Milk-Based Cultures in Stonyfield Soy Yogurt

I've seen several questions pop up about Stonyfield's O'Soy Soy Yogurt. Although it's a soy yogurt and none of the ingredients contain milk, the packaging contains a "CONTAINS SOY AND MILK" warning. Why? Because two of the six cultures that they use to make the yogurt are milk-based.

Michelle Civalier went the extra step and called the company in concern.

The representative informed me that this specific product has six probiotic cultures, two of which are grown in milk. (The details are proprietary, however, the spokeswoman did say there is no alternative method of growing those two cultures at this time.) The cultures ingest lactose, casein, and milk protein, meaning that those three things should not be present in the final product. What’s left of the milk after those parts are removed is present in the yogurt in amounts no greater than 5 ppm (parts per million). Stonyfield does not believe that these levels are high enough to cause a reaction in most sensitive or allergic people, but if there is concern, please consult a doctor before eating any of the product.

It's true that I've never heard of a documented reaction from anyone eating an O'Soy product. From the description given only the most extremely allergic would have even the possibility of a reaction. I'm sure most parents of allergic children would be concerned deposit this.

Civalier was. She asked:

Stonyfield promised to send my complaint to product development, though that didn’t provide me with any satisfaction as to why cultures that require milk to grow are being used in soy yogurt.

That's an interesting question. I haven't found any other soy yogurt to use milk-based cultures. They all claim to be dairy free. The Nancy's Yogurt FAQ page even explicitly states:

My son is allergic to dairy. Which of your products are completely casein-free?

All of our Organic Cultured Soy products are completely casein and dairy-free. We use nondairy cultures to culture our soy yogurt.

So it's not necessary to use milk-based cultures in soy yogurt. It's a choice that Stonyfield makes. Thus far it's been a successful choice, but it's one you need to think about.

You can find soy yogurts on the Nondairy Milk Alternatives - Other Nondairy Products of my Product Clearinghouse. I've made a note to the O'Soy Yogurt listing that states that it's made from milk-based cultures.