The B vitamins don?t usually generate as much excitement as some of the more glamorous antioxidant members of the vitamin family, such as C and E. Long known for their important functions during energy production in the body, the Bs are now gaining new respect as researchers begin to uncover a wide range of roles for this long-neglected group. As it turns out, their health benefits range from helping to prevent heart attack, Alzheimer?s disease and cancer to helping fight depression, bone loss and pain. Here?s what you should know about the B vitamins, from the basics to the latest research, on their multiplicity of health roles.
Bs for heart health—While high cholesterol, smoking and obesity are long-established risk factors for heart disease, researchers also have found that inadequate levels of the three B vitamins—folic acid, B6 and B12—can lead to a buildup of homocysteine in the bloodstream.
Homocysteine is an amino acid produced when the body breaks down and metabolizes protein. It?s a normal byproduct that the body recycles with the help of these three Bs. When homocysteine levels rise, damage begins to occur in the lining of the arteries, leading to plaque buildup, blocked arteries and heart disease. In certain people, increased levels of B vitamins are needed to keep homocysteine recycled. These people may therefore need higher dosages of them than others. Several studies have shown a connection between higher intakes of these three B vitamins and reduced risk of heart disease and stroke, as well as a reduced need for repeat angioplasty one year after having the procedure.1,2,3,4
This newly discovered homocysteine connection also has implications reaching beyond heart health, as can be seen in later sections of this article.
Bs to prevent birth defects—Years of research have shown that high intakes of the B vitamin folate reduces the risk for a group of birth defects known as neural tube defects (such as spina bifida) that affect the spinal cord and brain. Based on this, in 1992 the U.S. Public Health Service recommended that women of childbearing age take 400 mcg of folic acid per day (the form of this B vitamin found in supplements and fortified foods).5 To ensure that more women received this recommended amount of folic acid, the U.S. Food and Drug Administration in 1996 announced it would begin requiring food companies to fortify grains with about 40 mcg of folic acid per 100 grams (3.5 ounces).6
Further underscoring the importance of getting enough folic acid before and during early pregnancy, a recent study found that half the population carries a genetic variant that puts them at high risk for passing on neural tube defects to their children.7
Supplementation with folic acid is important because, it is estimated, the folic acid found in supplements is twice as available to the body as the natural form of folate found in foods.8
Bs for brain function—The link between folic acid and the brain doesn?t end during pregnancy; it lasts into old age. It turns out that the elevated levels of homocysteine in the blood resulting from inadequate intake of folic acid, B6 and B12 can impair cognitive function, including reasoning and memory, in much the same way it impairs heart health—by clogging arteries and preventing blood flow.9,10,11
Another B vitamin known for its ability to improve circulation is niacin (vitamin B3). Recently, a study out of Rush University in Chicago found that niacin may offer some protection against Alzheimer?s. The study followed a group of people 65 years of age and older for three years, and found that those who consumed more than 22.4 mg of vitamin B3 per day were 80 percent less likely to develop Alzheimer?s than those in the lowest intake group. The researchers also point out that earlier research has shown B3 to have an important role in the synthesis and repair of DNA, and to act as an antioxidant.12
It?s long been known that B vitamins are essential for optimal mental function, but a recent study out of Sweden throws genetics into the mix as well. Researchers found that low levels of vitamin B12 showed the strongest association with poor memory in older people who carry a specific high-risk genetic marker for Alzheimer?s, suggesting that inadequate B vitamins may be a bigger risk factor only for this segment of the population.13
Bs to treat depression—There?s an increasing amount of evidence linking low blood levels of vitamins B6, B12 and folate with depression. Though the exact mechanisms for how these nutrients might affect depression aren?t known, there may be a homocysteine connection here as well.14
One recent review of randomized, controlled trials suggested that folate may have a potential role as a supplement to other treatments for depression.15
Vitamin B6 is needed for the synthesis of neurotransmitters such as serotonin and dopamine,16 so it?s not surprising that inadequate intake of this B vitamin also has been linked with depression. However, a recent review of the literature found only two studies that actually tested the effectiveness of vitamin B6 for the treatment of either depression or cognitive decline in the elderly. Neither found a significant beneficial effect. The reviewers recommended that more research be conducted.17
On a more definitive note, one study out of Finland found that higher blood levels of vitamin B12 were significantly associated with a better outcome after conventional depression treatments that included prescription drugs.18
Bs for bone health—One of the newest vitamin B health connections relates it to stronger bones. New research conducted at the University of California, San Francisco, found that women over the age of 64 with low levels of vitamin B12 are more likely to experience rapid bone loss from the hip than those with normal levels.19 And in that same vein, researchers in the Netherlands, who tracked 2,406 men and women aged 55 and older, found that those with the highest levels of homocysteine in their blood had nearly twice the risk of experiencing a fracture from osteoporosis, compared with those in the lowest quartile.20 Researchers believe that homocysteine may have a negative effect on bone structure. So getting enough folic acid along with vitamins B6 and B12 is important to keep homocysteine levels under control and possibly benefit bone health.
