Kelp

Brown seaweeds are harvested for food, alginate, fertilizer and animal feed. Fresh fronds hold too much water for convenient storage, so feed processors mill and dry them into seaweed meal.^5,7

1. 01 // Source Coastal seaweed Brown seaweeds used for feed grow on shoreline rocks or in shallow water.
2. 02 // Process Freshly harvested Seaweed for meal is cut fresh because old beach drift has lost minerals and can grow mold.
3. 03 // Process Milled and dried Processors reduce the wet fronds to small pieces, dry them, then mill them again.
4. 04 // Output Seaweed meal The dry meal is stored in sealed bags because it picks up moisture from air.

1. 01

   Supplies iodine

   Kelp contributes iodine to the recipe's mineral mix. Because iodine content differs among seaweeds, the maker needs a measured ingredient and finished food to control the dose.^5,8

2. 02

   Supports dental marketing

   A measured Ascophyllum treat reduced plaque and calculus after professional cleaning in one dog trial. That gives manufacturers a reason to feature kelp, but does not test an undisclosed kibble amount.¹

3. 03

   Delivers naturally chelated minerals

   Seaweed minerals bind to organic compounds rather than sitting as plain salts, a chelated form that 1970s research found more available to livestock than inorganic mineral sources.⁵

4. 04

   Adds a recognizable name

   Suppliers promote kelp for digestion and thyroid function. Those claims make a small seaweed addition marketable even though extra benefit from ordinary kibble has not been shown.^2,9

How much A crossover study fed whole seaweed at 1.5% of food to 10 dogs; that tested amount does not describe typical kibble.²

1. Brands say

   Kelp supplies iodine to dog food

   Evidence

   1. Strong
   2. Some
   3. Thin
   4. None

   Published Ascophyllum composition ranges from 100 to 1,000 mg iodine per kg dry matter. Adding it therefore contributes iodine, but the ingredient name alone cannot tell an owner the finished food's iodine level.⁸

2. Brands say

   Kelp keeps a dog's teeth cleaner

   Outruns the evidence

   Evidence

   1. Strong
   2. Some
   3. Thin
   4. None

   In a manufacturer-funded trial, 60 dogs, half given a measured Ascophyllum treat after dental cleaning, had less plaque and calculus than the placebo half after 90 days. An unspecified amount in regular kibble was not tested.¹

3. Brands say

   Kelp improves gut health as a prebiotic

   Outruns the evidence

   Evidence

   1. Strong
   2. Some
   3. Thin
   4. None

   At 1.5% of food, whole seaweed changed no measured fecal outcome in 10 healthy dogs. In a 9-dog pilot in dogs with chronic gut disease, 4% Ascophyllum raised fecal acetate and fermenting bacteria, but the authors state it failed to improve clinical scores.^2,3

4. Brands say

   Kelp boosts thyroid health

   Outruns the evidence

   Evidence

   1. Strong
   2. Some
   3. Thin
   4. None

   Iodine is necessary for thyroid hormones, but extra kelp has not been shown to improve a healthy dog's thyroid. In an 18-puppy study, high dietary potassium iodide raised TSH and lowered thyroid hormone; kelp was not fed.^4,8,9