Iodine Intake Trends in U.S. Girls and Women (2011-2020): Why We Should Care and What to Do About It

Iodine is an essential nutrient that often flies under the radar, overshadowed by its more glamorous micronutrient cousins like vitamin D and iron. However, it may be important to pay closer attention to iodine, especially given the latest findings on iodine intake trends among U.S. girls and women. This article dives deep into the study “Iodine Intake Trends in United States Girls and Women between 2011 and 2020” (1) and explores why we should care about iodine intake, what the data reveals, and what steps we can take to ensure optimal iodine status in our patients.

Why Iodine Matters: The Unsung Hero of Nutrients

Iodine is a key component of thyroid hormones, which regulate metabolism, growth, and development. Adequate iodine intake is particularly critical during pregnancy and early childhood for brain development and cognitive function. A deficiency can lead to a range of health issues, including goiter, hypothyroidism, impaired neurodevelopment, and increased risk of miscarriage or preterm birth (2). Despite its importance, iodine often doesn’t get the attention it deserves in conversations about diet and nutrition.

What the Data Says: Trends in Iodine Intake from 2011 to 2020

A recent analysis of National Health and Nutrition Examination Survey (NHANES) data from 2011 to 2020 provides insight into iodine intake trends among girls and women in the U.S. (3). The study examined urinary iodine concentration (UIC)—a reliable biomarker of iodine intake—in girls aged 6-19 and women aged 20-59. Here’s what the data revealed:

1. Overall Trends: Iodine intake among U.S. girls and women fluctuated over the decade, with periods of adequate intake interspersed with concerning dips.
2. Age Group Differences:
• Girls aged 6-19 generally had higher UIC levels compared to women, suggesting that younger females might be faring better in terms of iodine status.
• Women of reproductive age (20-39 years) consistently showed the lowest UIC levels, raising red flags about iodine sufficiency during critical reproductive years (3).
3. Insufficient Intake Prevalence: A significant proportion of women, especially those of reproductive age, had UIC levels below 100 µg/L, the threshold for iodine sufficiency according to World Health Organization (WHO) guidelines (4). This puts them at risk for iodine deficiency and its associated health impacts.
4. Dietary Sources and Supplement Use:
• Iodine intake was closely tied to dietary habits, particularly the consumption of dairy products, iodized salt, and seafood—primary sources of iodine.
• Supplement use was inconsistent, with many women not meeting iodine requirements through diet alone (3).

Why the Fluctuations? Unpacking the Trends

Several factors could explain the fluctuating iodine levels among U.S. girls and women. Dietary shifts, public health policies, and lifestyle changes all play roles.

1. Declining Use of Iodized Salt: While iodized salt remains one of the most reliable sources of dietary iodine, there has been a gradual decline in its use in the American diet. As health-conscious individuals reduce their salt intake or switch to non-iodized sea salt, overall iodine consumption decreases (5).
2. Variability in Dairy and Seafood Intake: Dairy and seafood are naturally rich in iodine, but their consumption varies widely among individuals. The growing popularity of plant-based diets may also contribute to lower iodine intake, as many plant foods are low in iodine (6).
3. Inconsistent Supplementation: Although iodine-containing prenatal vitamins are recommended for pregnant women, not all supplements include adequate iodine, and many women of reproductive age are unaware of their specific needs (7).

Implications for Healthcare Practitioners and Consumers: Why Should We Care?

These findings have significant implications, especially for healthcare practitioners advising patients on nutrition and supplementation. The consistent trend of insufficient iodine intake among women of reproductive age is particularly concerning, as this group is at higher risk for thyroid dysfunction and adverse pregnancy outcomes. Moreover, the potential impact on fetal and cognitive development cannot be overstated (8).

Understanding iodine’s role and ensuring sufficient intake can have profound long-term benefits. This isn't just about avoiding goiter; it’s about optimizing thyroid health, supporting metabolic function, and safeguarding future generations.

Actionable Steps: How to Ensure Adequate Iodine Intake

So, what can we do about it? Here are some practical steps for healthcare practitioners and prosumers alike:

1. Promote Iodine Awareness: Educate patients and the broader community about the importance of iodine, especially for women of reproductive age. This nutrient is not just a footnote in thyroid health; it’s a cornerstone.
2. Encourage Dietary Sources of Iodine:
• Dairy Products: Milk, yogurt, and cheese are excellent sources of iodine. Encourage their inclusion, when appropriate and when sensitivities or allergens to dairy proteins have been excluded, especially in populations that may have lower intake, like teenagers and young women.
• Seafood: Fish, shellfish, and seaweed are rich in iodine and should be regularly included in the diet. Again, shellfish have a high allergenic potential so it is wise to personalize these recommendations.
• Iodized Salt: Using iodized salt can help maintain adequate iodine levels yet the proportions of necessary iodine compared to the relative sodium chloride may not be ideal (9).
3. Monitor and Test: For healthcare practitioners, consider testing UIC in at-risk populations, such as women planning pregnancy or experiencing thyroid-related symptoms. Regular monitoring can help tailor individual recommendations and prevent deficiencies before they lead to clinical issues.

The Takeaway: Keep Iodine on the Radar

The findings from this study underscore a critical gap in iodine intake among U.S. girls and women, particularly those of reproductive age. Staying informed and proactive about iodine can help bridge this gap. Ensuring adequate iodine intake is an investment in lifelong health, cognitive function, and the next generation’s wellbeing.

Corey Schuler, PhD, FNP, CNS has dedicated his career to advancing the science and clinical art of integrative medicine and serves as director of medical affairs for Allergy Research Group. He is a family nurse practitioner and practices holistic primary care at Synergy Family Physicians in White Bear Lake, Minnesota.