Bs for cancer prevention—Several population studies have found that people with higher intakes of folate are less likely to develop certain kinds of cancer than people with lower intakes.21,22,23 Harvard University?s Nurses Health Study found that women with low intakes of folic acid (less than 200 mcg per day) with a family history of colon cancer had double the risk of colon cancer, compared with women who consumed more than 400 mcg of folic acid per day and had the same family history of the disease.24 An earlier study of the same population concluded that long-term use of multivitamins that included folic acid substantially reduced the risk for colon cancer.25
The folate protection connection seemed to be especially strong for women who drink. A recent study in Sweden found that higher intakes of dietary folate in women who drank more than two alcoholic drinks per week resulted in a 74 percent lower risk of ovarian cancer than the women who drank and had low intakes of dietary folate.26 Similarly, a more recent Harvard study found that women with the highest blood-folate levels who drank at least one drink a day were 89 percent less likely to develop breast cancer than those who had the lowest levels of the B vitamin.27 Based on the population studies to date, women who drink even two drinks a week should ensure an adequate intake of B vitamins, especially folic acid.
Bs for pain relief—Vitamin B6 has been the focus of considerable pain research because of its potential benefits on pain perception and its ability to increase a person?s pain threshold.28 Vitamin B6 is needed for the synthesis of neurotransmitters such as serotonin and dopamine, which are involved in pain perception. It was first recommended as a treatment for carpal tunnel syndrome almost 30 years ago.15 Carpal tunnel syndrome occurs when inflamed tendons compress nerves in the wrist, usually as the result of repetitive motions, such as typing. Though B6 hasn?t been proven to be an effective treatment on its own, some experts recommend doses of 50 to 300 mg per day as an effective adjunct therapy for treatment of the condition.29 However, there is a caution to this: Long-term use of extremely high doses of vitamin B6 (2,000 mg to 6,000 mg per day) is associated with reversible nerve damage, known as neuropathy. Though there is little evidence regarding the risk of side effects at the doses recommended for carpal tunnel syndrome, the Institute of Medicine in Washington, D.C., set the upper limit for B6 at 100 mg a day.8
Riboflavin (vitamin B2) is another promising B vitamin treatment for the prevention of migraines, and it is found as an ingredient in some migraine-prevention-formula supplements. One recent German study found that 400 mg of riboflavin per day significantly reduced the frequency of migraine headaches and reduced the need for prescription medications.30
Though there is not yet a scientific consensus regarding the effectiveness of the B vitamins for the prevention or treatment of heart disease, Alzheimer?s, depression, osteoporosis or migraines, much of the research to date is promising and investigations are ongoing. In the meantime, for a few cents a day, many experts believe it is worth it to supplement with the health-promoting B vitamins.
Densie Webb, Ph.D., R.D., is a free-lance writer and editor specializing in health and nutrition. She is the co-author of The Dish on Eating Healthy and Being Fabulous (Atria Books, 2004).
1. 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(8):973-9.
2. Folsom AR, et al. Prospective study of coronary heart disease incidence in relation to fasting total homocysteine-related genetic polymorphisms, and B vitamins: the Atherosclerosis Risk in Communities (ARIC) study. Circulation 1998;98(3):204-10.
3. Clarke R, Armitage J. Vitamin supplements and cardiovascular risk: review of the randomized trials of homocysteine-lowering vitamin supplements. Semin Thromb Hemost 2000;26(3):341-8.
