DBI Side Effects & Health Impacts

Low folate status contributes to elevated homocysteine, a metabolite that has been associated with endothelial dysfunction, arterial stiffness, and a higher risk of stroke and coronary heart disease. Large observational studies consistently show that individuals with higher homocysteine levels have greater rates of cardiovascular events, and folate intake is one of the key nutritional determinants of homocysteine. Clinically, folic acid supplementation (often combined with vitamins B6 and B12) can lower homocysteine and appears to modestly reduce stroke risk in some populations, making the identification and correction of folate deficiency an important part of broader cardiovascular risk reduction.

Research: Yanping Li, et al. Folic Acid Supplementation and the Risk of Cardiovascular Diseases: A Meta‐Analysis of Randomized Controlled Trials. Journal of the American Heart Association. Volume 5, Number 8. August 15 2016.Yi X, Zhou Y, Jiang D, Li X, Guo Y, Jiang X. Efficacy of folic acid supplementation on endothelial function and plasma homocysteine concentration in coronary artery disease: A meta-analysis of randomized controlled trials. Exp Ther Med. 2014 May;7(5):1100-1110. Kaye AD, Jeha GM, Pham AD, Fuller MC, Lerner ZI, Sibley GT, Cornett EM, Urits I, Viswanath O, Kevil CG. Folic Acid Supplementation in Patients with Elevated Homocysteine Levels. Adv Ther. 2020 Oct;37(10):4149-4164. Lonn E, Yusuf S, Arnold MJ, Sheridan P, Pogue J, Micks M, McQueen MJ, Probstfield J, Fodor G, Held C, Genest J Jr; Heart Outcomes Prevention Evaluation (HOPE) 2 Investigators. Homocysteine lowering with folic acid and B vitamins in vascular disease. N Engl J Med. 2006 Apr 13;354(15):1567-77. Wald DS, Bishop L, Wald NJ, et al. Randomized Trial of Folic Acid Supplementation and Serum Homocysteine Levels. Arch Intern Med. 2001;161(5):695–700.

Folate deficiency in the periconceptional period significantly increases the risk of neural tube defects (NTDs) such as spina bifida and anencephaly, because adequate folate is required for proper closure of the embryonic neural tube in the first month of pregnancy. Large observational datasets and randomized trials have shown that appropriate folic acid supplementation before conception and in early pregnancy can reduce NTD risk by roughly 50–70% in the general population, with even greater risk reduction in women with a prior NTD‑affected pregnancy. The practical implication is that all women of childbearing potential, not just those actively planning pregnancy, are typically advised to maintain adequate daily folic acid intake so that red‑cell folate stores are sufficient well before conception occurs.

Research: Viswanathan M, Urrutia RP, Hudson KN, Middleton JC, Kahwati LC. Folic Acid Supplementation to Prevent Neural Tube Defects: Updated Evidence Report and Systematic Review for the US Preventive Services Task Force. JAMA. 2023;330(5):460–466. Wald NJ. Folic acid and neural tube defects: Discovery, debate and the need for policy change. J Med Screen. 2022 Sep;29(3):138-146. Mathieu d'Argent E, Ravel C, Rousseau A, Morcel K, Massin N, Sussfeld J, Simon T, Antoine JM, Mandelbaume J, Daraï E, Kolanska K. High-Dose Supplementation of Folic Acid in Infertile Men Improves IVF-ICSI Outcomes: A Randomized Controlled Trial (FOLFIV Trial). J Clin Med. 2021 Apr 26;10(9):1876. Jadhav, S. N., & Pitale, D. L. (2020). Effectiveness of folic acid in unexplained infertility. International Journal of Reproduction, Contraception, Obstetrics and Gynecology, 9(9), 3780–3783.

