These “good fats” must come from the diet and are essential for health.
All mammals need omega-3 and omega-6 fatty acids in their diet. The ratio between them is also important. Like the modern human diet, canine and many equine diets are heavy on omega-6. If you have frequent online equine presence you have probably heard of Chia seeds as the next latest and greatest equine supplement, a good source of omega-3 fatty acids. Fish oil has also been promoted as a superior omega-3 source for horses and is touted as good for dogs. How do you choose?
The horse’s natural diet, grass, has an omega-3 to omega-6 fatty acid ratio of around 4:1. The same is true for browse foods the horse might eat, like leaves and buds. When grass is cut, dried and baled as hay, the fragile omega-3 fatty acids are lost. Other common diet elements like grains, brans and vegetable oils, are very high in omega-6 fatty acids, all leading to a deficiency of omega-3.
Dogs evolved with a very different diet than they have now. The meat of grass-eating animals has an omega-3:omega-6 ratio of about 1:6. However, the advent of modern high grain feeding for animals and birds in heavy production situations has led to ratios as low as 1:20. Plant sources of omega-3 provide alpha-linolenic acid while animal sources also contain some DHA and EPA omega-3, which are the most active forms.
Flax seeds, and flax seed oil, with an omega-3 to omega-6 ratio of 4:1 have been the traditional fatty acid supplement for horses. The omega-3 linolenic acid and omega-6 linoleic acid cannot be manufactured in the body and have to come from the diet. Omega-3 and -6 fatty acids are also essential for dogs.
Compared to flax, Chia has a similar to somewhat lower ratio of omega-3:6, depending on where you are reading, and is also a reasonable source of omega-3 but there are claims by some it is superior. It’s not. It has been claimed Chia is more convenient because it doesn’t require grinding but recent research has found this is not true – it also needs to be ground.
It is said flax seed can cause cyanide poisoning because it contains cyanogenic glycosides. Cyanogenic glycosides are common in plants with over 2500 species containing them. Some frequently consumed human foods like lima beans and almonds contain higher levels than flax seed. Green flax seeds have higher levels and should be avoided but there has never been a report of cyanide toxicity from flax in any species.
Chia is claimed to have a higher protein level than flax seeds but in reality they are virtually identical. The protein in both types of seeds is very high quality and contains all the essential amino acids.
Estrogenic lignans in flax seed are said to be a negative. It’s true the lignans can bind to estrogen receptors but they do not have any estrogen-like effects. In fact, they can protect against high levels of estrogen by shielding the receptors and are classified as anti-estrogen. Oats and barley contain the same lignans.
The oils of some fish are very high in omega-3 fatty acids, including DHA and EPA, and they cause higher blood levels of DHA and EPA than feeding plant fats high in their precursor alpha-linolenic acid. Fish oil is obviously not a natural part of the equine diet – nor of dogs for that matter but they would normally get DHA and EPA in their diet unlike horses.
Why feed fatty acids? The immune system uses them to synthesize signalling molecules. The omega-6 fatty acids predominately are made into inflammatory signals while the omega-3 are antiinflammatory. Both are required for robust immune reactions. Omega-3s are also important in brain development, behavior and eye health. Horses not on fresh pasture will have a dietary deficiency of omega-3. Most dogs will as well unless they are on diets of grass fed animals and fatty fish.
Which to use? DHA and EPA from fish oil bypass the normal pathways for their production from the plant omega-3 alpha-linolenic acid and are found in fish and meat fat. Fish oil should only be used in recommended amounts to avoid interfering with normal immune function but is certainly useful, especially in dogs, for balancing out the high omega-6 diet. Judicious amounts may also be helpful in horses but since it is foreign to their normal diet it is wise to primarily rely on flax seed for omega-3 supplementation. Chia is fine too but there is no truth to the idea it is superior – and it costs more.
Eleanor Kellon, VMD