Does Unsalted Butter Have Iodine in It? A Comprehensive Look at Dairy and Dietary Minerals

October 30, 2025 •

4 min read

According to scientific reviews, milk and dairy products are significant sources of iodine in industrialized countries. But when you remove the salt, does unsalted butter have iodine in it? The answer lies in the cow's diet, not the salt shaker.

Quick Summary

Unsalted butter contains trace amounts of iodine, a mineral that originates from the diet of dairy cows. Its content is not high enough to be a primary dietary source, unlike iodized salt. Choosing unsalted butter allows for better control of sodium intake while still providing minor nutritional benefits.

Key Points

Trace Iodine: Unsalted butter contains only trace amounts of iodine, which originates from the cow's diet and farming practices.
Not a Primary Source: Butter is not a reliable or significant source of dietary iodine, unlike fortified salt, seafood, or eggs.
Salt for Sodium, Not Iodine: The difference between salted and unsalted butter is primarily the sodium content, not the iodine.
Control Over Sodium: Unsalted butter is the preferred choice for cooking and baking when managing sodium intake and controlling flavor balance.
Thyroid Health: The iodine in butter contributes to thyroid function but is insufficient to prevent deficiency symptoms like goiter.
Other Sources are Key: For adequate iodine, a balanced diet should include other rich sources like seafood and iodized salt.

The Origin of Iodine in Dairy Products

Iodine is an essential trace mineral vital for the synthesis of thyroid hormones, which regulate metabolic processes. The iodine content in dairy products like milk, cheese, and butter is not an inherent property of the fat but rather a result of agricultural practices.

The primary source of iodine in dairy comes from the dairy cow's diet and care. Here's how it works:

Fortified Feed: Many dairy cows receive feed that is supplemented with iodine to ensure their health and boost milk production. This added iodine is then transferred to the milk they produce.
Teat Disinfectants: Iodized sanitizers, known as iodophors, are sometimes used to clean the teats of milking cows. While the goal is not to fortify the milk, some iodine can be absorbed through the cow's skin and secreted into the milk.
Pasture Quality: The mineral content of the soil and pasture where cows graze also influences the iodine content of their milk. Areas with iodine-deficient soil produce dairy products with lower iodine levels.

Unsalted Butter and Its Iodine Content

So, does unsalted butter have iodine in it? Yes, it does, but only in very small, trace amounts. Since butter is made by churning the cream from milk, any iodine present in the milk will also be present in the butter. The key takeaway is that the amount of iodine in butter, whether salted or unsalted, is not a result of salt fortification. The distinction between salted and unsalted butter relates to sodium content, not iodine. For example, one source suggests a 100g serving of unsalted butter contains around 3.8 µg of iodine, which is about 3% of the daily recommended intake.

The Role of Iodine in Thyroid Health

The small amount of iodine you might get from unsalted butter, combined with other dietary sources, contributes to overall thyroid function. However, relying on butter as a significant source is not recommended. Severe iodine deficiency can lead to goiter (an enlarged thyroid gland) and hypothyroidism, causing symptoms like fatigue, weight gain, and dry skin. For pregnant and lactating women, iodine is especially crucial for proper fetal and infant neurological development.

Comparing Unsalted vs. Salted Butter

While both salted and unsalted butter contain similar trace levels of iodine derived from the cow's milk, their primary difference lies in sodium. Here is a comparison:


Feature	Unsalted Butter	Salted Butter
Iodine Content	Trace amounts, derived from milk.	Trace amounts, derived from milk.
Sodium Content	Very low to none.	Significant amounts of added sodium.
Best For Baking?	Yes, allows precise control of salt level.	No, can disrupt flavor balance due to variable salt levels.
Shelf Life	Shorter due to no added preservative.	Longer due to salt acting as a preservative.
Flavor Profile	Pure, creamy, and delicate.	Salty flavor, can mask other ingredients.

Reliable Sources of Dietary Iodine

For those concerned about their iodine intake, there are more potent and reliable dietary sources than butter. These foods are excellent additions to a balanced diet:

Seafood: Fish like cod and tuna are excellent sources, as are shrimp and seaweed, which is one of the most concentrated sources of iodine.
Eggs: The yolk of an egg is a good source of iodine, with the amount varying based on the chicken's diet.
Dairy Products: Milk, yogurt, and cheese are all good sources of iodine, particularly in countries where cattle feed is fortified. Lactose-free and conventional milks can contain iodine, but plant-based alternatives are not naturally high in it unless fortified.
Iodized Salt: The most common and effective way to ensure adequate intake for most populations is the use of iodized salt. However, excessive salt consumption should be avoided.

Conclusion

In summary, while unsalted butter does have iodine in it, the amount is negligible and should not be considered a significant dietary source. The iodine content in butter is a consequence of the dairy cow's diet and the agricultural processes used, not the addition of salt. The primary nutritional advantage of unsalted butter is its low sodium content, which gives you greater control over seasoning in your cooking and baking. For a reliable intake of iodine, focus on consuming iodine-rich foods like seafood, eggs, and fortified dairy products, or use iodized salt in moderation. For specific dietary concerns, consulting a healthcare provider or a registered dietitian is always recommended. For further reading on the critical role of iodine in human health, consult reliable medical sources like the World Health Organization.

How to Ensure Adequate Iodine Intake

Eat seafood regularly: Incorporate fish and shellfish into your meals a couple of times per week to get a solid dose of iodine.
Use iodized salt: For seasoning at home, switch to iodized salt to ensure you and your family are getting a consistent, small dose of iodine.
Include dairy: Regularly consume milk, yogurt, and cheese, as these products are good sources of iodine in many regions.
Consider supplements: If your dietary intake of iodine is a concern, especially during pregnancy or lactation, speak to your doctor about an iodine supplement.
Be mindful of processed foods: Most processed foods use non-iodized salt, so don't rely on them for your iodine needs.

Frequently Asked Questions

The iodine found in unsalted butter originates from the diet of the dairy cows. When cows eat iodine-enriched feed or graze on iodine-rich pastures, the mineral is transferred to their milk, and subsequently, into the butter made from that milk.

No, the iodine content in both salted and unsalted butter is similar and in trace amounts. The main difference is the sodium. Salted butter has sodium added for flavor and preservation, while unsalted butter does not.

No, you should not rely on unsalted butter for your daily iodine intake. While it contains trace amounts, the quantity is too small to serve as a reliable source. Other foods like seafood, dairy, and iodized salt are much better sources.

Better sources of iodine include seafood (cod, tuna, shrimp, seaweed), eggs, dairy products (milk, yogurt, cheese), and iodized salt.

Yes, because the iodine level in milk can be influenced by the cow's diet and whether they are grazing on pasture, the iodine content can vary seasonally. Studies have found differences in iodine levels based on the time of year.

Iodine is crucial for the thyroid gland to produce hormones that regulate metabolism, growth, and development. It is especially vital during pregnancy for proper fetal brain development.

People choose unsalted butter to have more control over the sodium content of their food, which is particularly important in baking. It also allows the pure, creamy flavor of the butter to stand out.