CoQ10 deficiency can present in infancy as a severe encephalomyopathy or multisystemic mitochondrial disease, with features such as hypotonia, developmental delay, intractable seizures, lactic acidosis, cardiomyopathy, and failure to thrive. Reports of infantile‑onset multisystem CoQ10 deficiency describe very early presentations, sometimes in the neonatal period, with rapid neurologic deterioration and involvement of brain, heart, kidney, and liver, and many affected children die in the first months or years of life despite intensive care. The important clinical point is that, although outcomes are often poor in the most severe cases, some infants and young children show neurologic improvement or stabilization when CoQ10 deficiency is recognized early and high‑dose CoQ10 supplementation is started promptly, which is why this diagnosis is considered a treatable cause of infantile encephalomyopathy

Research: Quinzii CM, Hirano M. Coenzyme Q and mitochondrial disease. Dev Disabil Res Rev. 2010;16(2):183-8. Chen RS, Huang CC, Chu NS. Coenzyme Q10 treatment in mitochondrial encephalomyopathies. Short-term double-blind, crossover study. Eur Neurol. 1997;37(4):212-8. Boitier E, Degoul F, Desguerre I, Charpentier C, François D, Ponsot G, Diry M, Rustin P, Marsac C. A case of mitochondrial encephalomyopathy associated with a muscle coenzyme Q10 deficiency. J Neurol Sci. 1998;156(1):41-6. Sobreira C, Hirano M, Shanske S, Keller RK, Haller RG, Davidson E, Santorelli FM, Miranda AF, Bonilla E, Mojon DS, Barreira AA, King MP, DiMauro S. Mitochondrial encephalomyopathy with coenzyme Q10 deficiency. Neurology. 1997 May;48(5):1238-43.

CoQ10 is a key mitochondrial antioxidant, and circulating levels are often reduced in people with chronic kidney disease and chronic heart failure, where deficiency is linked to greater oxidative stress and poorer organ function. In CKD cohorts, lower CoQ10 levels correlate with increased cardiovascular risk, and supplementation has been reported to improve markers such as proteinuria, mitochondrial function, and oxidative stress, with some studies suggesting better preservation of kidney function over time. In patients with chronic heart failure, trials such as Q-SYMBIO have shown that CoQ10 supplementation can improve cardiac function parameters and significantly reduce major adverse cardiovascular events, cardiovascular mortality, and heart‑failure–related hospitalizations.

Research: Xu Y, Liu J, Han E, Wang Y, Gao J. Efficacy of coenzyme Q10 in patients with chronic kidney disease: protocol for a systematic review. BMJ Open. 2019 May 14;9(5):e029053. Bakhshayeshkaram M, Lankarani KB, Mirhosseini N, Tabrizi R, Akbari M, Dabbaghmanesh MH, Asemi Z. The Effects of Coenzyme Q10 Supplementation on Metabolic Profiles of Patients with Chronic Kidney Disease: A Systematic Review and Meta-analysis of Randomized Controlled Trials. Curr Pharm Des. 2018;24(31):3710-3723. Di Lorenzo A, Iannuzzo G, Parlato A, Cuomo G, Testa C, Coppola M, D'Ambrosio G, Oliviero DA, Sarullo S, Vitale G, Nugara C, Sarullo FM, Giallauria F. Clinical Evidence for Q10 Coenzyme Supplementation in Heart Failure: From Energetics to Functional Improvement. J Clin Med. 2020 Apr 27;9(5):1266. DiNicolantonio JJ, Bhutani J, McCarty MF, O'Keefe JH. Coenzyme Q10 for the treatment of heart failure: a review of the literature. Open Heart. 2015;2:e000326.

In older adults, low folate status has been associated with a higher risk of mild cognitive impairment (MCI) and faster cognitive decline over time, likely through effects on one‑carbon metabolism and homocysteine. Several longitudinal cohort studies have found that individuals with lower serum or red‑cell folate and higher homocysteine show steeper declines on memory and global cognition tests, and in some cohorts have a significantly higher incidence of MCI or dementia over follow‑up. The clinically important takeaway is that, when folate deficiency is detected and corrected (usually along with ensuring adequate vitamin B12), some patients demonstrate stabilization or modest improvement in cognitive performance, particularly when interventions are combined with aggressive management of vascular risk factors such as hypertension and diabetes.

