One of the markers to predict a person’s overall health status is by measuring homocysteine levels in the blood. In fact, research shows that homocysteine levels are a better indicator of heart attacks and strokes than high cholesterol levels.
Many people have never heard of homocysteine and don’t know to ask their doctor for a homocysteine blood test as part of a health and wellness check-up. The reason most doctors do not suggest this test is because, currently, there are no patented drugs that are designed to specifically lower blood levels of homocysteine. And those doctors who actually understand the diagnostic value of homocysteine may be reluctant to order a homocysteine level test for their patients because they wouldn’t know what to prescribe for those patients with high levels.
What is Homocysteine?
Homocysteine is an amino acid that the body makes from another amino acid called methionine. You obtain methionine from many protein-dense foods including sunflower seeds, eggs, meat, and fish.
In the best-case scenario, homocysteine is converted into two substances called SAMe (S-adenosyl methionine) and glutathione. Both SAMe and glutathione have health-promoting effects. Specifically, SAMe helps to prevent depression, arthritis, and liver damage. Glutathione is a powerful antioxidant and detoxifying agent that helps to slow down aging. Therefore we see the necessity of the body being able to convert homocysteine into SAMe and glutathione.
Conversion of homocysteine to SAMe requires adequate levels of folate, vitamin B12, vitamin B2, zinc, TMG (trimethylglycine from choline), and magnesium. Conversion of homocysteine to glutathione requires vitamin B6, vitamin B2, and zinc. When the body does not efficiently convert homocysteine into SAMe and glutathione, the amount of toxic homocysteine in the blood begins to rise
Health reasons one might have a high homocysteine level are kidney disease, psoriasis, and thyroid disease. It has also been recognized that some people have a common genetic variant (called methylenetetrahydrofolate reductase, abbreviated MTHFR) that impairs their ability to process folate. This defective gene leads to elevated levels of homocysteine in some people who inherit MTHFR variants from both parents. There are blood tests available to detect MTHFR variants.
Elevated Homocysteine Levels May Lead to
- Heart Attack
- Plaque formation by damaging arterial walls
- Risk of blood clot formation
- Risk of developing Alzheimer’s disease
- Oxidation and Aging
- Weakened Immune System
- Vascular Damage
- Congestive Heart Failure
- Macular Degeneration
- Hearing Loss
- Brain Atrophy
- Pain and Inflammation
Producers of High Homocysteine Levels
Many factors can contribute to high homocysteine (Hyperhomocysteinemia) levels:
- Inadequate intake of folate, vitamin B6, vitamin B12, betaine, vitamin B2, and magnesium
- Prescription drug (see list at end of the article)
- Diet high in methionine (including red meat and dairy products)
- Alcohol consumption
- Advancing age
- High-stress levels
- A genetic variant that causes an impaired ability to metabolize active folate from folic acid
What is Considered a High Level for Homocysteine?
Homocysteine levels are measured in the blood by taking a blood sample. Normal levels are in the range between 5 to 15 micromoles (measurement unit of a small amount of a molecule) per liter. Elevated levels are classified as follows:
- 15-30 micromoles per liter as moderate
- 30-100 micromoles per liter as intermediate
- Greater than 100 micromoles per liter as severe
Note: Many practitioners believe that the optimal range for homocysteine levels is <8 µmol/L, much lower than the currently accepted <15 µmol/L. Studies indicate that adults with homocysteine value ≥6.3 µmol/L are at increased risk of atherosclerosis (Homocysteine Studies Collaboration), heart attack, and stroke (Broxmeyer 2004).
Natural Ways to Lower Homocysteine Levels
Healthy Foods (organic is best)
- Turnip Greens
- Free Range Eggs
- Raw Nuts
- Black-Eyed Peas
- Organic Brown Rice
- Chick Peas
- Healthy fats and oils
Vitamins and Supplements
- Vitamin B12 Methylcobalamin
- Folic Acid (5-MTHF)
- Vitamin B2 (riboflavin)
- Vitamin B6
- Omega-3 rich fish oil (PUFAs)
- Trimethylglycine (TMG) and Choline
- Magnesium Orotate
- SAMe (S-adenosyl-L-methionine)
- Healthy Diet
- Avoid methionine-rich foods – red meats and dairy.
