Scientific research long ago uncovered the links between poor diets and the classic “deficiency diseases” common in the 18^th and 19^th Centuries—things like scurvy beri-beri and pellagra. We know that long-term depletion of certain nutrients can result in specific conditions with undeniable signs and symptoms. But in the developed world in the 21^st Century rarely do patients and clients present with full-blown deficiency diseases. When was the last time someone walked into your office with gums bleeding so badly and skin so easily bruised that you had to dust off your history book and diagnose a case of scurvy?

But what about more moderate deficiencies that don’t lead to glaringly obvious problems? As we know patients can be insufficient in nutrients without displaying overt symptoms. Just because someone doesn’t show the classic “3 D’s of pellagra”—dermatitis dementia and diarrhea—doesn’t mean they’re getting enough niacin. And they don’t have to be bow-legged to be low in vitamin D. Modern functional medicine testing reveals that in the presence of mild to moderate nutrient insufficiencies the body can survive but not thrive.

The consequences of suboptimal nutrient intake take a difficult toll on adults but what about the price they exact from children? What are the effects of long-term suboptimal nutrient intake in children including—and perhaps especially—their time in the womb? Could this have repercussions for their cognitive and emotional development?

In discussions regarding nutritional therapies for ADD ADHD and autism spectrum conditions a lot of focus is given to essential fatty acids zinc magnesium and folate (for methylation). One trace mineral that might be part of the puzzle but doesn’t get much attention is iodine.

In that same dusty old medical history book where they talked about beri-beri they also mentioned goiter—a swelling of the thyroid gland as a result of iodine insufficiency. But just like full-blown rickets isn’t the only result of low vitamin D levels goiter isn’t the only sign of insufficient iodine intake. Children born to mothers with severe iodine deficiency are referred to with the now somewhat politically incorrect term “cretin.” Cretinism involves stunted physical growth as well as lowered IQ and mental retardation.

But just as scurvy is the most severe manifestation of vitamin C depletion—and there are other more mild effects from low intake—it’s possible that low maternal iodine intake and low intake during early childhood can have effects on a child’s IQ learning and behavior that don’t approach cretinism but that might result in things like ADD and ADHD. In a small Italian study ADHD was diagnosed in 11 of 16 children (~69%) from an iodine-deficient area and in none from an area just marginally sufficient. Total IQ was lower in the ADHD children of the iodine insufficient area than in the children from the control area. For sure there is a connection between maternal iodine levels thyroid hormones and fetal brain development.

Iodine is in short supply in the modern American diet and iodine insufficiency is common among pregnant women. Among the U.S. population as a whole data from the large NHANES study indicate that urinary iodine levels have fallen by as much as 50% since the 1970s. The richest sources of iodine—shellfish and sea vegetables—are relatively uncommon on dinner tables and popular restaurant menus alike. And in following the U.S. government’s seemingly misguided yet longstanding across-the-board recommendations for low-sodium diets health-conscious people may be unnecessarily avoiding the major source of iodine in the modern American diet—iodized salt. (Sodium restriction has very little effect on hypertension.) Dairy products can sometimes be a good source of iodine but only if the milking animals’ feed is supplemented with it. 

Commercially prepared bread was formerly made using potassium iodate a dough conditioner that provided at least some iodine but this has largely been replaced by potassium bromate. Bromine and other halogen elements can displace iodine in the body. We come in contact with bromine in many ways. It’s used in food processing (in some soft drinks and sports drinks) and is employed as a fire-retardant in clothing mattresses vehicle upholstery and more. So in a double-whammy to health not only do most people not take in much iodine but what little they do get might be bullied out by bromine or perchlorate a nearly ubiquitous environmental toxin. 

Maternal iodine (and thyroid hormone) levels are important for childhood neurological and cognitive development. Even taking in adequate iodine during early childhood might not be enough to make up for maternal deficiencies that possibly lead to lowered educational performance. 

As a proxy for iodine status maternal thyroid hormone levels could be monitored to ensure adequate intake as part of prenatal wellness screenings. In children with diagnosed or suspected ADD/ADHD or other learning impairments thyroid levels could be checked or a urinary iodine excretion test performed. It’s possible the exponential rise in learning and behavioral disorders among our children is connected to epidemic levels of subclinical low thyroid function secondary to iodine insufficiency and hypothalamic/pituitary/adrenal (HPA) axis dysfunction in expectant mothers.