Research: Ma, F., Wu, T., Zhao, J. et al. Folic acid supplementation improves cognitive function by reducing the levels of peripheral inflammatory cytokines in elderly Chinese subjects with MCI. Sci Rep 6, 37486 (2016). Wang M, Fang M, Zang W. Effects of folic acid supplementation on cognitive function and inflammation in elderly patients with mild cognitive impairment: A systematic review and meta-analysis of randomized controlled trials. Arch Gerontol Geriatr. 2024 Nov;126:105540. O’Connor, D.M.A., Scarlett, S., De Looze, C. et al. Low folate predicts accelerated cognitive decline: 8-year follow-up of 3140 older adults in Ireland. Eur J Clin Nutr 76, 950–957 (2022).Putu Eka Widyadharma. Folic acid supplementation improves cognitive function: A systematic review. December 2020 Romanian Journal of Neurology 19(4):219-223.

CoQ10 deficiency has been identified as a potentially reversible cause of steroid‑resistant nephrotic syndrome and glomerular nephropathy, particularly in children and young adults with genetic defects in CoQ10 biosynthesis. In reported series, affected patients often present with heavy proteinuria and progressive kidney dysfunction that fail to respond to standard steroid therapy, but genetic testing sometimes reveals mutations in CoQ10‑related genes (such as COQ2, COQ6, or ADCK4). The encouraging part is that in a subset of these cases, early and sufficiently dosed CoQ10 supplementation has been associated with reduced proteinuria and stabilization or partial improvement of kidney function, making it an important, treatable consideration in otherwise unexplained steroid‑resistant nephrotic syndrome.

Research: Frehat MQ Sr, Alhadidi A, Almheairat A, Alkhatib L, Al Thaher S, Al Assaf R, Al Qawaqenah M, Mansour B, Khair F. Success of Coenzyme Q10 in Treating Steroid-Resistant Nephrotic Syndrome in Jordan: A Case Series. Cureus. 2025 Apr 30;17(4):e83231. Drovandi S, Lipska-Ziętkiewicz BS, Ozaltin F, et al. Oral Coenzyme Q10 supplementation leads to better preservation of kidney function in steroid-resistant nephrotic syndrome due to primary Coenzyme Q10 deficiency. Kidney Int. 2022 Sep;102(3):604-612. Drovandi S, Lipska-Ziętkiewicz BS, et al. Variation of the clinical spectrum and genotype-phenotype associations in Coenzyme Q10 deficiency associated glomerulopathy. Kidney Int. 2022 Sep;102(3):592-603. Salviati L, Sacconi S, Murer L, Zacchello G, Franceschini L, Laverda AM, Basso G, Quinzii C, Angelini C, Hirano M, Naini AB, Navas P, DiMauro S, Montini G. Infantile encephalomyopathy and nephropathy with CoQ10 deficiency: a CoQ10-responsive condition. Neurology. 2005 Aug 23;65(4):606-8.

In some children and young adults, primary CoQ10 deficiency has been linked to hypertrophic cardiomyopathy (HCM), where the heart muscle becomes abnormally thick and stiff despite the absence of more common causes like longstanding hypertension. Case series and reports describe patients with genetically confirmed CoQ10 biosynthetic defects who develop HCM alongside other mitochondrial features such as exercise intolerance, muscle weakness, or neurologic symptoms, and cardiac imaging often shows concentric or asymmetric left ventricular hypertrophy. The hopeful aspect is that early recognition and CoQ10 supplementation have, in some documented cases, led to improved cardiac function or stabilization of wall thickness over time, making CoQ10 deficiency a particularly important and potentially treatable consideration in otherwise unexplained or familial‑appearing HCM.

Research: Adarsh K, Kaur H, Mohan V. Coenzyme Q10 (CoQ10) in isolated diastolic heart failure in hypertrophic cardiomyopathy (HCM). Biofactors. 2008;32(1-4):145-9. Sharma A, Fonarow GC, Butler J, Ezekowitz JA, Felker GM. Coenzyme Q10 and Heart Failure: A State-of-the-Art Review. Circ Heart Fail. 2016 Apr;9(4):e002639. Sondheimer N, Hewson S, Cameron JM, Somers GR, Broadbent JD, Ziosi M, Quinzii CM, Naini AB. Novel recessive mutations in COQ4 cause severe infantile cardiomyopathy and encephalopathy associated with CoQ10 deficiency. Mol Genet Metab Rep. 2017 May 11;12:23-27. Smet J, De Meirleir L. Early myoclonic epilepsy, hypertrophic cardiomyopathy and subsequently a nephrotic syndrome in a patient with CoQ10 deficiency caused by mutations in para-hydroxybenzoate-polyprenyl transferase (COQ2). Eur J Paediatr Neurol. 2013 Nov;17(6):625-30.