- Lose Extra Weight
- Control Diabetes
- Control High Blood Pressure
- Decrease Stress
- Daily Exercise
- Eliminate caffeine
- No Smoking
- Limited Alcohol
Drugs That Raise Homocysteine Levels
A number of prescription drugs and natural compounds can elevate blood levels of homocysteine by interfering with folate absorption or the metabolism of homocysteine. These include:
- Caffeine (Verhoef 2002): Cafcit®, Cafergot®, Esgic®, Excedrin Migraine®, Fioricet®, Fiorinal®, Norgesic®, Synalgos-DC®
- Cholestyramine (Tonstad 1998): Questran®, Questran Light®, Cholybar®
- Colestipol: Cholestid® (Seshadri 1999)
- Fenofibrate (Foucher 2010): Antara®, Fenoglide®, Lipfen®, Lofibra®, Tricor®, Trilpix®
- Levadopa (Lee 2010): Parcopa®, Sinemet®, Stalevo®
- Metformin (Desouza 2002): ActoPlus Met®, Avandamet®, Fortamet®, Glucophage® Glucovance®, Glumetza®, Janumet® Metaglip® Prandimet® Riomet®
- Methotrexate (Desouza 2002): Rheumatrex®
- Niacin (Desouza 2002): Advicor®, Ocuvite®, Cardio Basics®CitraNatal®, Heplive®, Niaspan®, Simcor®
- Nitrous oxide (Myles 2008)
- Pemetrexed (Li 2007) Alimta®
- Phenytoin(Mintzer 2009): Dilantin®, Phenytek®
- Pyrimethamine (Das 1976): Daraprim®, Fansidar®
- Sulfasalazine (Haagsma 1999): Asulfidine®
In summary, high homocysteine levels, if not taken care of, can lead to serious disease. The good news is that the implementation of a very healthy diet and lifestyle changes go very far in supporting your body’s natural healing abilities. Not everyone can or will go cold-turkey and it’s okay to make these diet and lifestyle changes one-step-at-a-time as you climb your own personal nutritional and health ladder. God gave you one mouth and 4-5 (men 4 and women 5) elimination routes, thus your body can be very forgiving…for a time. The keywords are “for a time.” It is imperative to understand that everyone has a toxic threshold. If you are already experiencing chronic disease, I encourage you to begin to make changes as quickly as possible. Chances are you will begin to see some results quickly. Never give up!
Ahn CS. Effect of taurine supplementation on plasma homocysteine levels of the middle-aged Korean women. Adv Exp Med Biol. 2009;643:415-422.
Akoglu B, Schrott M, et al. The folic acid metabolite L-5-methyltetrahydrofolate effectively reduces total serum homocysteine level in orthotopic liver transplant recipients: a double-blind placebo-controlled study. Eur J Clin Nutr. 2008;62:796-801.
Albert C. A randomized trial of folic acid and B-vitamins in the secondary prevention of cardiovascular events in women: Results from the Women’s Antioxidant and Folic Acid Cardiovascular Study (WAFACS). American Heart Association 2006 Scientific Sessions; November 13, 2006; Chicago, IL. PS.03.Late-Breaking Clinical Trials I.
Albert CM, Cook NR, et al. Effect of folic acid and B vitamins on risk of cardiovascular events and total mortality among women at high risk for cardiovascular disease: a randomized trial. JAMA. 2008;299:2027-2036.
Ali A, Mehra MR, et al. Modulatory impact of cardiac rehabilitation on hyperhomocysteinemia in patients with coronary artery disease and “normal” lipid levels. Am J Cardiol. 1998;82:1543-5.
Alvares Delfino VD, de Andrade Vianna AC, et al. Folic acid therapy reduces plasma homocysteine levels and improves plasma antioxidant capacity in hemodialysis patients. Nutrition. 2007;23:242-247.
Bazzano LA, Reynolds K, et al. Effect of folic acid supplementation on risk of cardiovascular diseases: A meta-analysis of randomized controlled trials. JAMA. 2006;296:2720-2726.
