doi: 10.1002/(sici)1098-2825(2000)14:3 3.0.co;2-o 79
2017 Jul 10 [cited 2021 Apr 24];2017
People seek B12 injections for a variety of medical and lifestyle reasons, including: 1

And when youre talking about changes to such major processes as aging, immunity, and sleep, the subsequent effects can be similarly significant for example: Cardiovascular health: In 2004, the American Heart Association described telomere dysfunction as an important factor in the pathogenesis of hypertension, atherosclerosis, and heart failure, a claim that has been borne out in research since.25 26 Poor sleep is also linked to cardiovascular risk factors like high blood pressure and diabetes, so epitalons actions on telomere length and sleep may affect two aspects of healthy heart maintenance.27 Hormone regulation: In addition to in vitro and in vivo studies showing that epitalon may directly improve hormone levels,28 the peptides effect on melatonin production suggests that it can improve the experience of hormone-related processes such as menopause, as melatonin supplementation has demonstrated an ability to alleviate menopausal symptoms.29 Better skin: Skin cells are susceptible to accelerated telomere shortening because of their high rate of replication and exposure to damaging agents.30 Therefore, maintaining telomere length in the skin can slow down the process that results in visible signs of aging, like wrinkles

Free Radical Biology and Medicine 48, 13701381 (2010)
This is likely due to the role of vitamin B12 in energy production and metabolism