by Reed Mangels, PhD, RD

I’ve written before about the very low levels of iodine in plant milks in the United States and said that one study (1) found that plant milks had about 3% as much iodine as cow’s milk does. Iodine is an essential nutrient which is needed for the thyroid gland to function properly. Although the iodine content of fruits, nuts, and vegetables varies depending on growing conditions, most of these staples of a vegan diet are low in iodine (2). Cow’s milk and other dairy products are a main source of iodine for many people in the United States.

A colleague recently contacted me and pointed out that Silk Soy Original (red carton) is fortified with iodine. According to the product label which I checked on October 15, 2025, a cup of Silk Soy Original has 15 micrograms of iodine (10% of the Daily Value). Also, according to the product label, Silk Soy Vanilla (also in a red carton) has 15 micrograms of iodine in a cup of soymilk. The Silk website indicates that Silk Kids Oatmilk Blend has 30 micrograms of iodine (20% of the Daily Value) in a cup. I am not aware of other plant milks that are fortified with iodine.

The Recommended Dietary Allowance (RDA) for iodine for adults is 150 micrograms per day so it’s unlikely that you’ll get all the iodine you need from fortified Silk. Vegans can also get iodine from iodized salt, iodine supplements, and sea vegetables although the amount of iodine in sea vegetables is variable.

References

1. Ma W, He X, Braverman L. Iodine content in milk alternatives. Thyroid. 2016;26(9):1308-10.
2. Ershow AG, Skeaff SA, Merkel JM, Pehrsson PR. Development of databases on iodine in foods and dietary supplements. Nutrients. 2018;10(1):100.

To read more about iodine see:

Iodine in the Vegan Diet

Iodine in Prenatal Supplements

Iodine in Plant Milks

Food Sources of Iodine

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