Access to all articles, new health classes, discounts in our store, and more!
The B vitamins are involved in many diverse processes in the body – from energy metabolism and blood cell production to nervous system and brain function. Known as the B vitamin complex, they are a group of eight water-soluble vitamins with similar functions that work synergistically within the body. Each of them is needed in sufficient quantities in order for us to achieve optimal physical and mental health.
These critical nutrients are often referred to as the “stress vitamins” because of their role in helping the body handle stress. Not only are the B vitamins vital to the conversion of dietary carbohydrates and fats into fuel for proper cellular functioning, they also play important roles in the production of neurotransmitters that boost our mood. It is important to note that stress of any kind – due to illness, injury, exercise, pregnancy, lactation, mental/emotional distress, etc. increases the body’s need for the B vitamins.
Because they are water soluble, only minute amounts of these vitamins can be stored in body tissues. The remainder is either quickly used or eliminated from the system, so they need to be replenished regularly. The exceptions to this rule are vitamins B12 and B6. Given adequate tissue stores, B12 can remain in the body (primarily in the liver) for several months; and B6 can be stored in muscle tissue for a few weeks. Some B vitamins are also synthesized in small quantities by healthy intestinal bacteria; nonetheless, most of our daily needs must be supplied through food or supplementation.
B vitamins can be found in a variety of foods, particularly vegetables, yeasts, organ meats, and whole grains. Under optimal conditions, a varied diet of unprocessed whole foods, including animal products, should provide us with all the B vitamins required for a healthy body and mind. B vitamin absorption is a complex process, however, and conditions or complications that inhibit their uptake can occur. These include heavy alcohol consumption and digestive disorders such as low stomach acid, Crohn’s disease, and celiac. In addition, various conditions can increase the body’s requirements. For example, older adults, pregnant women, and women taking oral contraceptives have a greater need for B vitamins.
Despite the importance of the B vitamins, some controversy exists as to how much of them we actually need and how many of us are suffering deficits. Some healthcare professionals feel that deficiencies – particularly chronic, low-grade ones – are far more widespread than the conventional medical establishment believes. Deficiencies can manifest in many ways, including fatigue, confusion, anemia, skin rashes, or a compromised immune system. They may contribute to or exacerbate inflammatory conditions from cardiovascular disease to Alzheimer’s and multiple sclerosis. The wide range of deficiency symptoms – along with the underutilization of testing protocols and the use of questionable reference ranges to determine sufficiency – means that vitamin B deficiencies often remain undiagnosed. For reasons such as these, some health practitioners recommend off-the-shelf B-complex supplements for everyone. Others, however, suggest that people without marked deficiencies can generally obtain sufficient amounts from a varied diet of whole foods.
Although all the B vitamins are critical to health, the remainder of this article will focus on three – vitamin B6, folate, and vitamin B12 – that work as partners to protect the cardiovascular and nervous systems. Two of these – folate and B12 – are also particularly important in preconception and pregnancy.
Involved in around 100 enzymatic reactions, vitamin B6, also known as pyridoxine, is used widely in almost all body tissues and functions. It plays a vital role in the metabolism of protein and the production of energy. It is also necessary for proper brain development, maintenance of the protective myelin sheaths that surround nerve cells, and production of neurotransmitters that influence mood, including GABA, dopamine, and serotonin. In fact, research suggests that many cases of depression may be associated with low B6 levels. In addition to brain health, vitamin B6 helps with the production of red blood cells, antibodies, and the sleephormone melatonin. It is connected to hormone balance in women, and the need for it increases during pregnancy and lactation and when using oral contraceptives. Vitamin B6 is also needed to convert tryptophan into niacin (vitamin B3), and alpha-linoleic acid into the fatty acid DHA (docosahexaenoic acid).
