Nutraceuticals in pet food

A long way to go

Over the past decade, we have seen an increase in the range of nutraceuticals used in pet food, partly as the result of humanization and the trend towards human dietary supplements. This is a direct consequence of the evolution of the relationship between owners and their pets. With simple extruded or canned diets no longer adequate for their needs, companion animal owners nowadays search for ‘added value’ in pet food – through the addition of natural ingredients and nutraceuticals, for example. All natural ingredients often imply the addition of nutraceuticals that have a long history of use in human nutrition. Thanks to developments in the pet food industry and improvements in small animal nutrition research, we now have scientific proof of the beneficial effects of many compounds, but there is still a long way to go.

Well-known and novel nutraceuticals

The fatty acid supplements eicosapentaenoic (EPA) and docosahexaenoic (DHA) – from fish oils like salmon and anchovy, for example –  are well documented and used extensively in pet food, mostly in many essential nutritional roles and for their beneficial effects in modulating immune response and delaying the onset and progression of several physiological aging changes. 

Dietary enrichment with a variety of antioxidant cocktails (vitamin C, vitamin E, L-carnitine, lipoic acid, glutathione, etc.) is also considered beneficial in situations where companion animals experience great amounts of stress: pregnancy, lactation, work, exercise, inflammation, ageing and obesity. 

Novel botanical nutraceuticals pose their own challenges when included in pet food. 

Extracts of plants like vaccinium myrtillus (European blueberry), curcuma longa (turmeric), echinacea angustifolia (echinacea) and silybum marianum (milk thistle) contain many compounds with pharmacological and nutraceutical properties. Not only do they represent a challenge for effective dose determination, but also for standardization. 

Propolis is a resinous mixture that honeybees collect from various botanical sources. It has a complex chemical composition with more than 300 active components identified (essential oils, polyphenols, flavonoids, esters, etc.). This material is another promising nutraceutical for companion animals due to its numerous biomedical properties – that have been confirmed in dogs and in humans – including immunomodulating, antioxidative and antimicrobial effects.

A gap in legislation

The term nutraceutical is defined as a ‘nondrug substance that is produced in a purified or extracted form, administered orally to provide agents required for normal body structure and function, with the intent of improving the health and well-being of animals’. However, from a regulatory viewpoint, the term nutraceutical has no legal definition. Consequently, no specific indications can be legally recognized and manufacturers do not have to prove their alleged benefits. Terms like nutraceuticals and functional compounds are used to sell many pet foods without good-quality scientific evidence of health benefits. Many commercial pet foods may contain substances for which safety and benefits have not been established. 

Also, the exact mechanisms by which specific compounds might achieve the claimed effects are not yet understood, making it impossible to define specific ‘dose regimens’ in which these nutrients should be administered under certain conditions. Due to this highlighted lack of pharmacodynamic and pharmacokinetic data, ‘dosing’ is an uncertain and mostly empirical process, even with well-known and long-used substances, let alone novel ingredients. 

Finally, the lack of good-quality clinical studies and systematic reviews on the health effects of nutraceuticals in small animals makes it impossible for veterinary professionals to draw conclusions on the clinical significance of nutraceutical use in companion animals. 

Nutraceuticals in the spotlight

For many years, a complete, balanced, high-quality diet has been the focus of dietary recommendations in companion animal nutrition. However, today’s pet owners are being encouraged to use foods containing functional ingredients in their pets’ diets. The phenomenon occurring in the human supplement market is reflected in pet food and, just as with other health professionals, veterinarians must educate themselves and be cautious, whilst communicating the risks and benefits of certain nutraceuticals to pet owners. 

Also, the pet food industry must be urged to act responsibly by only making health or therapeutic claims that are supported by high-quality scientific evidence.