Absorption must become a problem as we age. Low b12 is quite common with people as they age. Supplementing is ok as long as you know the reasons WHY it's low. All other factors need addressing.. ferritin, magnesium, potassium and folate levels are all needed to be good in order for the b12 to reach cellular level, not just floating around in the blood giving high levels because of supplementation. That's why so many patients are missing out on injections because they're supplementing and the results are giving false levels
To give a true b12 result there needs to be no supplementing for 4 months