Together with vitamins B12 and folate, B6 is also required in order to metabolize homocysteine, a by-product of protein metabolism, so that it does not reach toxic levels in the body. In combination, these three vitamins can lower elevated homocysteine, which is a risk factor for cardiovascular disease, stroke, and peripheral vascular disease. High homocysteine levels increase risk of damage to the arterial linings, leading to the buildup of plaque, which can promote vascular diseases, such as heart disease and stroke. While it is not yet proven that taking B vitamins can reduce risk of cardiovascular disease, research suggests that supplementing with a combination of vitamins B6, B12, and folate may have some protective effect against primary stroke.
Elevated homocysteine has also been associated with cognitive decline. High blood levels can result in brain shrinkage, a notable symptom of neurodegeneration and a predictor of Alzheimer’s. Studies have shown that this combination of B vitamins can slow cognitive decline when taken long term and, in people with high homocysteine levels, can reduce the amount of shrinkage in regions of the brain commonly associated with Alzheimer’s.
Ensuring adequate levels of B6 may help protect against the chronic inflammatory diseases so prevalent in Western society. Low levels of pyridoxal-5-phosphate (known as P5P or PLP), the active form of B6, have been seen in people with diseases associated with inflammation, such as type 2 diabetes, rheum atoid arthritis, and inflammatory bowel disease. Even marginally low P5P levels have been linked with elevated risk of coronary artery disease and stroke. Moreover, adequate B6 intake may significantly decrease colorectal cancer risk.
Statistics indicate that B6 deficiency is widespread in the U.S. It has been estimated that more than 30 million Americans are deficient in this vitamin, using a P5P blood serum level of 20 nmol/L for the cutoff. However, even more of us may have health problems related to low B6, since P5P levels of 20-30 have been linked to increased risk of heart disease and other disorders. (Note, however, that deficiency symptoms may not manifest immediately, as 80 percent of the body’s B6 is stored in muscle tissue, and levels will remain stable until intake has been low for several weeks.
Despite the prevalence of mild B6 deficiency in the U.S., this nutrient is readily found in food. Good dietary sources include animal products, such as salmon, turkey, chicken, beef, beef liver, and other organ meats; and a wide variety of plant-based foods, including potatoes, sweet potatoes, avocados, bananas, sunflower seeds, pistachios and spinach. While the animal foods provide B6 in a more bioavailable form, the form that is found in plants is more stable when heated.
Most B6 supplements in the U.S. are composed of pyridoxine hydrochloride, which is converted to P5P in the body. Others are made up of P5P or a combination of the two. Although both pyridoxine hydrochloride and P5P may have similar bioavailability for most people, those with genetic conditions that hamper the body’s conversion of pyridoxine to its active form may be advised to take P5P. Although excessive doses of pyridoxine can cause nerve damage and skin lesions, some evidence suggests that P5P may not have this effect.
Folate, or vitamin B9, also known as folic acid when in its synthetic form, is crucial to protein synthesis, tissue growth, and the health of rapidly dividing cells, such as red blood cells and those in the gastrointestinal tract. Adequate intake may reduce the risk of heart disease and certain cancers. Low folate levels can lead to megaloblastic anemia – a type of anemia in which red blood cells are fewer and larger than normal – resulting in fatigue, weakness, irritability, forgetfulness, and shortness of breath. Symptoms of folate deficiency also include diarrhea and abdominal pain after eating, tongue inflammation, and gingivitis. Because of its role in cell division and replication, folate is particularly important during pregnancy, in order to prevent anemia in the mother and severe birth defects in the baby. Due in part to the high consumption of refined grain products in the U.S., which are fortified with folic acid, the prevalence of deficiency is relatively low (less than 1 percent) among the general population. Individuals most susceptible to folate deficiency include heavy drinkers and people suffering from digestive disorders, such as celiac, inflammatory bowel disease, and small intestinal bowel overgrowth (SIBO).
