Glad to see someone else asking for actual evidence instead of just jumping on the latest trend. What’s often overlooked is that the bioavailability (how well nutrients are absorbed and used) of vitamins and supplements has more to do with the nutrient itself, the matrix it’s in, and your dog’s own digestive system, rather than just whether it comes as a powder, pill, or chew.
Right now, you’ll be hard pressed to find head-to-head peer-reviewed studies comparing powdered dog vitamins to other forms, especially under real-world feeding conditions. Most of what’s out there is extrapolated from human data or lab models. The notion that powders are automatically better absorbed is a hefty claim, but there’s nothing published to actually back it in canines—just lots of marketing.
You’re spot on about manufacturing possibly affecting potency. Water-soluble vitamins (especially B vitamins and vitamin C) degrade much faster with heat, light, and air. If the powder is made by high-heat spray drying or isn’t well-sealed, potency loss is real, unless overages are built into the formula (which isn’t consistently required or regulated). Capsules and tablets often offer a more stable environment—though not perfect.
As for variability in dose and long-term impact, powdered supplements are notorious in the industry for “hot spots” or clumping, which can lead to dose inconsistencies. That’s not a concern you usually have with regulated tablets or chews, since those go through more rigoruos uniformity testing.
The only halfway decent research I’ve seen tends to focus on micronutrient status before and after supplementation, not delivery form. There’s a real lack of longitudinal studies tracking actual clinical outcomes in dogs using powder versus other formats—partly because these are complicated and expensive.
Until someone invests in a blinded, controlled study using bloodwork or tissue levels to measure nutrient uptake over time (and compares it across delivery forms), I remain pretty critical. If someone else has spotted such a study, I’d love to be proven wrong.
In the meantime, I’d focus more on the quality and transparency of the ingredient sourcing, manufacturing practices (like NASC or AAFCO standards), and what your particular dog will reliably eat, rather than claims about powder vs pill. Anyone promising “superior absorption” based only on form is selling sizzle, not steak.