Rating: avoid

Dough strengthener: Bread, rolls.

Potassium iodate is sometimes used as a dough strengthener in bread and rolls. Some bakers may switch to this ingredient when they stop using its chemical cousin potassium bromate, which poses a small cancer risk. However, potassium iodate, too, is not well tested and may also pose a slight cancer risk. It conceivably could lead to excessive iodine intake.

Potassium iodate is a source of iodine, an essential trace element, necessary for the body to make thyroid hormones. That’s the good news. But too little or too much iodine can be harmful. A committee of the World Health Organization concluded that use of potassium iodate as a flour treatment agent was unacceptable because it could result in an excessive intake of iodine. At the same time, the committee endorsed the use of potassium iodate to fortify salt, since use in salt results in a lower intake of iodine than widespread use in bread and rolls and is used to prevent iodine deficiency disorders such as goiter and mental retardation, to name a few.

In the United States, potassium iodide, not potassium iodate, is used in iodized salt, but in other countries, especially tropical countries, potassium iodate is favored because it is more stable in warm, humid conditions. Iodized salt has virtually eliminated iodine deficiency in the United States, Canada, and several other countries.

Some people, such as those with thyroid disease, are especially sensitive to iodine intake and should make a special effort to avoid potassium iodate in bread and rolls. One other possible concern is that iodate breaks down in dough and in the body to form iodide. In a study conducted by Japanese government scientists, high doses of potassium iodide caused cancer in rats, suggesting it may be a weak carcinogen. The same research found that it also increased the potency of a known carcinogen.

As a sidelight, both potassium iodate and potassium iodide can also be used to prevent damage to the thyroid in the event of an accident at a nuclear reactor, although the iodide form is generally recommended.

Bottom line: Potassium iodate is not widely used in baked goods, and any risk is small. Still, it may be worth choosing baked goods without this ill-tested additive, and bakers should stop using it.