Mineral Forms — the part of the label almost nobody can read
The mineral and vitamin block sits at the bottom of every bag, in the smallest print, and it is where cheap foods and good ones actually separate. It's also the one part of a label that marketing never touches — no bag advertises proteinates on the front.
The one rule that covers most of it
Same mineral, three grades of form. The word after the metal is what you're reading.
CHELATED — best. proteinate · amino acid chelate · amino acid complex · methionine · "yeast" Bound to protein, absorbed like food.
SULFATE — middle. zinc sulfate · ferrous sulfate · manganese sulfate Inorganic, absorbed adequately, mildly pro-oxidant.
OXIDE — worst. zinc oxide · manganese oxide · iron oxide · copper oxide Barely absorbed. Cheapest to buy, closest to useless.
This isn't holistic opinion — it's regulatory. AAFCO forbids copper oxide from counting toward a food's copper minimum at all, citing "very poor apparent digestibility." When a regulator says an ingredient can't count as the nutrient it's named after, that's about as clear as this gets.
On a label: Zinc Proteinate beats Zinc Sulfate beats Zinc Oxide. Every time. Same money to the dog, very different money to the manufacturer.
The minerals, exactly
| Mineral | ✅ Look for | ⚠️ Acceptable | ❌ Avoid |
|---|---|---|---|
| Zinc | zinc proteinate · amino acid chelate · zinc methionine | zinc sulfate | zinc oxide |
| Iron | iron proteinate · amino acid chelate | ferrous sulfate | iron oxide |
| Manganese | manganese proteinate · amino acid chelate | manganese sulfate | manganese oxide |
| Copper | copper proteinate · amino acid chelate — but watch total load | copper sulfate | copper oxide |
| Selenium | selenium yeast / selenomethionine | — | sodium selenite · sodium selenate |
| Magnesium | magnesium proteinate | magnesium sulfate | magnesium oxide |
Selenium has the narrowest margin of any nutrient in the profile — a 0.35 mg/kg minimum against a 2 mg/kg maximum, a ceiling only about six times the floor. Organic selenium (yeast) is both better absorbed and better tolerated than the inorganic salts.
⚠️ Copper is the exception — and it runs backwards
For every other mineral, better absorbed is better. For copper, better absorbed can be the problem.
Copper accumulates in the liver and dogs have no good way to clear the excess. AAFCO deleted the copper maximum in 2007 and never replaced it, so foods moved to highly bioavailable copper forms with no ceiling on the total.
Predisposed breeds: Bedlington Terrier · West Highland White · Doberman · Labrador · Dalmatian. Labradors are the one most owners don't know about.
- Copper-restricted target: under ~1.2 mg per 1,000 kcal
- Liver enzymes are not sensitive in the early stages — a normal chemistry panel does not rule this out
- "Meets AAFCO" tells you nothing about the copper ceiling, because there isn't one
Don't apply "chelated is always better" blindly to copper. In a predisposed dog, total copper load matters more than form.
Vitamins — and the honest part
Most synthetic vitamins are fine. The panic about "40 added vitamins" is mostly misplaced, and overstating it is how you lose credibility with anyone who knows nutrition.
- Vitamin E —
d-alpha-tocopherol(natural) beatsdl-alpha-tocopherol(synthetic). Thedl-is a 50/50 mix of mirror-image molecules and the dog can only use half. One letter, half the vitamin. - Vitamin K3 — menadione. The genuinely contested one. Banned from human OTC supplements in the US, still permitted in animal feed. Depletes glutathione and generates reactive oxygen species — mechanism only. Over 50+ years there is no published report of nutritional toxicity in dogs at pet-food levels. Prefer foods without it; don't claim it's proven to harm dogs.
- Vitamin A — retinyl acetate or palmitate. Fine. Dogs tolerate vitamin A far better than most species. Not the thing to worry about.
- Vitamin D — the one with a genuinely narrow range: 500 IU/kg minimum, 3,000 maximum. Recalls have happened from over-fortification. Cholecalciferol (D3) is the right form.
- Thiamine — mononitrate or hydrochloride, both fine. It's heat-fragile, which is why it's added back.
- Ascorbic acid (C) — dogs make their own. Neither good nor bad; often present as a preservative rather than a nutrient.
- Choline chloride — fine and genuinely needed. Ignore it.
What a long vitamin list actually tells you
Not "these vitamins are dangerous." The honest read:
A 40-item synthetic premix means the ingredients before it didn't deliver the nutrients. Extrusion at high heat destroys them, so they're sprayed back on afterwards. The list is a symptom of the processing, not a poison in itself.
And the reverse trips people up too: a food with no added vitamins and minerals isn't automatically superior — it may simply be incomplete. A fresh food that hits requirements from real ingredients is the goal; a fresh food that misses them is worse than fortified kibble.
Ask "why did this food need 40 additions?" — not "are these 40 additions toxic?"
Reading the label in 60 seconds
- First five ingredients. Named meat first? Or a grain or legume in the top three?
- Named vs generic.
Chicken meal✅ ·Poultry meal/Meat meal/Animal digest❌ — generic means the species isn't disclosed, which means it varies batch to batch. - Fat source and its preservative.
Chicken fat preserved with mixed tocopherols✅ ·preserved with BHA/BHT❌ ·Animal fat❌. - Jump to the mineral block. Count the oxides. Two or more means the manufacturer bought the cheapest forms available — and that tells you what they did everywhere else you can't see.
- Find the salt. Salt sits at roughly 1% of the recipe, so everything listed below it is under 1%. Those superfood berries near the bottom are a sprinkle, not a serving.