That’s a concern in women of childbearing age in particular, researchers say, because a baby’s brain can’t develop normally without it.
“They may need special attention because we want to make sure they have the best possible brain development of the fetus,” Pfeiffer says. Additionally, iodine is essential to the production of thyroid hormones, which help regulate energy.
Iodine levels appear to be falling in the U.S. and in several other industrialized countries because of changes to the way milk and bread are processed.
Also, people now get most of their dietary sodium from processed foods, not table salt. “Processed foods probably do not contain iodized salt, so the majority of salt in the diet -- 85% from processed foods -- is not providing iodine with it,” says Karen Charlton, PhD, MPhil, MSc, an associate professor of health science at the University of Wollongong in New South Wales, Australia, in an email.
Charlton is an expert on iodine deficiency but was not involved in the research.
Besides iodized salt, good sources of iodine include seafood such as fish and shrimp. Seaweed is also rich in iodine. Beans, potatoes, meat, and eggs also contain substantial iodine.
Nearly 1 in 10 women between the ages of 12 and 50 had low iron levels. That’s not a new problem, but it also doesn’t appear to be getting any better, researchers say.
Certain groups appear to be at greater risk for iron deficiency.
“Non-Hispanic blacks and Mexican-Americans have higher rates of iron deficiency than non-Hispanic whites have,” Pfeiffer says.
Low iron typically causes fatigue, shortness of breath, paleness, and difficulty concentrating. A doctor can check for iron deficiency with a simple blood test.
Important food sources include seafood, red meat, and poultry, fortified cereals, beans, and leafy greens like spinach. Iron can sometimes be hard to absorb from dietary sources alone. People who are low on iron, particularly vegetarians, may need supplements.