Iodine on Keto: Salt, Seafood and Supplementation

The ketogenic diet changes how we source essential nutrients, and iodine is no exception. This trace mineral, vital for thyroid function, often comes from processed foods that keto eliminates. Understanding where to find iodine becomes crucial when cutting carbohydrates.

Why iodine matters on keto

Iodine supports thyroid hormone production, which regulates metabolism, growth and development. A 2017 review in Nutrients noted that low-carb diets may alter thyroid hormone levels, making adequate iodine intake particularly important. While table salt is a common source, many keto followers switch to sea salt or Himalayan pink salt, which contain minimal iodine. keto electrolyte imbalances can occur if intake isn’t monitored.

Best food sources

Seafood provides the most concentrated iodine. A 100g portion of cod contains about 100μg, while prawns offer 40μg. Seaweed is exceptionally rich – just 1g of dried kelp may provide 2000μg. Eggs (25μg each) and dairy (56μg per 100ml of whole milk) contribute too. For those avoiding dairy, Tesco sells tinned sardines at £1.20 per 120g tin, providing around 30μg of iodine.

Supplementation considerations

The NHS recommends 140μg of iodine daily for adults. Some may need supplements, especially if avoiding seafood. Kelp tablets are popular but vary widely in potency – a 2017 study found some contained up to 5000μg per dose. A safer approach is a standard 150μg potassium iodide tablet, available at Boots for £4.50 per month’s supply.

What this means in practice

During British winter months when fresh seafood is less appealing, focus on tinned fish and eggs. Use iodised salt when cooking – Saxa table salt at 35p per 750g provides consistent iodine levels. Those following strict carnivore keto should consider supplements, as muscle meats are poor iodine sources. Always check the keto flu symptoms if adjusting intake.

Frequently asked questions

Can too much iodine be harmful?

Yes. The European Food Safety Authority sets 600μg as the safe upper limit for adults. Excessive intake may cause thyroid dysfunction, particularly in people with existing conditions.

Do I need iodine if I eat seafood twice weekly?

Possibly not. Two 100g portions of white fish plus daily eggs and dairy typically meets requirements. Those avoiding these foods should track intake more carefully.

Is sea salt a good iodine source?

No. While containing trace minerals, most sea salts provide less than 2μg per gram. Iodised table salt remains the most reliable culinary source.

The bottom line

Maintaining iodine on keto requires conscious choices – prioritising seafood, considering iodised salt, and supplementing when necessary. Blood tests can identify deficiencies, though most people manage intake through diet alone. If you’d rather not do the macro maths yourself, the Keto Dieting app does it for you on Google Play and the App Store.

Educational only — not medical advice. This article is for general information. Speak to your GP before changing your diet, especially if you have type 1 or type 2 diabetes, kidney or liver disease, are pregnant or breastfeeding, or take medication for blood pressure, cholesterol, or blood glucose.

References

Kosinski C, Jornayvaz FR (2017). Effects of Ketogenic Diets on Cardiovascular Risk Factors: Evidence from Animal and Human Studies. Nutrients. https://doi.org/10.3390/nu9050517
Paoli A, Rubini A, Volek JS, Grimaldi KA (2013). Beyond weight loss: a review of the therapeutic uses of very-low-carbohydrate (ketogenic) diets. European Journal of Clinical Nutrition. https://doi.org/10.1038/ejcn.2013.116