Complementary food

A complementary food is one that is rich in certain nutrients but, by design, only meets an animal's daily needs when it is combined with other foods, so it cannot serve as the sole ration. The category is defined in EU law under Regulation (EC) 767/2009 and sits in direct contrast to a [complete food](/glossary/complete-food), which is balanced on its own (Regulation (EC) 767/2009). The reason this matters to premium buyers is that the label rarely shouts about it: many appealing products fall here without obvious signposting, including most [treats](/glossary/treat), a large number of artisanal and gourmet wet recipes, gravies, and meal toppers. A telling fact is that a pouch can read like a luxurious main course and still be complementary, meaning it would slowly starve an animal of key nutrients if fed alone day after day. The practical rule is simple: check whether the packaging says complete or complementary before deciding what role a product plays. A complementary food can be perfectly good when used as intended, for example mixing a high-quality wet topper into a complete dry diet, but it should be counted within the daily [ration](/glossary/ration) so that total energy stays controlled. In the US the same logic applies through the AAFCO framework, where products lacking a complete-and-balanced [nutritional adequacy statement](/glossary/nutritional-adequacy-statement) are typically labelled for intermittent or supplemental feeding only. See the [Petipedia glossary](/glossary) for the complete versus complementary comparison in full.

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