Blacher J, Demuth K, et al. Association between plasma homocysteine concentrations and cardiac hypertrophy in end-stage renal disease. J Nephrol. 1999;12:248-255.
Bønaa KH. NORVIT: Randomized trial of homocysteine-lowering with B-vitamins for secondary prevention of cardiovascular disease after acute myocardial infarction. Program and Abstracts from the European Society of Cardiology Congress 2005; September 3-7, 2005; Stockholm, Sweden. Hot Line II.
Bostom AG, Selhub J, et al. Power shortage: clinical trials testing the “homocysteine hypothesis” against a background of folic acid-fortified cereal grain flour. Ann Intern Med. 2001;135: 133-137.
Botto LD, Yang Q. 5,10-Methylenetetrahydrofolate reductase gene variants and congenital anomalies: a HuGE review. Am J Epidemiol. 2000;151:862-877.
Brosnan JT, Brosnan ME. The sulfur-containing amino acids: an overview. J Nutr. 2006; 136:1636S-1640S.
Brosnan JT, Jacobs RL, et al. Methylation demand: a key determinant of homocysteine metabolism. Acta Biochim Pol. 2004;51:405-413.
Broxmeyer L. Heart disease: the greatest ‘risk’ factor of them all. Med Hypotheses. 2004;62:773-779.
Carlsen SM, Jacobsen G, et al. In pregnant women who smoke, caffeine consumption is associated with an increased level of homocysteine. Acta Obstet Gynecol Scand. 2005;84:1049-1054.
Chen P, Poddar R, et al. Homocysteine metabolism in cardiovascular cells and tissues: implications for hyperhomocysteinemia and cardiovascular disease. Adv Enzyme Reg. 1999;39:93-109.
Cho E, Zeisel SH, et al. Dietary choline and betaine assessed by food-frequency questionnaire in relation to plasma total homocysteine concentration in the Framingham Offspring Study. Am J Clin Nutr. 2006;83:905–911.
Christen WG, Glynn RJ, et al. Folic acid, pyridoxine, and cyanocobalamin combination treatment and age-related macular degeneration in women: the Women’s Antioxidant and Folic Acid Cardiovascular Study. Arch Intern Med. 2009;169:335-341.
Clarke R. Homocysteine-lowering trials for prevention of heart disease and stroke. Semin Vasc Med. 2005;5:215-222.
da Costa KA, Gaffney CE, et al. Choline deficiency in mice and humans is associated with increased plasma homocysteine concentration after a methionine load. Am J Clin Nutr. 2005;81:440-444.
Das KC, Herbert V. Vitamin B12–folate interrelations. Clin Haematol. 1976;5:697-745.
Desouza C, Keepler M, et al. Drugs affecting homocysteine metabolism: impact on cardiovascular risk. Drugs. 2002;62:605-616.
Devlin TM. Textbook of Biochemistry with Clinical Correlations . 5th ed. New York , NY : Wiley-Liss; 2001.
Durga J, Verhoef P, et al. Effects of folic acid supplementation on hearing in older adults: a randomized, controlled trial. Ann Intern Med. 2007;146:1-9.
Ebbing M, Bleie Ø, et al. Mortality and cardiovascular events in patients treated with homocysteine-lowering B vitamins after coronary angiography: a randomized controlled trial. JAMA. 2008;300:795-804.
Elias MF, Sullivan LM, et al. Homocysteine and cognitive performance in the Framingham offspring study: age is important. Am J Epidemiol. 2005;162:644-653.
Foucher C, Brugère L, et al. Fenofibrate, homocysteine, and renal function. Curr Vasc Pharmacol. 2010;8:589-603.
Gallai V, Caso V, et al. Mild hyperhomocyst(e)inemia: a possible risk factor for cervical artery dissection. Stroke. 2001;32:714-718.
Ganji V, Kafai MR. Population reference values for plasma total homocysteine concentrations in US adults after the fortification of cereals with folic acid. Am J Clin Nutr. 2006;84:989-994.
Gok U, Halifeoglu I, et al. Comparative analysis of serum homocysteine, folic acid and Vitamin B12 levels in patients with noise-induced hearing loss. Auris Nasus Larynx. 2004;31:19-22.
