Metformin Side Effects & Health Impacts

B12 depletion impairs DNA synthesis in rapidly dividing cells, leading to macrocytic (megaloblastic) anemia, fatigue, pallor and, in severe cases, pancytopenia.

Clinical reviews identify vitamin B12 deficiency as a common cause of megaloblastic anemia; hematologic abnormalities often improve with replacement, underscoring the hematopoietic consequences of depletion.

Langan RC, Zawistoski KJ. Update on vitamin B12 deficiency. Am Fam Physician. 2017;96(6):384-389.; Green R. Vitamin B12 deficiency from the perspective of a practicing hematologist. Blood. 2017;129(19):2603-2611.

Sustained B12 deficiency damages myelin in the peripheral and central nervous system, resulting in paresthesias, gait disturbance, impaired proprioception and cognitive or mood changes.

Systematic reviews and observational data show associations between low B12 levels and peripheral neuropathy, myelopathy and cognitive impairment; neurological manifestations may become irreversible if depletion is prolonged.

Badar A et al. Neuropsychiatric disorders associated with vitamin B12 deficiency: an updated review. Cureus. 2022;14(2):e22052.; Dekker MJHJ et al. Vitamin B12 deficiency-induced neuropathy and cognitive impairment. J Nutr Gerontol Geriatr. 2024;43(1):1-15.; NHS. Vitamin B12 or folate deficiency anaemia – complications. 2017.

Lower CoQ10 impairs mitochondrial ATP production in skeletal muscle, which can manifest as fatigue, myalgias and weakness, particularly in patients taking statins that further reduce endogenous CoQ10 levels.

Randomized trials and meta-analyses in statin-treated patients have shown that CoQ10 depletion and/or low circulating levels are associated with muscle symptoms, while supplementation has produced mixed but suggestive improvements in statin-associated myalgia and muscle pain severity.

Caso G et al. Effect of coenzyme Q10 on myopathic symptoms in patients treated with statins. Am J Cardiol. 2007;99(10):1409-1412.; Qu H et al. Effects of coenzyme Q10 on statin-induced myopathy: a meta-analysis of randomized controlled trials. J Am Heart Assoc. 2018;7(19):e009835.; Parker BA et al. A randomized trial of coenzyme Q10 in patients with confirmed statin myopathy. Atherosclerosis. 2013;231(1):282-287.

CoQ10 is a key electron carrier in the mitochondrial respiratory chain and an important lipid-soluble antioxidant; depletion reduces cellular energy output and increases susceptibility of membranes and LDL particles to oxidative damage.

Mechanistic and clinical studies link lower CoQ10 status with impaired oxidative phosphorylation and higher markers of oxidative stress, particularly in tissues with high metabolic demand such as myocardium and skeletal muscle.

Littarru GP, Tiano L. Clinical aspects of coenzyme Q10: cardiology and beyond. Antioxid Redox Signal. 2010;12(10):1535-1546.; Mancini A et al. Coenzyme Q10: clinical applications in cardiovascular diseases. Antioxidants (Basel). 2020;9(4):341.

Folate depletion impairs one-carbon metabolism, leading to elevated homocysteine, endothelial dysfunction and potential promotion of atherothrombotic events.

Meta-analyses of randomized trials show that folic acid supplementation lowers homocysteine and modestly reduces stroke and overall cardiovascular disease risk in some populations, especially where baseline folate status is low, highlighting the adverse vascular profile of folate deficiency.

Li Y et al. Folic acid supplementation and the risk of cardiovascular diseases: a meta-analysis of randomized controlled trials. J Am Heart Assoc. 2016;5(8):e003768.; Wang Y et al. The effect of folic acid in patients with cardiovascular disease: a meta-analysis. Medicine (Baltimore). 2019;98(38):e17106.; Miller ER et al. Meta-analysis of folic acid supplementation trials on risk of cardiovascular disease. Am J Cardiol. 2010;106(4):517-527.

Folate deficiency impairs DNA synthesis, resulting in ineffective erythropoiesis, macrocytosis and megaloblastic anemia, often accompanied by glossitis, mucosal changes and fatigue.

Hematology and nutrition reviews describe folate deficiency as a classic cause of megaloblastic anemia and mucosal abnormalities, frequently exacerbated by medications that antagonize folate metabolism.

O’Leary F, Samman S. Vitamin B12 in health and disease. Nutrients. 2010;2(3):299-316. (discussion of folate and B12 in megaloblastic anemia); Lešić S et al. The impact of vitamin deficiencies on oral manifestations. Dent J (Basel). 2024;12(4):109.