Also susceptible to folate deficiency are people with a specific genetic mutation that impacts the function of the MTHFR (methylene tetrahydrofolate reductase) enzyme. This important enzyme is required for the metabolism of homocysteine to methionine, an essential amino acid, and the conversion of folate into its active form, L-5 – methyl tetrahydrofolate. People who carry two copies of the MTHFR gene mutation known as C677T are especially at risk for deficiency and have significantly increased likelihood of developing coronary heart disease, as well as elevated levels of homocysteine in their blood or urine. They may have difficulty metabolizing synthetic folic acid, and may require higher amounts of natural folate from food or supplements, along with vitamins B12 and B6, to mitigate nutritional risks. Methyl folate, which is now available in supplements, may be recommended for those with MTHFR mutations.
In pregnancy, folate deficiencies increase the likelihood of neural tube defects (NTDs), such as spina bifida and anencephaly. Under normal conditions, the spinal column of a fetus begins as a flat structure that turns into a tube during the first month of gestation. NTDs occur when the tube does not close completely, resulting in abnormal development of the spinal cord or of the skull and brain. Folate is also needed for other functions in pregnancy, as it is involved in the production of genetic material (DNA and RNA) and the process of cell division. Pregnancy also significantly increases blood volume and the formation of red blood cells, adding to the body’s demand for folate.
Thus, many doctors recommend supplementing with folate or folic acid during pregnancy. However, the timing of supplementation is particularly important in preventing NTDs. The risk of having children born with NTDs can be reduced by 72-100 percent when women supplement with this nutrient before conception and during the first trimester. Neurulation, the development of the neural tube, begins about 21 days following fertilization and is completed by day 28 – so early in the pregnancy that many women may not even realize they are with child. Therefore, if a woman is considering pregnancy, it is important for her to ensure adequate folate intake prior to conception.
In cases where supplementation is required (due either to pregnancy or deficiency), there is some contention about whether to use natural folate or folic acid. While these terms are often used interchangeably among scientists, researchers, and doctors, they are not synonymous. Folic acid is the synthetic, oxidized form used to fortify grains and cereals in the U.S. and, frequently, to manufacture supplements. The term folate can refer to either folic acid or the forms of the vitamin naturally found in foods. Folic acid is touted as being more bioavailable and rapidly absorbed by the intestines than natural folate. However, there are significant differences in how the body converts each of them into forms that can be used in metabolic functions and enzyme processes.
Unlike natural folates, which are metabolized in the small intestine to the active form tetrahydrofolate (THF), conversion of folic acid to THF takes place in the liver and requires the enzyme dihydrofolate reductase. The low activity of this enzyme in the liver, combined with a high folic acid intake, may result in abnormally high levels of unmetabolized folic acid entering the bloodstream, which can lead to health problems. A few studies – since very few actually distinguish between natural folate and folic acid – have found that a high folic acid level may mask or aggravate symptoms of B12 deficiency, can result in a decrease in activity of natural killer (NK) cells, and may be associated with an increased risk for certain cancers.
If fortified bread, flour, and breakfast cereals are included in one’s diet, their folic acid content should be taken into consideration when determining whether supplementation is warranted. If you do supplement, folate should be taken together with vitamins B6 and B12. Also keep in mind that adequate quantities of zinc are required for folate absorption, and vitamin C helps convert it into its active form.
When providing instruction on the food sources of folate, experts often recommend thinking of “foliage” – referring to the dark leafy greens that are among the best natural sources of this nutrient. Other green vegetables, such as asparagus, broccoli, and Brussels sprouts, are also good sources, as are legumes, particularly sprouted ones. Animal livers, such as beef, lamb, and chicken, are also high in folate. Reducing consumption of processed foods and increasing the amount of high-quality vegetables and animal protein in your diet will lower the risk of having unmetabolized folic acid in your body. Although easily absorbed from fresh, unprocessed foods, folate is highly vulnerable to destruction by light, heat, and a pH level below 4.0. Thus, eating vegetables raw or lightly steaming them is preferable to cooking methods such as boiling.
