Disclosure: this page is published by Vyarna OÜ, which sells a freeze-dried human milk complement intended to be used alongside breastfeeding and formula, not instead of either.
Your own milk, at the breast or expressed. The only source that maintains your supply [5] [2].
Infant formula. Nutritionally complete, regulated, and governed by strict preparation and timing rules: use within two hours of preparation and one hour of starting a feed; refrigerate unused bottles at once and use within 24 hours; discard leftovers [4].
Donor or provider milk, fresh, frozen or freeze-dried. The FDA's rule applies regardless of form: only from a source that screens donors and takes other safety precautions, and never from individuals or the internet [3]. The AAP notes infectious and contamination risks with informal sharing [1].
Supply follows demand. Any feed given from a source other than your breast, without a breastfeed or expressing session at that time, reduces production [5]. So decide which breastfeeds you are keeping, keep them every day, and express at the times you replace if you want to keep that milk [2]. How you fill the other feeds — formula, donor milk, or both — does not change that arithmetic.
Neither the CDC nor the NHS guidance addresses mixing sources in a single bottle. If you do it, two rules follow from the formula guidance: prepare the formula with water exactly as the tin says before adding anything, so the concentration is right; and apply the formula timing to the whole bottle — one hour from the start of the feed, then discard [4]. Reconstituted freeze-dried milk should be treated like fresh expressed milk once mixed with water, and like formula once combined with it.
Freeze-dried milk is reconstituted with water at the time of use. Use water prepared the same way you would for formula, mix only what you will use, and do not keep reconstituted milk beyond the times you would keep fresh expressed milk. Freeze-drying does not kill microorganisms, so the safety of a freeze-dried source depends on its screening and testing, not on the powder form — see freeze-dried breast milk.
Vyarna's powder is intended as one component of a mixed diet. It is not a substitute for breastfeeding or for formula and we make no claim that it replaces either. Our process has no validated pathogen-inactivation step; safety rests on provider screening and testing. If you are considering it, the questions on the freeze-dried breast milk page are the ones to ask us.
Yes, as separate feeds or in combination, provided each source meets its own safety rules — your own milk stored correctly, formula prepared and timed per CDC guidance, and any donor milk from a screened source as the FDA advises.
Only breastfeeding or expressing maintains supply. Every feed that comes from another source without a corresponding breastfeed or pumping session tells your body to make less. Keep the breastfeeds you want and express at the ones you replace.
Official guidance does not cover mixing. If you do, make formula with water first exactly as instructed, then add other milk, and treat the whole bottle by the strictest rule that applies — the CDC's one-hour limit from the start of a formula feed.