Guo H, Chi J, et al. Influence of folic acid on plasma homocysteine levels & arterial endothelial function in patients with unstable angina. Indian J Med Res. 2009;129:279-284.
Guzelmeric K, Alkan N, et al. Chronic inflammation and elevated homocysteine levels are associated with increased body mass index in women with polycystic ovary syndrome. Gynecol Endocrinol. 2007;23:505-510.
Haagsma CJ, Blom HJ, et al. Influence of sulphasalazine, methotrexate, and the combination of both on plasma homocysteine concentrations in patients with rheumatoid arthritis. Ann Rheum Dis. 1999;58:79-84.
Hamed SA. The vascular risk associations with migraine: relation to migraine susceptibility and progression. Atherosclerosis. 2009;205:15-22.
Held C, Sumner G, et al. Correlations between plasma homocysteine and folate concentrations and carotid atherosclerosis in high-risk individuals: baseline data from the Homocysteine and Atherosclerosis Reduction Trial (HART). Vasc Med. 2008;13:245-253.
Hofmann MA, Lalla E, et al. Hyperhomocysteinemia enhances vascular inflammation and accelerates atherosclerosis in a murine model. J Clin Invest. 2001;107:675-683.
Huang T, Wahlqvist ML, et al. Docosahexaenoic acid decreases plasma homocysteine via regulating enzyme activity and mRNA expression involved in methionine metabolism. Nutrition. 2010;26:112-119.
Hustad S, Ueland PM, et al. Riboflavin as a determinant of plasma total homocysteine: effect modification by the methylenetetrahydrofolate reductase C677T polymorphism. Clin Chem. 2000;46:1065-1071.
Jacobsen DW. Homocysteine and vitamins in cardiovascular disease. Clin Chem. 1998;44:1833-1843.
Jacques PF, Rosenberg IH, et al. Serum total homocysteine concentrations in adolescent and adult Americans: results from the third National Health and Nutrition Examination Survey. Am J Clin Nutr. 1999;69:482-489.
Jahangir E, Vita JA, et al. The effect of L-arginine and creatine on vascular function and homocysteine metabolism. Vasc Med. 2009;14:239-248.
Khandanpour N, Armon MP, et al. Randomized clinical trial of folate supplementation in patients with peripheral arterial disease. Br J Surg. 2009;96:990-998.
Kurth T, Ridker PM, et al. Migraine and biomarkers of cardiovascular disease in women. Cephalalgia. 2008;28:49-56.
Lange H, Suryapranata H, et al. Folate therapy and in-stent restenosis after coronary stenting. N Engl J Med. 2004;350(26):2673-2681.
Lea R, Colson N, et al. The effects of vitamin supplementation and MTHFR (C677T) genotype on homocysteine-lowering and migraine disability. Pharmacogenet Genomics. 2009;19:422-428.
Lee SH, Kim MJ, et al. Hyperhomocysteinemia due to levodopa treatment as a risk factor for osteoporosis in patients with Parkinson’s disease. Calcif Tissue Int. 2010;86:132-141.
Lever M, George PM, et al. Fibrates may cause an abnormal urinary betaine loss which is associated with elevations in plasma homocysteine. Cardiovasc Drugs Ther. 2009;23:395-401.
Levitt M, Nixon PF, et al. Transport characteristics of folates in cerebrospinal fluid; a study utilizing doubly labeled 5-methyltetrahydrofolate and 5- formyltetrahydrofolate. J Clin Invest. 1971;50:1301-1308.
Li KM, Rivory LP, et al. Pemetrexed pharmacokinetics and pharmacodynamics in a phase I/II study of doublet chemotherapy with vinorelbine: implications for further optimisation of pemetrexed schedules. Br J Cancer. 2007;97:1071-1076.
Loehrer FM, Schwab R, et al. Influence of oral S-adenosylmethionine on plasma 5-methyltetrahydrofolate, S-adenosylhomocysteine, homocysteine and methionine in healthy humans. J Pharmacol Exper Ther. 1997;282:845-850.
