How much iodine is in McDonald's?

October 31, 2025 •

3 min read

According to a 2010 study published in Endocrine Practice, a McDonald's vanilla milkshake was found to contain approximately 163.7 µg of iodine, while a small order of fries had only 2.72 µg. This stark difference highlights the surprising reality of how much iodine is in McDonald's, revealing that levels vary dramatically depending on the menu item.

Quick Summary

This article examines the varied iodine content of popular McDonald's menu items, detailing which foods are surprising sources and why fast food, overall, is an unreliable source for this essential mineral.

Key Points

Low Overall Content: Most McDonald's items, including fries and burgers, contain very little iodine, making fast food an unreliable source for this essential mineral.
High in Dairy and Fish Items: Milkshakes and fish sandwiches contain the highest iodine levels due to dairy products and the natural content of fish, respectively.
Non-Iodized Salt is Key: McDonald's reportedly does not use iodized salt, a factor that significantly contributes to the low iodine content of many of its non-dairy, non-fish menu items.
Not a Substitute for Healthy Sources: Fast food should not replace a balanced diet rich in reliable iodine sources like seafood, eggs, and dairy for maintaining proper thyroid function.
Look for Other Sources: For consistent iodine intake, rely on iodized table salt and naturally rich foods, as fast food provides inconsistent and often insufficient amounts.
Pregnant Women at Risk: Pregnant women, who have a higher iodine requirement, are particularly advised against relying on fast food, which lacks the consistent levels needed for fetal development.

Understanding Iodine in Fast Food

In the ongoing discussion about dietary health, questions frequently arise about the nutritional value of fast food. Specifically, many people wonder about the mineral content of popular menu items. For a trace mineral like iodine, vital for thyroid function and overall health, the source can be surprising. Studies have shown that fast food, particularly from chains like McDonald's, is generally not a reliable source of iodine, with most items containing low or inconsistent amounts. However, a few specific items, primarily those containing dairy or fish, stand out for their higher iodine levels.

Iodine Levels in Key McDonald's Menu Items

Research has provided specific data on the iodine content of various McDonald's products. This information is crucial for individuals monitoring their mineral intake, especially those who rely heavily on fast food as a significant portion of their diet. The data indicates a wide range, from very low amounts in staples like fries to much higher concentrations in dairy-based drinks and fish sandwiches.

The Surprising Role of Dairy and Fish

The primary reason for the higher iodine content in certain fast-food items is the presence of dairy products and fish. Dairy is a known source of iodine, largely due to agricultural practices. For instance, iodophor cleansers used on cows' udders and iodine in cattle feed contribute to the milk's mineral content. This is why a milkshake, which is dairy-heavy, registers as a significant source. Similarly, fish are naturally rich in iodine, which explains the higher levels found in a fish sandwich.

The Salt Factor: Why McDonald's is Different

One crucial distinction concerning fast-food iodine content is the use of iodized versus non-iodized salt. While some chains may have used iodized salt in the past, McDonald's has reportedly not endorsed its use in food preparation, according to a 2010 study. This differs from table salt typically used in home cooking, which is often iodized. A significant portion of the salt used in commercially prepared and packaged foods across the United States is non-iodized. This voluntary system means that fast food manufacturers are not required to use iodized salt, further reducing the reliability of these foods as a consistent iodine source.

Fast Food as an Unreliable Iodine Source

For those seeking a reliable source of iodine, fast food is not the answer. The reasons for this unreliability include:

Inconsistent Content: Iodine levels vary dramatically between different items, making it difficult to track intake accurately.
Reliance on Specific Items: Higher levels are concentrated in a few select items (dairy, fish), while the bulk of the menu contains very little.
Non-Iodized Salt: The widespread use of non-iodized salt in commercial food production removes a key potential source of the mineral.
Dietary Imbalance: Relying on fast food can lead to a generally unhealthy diet, which is counterproductive for overall nutrition.
Manufacturing Variation: Regional differences and changes in suppliers or preparation techniques can alter nutrient content over time.

Fast-Food Iodine Comparison Table


McDonald's Menu Item	Approximate Iodine Content (µg)	Main Source of Iodine
Vanilla Milkshake	163.7	Dairy products
Fish Sandwich	69.9	Fish (natural source)
Big Mac with Cheese	16.7	Dairy, meat (minimal)
Kids' Meal Hamburger	4.35	Meat, bun (minimal)
French Fries	2.72	Negligible
Chicken Nuggets	2.98	Negligible

The Importance of Sufficient Iodine

Iodine is a critical mineral for producing thyroid hormones, which regulate metabolism, bone growth, and brain development. Deficiency can lead to issues like goiter, hypothyroidism, and developmental problems, especially in pregnant women and children. Given the unreliability of fast food, it is essential to seek out more consistent and dependable dietary sources. Foods naturally rich in iodine include seafood like fish and seaweed, eggs, and dairy products. Using iodized table salt for home cooking is another simple way to ensure adequate intake. Those concerned about their iodine status should consult a healthcare professional. Information on recommended daily intake can be found on the Office of Dietary Supplements website for the National Institutes of Health.

Conclusion

While certain McDonald's items, notably milkshakes and fish sandwiches, contain measurable amounts of iodine due to their dairy and fish ingredients, fast food in general is not a reliable source of this essential mineral. The inconsistent and often low iodine levels, coupled with the prevalent use of non-iodized salt in commercial food production, means that individuals should not depend on fast food to meet their daily iodine needs. A balanced diet incorporating naturally iodine-rich foods and using iodized salt for home cooking remains the most dependable strategy for maintaining adequate iodine intake.

Frequently Asked Questions

According to research from 2010, McDonald's does not endorse the use of iodized salt in its food preparation, unlike some other fast-food chains. This means that for many items, salt does not contribute significantly to iodine content.

Milkshakes are dairy-based, and milk is a known source of iodine. The presence of iodine in milk comes primarily from the use of iodine-based disinfectants in dairy farming practices.

A McDonald's fish sandwich does contain a notable amount of iodine, as fish is naturally rich in this mineral. However, relying on any single fast-food item for a consistent nutrient supply is generally not recommended.

No, a small portion of McDonald's french fries contains very little iodine, with one study showing only 2.72 µg per serving. They are not considered a meaningful source of the mineral.

For most people, it would be difficult to get a sufficient and reliable amount of iodine solely from McDonald's. The levels are inconsistent and vary greatly between menu items, with many core products containing very little.

Fast food is generally less reliable for iodine intake than home-cooked meals, especially if you use iodized salt at home. The salt used in most processed and fast foods is typically non-iodized.

For those on a low-iodine diet, such as before a radioactive iodine treatment for thyroid cancer, items containing dairy (like milkshakes and cheese) and fish should be avoided due to their higher iodine content.