Kelp and Iodine for Dogs and Cats
What is Kelp?
Kelp is the largest plant in the seaweed family (considered a brown seaweed), usually found and cultivated as dense forests of kelp usually found 25 to 100 feet under water. Sea kelp is a natural source of vitamins A, B1, B2, C, D and E, as well as minerals including zinc,
Why is Kelp Found in so Many Supplements and Foods for Dogs and Cats?
Seaweeds and kelp are commonly used as multivitamin and mineral sources for pet supplements and foods. This is because they have the broadest spectrum of trace minerals and vitamins of any plant group in the world. The reason for this is that they absorb minerals directly from ocean water, especially the high iodine content, into the plant tissue. This differentiates them from land plants that require root systems to absorb minerals.
Let’s also not forget that companies are in business to make money and you can purchase bulk, high-quality kelp for a couple of dollars per pound or less depending on quantity. Just imagine the cost for which less ethical companies can purchase lower quality bulk kelp. How much are they charging you for that multivitamin for your dog or cat containing kelp?
Dangers of Kelp for Dogs and Cats
Seaweeds contain naturally high levels of iodine and this makes them popular in many supplements. However, many consumers don’t realize that iodine is a micronutrient. This means that it is required in trace amounts for the normal growth and development of living organisms. For example, the FDA’s recommended daily dietary intake for adults is only 150 micrograms!(1)
Unfortunately, the iodine content of kelp and other sea vegetables varies widely, so there is no single dose of kelp that can be recommended. For instance the standard kelp variety Laminaria sp. can have 1,259 mcg/g of iodine but vary 200 mcg between samples. Alternatively, another common species of kelp used in supplements, Ascophyllum nodosum, can have 646 mcg/g of iodine and vary 392 mcg/g! Keep in mind that these figures will be even more concentrated in the dried supplement form. The only way to be sure of the iodine content is to ask the manufacturer about the certificate of analysis (COA) for that particular supplement. You must also determine what encompasses a gram/serving be it 1/2 tsp, 1 tsp etc… Complicating matters is that kelp is commonly included in many pet vitamin supplements, and even pet foods, and the iodine content of these must be determined as well.
Dogs that receive excessively high levels of iodine in their diet can suffer with some of the same symptoms as iodine deficiency, including goiter (an enlarged thyroid gland). High iodine intake can also cause thyroid gland inflammation and thyroid cancer and of course hyperthyroidism in our feline companions.
When adding kelp or other seaweeds to a home-prepared diet, be sure to consider their source because plants grown in polluted waters can be contaminated by heavy metals. As they readily absorb minerals from seawater, so do they absorb toxic heavy metals. In 2007, researchers at the University of California/Davis found that eight out of nine kelp supplements tested contained abnormal levels of arsenic. Look for organic certification on labels and check with manufacturers regarding their testing for heavy metals and other contaminants.
Lastly, there is a concern that kelp supplements can be unpredictable as there are a variety of different types of algae that all come under the name 'kelp', which may affect an animal’s body in different ways.
Should I Add Kelp, or Supplements Containing Kelp, to Kibble or Canned or other Fortified Diets?
There short answer is “NO”. This is because commercial diets already contain sources of iodine such as kelp or iodized salt. As mentioned earlier too much iodine is not good. Some extra iodine found in whole foods like leafy greens or herbs is fine for our pets, but more concentrated sources like kelp should be used cautiously with dogs (even more cautiously in cats). However, continuous daily supplementing with kelp, or kelp products, is not recommended without first making sure extra iodine is in fact needed.
Spirulina Vs. Kelp for Dogs and Cats
Spirulina is a microscopic, blue-green algae that can typically be found in warm, alkaline freshwater in milder climates. Alternatively, kelp thrives in colder, nutrient-rich saltwater. Generally, kelp forests are coastal and require shallow, relatively clear water as it, like spirulina, relies on sunlight to generate food and energy.
Kelp is renowned for providing minerals and vitamins, but especially for its iodine content. However, many may not be aware that spirulina provides a substantially higher mineral and vitamin content. Plus, if you are interested in providing additional protein this is where spirulina shines due to its phycocyanin content (the "blue" in blue/green algae) that makes it a great vegetarian protein source.