In some adults, chronic folate deficiency has been linked to neurological manifestations such as peripheral neuropathy, gait disturbance, and subtle to more overt cognitive impairment, especially in older age. Cohort studies have reported that low serum or red cell folate, and elevated homocysteine, correlate with worse performance on memory and executive‑function tests, and may be associated with increased risk of vascular dementia. The encouraging aspect is that, when folate deficiency is identified early and corrected alongside vitamin B12 when needed, some patients experience improvement in neuropathic symptoms and stabilization or modest gains in cognitive performance, particularly when other vascular risk factors are also addressed.

Research: Boumenna T, Scott TM, Lee JS, Palacios N, Tucker KL. Folate, vitamin B-12, and cognitive function in the Boston Puerto Rican Health Study. Am J Clin Nutr. 2021 Jan 4;113(1):179-186. Alves Maues AC, Moren Abat MG, Benlloch M, Mariscal G. Folate Supplementation for Peripheral Neuropathy: A Systematic Review. Nutrients. 2025 Oct 20;17(20):3299. Mottaghi T, Khorvash F, Maracy M, Bellissimo N, Askari G. Effect of folic acid supplementation on nerve conduction velocity in diabetic polyneuropathy patients. Neurol Res. 2019 Apr;41(4):364-368. Manzoor M, Runcie J. Folate-responsive neuropathy: report of 10 cases. Br Med J. 1976 May 15;1(6019):1176-8. Kang WB, Chen YJ, Lu DY, Yan JZ. Folic acid contributes to peripheral nerve injury repair by promoting Schwann cell proliferation, migration, and secretion of nerve growth factor. Neural Regen Res. 2019 Jan;14(1):132-139.

In pregnancy, inadequate folate status not only increases neural tube defect risk but is also associated with maternal megaloblastic anemia, which can worsen fatigue, reduce exercise tolerance, and increase the likelihood of transfusion around delivery. Observational studies have linked low folate and elevated homocysteine with a higher risk of miscarriage, placental complications, and low birth weight, and some data suggest that suboptimal folate status may contribute to certain infertility contexts, particularly when combined with other nutritional or metabolic stressors. The clinical takeaway is that maintaining sufficient folate intake before conception and throughout pregnancy is a key strategy to reduce anemia and support healthier fertility and pregnancy outcomes beyond neural tube defect prevention.

Research: Murto, T. et al. Folic acid supplementation and IVF pregnancy outcome in women with unexplained infertility. Dey M, Dhume P, Sharma SK, Goel S, Chawla S, Shah A, Madhumidha G, Rawal R. Folic acid: The key to a healthy pregnancy - A prospective study on fetomaternal outcome. Tzu Chi Med J. 2023 Oct 31;36(1):98-102. Hariz A, Bhattacharya PT. Megaloblastic Anemia. [Updated 2023 Apr 3]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026 Jan. Lazar VMA, Rahman S, Chowdhury NH, Hasan T, Akter S, Islam MS, Ahmed S, Baqui AH, Khanam R. Folate deficiency in pregnancy and the risk of preterm birth: A nested case-control study. J Glob Health. 2024 Jul 12;14:04120. Zheng J-S, Guan Y, Zhao Y, et al. Pre-conceptional intake of folic acid supplements is inversely associated with risk of preterm birth and small-for-gestational-age birth: a prospective cohort study. British Journal of Nutrition. 2016;115(3):509-516. Reproductive BioMedicine Online, Volume 28, Issue 6, 766 - 772

Folate deficiency has been associated with a higher risk of depressive symptoms, irritability, and other mood disturbances, likely through its role in one‑carbon metabolism, monoamine neurotransmitter synthesis, and methylation processes in the brain. Clinical and epidemiologic studies have found that people with low folate or elevated homocysteine are more likely to experience major depression, and lower folate status has been linked to poorer response to certain antidepressant medications. The encouraging clinical point is that, in folate‑deficient individuals, correcting folate status (often with folic acid or methylfolate, and alongside vitamin B12 when indicated) may improve mood symptoms and, in some cases, enhance antidepressant treatment response, especially when combined with comprehensive psychiatric and lifestyle interventions.