4. Rimm EB, et al. Folate and vitamin B6 from diet and supplements in relation to risk of coronary heart disease among women. JAMA 1998;279(5):359-64.
7. Ray JG, et al. Evidence for suboptimal use of periconceptional folic acid supplements globally. British J Obst and Gyn 2004;111(5):399-408.
8. Institute of Medicine. Dietary reference intakes for thiamin, riboflavin, niacin, vitamin B6, folate, vitamin B12, pantothenic acid, biotin, and choline, Washington, D.C.: National Academy Press; 1998.
9. O?Suilleabhain PE, et al. Elevated plasma homocysteine level in patients with Parkinson disease: motor, affective, and cognitive associations. Arch Neurol 2004;61916):865-8.
10. Quadri P, et al. Homocysteine, folate, and vitamin B-12 in mild cognitive impairment, Alzheimer disease, and vascular dementia. Am J Clin Nutr 2004:80(1):114-22.
11. Wright CB, et al. Total homocysteine and cognition in a tri-ethnic cohort: the Northern Manhattan Study. Neurology 2004;63(2):254-60.
12. Morris MC, Evans DA, et al. Dietary niacin and the risk of incident alzheimer?s disease and of cognitive decline. J Neurol Neurosurg Psychiatry 2004;75(8):1093-9.
13. Bunce D, et al. Utilization of cognitive support in episodic free recall as a function of apolipoprotein E and vitamin B12 or folate among adults aged 75 years and older. Neuropsychology 2004;18(2):362-70.
14. Tiemeier H, et al. Vitamin B12, folate, and homocysteine in depression: the Rotterdam Study. Am J Psychiatry 2002;159(12):2099-2101.
15. Taylor MJ, et al. Folate for depressive disorders. Cochrane Database Syst Rev 2003;(2):CD003390.
17. Malouf R, Grimley EJ. The effect of vitamin B6 on cognition. Cochrane Database Syst Rev 2003;(4):CD004393.
18. Hintikka J, et al. High vitamin B12 level and good treatment outcome may be associated in major depressive disorder. BMC Psychiatry 2003;3(1):17.
19. Stone KL, et al. Low serum vitamin B12 levels are associated with increased hip bone loss in older women: a prospective study. J Clin Endocrinol Metab 2004;89(3):1217-21.
20. Van Meurs JB, et al. Homocysteine levels and the risk of osteoporotic fracture. NEJM 2004;350(20):2033-41.
21. Le Marchand L, et al. B-vitamin intake, metabolic genes, and colorectal cancer risk (United States). Cancer Causes Contro, 2002; 13(3):239-48.
22. Hernandez BY, et al. Diet and premalignant lesions of the cervix: evidence of a protective role for folate, riboflavin, thiamin, and vitamin B12. Cancer Causes Control 2003;14(9):859-70.
23. Shen H, et al. Dietary folate intake and lung cancer risk in former smokers: a case-control analysis. Cancer Epidemiol Biomarkers Prev 2003;12(10):980-6.
24. Fuchs CS, et al. The influence of folate and multivitamin use on the familial risk of colon cancer in women. Cancer Epidemiol Biomarkers Prev 2002;11(3):227-34.
25. Giovannucci E, et al. Multivitamin use, folate, and colon cancer in women in the Nurses? Health Study. Ann Intern Med 1998;129(7):517-24.
26. Larson SC, et al. Dietary folate intake and incidence of ovarian cancer: the Swedish Mammography Cohort. J Natl Cancer Inst 2004;96(5):396-402.
27. Zhang SM, et al. Plasma folate, vitamin B6, vitamin B12, homocysteine, and risk of breast cancer. J Natl Cancer Inst 2003;95(5):373-80.
28. Jacobson MD, Plancher KD, et al. Vitamin B6 (pyridoxine) therapy for carpal tunnel syndrome. Hand Clin 1996;12(2):253-7.
29. Aufiero E, Stitik TP, et al. Pyridoxine hydrochloride treatment of carpal tunnel syndrome: a review. Nutr Rev 2004;62(3):96-104.
30. Boehnke C, Reuter U, et al. High dose riboflavin treatment is efficacious in migraine prophylaxis: an open study in a tertiary care centre. Eur J Neurol 2004;11(7):475-7.
Natural Foods Merchandiser volume XXV/number 10/p. 112, 118