It may be interesting to note that since spirulina often grows in shallow waters, it must produce a natural protection from the sun called carotenoids - "nature's sunscreen". If you want to protect yourself or animals from the sun load up on sources of these important antioxidant nutrients.
You may be wondering why kelp is found in so many nutritional supplements and pet foods even though spirulina is higher in most nutrients? The answer is fairly simple - bulk. Kelp has much more "bulk" than spirulina and is therefore a less expensive addition to pet products.
Kelp for Dog’s Dental Health
Kelp contains a polysaccharide constituent with a thick, sticky consistency called alginate. These polysaccharides provide antibacterial activities for the mouth, creating a thin coating of film on the teeth and gums that helps to protect and support healthy bacterial balances in the mouth.
Additionally, recent studies have shown that a strain of beneficial bacteria, called Bacillus lichenformis, resides on the surfaces of kelp. After entering the mouth the Bacillus lichenformis releases an enzyme that can help to break down the bacterial biofilm that causes dental plaque that can lead to tartar.
This can help prevent periodontal disease in our canine and feline companions by helping to prevent plaque staying on teeth long enough for bacteria to grow and secrete acids that damage teeth and possibly leading to tarter that can cause receding gums and bone loss.
The potential issue with using kelp for this purpose is: how much kelp does an animal have to take to enjoy these results? In other paragraphs in this article we provide concerns with the ingestion of too much kelp. Because of our concern for the potential of too much iodine in the diet from the daily use of kelp, we would focus on a whole food diet to avoid all the carbohydrates and starches found in processed kibble pet foods that can damage the teeth of dogs and cats by providing food for plaque growth. We would also consider providing an oral probiotic supplement to provide beneficial bacteria that can out-compete undesirable oral bacteria strains for a healthy, well balanced mouth.
Kelp for Hypothyroidism in Dogs
Thyroid cells are the only cells in the body which can absorb iodine. Their function is to take iodine, such as that found in kelp, and convert it into thyroid hormones: thyroxine (T4) and triiodothyronine (T3). These hormones are then released into the blood stream and transported throughout the body where they control metabolism.
Because of this process it might seem like a good idea to provide kelp to everyone. However, not all cases of hypothyroidism are caused by a deficiency in iodine. And as discussed elsewhere in this article, there are potential consequences associated with providing too much iodine. In addition, iodine deficiency is an uncommon condition in our modern society because of the availability of fortified, processed foods and iodized salt.
Other causes of hypothyroidism in our canine friends include vaccines that can damage thyroid tissue as part of the immune response caused by the vaccination. The more vaccinations, the bigger the chance your dog's thyroid tissue gets damaged. Abnormal growths in the thyroid can damage healthy tissue, and problems in the pituitary gland that controls the thyroid gland can impact the production of thyroid hormones. So, just giving kelp, or more iodine, may not be the answer. If you suspect, or want to rule out, iodine deficiency as a cause for your dog's hypothyroidism you should test for this nutrient before randomly providing kelp.
Dangers of Kelp for Hyperthyroidism in Cats
At the North American Veterinary Conference 2005 Dr. P. Schenck showed studies which suggested that cats fed a canned food diet were more at risk from hyperthyroidism. This may be because of chemical substances in the lining of the can, or because continuously feeding this diet results in excessive iodine levels because cat food commonly relies on fish as the protein source. In addition, more and more pet food companies are relying on kelp to provide minerals for their food, treats and supplements.
As mentioned previously, kelp can have extremely varied levels of iodine and powdered kelp can be a very concentrated source of this micronutrient making it very easy for over-supplementation. This can be dangerous for cats susceptible to hyperthyroidism because consuming too much iodine (either from food or supplements) can cause the thyroid gland to overproduce thyroid hormones.(2)
Contaminants in Kelp
Kelp is commonly used as a mineral source in pet supplements and foods because of its broad spectrum of trace minerals and vitamins. The reason for this is that kelp very efficiently absorbs minerals directly from ocean water into its tissue.
