the soybean controversy:

  • Soybeans are super high in isoflavones, compounds with a very similar chemical structure to oestrogen.
  • There have been studies (many of them in animals) suggesting isoflavones can affect hormone levels, increase the risk of certain cancers, and suppress thyroid function.
  • However, a 2016 research review found a lack of human studies to back up these claims. The researchers also noted that animals metabolize isoflavones differently, meaning many of these findings don’t apply to humans.
  • For more information see www.nznutritionfoundation/protein/ and https://www.healthline.com/nutrition then scroll down the page and click on ‘Plant-based Protein: The Best, The Worst, and Everything in Between’, please note they use the word tofu not soy (Note this is American Healthline not NZ).

Bean benefits. These unfounded claims tend to distract us from the fact that soy is a uniquely nutritious food. For example, it’s an excellent plant-based source of high-quality protein and calcium, two nutrients we often lack. Soy is also linked to an impressive list of health benefits, including a reduced risk of breast and other types of cancer.

Want to eat more soy? Try foods like tofu, tempeh, miso, and soy milk.

Soy is often the non-dairy choice for baristas because with a little bit of skill and technique it can create a foam comparable to dairy milk. Paired with good quality coffee, soy milk's nutty, creamy flavour can even enhance the taste of your favourite blend.


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Published.  February 2024

To be reviewed: February 2027