Flaxseed in Dog Food

Flaxseeds in dog food provide lots of short-chain omega-3 fatty acids and some protein and fiber. They are a good option among vegetable oils but not as beneficial as marine oils.

Contents

What is Flaxseed?

Flaxseed (Linum usitatissimum) is a flowering plant that is grown for its oil seeds or fiber, which is used to make linen.

The seeds are small, flat, and oval-shaped with a nutty flavor. Flax varieties produce either golden linseed or brown linseed.

Flaxseed in dog food is included as whole or ground seeds, flaxseed oil, and rarely as flaxseed meal.

The composition of flaxseeds can vary based on variety or environmental factors, but whole flax seeds are on average 42% fat, 27% fiber, and 18% protein^[8].

They are a very rich source of alpha-linolenic acid (ALA), a short-chain omega-3 fatty acid.

Flax seeds also contain several B vitamins, and dietary minerals, especially thiamine, magnesium, and phosphorus.

Flaxseed also contains compounds called lignans, which are precursors to phytoestrogens, which may affect fat metabolism.

However, because it is so high in polyunsaturated fat, ground flaxseed and flaxseed oil may go rancid when left exposed to air.

Raw flaxseeds also contain potentially toxic or anti-nutritional compounds such as cyanogenic glycosides or tannins^[4].

But heat treatment during dog food processing removes most of these undesired compounds, so that is not a reason for concern^[4].

Flax seeds are known to provide lots of soluble fibers that can absorb large quantities of water.

This mucilage can increase satiety, delay gastric emptying, decrease fat digestibility, or lower blood glucose levels

Some dog owners feed flaxseeds as a dietary supplement.

But intake of large amounts can act as a laxative or worsen constipation if not combined with drinking enough water.

Dry foods may contain up to 10% flaxseed or 4% flaxseed oil^[3].

Flaxseed oil is the best source of fatty acids, obviously. But whole or ground seeds can additionally add some protein and fiber.

Whole seeds are more stable against oxidation but less digestible. Grinding seeds or extracting their oil enhances fatty acid availability but simultaneously makes them more sensitive to rancidity.

Flaxseeds in dog food are a very common ingredient. They mainly provide omega-3 fatty acids.

For dog food products […] flaxseed, peas and carrots are the top three most commonly used plant ingredients
Pet Food Production and Ingredient Analysis 2020^[1]

Many dog foods do not contain sufficient amounts of omega-3 fatty acids, which are nowadays thought of as essential nutrients.

The intake of omega-3 fatty acids is linked to numerous health benefits and can improve coat and skin conditions.

But flaxseed mainly contains alpha-linolenic acid (ALA).

However, ALA provides only indirect health benefits, it has to be converted to longer-chain omega-3s such as EPA and DHA.

Long-chain omega-3 fatty acids such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are known to reduce oxidative stress and can improve coat and skin health in dogs.

EPA and DHA come mainly from fish, krill or microalgae, so they are sometimes called marine omega-3s.

ALA is a short-chain omega-3 fatty acid and the most common omega-3 in vegetable oils. But it is often burned for energy since conversion into EPA and DHA is so very limited in mammals.

Dogs don’t even seem to convert ALA into DHA but only into EPA.

Dogs can not convert ALA into DHA which is important for canine retina and brain functionality. They can, however, turn ALA into EPA but are not very efficient at doing so^[5].

So while flaxseeds are a rich source of omega-3 fatty acids, they don’t provide the most beneficial type of omega-3s.

A 2023 study found that ALA from flaxseed meal was not an effective precursor for EPA + DHA, especially when compared to marine-sourced ingredients^[5].

Flaxseed is considered a fat source but also has a high protein content.

Flaxseed is lower in saturated fatty acids compared with oils from soybeans or corn, which are also lower in omega-3 fats and higher in omega-6 linoleic acids.

Some anecdotal claims suggest that flaxseed causes food allergies in dogs. But canine food allergy is rare, and flaxseed is not a common allergen in dogs^[3].

In summary, flaxseed is a good source of omega-3 fatty acids, but it is not as effective and beneficial as marine oils that directly provide essential long-chain EPA and DHA.

Flaxseed Oil

Flaxseed oil is obtained from linseeds by pressing, sometimes followed by solvent extraction.

Flaxseed oil in dog food provides an unusually large amount of α-linolenic acid^[3]. The oil contains about 50-60% α-linolenic acid (omega-3), 20% oleic acid, and 10-20% linoleic acid (omega-6).

Flaxseed oil has a favorable omega-6:omega-3 ratio^[2].

Oil from the seeds is often used as an alternative to fish oil because it is easier to source and fish oil production for omega-3s in pet foods is not as environmentally sustainable^[2].

Unfortunately, linseed in dog food is not as good a source of long-chain omega-3s such as DHA or EPA when compared to marine oils^[5].

Nevertheless, flaxseed is a better option among vegetable oils and can be used to fortify foods with some omega-3 fatty acids.

Flaxseed Meal

Flaxseed meal is made from the ground seed cake that remains after oil extraction by mechanical or solvent extraction.

Flax seed meal in dog food can not exceed 10% fiber^[7]. It also contains some residual oil, depending on the extraction method.

But flaxseed meal made from defatted seeds is a protein-rich ingredient with an amino acid composition similar to soybeans. It is often used in livestock nutrition but rarely used in pet food^[3].

Flaxseed is a by-product of flaxseed oil production and a cheaper substitute for whole flax seeds.

What is Flaxseed?