However, this efficient process can also create toxicity concerns, especially when the water source is highly polluted as are our oceans. Sea kelp grown in polluted waters will absorb toxic heavy metals, like arsenic(3), which if ingested can cause major health problems. Alarmingly, Scientists at California State University, Long Beach found that radioactive iodine from the Fukushima nuclear reactor contaminated kelp near Orange County a month after the accident. Luckily, iodine 131’s short half-life of 8 days left it undetectable in the kelp a month later.
This concern has lead to recommendations that kelp not be ingested if an individual is pregnant or breastfeeding, or by children or people with health issues, especially liver or kidney problems. This most certainly would apply to our dogs and cats as well.
When purchasing kelp, obtain that which is certified organic. These kelp products are obtained from waters considered to be cleaner and meet certain guidelines to obtain this certification. Does this mean that this kelp is free of heavy metal contaminants? Probably not, but contaminant levels should be much lower in these kelp products.
How Much Iodine is in Kelp for My Dog or Cat?
The National Research Council (NRC) recommends about 100 mcg iodine daily for a dog weighing 10 pounds, 300 mcg for a 50-pound dog, and 500 mcg for a 100-pound dog.
Unfortunately, the iodine content of kelp and other sea vegetables varies widely, so there is no single dose of kelp that can be recommended. For instance the standard kelp variety Laminaria sp. can have 1,259 mcg/g of iodine but vary 200 mcg between samples. Alternatively, another common species of kelp used in supplements, Ascophyllum nodosum, can have 646 mcg/g of iodine and vary 392 mcg/g! Keep in mind that these figures will be even more concentrated in the dried supplement form. The only way to be sure of the iodine content is to ask the manufacturer about the certificate of analysis (COA) for that particular supplement. You must also determine what encompasses a gram/serving be it 1/2 tsp, 1 tsp etc… Complicating matters is that kelp is commonly included in many pet vitamin supplements, and even pet foods, and the iodine content of these must be determined as well.
Can too Much Kelp or Iodine Harm My Pet’s Thyroid Gland?
Yes, consuming too much iodine (either from food or supplements) can cause the thyroid gland to overproduce thyroid hormones resulting in a condition called hyperthyroidism more commonly found in our feline companion animals.
In general for dogs, cats and even people, getting high levels of iodine can cause some of the same symptoms as iodine deficiency, including goiter (an enlarged thyroid gland). High iodine intakes can also cause inflammation of thyroid tissue and possibly even thyroid cancer.(4) Thyroid dysfunction caused by excess iodine can be either transient or permanent.(5)
Resources
Puotinen, CJ, & Straus, M. (August 2012). Hypothyroidism in dogs. Retrieved from: http://dogaware.com/articles/wdjhypothyroid.html<>/p>
Kelp: boost your dog naturally. Retrieved from: https://www.ziwipets.com/blog/ingredients/kelp-boost-your-dog-naturally
Iodine. Retrieved from: https://ods.od.nih.gov/factsheets/Iodine-Consumer/
Sea kelp: super supplement or health risk? (December 19, 2013). Retrieved from: https://www.cosmopolitan.com/uk/body/diet-nutrition/a24605/sea-kelp-benefits-7987/
Wilde, M. (January 2015). How much iodine is in seaweed? Retrieved from: https://napiers.net/how-much-iodine-is-there-in-seaweed.html
Lane, C. (January 5, 2017). Kelp for dogs - the good, the bad and the mumbo jumbo. Retrieved from: https://www.thepossiblecanine.com/kelp-for-dogs
Appleby, M. (December 16, 2018). Kelp vs spirulina. Retrieved from: https://healthyeating.sfgate.com/kelp-vs-spirulina-7607.html
(October 5, 2019). Kelp is key for good dental health in dogs and cats. Retrieved from: https://www.holisticpetinfo.com/Kelp-Is-Key-for-Good-Dental-Health-in-Dogs-Cats_b_28.html
How your thyroid works. Retrieved from: https://www.endocrineweb.com/conditions/thyroid/how-your-thyroid-works
Carson, A. (April 2, 2012). Fukushima contaminants found in California kelp one month later. Retrieved from: https://www.fondriest.com/news/fukushima-contaminants-found-in-california-kelp-one-month-later.htm