Why combine a berry with leafy greens?
Bilberry, spinach and kale look like minor ingredients beside collagen, green-lipped mussel or salmon oil. That is partly the point. Not every component of a balanced formula has to be the headline.
These plants contribute different families of naturally occurring compounds. Bilberry is known for dark anthocyanin pigments. Spinach and kale contain carotenoids such as lutein and beta-carotene, as well as polyphenols and micronutrients. Their exact composition varies with cultivar, growing conditions and processing.
Together, they add botanical diversity to FieldStrength Naturals Maintenance — The Original Paste. We describe them as supporting ingredients within a broad formula for normal mobility, recovery, coat and condition—not as a concentrated fruit-and-vegetable treatment.
What does “antioxidant” really mean?
Antioxidant is one of the most overused words in pet marketing. In chemistry, it describes a substance that can inhibit oxidation under particular conditions. In the body, oxidative balance involves networks of enzymes, nutrients and signalling pathways. It is not a simple battle between “good antioxidants” and “bad free radicals”.
A food containing antioxidant compounds does not automatically prevent disease, detoxify the body or slow ageing. Laboratory antioxidant-capacity tests cannot predict a clinical outcome in a dog.
It is fair to say bilberry, spinach and kale supply naturally occurring phytonutrients, including coloured plant compounds studied in relation to oxidative processes. It is not fair to promise that a small dietary inclusion will prevent eye disease, cancer or cognitive decline.
The measured version may be less sensational, but it respects both the science and the owner.
Bilberry and anthocyanins
Bilberry, Vaccinium myrtillus, is related to blueberry. Its deep purple-blue colour comes largely from anthocyanins, a diverse group of polyphenol pigments.
Bilberry is commonly associated with vision stories, some of which trace back to wartime folklore rather than robust clinical proof. Human research on bilberry and eye outcomes is mixed and formulation-specific. Direct canine evidence for bilberry as a stand-alone ingredient is sparse.
That means we should not say bilberry improves night vision or protects a dog’s eyes. Its defensible role in Maintenance — The Original Paste is broader: it contributes a small, distinct range of plant compounds to the whole formula.
The difference between bilberry and blueberry also matters. They are related, not identical, and published data on one cannot always be transferred to the other.
Spinach, kale and carotenoids
Dark leafy vegetables contain carotenoids, including lutein, which has been studied as part of antioxidant combinations in dogs. Some canine research has investigated multi-antioxidant diets or supplement blends and reported changes in immune, cognitive or eye-related measures.
Again, combination evidence cannot prove that spinach or kale alone caused the result. Purified lutein at a measured dose is not the same as a small amount of whole leaf material. A complete commercial diet may also already contain vegetables, carotenoids or added vitamins.
Spinach and kale therefore belong in the formulation as whole-food botanical contributors, not as excuses to attach every lutein study to the product.
Dogs can digest appropriately processed plant material, but they have no nutritional requirement to receive fashionable “superfoods” by name. The overall diet must still be complete and balanced.
Why small supporting ingredients can still matter
Formulation is not a talent contest in which every ingredient has to win. A supporting component may broaden the nutrient and phytonutrient profile, complement other ingredients, contribute flavour or colour, and help create a coherent whole.
The key is proportion. A small inclusion should receive a small claim. We do not want a trace of kale to carry a page of promises.
This principle helps owners read labels more intelligently. Ask whether the claim matches the ingredient’s amount, form and evidence. Be cautious when a product lists many attractive plants but does not explain why they are there.
At FieldStrength Naturals, bilberry, spinach and kale are not positioned as the main joint ingredients. They are part of Original’s broader everyday-support identity.
Food safety and individual dogs
The fact that an ingredient is a familiar food does not mean unlimited quantities are suitable for every dog. Concentrated plant products can affect digestion, and dogs with diagnosed conditions may have specific dietary restrictions.
Spinach contains oxalates, for example, but risk depends on amount, total diet and individual health. A measured inclusion in a formulated complementary feed is different from feeding large daily bowls of spinach. Dogs with urinary disease or prescribed diets should be discussed with the vet before any additional supplement is introduced.
Watch for digestive changes whenever the diet changes. Follow the label and avoid stacking several “greens” powders on top of one another without knowing the total intake.
The wider routine still wins
For coat and condition, adequate protein, essential fatty acids, energy balance and management of skin disease matter. For mobility, body condition, appropriate exercise and veterinary diagnosis matter. For recovery, workload, rest and complete nutrition matter.
Bilberry and leafy greens can sit within that foundation, but they cannot compensate for a deficient diet, excessive weight, overtraining or untreated illness.
This is why Maintenance — The Original Paste is a complementary feed. It is designed to be fed alongside the dog’s normal complete food and daily care.
The practical takeaway
Bilberry, spinach and kale provide naturally occurring anthocyanins, carotenoids and other plant compounds. They add breadth to a multi-ingredient formula, but direct canine clinical evidence for this exact trio is limited.
Their honest value is as supporting players. They do not need “superfood” mythology, detox claims or disease-prevention promises. In Maintenance — The Original Paste, they complement marine and plant oils, green-lipped mussel, turmeric and rosehip as part of broad everyday nutritional support.
See every ingredient in context on our Ingredients page, browse Original in the shop, or read our FAQs.
Sources and further reading
- review of plant-derived phytonutrients in companion-animal nutrition, https://pmc.ncbi.nlm.nih.gov/articles/PMC9291198/
- canine dietary antioxidant study context, https://pubmed.ncbi.nlm.nih.gov/15892572/
- USDA FoodData Central for food composition reference, https://fdc.nal.usda.gov/
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