Unless you have a diagnosed vitamin or mineral deficiency, nutritional needs are best met with food, not supplements
The 5mg COA can support that first comparison because its lot matches the page reviewed for this article
: Each Vitamins B12 supplements for men & women contains max 1500 mcg in its most active and pure form : Methylcobalamin
Now, the difficulty with low B12 levels are that yes, they are more likely to be associated with intestinal problems, but we don't always get overt diarrhea or vomiting with those diseases
Obtaining injections outside regulated NHS settings may involve inappropriate dosing, lack of monitoring, non-sterile technique, and unnecessary financial cost without clinical benefit
Healthier Hair, Skin, and Nails Because B12 supports cell regeneration, it may improve the appearance of skin and hair over time