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Linoleic to alpha-linolenic acid ratio (LA:ALA) in dog and cat diets

A short guide to the role of Linoleic to alpha-linolenic acid ratio (LA:ALA) in dog and cat nutrition.

Linoleic to alpha-linolenic acid ratio (LA:ALA)

Linoleic acid (LA, omega-6) and alpha-linolenic acid (ALA, omega-3) are the two "parent" polyunsaturated fatty acids that compete for the same enzymes that desaturate and elongate the chain. That's why, when assessing a diet, their mutual proportion counts, not the amount of LA alone. In the diet of land animals LA clearly dominates, so without correction the LA:ALA ratio easily becomes extremely tilted towards omega-6.

Why the proportion, not the amount alone

The more LA in the diet, the more strongly it blocks the conversion of ALA — and that conversion is weak anyway: in the dog only a few percent of ALA is converted to EPA, and to DHA practically a negligible amount; the cat has this ability at nearly zero [1] [2]. Diets rich in poultry and skin supply plenty of LA, which additionally stifles the already inefficient conversion of ALA [3]. The practical conclusion: the value of LA or ALA alone cannot be sensibly interpreted in isolation from the broader omega-6:omega-3 ratio.

What it means in practice

  • Extremely high LA:ALA (lots of omega-6, trace ALA) — typical for a poultry-pork diet, shifts the profile towards a pro-inflammatory state [2]. But don't try to fix it with flaxseed oil — ALA is 10–20 times less effective than sardines, sprats or algal oil, and in the cat it is outright worthless [2] [4]. The sensible correction is adding ready-made EPA and DHA from marine fish, not boosting ALA. More in the article EPA and DHA.
  • Low LA — in a raw diet with any animal fat practically unattainable; if the calculator shows a deficiency, the problem is too lean a diet overall, not a lack of LA itself [1]. Rotating meat species (less poultry, more beef/lamb) is the simplest way to a better profile. More in the articles Linoleic acid and Alpha-linolenic acid.
  • If the diet includes fish or fish/algal oil 2–3× a week, you can in practice let go of the LA:ALA ratio itself — the balance of LA, EPA and DHA is more important then [2]. Any larger PUFA supply also raises the requirement for vitamin E [1].

Sources

  1. National Research Council (2006). Nutrient Requirements of Dogs and Cats. National Academies Press. https://nap.nationalacademies.org/catalog/10668/nutrient-requirements-of-dogs-and-cats
  2. Burron S, Richards T, et al. (2024). The balance of n-6 and n-3 fatty acids in canine, feline, and equine nutrition: exploring sources and the significance of alpha-linolenic acid. J Anim Sci. https://doi.org/10.1093/jas/skae143
  3. Bauer JE, Dunbar BL, Bigley KE (1998). Dietary flaxseed in dogs results in differential transport and metabolism of (n-3) polyunsaturated fatty acids. https://doi.org/10.1093/jn/128.12.2641S
  4. Bauer JE (2016). The essential nature of dietary omega-3 fatty acids in dogs. JAVMA 249(11):1267. https://doi.org/10.2460/javma.249.11.1267