The Canine Ledger

Balancing Premixes: What They Do, and the Evidence Gap

A premix is meant to complete a homemade recipe. What lab tests of these products found, what nobody has tested yet, and how to use one safely.

Written by thecanineledger

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In 2021, researchers in São Paulo bought every vitamin-mineral supplement they could find on the Brazilian market that was sold to be added to homemade food. There were seven. They analysed each one in a laboratory and worked out what a dog would get at the amount on the label. Their conclusion:

“Most of the vitamin-mineral supplements, in the quantities recommended by the manufacturers, do not guarantee the minimum recommendations of NCR (2006) and FEDIAF (2020) for the following elements: calcium, potassium, magnesium, sodium, phosphorus, selenium, and zinc.” — Zafalon et al., PLOS ONE 2021 (“NCR” is the paper’s typo for NRC, the US National Research Council)

Three of the seven also contained enough mercury to exceed a safe upper limit at the label amount.

While a balancing premix used inside a properly formulated recipe is the mainstream professional approach to homemade food, the evidence that these products do their job is thinner than most owners assume. This page sets out what a premix is, what the testing has found, and the gap nobody has filled.

1. What a premix is, and isn’t

A balancing premix, or vitamin-mineral supplement for homemade diets, is a powder or tablet meant to supply the vitamins and minerals that meat, starch and vegetables can’t. The 2021 study puts the need plainly: “In the formulation of unconventional diets, the use of vitamin-mineral supplementation is a mandatory practice”, because ordinary ingredients alone can’t meet the requirements.

A premix is not a complete food. The same paper notes that under the US feed officials’ definitions, these products are blends meant to be mixed with other ingredients, and “it is not mandatory that they meet the minimum recommended vitamin and mineral requirement” on their own. They are designed to work with a recipe, not instead of one.

A premix is not a multivitamin either. A general multivitamin isn’t designed around the gaps in a dog’s homemade diet. Cailin Heinze, a board-certified veterinary nutritionist, notes that a properly formulated recipe may need “specific veterinary supplements or multiple human supplements (potentially as many as 7-9 different products, depending on the diet ingredients)” (Tufts Petfoodology, 2016, vet-school blog, not peer-reviewed).

→ Why Adding a Multivitamin Doesn’t Fix an Unbalanced Recipe

2. What the testing has found

Two laboratory studies have looked at the products themselves.

Brazil, 2021: seven products, minerals only. At the label amounts, most fell short of minimum recommendations for several minerals. Only one had detectable selenium. The authors’ reading: “if formulated by untrained professionals, even with supplementation, homemade foods may still be nutritionally deficient.” The study did not measure vitamins, and all seven products were Brazilian.

United States, 2026: 70 products, mostly about accuracy. A UC Davis team analysed 70 dog and cat supplements for minerals and heavy metals (Pestalozzi, Fascetti & Larsen, Journal of Animal Physiology and Animal Nutrition 2026). Two findings matter here:

  • “Of 18 supplements with label claims for one or more of the minerals analysed, eight did not meet one or more claims.”
  • Selenium, “an essential nutrient with a narrow margin of safety, was detected in 52 samples … but only declared as an ingredient in 10 products.”

The same team found that “None of the analysed supplements exceeded the MTL for any mineral, suggesting that the risks are low when following label directions.” MTL means the maximum tolerable level. This study is about whether the label is accurate, not about whether a product completes a diet, and the abstract doesn’t say how many of the products were premixes for homemade food. We have read only its abstract.

The 2013 recipe study had already raised the label problem. Its authors noted that “discrepancies between label nutrient concentration and analyzed values in supplement-type products may have also accounted for some differences in these nutrient profiles” (Stockman et al., JAVMA 2013).

Our note: The mercury finding comes from Brazilian products. The US study found no product over the tolerable limit for any mineral.

3. The gap

We found no published study that tests whether a recipe built around a named premix is complete when cooked and analysed, or follows dogs fed one over time. We searched Europe PMC on 4 November 2026. The formulation article reports the same gap.

That is the gap the title means. The products are widely recommended by veterinary nutritionists as part of a formulated recipe, and for good reason: a recipe needs vitamins and minerals that ordinary ingredients can’t supply. But “recommended by professionals” and “tested and shown to work” are different claims. Only the first is established.

What the studies do show is the other side. When a supplement is added to a recipe that nobody formulated around it, the recipe stays unbalanced. The 2021 Brazilian recipe study, using a commercial homemade-diet supplement wherever a recipe was vague, found that “Even when a multi-mineral supplement was added according to the manufacturer’s instructions, the diets remained unbalanced” (Pedrinelli et al., BMC Veterinary Research 2021).

Our note: We searched and found no study, but that doesn’t prove none exists.

→ How to Get a Properly Formulated Recipe (and What It Costs)

4. Two ways to use a premix

The distinction this whole section of the site rests on:

Premix inside a formulated recipePremix added to an unformulated recipe
Who chose itA nutritionist, for that recipeThe owner, or the recipe’s author, generically
AmountCalculated against the rest of the recipeUsually the label amount
EvidenceMainstream professional practice; not trial-tested (§3)The studies above: recipes stayed unbalanced

The left column is a reasonable choice with a known evidence gap. The right column has evidence, and the evidence is against it.

5. If you use one

Use the exact product the recipe names. The recipe’s amounts were calculated for that product’s contents, and labels don’t always match contents (§2). A different brand is a different recipe.

Put it in every time. In a Brazilian survey of owners given formulated recipes, “thirteen of forty six (28·3 %) omitted these supplements from the diets and three of forty six (6·5 %) fed empirical amounts” (Oliveira et al., Journal of Nutritional Science 2014).

Don’t add a multivitamin on top. The premix amount was calculated without it. Doubling up is how nutrients with narrow margins overshoot.

If your dog refuses it, or you can’t get it, ask whoever formulated the recipe for an alternative. Don’t choose one yourself.

We are deliberately not naming a premix or giving an amount. Any product we named would be applied to recipes we haven’t seen, and the evidence to rank them doesn’t exist.

→ How to Follow a Recipe Exactly, and Why Substitutions Aren’t Small

Our note: “A different brand is a different recipe” means a switch changes the nutrient totals in ways the formulator didn’t plan for.

Our note: The 2013 and 2026 studies share authors at UC Davis. The 2013 paper analysed its recipes with software from a company that also sells supplements. We haven’t confirmed whether any author had a business link to it.

6. What we could not verify

Commonly saidWhat we found
“A premix makes any recipe complete”Contradicted. Supplemented but unformulated recipes stayed unbalanced (Pedrinelli 2021).
“Premixes have been proven to work in a formulated recipe”No published test found. It is professional practice, not a tested claim (§3).
“Supplement labels are accurate”Not always. 8 of 18 US products with mineral claims missed at least one (Pestalozzi 2026, abstract).
“Pet supplements contain heavy metals”Some do, at low levels in the US study. Mercury exceeded a safe upper limit in 3 of 7 Brazilian products.
“All premixes are basically the same”We found no comparison of premixes. The Brazilian study anonymised its seven products.

Sources

Always confirm with your vet before acting on anything on this page.