Loscalzo J. The oxidant stress of hyperhomocyst(e)inemia. J Clin Invest. 1996;98:5-7.
Lv S, Fan R, et al. Betaine supplementation attenuates atherosclerotic lesion in apolipoprotein E-deficient mice. Eur J Nutr. 2009;48:205-212.
Mann JF, Sheridan P, et al. Homocysteine lowering with folic acid and B vitamins in people with chronic kidney disease—results of the renal Hope-2 study. Nephrol Dial Transplant. 2008;23:645-653.
McKillop DJ, Pentieva K, et. al. The effect of different cooking methods on folate retention in various foods that are amongst the major contributors to folate intake in the UK diet. British J Nutr. 2002;88:681–688.
McLean RR, Jacques PF, et al. Homocysteine as a predictive factor for hip fracture in older persons. N Engl J Med. 2004;350:2042-2049.
McNulty H, Dowey le RC, et al. Riboflavin lowers homocysteine in individuals homozygous for the MTHFR 677C->T polymorphism. Circulation. 2006;113:74-80.
McNulty H, Pentieva K, et al. Homocysteine, B-vitamins and CVD. Proc Nutr Soc. 2008;67:232-237.
Méndez-González J, Rodríguez-Millán E, et al. [Vitamin treatments that lower homocysteine concentration: can they decrease cerebrovascular disease in primary prevention?]. Rev Neurol. 2010;50:235-244.
Miller A, Mujumdar V, et al. Reversal of endocardial endothelial dysfunction by folic acid in homocysteinemic hypertensive rats. Am J Hypertens. 2002;15:157-163.
Mintzer S, Skidmore CT, et al. Effects of antiepileptic drugs on lipids, homocysteine, and C-reactive protein. Ann Neurol. 2009;65:448-456.
Moschiano F, D’Amico D, et al. Homocysteine plasma levels in patients with migraine with aura. Neurol Sci. 2008;29 Suppl 1:S173-S175.
Must A, Jacques PF, et al. Serum total homocysteine concentrations in children and adolescents: results from the third National Health and Nutrition Examination Survey (NHANES III). J Nutr. 2003;133:2643-2649.
Myles PS, Chan MT, et al. Effect of nitrous oxide anesthesia on plasma homocysteine and endothelial function. Anesthesiology. 2008;109:657-663.
Namazi MH, Motamedi MR, et al. Efficacy of folic acid therapy for prevention of in-stent restenosis: a randomized clinical trial. Arch Iran Med. 2006;9:108-110.
Nolin TD, Ouseph R, et al. Multiple-Dose Pharmacokinetics and Pharmacodynamics of N-Acetylcysteine in Patients with End-Stage Renal Disease. Clin J Am Soc Nephrol. 2010; 5:1588-94.
Ntaios G, Savopoulos C, et al. The effect of folic acid supplementation on carotid intima-media thickness in patients with cardiovascular risk: A randomized, placebo-controlled trial. Int J Cardiol. 2010;143:16-19.
Nygård O, Vollset SE, et al. Total plasma homocysteine and cardiovascular risk profile. The Hordaland Homocysteine Study. JAMA. 1995;274: 1526-1533.
Osanai T, Fujiwara N, et al. Novel pro-atherogenic molecule coupling factor 6 is elevated in patients with stroke: a possible linkage to homocysteine. Ann Med. 2010;42:79-86.
Oterino A, Toriello M, et al. The relationship between homocysteine and genes of folate-related enzymes in migraine patients. Headache. 2010;50:99-168.
Papatheodorou L, Weiss N. Vascular oxidant stress and inflammation in hyperhomocysteinemia. Antioxid Redox Signal. 2007;9:1941-1958.
Plassman BL, Langa KM, et al. Prevalence of cognitive impairment without dementia in the United States. Ann Intern Med. 2008;148:427-434
Pooya Sh, Jalali MD, et al. The efficacy of omega-3 fatty acid supplementation on plasma homocysteine and malondialdehyde levels of type 2 diabetic patients. Nutr Metab Cardiovasc Dis. 2010;20:326-331.