Research: David Mischoulon, Maurizio Fava. Folate in Depression: Efficacy, Safety, Differences in Formulations, and Clinical Issues. The Journal of Clinical Psychiatry. 2009. Gao S, Khalid A, Amini-Salehi E, Radkhah N, Jamilian P, Badpeyma M, Zarezadeh M. Folate supplementation as a beneficial add-on treatment in relieving depressive symptoms: A meta-analysis of meta-analyses. Food Sci Nutr. 2024 Mar 8;12(6):3806-3818. Reynolds EH, Crellin R, Bottiglieri T, Laundy M, Toone BK, et al. Methylfolate as Monotherapy in Depression. A Pilot Randomised Controlled Trial. J Neurol Psychol. 2015;3(1): 5. Reynolds EH. Folic acid, ageing, depression, and dementia. BMJ. 2002 Jun 22;324(7352):1512-5. Gilbody S, Lightfoot T, Sheldon T. Is low folate a risk factor for depression? A meta-analysis and exploration of heterogeneity. J Epidemiol Community Health. 2007 Jul;61(7):631-7.

CoQ10 deficiency is a recognized cause of progressive cerebellar ataxia with cerebellar atrophy, often beginning in childhood or early adulthood and frequently accompanied by seizures, peripheral neuropathy, and cognitive or psychiatric changes. Case series and larger cohorts show that many patients with primary CoQ10 deficiency have prominent cerebellar atrophy on MRI and mixed neurologic features, and in some reports seizures occurred in roughly one‑third of affected individuals. The hopeful aspect is that, unlike many hereditary ataxias, early and sustained CoQ10 supplementation has led to meaningful improvement or stabilization of gait, strength, and seizure control in a substantial subset of patients, which is why CoQ10 deficiency is emphasized as a treatable cause of cerebellar ataxia that should not be missed.

Research: Lamperti C, Naini A, Hirano M, De Vivo DC, Bertini E, Servidei S, Valeriani M, Lynch D, Banwell B, Berg M, Dubrovsky T, Chiriboga C, Angelini C, Pegoraro E, DiMauro S. Cerebellar ataxia and coenzyme Q10 deficiency. Neurology. 2003 Apr 8;60(7):1206-8. Artuch R, Brea-Calvo G, Briones P, Aracil A, Galván M, Espinós C, Corral J, Volpini V, Ribes A, Andreu AL, Palau F, Sánchez-Alcázar JA, Navas P, Pineda M. Cerebellar ataxia with coenzyme Q10 deficiency: diagnosis and follow-up after coenzyme Q10 supplementation. J Neurol Sci. 2006 Jul 15;246(1-2):153-8. Hirano M, Quinzii C, DiMauro S. Restoring balance to ataxia with coenzyme Q10 deficiency. Journal of the Neurological Sciences, 246, 11-12. Naini A, Lewis VJ, Hirano M, DiMauro S. Primary coenzyme Q10 deficiency and the brain. Biofactors. 2003;18(1-4):145-52.

Folate (folic acid) deficiency impairs DNA synthesis in rapidly dividing cells, which leads to megaloblastic anemia characterized by enlarged red blood cells, fatigue, pallor, and sometimes shortness of breath. Population studies have shown that folate deficiency and macrocytosis can be present for months before overt symptoms appear, and in some cohorts, up to roughly one quarter of anemic adults had an underlying folate or B12 deficiency rather than iron deficiency alone. The encouraging clinical point is that, once identified, folate‑responsive megaloblastic anemia often improves within weeks of adequate folic acid repletion, with reticulocyte counts rising in about 5–7 days and hemoglobin recovering more gradually over several weeks.

