Giving B12 shots to milk-making cows doesn’t make the milk any better at delivering B12 to pigs’ guts — the pigs absorb about the same amount either way.

Pigs absorb way more vitamin B12 from cow's milk than from a lab-made version, and they don’t absorb the lab version at all — their bodies only seem to take in the natural kind.

In pigs, heating or filtering cow's milk doesn't change how well vitamin B12 gets absorbed in the gut — it's the same whether the milk is raw, pasteurized, or microfiltered.

When you eat fish, sheep meat, or chicken, your body absorbs vitamin B12 from them at different rates—fish gives you about 42% of the B12, sheep meat gives you 56% to 89%, and chicken gives you 61% to 66%, so not all meats give you the same amount of this important vitamin.