Rosemary Extract

Herb processors make rosemary extract from dried leaves. A solvent draws out antioxidant compounds, and filtration removes the spent leaf material. The concentrated fraction is sold to food makers as a preservative.^4,5

1. 01 // Source Dried leaves Rosemary leaves are dried and ground so the solvent can reach their antioxidant compounds.
2. 02 // Process Extract compounds Food-grade solvents, including ethanol or acetone, draw antioxidant compounds from the ground leaves.
3. 03 // Process Separate leaves Filtration removes the leaf solids from the liquid that holds the extracted compounds.
4. 04 // Process Remove solvent Evaporation concentrates the extract; further drying or purification depends on the product specification.
5. 05 // Output Rosemary extract The finished ingredient arrives as a powder or liquid for blending into food or fats.

1. 01

   Fats in the food stay fresher

   Carnosic acid and carnosol interrupt the chain reactions that turn fat rancid. EFSA expects the antioxidant effect seen in human food to carry into pet food, but one long kibble storage test was mixed.^1,4,9

   1. Strong
   2. Some
   3. Thin
   4. None
2. 02

   Later blood sugar peak after meals

   In beagles, rosemary extract postponed the post-meal glucose peak at 1,000 mg/kg, over 3 times the 300 mg/kg safe maximum EFSA set for the extracts it assessed. This study did not test typical food levels.^4,12

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

1. 01

   Slows fat oxidation

   Carnosic acid and carnosol interrupt reactions that make fats rancid. The effect in kibble depends on its fats, its recipe and the rest of its preservation system.^1,4

2. 02

   Protects stored food

   Rancidity shortens the time food remains saleable and changes its smell. Protecting fats matters during storage, although one rosemary and tocopherol blend did not reliably extend kibble shelf life.¹

3. 03

   Offers a plant preservative

   Brands use rosemary extract as a plant-sourced antioxidant. It is a concentrated additive used in small amounts, giving manufacturers a preservation option without adding much leaf material or flavor.^4,5,7

How much One supplier projected 500 mg/kg finished food; EFSA judged 300 mg/kg safe for the specific extracts it assessed in dog feed.⁴

1. Brands say

   Rosemary extract keeps kibble fats fresh

   Evidence

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

   Its antioxidant compounds have a food-preservation mechanism. In a 15-month kibble study, a 200 ppm blend of rosemary extract and tocopherols did not consistently delay oxidation or extend shelf life. Rosemary was not tested alone.^1,4,7

2. Brands say

   Its antioxidants protect the dog's cells

   Outruns the evidence

   Evidence

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

   EFSA assessed 2 solvent extracts for use as feed antioxidants, relying on food effects and safety data rather than a dog health trial. Protecting fat in a bag does not demonstrate protection of a dog's cells.⁴

3. Owners say

   Natural rosemary is safer than BHT

   Outruns the evidence

   Evidence

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

   EFSA used a 90-day rat toxicity study to assess the specified rosemary extracts. That assessment did not compare them with BHT in dogs, so it cannot rank the preservatives by safety.⁴

4. Owners say

   Rosemary extract in food triggers seizures

   Outruns the evidence

   Evidence

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

   At its assessed 300 mg/kg dog-feed level, EFSA judged camphor exposure from these extracts below its concern threshold. Rosemary essential oil has a different composition. No controlled dog feeding result here links food-grade extract to seizures.^3,4

1. 2024 // Feeding trial plus lab tests

   Rosemary extract delayed blood sugar peaks in beagles¹²

   Beagles fed 3 extruded diets; the abstract does not give the dog count

   Found. At 1.0 g/kg, rosemary extract did not change total starch digestibility but consistently pushed back the post-meal blood sugar peak on rice, round pea and wrinkled pea diets. It also raised the food's antioxidant capacity.

   What it means. A real effect in dogs, but at over 3 times the 300 mg/kg safe maximum EFSA set for 2 Kemin extracts. This study did not test typical food levels.

2. 2026 // Storage test, 15 months

   Rosemary and vitamin E coating did not reliably slow rancidity¹

   Coated dry dog food in storage; no dogs were fed

   Found. A 200 ppm blend of rosemary extract and mixed tocopherols raised starting vitamin E levels but did not consistently lower rancidity markers or delay failure, defined as a peroxide value of 5 mEq/kg or more.

   What it means. The fat type and kibble recipe drove freshness more than this preservative did. Kemin supplied the antioxidant and the lab analyzes.