Robinson K, Mayer EL, et al. Hyperhomocysteinemia and low pyridoxal phosphate: common and independent reversible risk factors for coronary artery disease. Circulation. 1995; 92:2825-2830.
Rochtchina E, Wang JJ, et al. Elevated serum homocysteine, low serum vitamin B12, folate, and age-related macular degeneration: the Blue Mountains Eye Study. Am J Ophthalmol. 2007;143:344-346.
Roes EM, Raijmakers MT, et al. Effects of oral N-acetylcysteine on plasma homocysteine and whole blood glutathione levels in healthy, non-pregnant women. Clin Chem Lab Med. 2002;40:496-498.
Ruscin JM, Page RL 2nd, et al. Vitamin B-12 deficiency associated with histamine (2)–receptor antagonists and a proton-pump inhibitor. Ann Pharmacother. 2002;36:812-816.
Sakuta H, Suzuki T. Alcohol consumption and plasma homocysteine. Alcohol. 2005;372:73-77.
Saposnik G, Ray JG, et al, Heart Outcomes Prevention Evaluation 2 Investigators. Homocysteine-lowering therapy and stroke risk, severity, and disability: additional findings from the HOPE 2 trial. Stroke. 2009;40:1365-1372.
Schnyder G, Roffi M, et al. Effect of homocysteine-lowering therapy with folic acid, vitamin B12, and vitamin B6 on clinical outcome after percutaneous coronary intervention: the Swiss Heart study: a randomized controlled trial. JAMA. 2002;288:973-979.
Schuster O, Weimann HJ, et al. Pharmacokinetics and relative bioavailability of iron and folic acid in healthy volunteers. Arzneimittelforschung.1993;43:761-766.
Schwab U, Törrönen A, et al. Betaine supplementation decreases plasma homocysteine concentrations but does not affect body weight, body composition, or resting energy expenditure in human subjects. Am J Clin Nutr. 2002;76:961-967.
Schwammenthal Y, Tanne D. Homocysteine, B-vitamin supplementation, and stroke prevention: from observational to interventional trials. Lancet Neurol. 2004;3:493-495.
Selhub J, Jacques PF, et al. Serum total homocysteine concentrations in the third National Health and Nutrition Examination Survey (1991-1994): population reference ranges and contribution of vitamin status to high serum concentrations. Ann Intern Med. 1999 (b);131:331-339.
Selhub J. Homocysteine metabolism. Annu Rev Nutr. 1999 (a);19:217-246.
Seshadri S, Beiser A, et al. Plasma homocysteine as a risk factor for dementia and Alzheimer’s disease. N Engl J Med. 2002 Feb 14;346(7):476-83.
Seshadri, N., Robinson, K. Homocysteine and coronary risk, Curr Cardiol Rep 1999; 1, 91-98.
Shidfar F, Homayounfar R, et al. Effect of folate supplementation on serum homocysteine and plasma total antioxidant capacity in hypercholesterolemic adults under lovastatin treatment: a double-blind randomized controlled clinical trial. Arch Med Res. 2009;40:380-386.
Smith AD, Smith SM, et al. Homocysteine-Lowering by B Vitamins Slows the Rate of Accelerated Brain Atrophy in Mild Cognitive Impairment: A Randomized Controlled Trial. PLoS ONE 2010; 5(9): e12244. doi:10.1371/journal.pone.0012244
Stead LM, Brosnan JT, et al. Is it time to reevaluate methyl balance in humans? Am J Clin Nutr. 2006;83:5-10.
Targher G, Bertolini L, et al. Cigarette smoking and plasma total homocysteine levels in young adults with type 1 diabetes. Diabetes Care. 2000;23:524-528.
Tavares NR, Moreira PA,et al. Riboflavin supplementation and biomarkers of cardiovascular disease in the elderly. J Nutr Health Aging. 2009;13:441-446.
Temple ME, Luzier AB, et al. Homocysteine as a risk factor for atherosclerosis. Ann Pharmacother. 2000;34:57-65.
Tonstad F, Refsum H, et al. The C677T mutation in the methylenetetrahydrofolate reductase gene predisposes to hyperhomocysteinemia in children with familial hypercholesterolemia treated with cholestyramine. J Pediatr. 1998;132: 365-368.