Research: Koury MJ, Price JO, Hicks GG. Apoptosis in megaloblastic anemia occurs during DNA synthesis by a p53-independent, nucleoside-reversible mechanism. Blood. 2000 Nov 1;96(9):3249-55. Daniel S. Socha, MD, Sherwin I. DeSouza, MD, Aron Flagg, MD, Mikkael Sekeres, MD, MS and Heesun J. Rogers, MD, PhD. Severe megaloblastic anemia: Vitamin deficiency and other causes. Cleveland Clinic Journal of Medicine March 2020, 87 (3) 153-164. H.B. Castellanos-Sinco, et al. Megaloblastic anaemia: Folic acid and vitamin B12 metabolism. Revista Médica del Hospital General de México. Vol. 78. Issue 3. Pages 105-150 (July - September 2015). Anis Hariz, et al. Megaloblastic Anemia. StatPearls April 3, 2023.

In some adolescents and adults, CoQ10 deficiency presents as an isolated mitochondrial myopathy with exercise intolerance, early fatigue, and proximal muscle weakness rather than a full multisystem syndrome. Muscle biopsies in these patients often show reduced CoQ10 content and ragged‑red fibers or other mitochondrial changes, even when brain, heart, and kidneys appear largely spared on standard evaluation. The encouraging piece is that many individuals with CoQ10‑deficient myopathy experience noticeable improvements in exercise capacity, muscle strength, and CK levels after several months of adequately dosed CoQ10 supplementation, highlighting the importance of recognizing this treatable cause of mitochondrial muscle disease early.

Research: Lalani SR, Vladutiu GD, Plunkett K, Lotze TE, Adesina AM, Scaglia F. Isolated Mitochondrial Myopathy Associated With Muscle Coenzyme Q10 Deficiency. Arch Neurol. 2005;62(2):317–320. Neergheen V, Chalasani A, Wainwright L, et al. Coenzyme Q10 in the Treatment of Mitochondrial Disease. Journal of Inborn Errors of Metabolism and Screening. 2017;5Sacconi S, Trevisson E, Salviati L, Aymé S, Rigal O, Redondo AG, Mancuso M, Siciliano G, Tonin P, Angelini C, Auré K, Lombès A, Desnuelle C. Coenzyme Q10 is frequently reduced in muscle of patients with mitochondrial myopathy. Neuromuscul Disord. 2010 Jan;20(1):44-8. Quinzii CM, Hirano M. Coenzyme Q and mitochondrial disease. Dev Disabil Res Rev. 2010;16(2):183-8.

In the gums and supporting tissues around the teeth, low CoQ10 levels have been linked to worse periodontal inflammation and deeper pocketing, likely because CoQ10 is essential for local mitochondrial energy production and antioxidant defense. Small human studies have found that people with periodontitis often have reduced CoQ10 in gingival tissue or crevicular fluid, and that topical or oral CoQ10 used alongside standard scaling and root planing can modestly improve measures such as bleeding on probing and pocket depth. The practical implication is that maintaining adequate CoQ10 status may help support healthier periodontal tissues and could be a useful adjunctive strategy, particularly in individuals with chronic gum disease or high oxidative stress in the oral cavity.

Research: Prakash S, Sunitha J, Hans M. Role of coenzyme Q(10) as an antioxidant and bioenergizer in periodontal diseases. Indian J Pharmacol. 2010 Dec;42(6):334-7. R. Nakamura, G.P. Littarru, K. Folkers, & E.G. Wilkinson. Study of CoQ10-Enzymes in Gingiva from Patients with Periodontal Disease and Evidence for a Deficiency of Coenzyme Q10*, Proc. Natl. Acad. Sci. U.S.A. 71 (4) 1456-1460. Ali K. Barakat et.al. Clinical Evaluation of Co-enzyme Q10 in Management of Chronic Periodontitis Patients: Mouth Split Study. International Journal of Health Sciences & Research. Vol.9; Issue: 1; January 2019.