Even people who get their B12 from animal-based products can still have difficulty absorbing B12
Vegans, vegetarians, people over the age 50, anyone with stomach/bowel issues like chronic gastritis, leaky gut, IBS or celiac, and anyone who regularly takes medications such as Metformin, PPIs (used for GERD), H2 Receptor Antagonists (used for peptic ulcers), or anything that interferes with stomach acid production are actually at risk for vitamin B12 deficiency, and should supplement B12 regularly
The lower the density, the more fragile and delicate your bones get over time
Q6B Specifications: Test Procedures and Acceptance Criteria for Biotechnological/Biological Products
My cat Cleo (who I had to put down after a lengthy illness with advanced renal disease) felt much better after I gave her a B12 shot and even though I knew it wasn't curing her it made me feel better to know that I was at least making her feel better