Iodine - can I give too much?

Yes.

Both iodine deficiency and chronic excessive iodine intake have the potential to affect thyroid function (NRC, 2006; Wedekind et al., 2010).

That said, healthy individuals often tolerate a fairly broad range of iodine intake before problems occur. In humans, some populations consuming traditionally high-seaweed diets appear to tolerate much higher iodine intakes than Western populations, though researchers suspect genetics, adaptation, gut microbiome differences, food combinations and overall diet composition may all play a role (Nagataki, 2008).

However, this does not mean unlimited iodine is harmless, particularly in dogs with pre-existing thyroid disease or thyroid autoimmunity.

Why seaweed products should be dosed properly

One important thing many people don’t realise is that iodine levels in natural seaweeds can vary enormously depending on:

• Species

• Harvest location

• Water conditions

• Season

• Processing methods

This means one seaweed product may naturally contain significantly more iodine than another.

This is also why I generally recommend rotation, moderation and variety in fresh food feeding rather than heavily relying on any one ingredient long-term.

The principle of fresh food feeding is to provide a broad variety of ingredients over time to reduce the risk of underdoing or overdoing any one element.

Cruciferous vegetables and iodine

There are also theories that certain compounds naturally found in cruciferous vegetables may influence iodine uptake by the thyroid gland.

Examples include:

• Broccoli

• Bok choy

• Brussels sprouts

• Cabbage

• Cauliflower

• Kale

• Radish

• Turnips

• Watercress

These vegetables contain compounds such as glucosinolates and isothiocyanates, which may interact with thyroid metabolism when consumed in very large amounts (Farebrother et al., 2018).

For most dogs eating a balanced fresh food diet with reasonable variety, this is generally not something owners need to obsess over.

What about dogs eating fresh food diets?

One challenge with some homemade fresh diets is that iodine can accidentally be overlooked completely.

Dogs eating balanced commercial diets are usually already receiving iodine through their formulated food. However, homemade diets that do not include seafood, seaweed, eggs, dairy or another iodine source may potentially become deficient over time if not properly balanced.

This is why properly balanced fresh feeding matters.

Let’s look at the My Doggie seaweed range

For our Australian followers, my “My Doggie” kelp range uses high-quality seaweed sources that are tested for safety and selected for their intended purpose.

My Doggie Weed

My Doggie Weed is an Ascophyllum nodosum seaweed product traditionally used to support dental health.

Ascophyllum nodosum has been investigated for its potential ability to alter saliva composition and reduce plaque and tartar accumulation in dogs (Gawor et al., 2018).

Dental disease is incredibly common in dogs and may be influenced by many factors including:

• genetics

• mouth structure

• diet

• gut health

• medication use

• saliva composition

• chewing behaviour
  

Some dogs may still require a multi-modal approach to dental care including brushing, dental chews, raw meaty bones (where appropriate), veterinary dentals and/or seaweed supplementation.

My Doggie Weed is sourced from Norway and is generally used daily for at least 2–3 months for best results and continued on to maintain results.

My Doggie King Island Kelp

My Doggie King Island Kelp is sourced from Tasmania.

Kelp contains a wide range of naturally occurring minerals, trace elements, amino acids and bioactive compounds. Many owners use kelp products to support coat condition, pigmentation and overall nutritional diversity within the diet.

Livestock producers have also traditionally used kelp products within feeding systems for many years.

Can both products be used together?

Yes, for most healthy dogs they can.

Some owners may choose to:

• rotate them

• alternate days

• or use both together
  

It really depends on the individual dog and the owner’s goals.

However, if your dog has a medically diagnosed thyroid condition, it is important to discuss iodine intake and seaweed supplementation with your veterinarian first.

Final thoughts

Seaweed can absolutely be a valuable addition to a dog’s diet when used appropriately.

The key is moderation, sensible dosing, variety and understanding that “natural” does not automatically mean unlimited.

Fresh food feeding should never be about megadosing single ingredients. It should be about building a broad, balanced and varied diet over time.

References

Farebrother, J. et al. (2018). Effects of iodine supplementation and excess on thyroid function in humans and animals. Nutrients, 10(11), 1654.

Gawor, J. et al. (2018). Evaluation of a seaweed additive on plaque and calculus accumulation in dogs. Frontiers in Veterinary Science, 5, 168.

Nagataki, S. (2008). The average of dietary iodine intake due to the ingestion of seaweeds is 1.2 mg/day in Japan. Thyroid, 18(6), 667–668.

National Research Council (NRC). (2006). Nutrient Requirements of Dogs and Cats. National Academies Press.

Wedekind, K.J. et al. (2010). Iodine concentration in commercial dog foods and effects of high iodine intake on canine thyroid function. Journal of Animal Physiology and Animal Nutrition, 94(6), 729–739.