Toole JF, Malinow MR, et al. Lowering homocysteine in patients with ischemic stroke to prevent recurrent stroke, myocardial infarction, and death: the Vitamin Intervention for Stroke Prevention (VISP) randomized controlled trial. JAMA. 2004;291:565-575.
Ueland PM, Clarke R. Homocysteine and cardiovascular risk: considering the evidence in the context of study design, folate fortification, and statistical power. Clin Chem. 2007;53:807-809.
Vasan RS, Beiser A, et al. Plasma homocysteine and risk for congestive heart failure in adults without prior myocardial infarction. JAMA. 2003;289:1251-1257.
Venn BJ, Green TJ, et al. Increases in blood folate indices are similar in women of childbearing age supplemented with [6S]-5-methyltetrahydrofolate and folic acid. J Nutr. 2002;132:3353-3355.
Verhoef P, Pasman WJ, et al. Contribution of caffeine to the homocysteine-raising effect of coffee: a randomized controlled trial in humans. Am J Clin Nutr. 2002;76:1244-1248.
Verhoef P, van Vliet T, et al. A high-protein diet increases postprandial but not fasting plasma total homocysteine concentrations: a dietary controlled, crossover trial in healthy volunteers. Am J Clin Nutr. 2005;82:553-558.
Wang X, Qin X, et al. Efficacy of folic acid supplementation in stroke prevention: A meta-analysis. Lancet. 2007;369:1876 –1882.
Weir DG, Scott JM. Brain function in the elderly: role of vitamin B12 and folate. Br Med Bull. 1999;55:669-682.
Wierzbicki AS. Homocysteine and cardiovascular disease: a review of the evidence. Diab Vasc Dis Res. 2007;4:143-150.
Wiklund O, Fager G, et al. N-acetylcysteine treatment lowers plasma homocysteine but not serum lipoprotein(a) levels. Atherosclerosis. 1996;119:99-106.
Willems FF, Boers GH, et al. Pharmacokinetic study on the utilization of 5-methyltetrahydrofolate and folic acid in patients with coronary artery disease. Br J Pharmacol. 2004;141:825-830.
Wright AJ, Dainty JR, et al. Folic acid metabolism in human subjects revisited: potential implications for proposed mandatory folic acid fortification in the UK. Br J Nutr. 2007;98:667-675.
Wulffelé MG, Kooy A, et al. Effects of short-term treatment with metformin on serum concentrations of homocysteine, folate and vitamin B12 in type 2 diabetes mellitus: a randomized, placebo-controlled trial. J Intern Med. 2003;254:455-463.
Xu T, Zhang XW, et al. Treatment of hyperhomocysteinemia and endothelial dysfunction in renal transplant recipients with B vitamins in the Chinese population. J Urol. 2008;179:1190-1194.
Yilmaz H, Sahin S, et al. Effects of folic acid and N-acetylcysteine on plasma homocysteine levels and endothelial function in patients with coronary artery disease. Acta Cardiol. 2007;62:579-85.
Zeng X, Dai J, et al. Homocysteine mediated expression and secretion of monocyte chemoattractant protein-1 and interleukin-8 in human monocytes. Circ Res. 2003;93:311-320.
Zettner A, Boss GR, et al. A long-term study of the absorption of large oral doses of folic acid. Ann Clin Lab Sci. 1981;11:516-524.
Zoccali C, Mallamaci F, et al. It is important to lower homocysteine in dialysis patients. Semin Dial. 2007; 20:530-533.
Zulli A, Lau E, et al. High dietary taurine reduces apoptosis and atherosclerosis in the left main coronary artery: association with reduced CCAAT/enhancer binding protein homologous protein and total plasma homocysteine but not lipidemia. Hypertension. 2009;53:1017-1022.
Zulli A, Lau E, Wijaya BP, et al. High dietary taurine reduces apoptosis and atherosclerosis in the left main coronary artery: association with reduced CCAAT/enhancer binding protein homologous protein and total plasma homocysteine but not lipidemia. Hypertension. 2009;53(6):1017-22.