Like all the B complex vitamins, B12, or cobalamin – named for the single cobalt atom at the center of its molecular structure – plays an important role in the production of energy from dietary fats and carbohydrates. It is essential to the formation of red blood cells, myelin, genetic material, and various proteins, and is involved in the utilization of iron. Together with folate and vitamin B6, it is integral in the production of serotonin, dopamine, and epinephrine.
Cobalamin is found exclusively in products of animal origin – namely, meat, shellfish, eggs, and dairy. (The livers of certain animals and raw dairy products are especially rich sources.) For this reason, deficiency is widespread in individuals following vegetarian or vegan diets. Although some vegetarians eat eggs, the assimilation of B12 from eggs – especially the whites – is rather poor. Moreover, certain plant-based foods reputed to serve as B12 sources, including spirulina, miso, nori, and wakame, actually contain B12 analogs and can worsen a state of deficiency, as they replace the body’s B12 transport molecules and hinder the absorption of actual vitamin B12. All of this means that vegetarians who avoid dairy must rely on supplements to ensure adequate B12 intake. This is particularly important for lifelong vegetarians, who have higher rates of B12 deficiency than those who adopt the diet later in life.
Some people have elevated risk of deficiency, due to problems with absorption of vitamin B12 from foods. Its complex absorption process can cause low B12 levels even in people who consume apparently sufficient amounts through their diet. First, during the digestive process, B12 must be freed from the animal proteins we eat by the action of hydrochloric acid. Then, it must bind with a glycoprotein called intrinsic factor, which is produced by the parietal cells in the stomach – the same cells that produce hydrochloric acid. Intrinsic factor protects B12 during its journey through the gastrointestinal tract and facilitates its absorption into the ileum, part of the small intestine. Therefore, healthy parietal cells with an ability to produce adequate intrinsic factor and sufficient stomach acid are necessary for B12 absorption. The health and function of parietal cells may be impacted by a variety of factors, including the aging process; digestive disorders, such as Crohn’s disease, irritable bowel syndrome, and gastroesophageal reflux disease; alcoholism; the use of medications that lower stomach acid production, such as antacids and proton pump inhibitors; and autoimmune disorders that damage these cells. Poor absorption of B12 due to a lack of intrinsic factor leads to pernicious anemia, characterized by abnormally large red blood cells; this is a different condition than B12-deficiency anemia, which is caused by insufficient intake of the nutrient.
Unlike the other B vitamins, which are immediately excreted after the body’s needs are met, B12 can be stored in the liver for several months. Some of the B12 secreted into the small intestine is also reabsorbed and reused by the liver. These mechanisms can safeguard against deficiencies when the diet is poor or absorption problems arise. However, if such conditions exist long-term, the body’s stores will eventually run out. When they are finally depleted, symptoms tend to progress quickly.
Deficiency is primarily exhibited as anemia, cognitive problems, and disorders of the nervous system. Symptoms may include pale skin, fatigue, shortness of breath, and heart palpitations. Low levels of B12 can also lead to depression, confusion, and tingling in the extremities, and have been associated with dementia, Alzheimer’s, and Parkinson’s disease. Because some of their neurological effects can be permanent, it is important to correct deficiencies early. High-dose supplementation can have remarkable effects. For example, B12 has been used as a therapeutic treatment for Alzheimer’s, with high rates of success.
B12 may also play a role in the prevention of certain cancers. Low blood levels of B12 have been linked to an increased risk of breast cancer in postmenopausal women, [14,15] while high B12 and folate intakes were associated with decreased breast cancer risk. In addition, B12 (along with vitamins B1, B2, and folate) has been found to help protect against the development of cervical cancer.
The importance of vitamin B12 – together with its partners, B6 and folate – in the metabolism of homocysteine, a risk factor for cardiovascular disease, has been previously noted. Additionally, recent research notes B12’s involvement in maintaining healthy bones through the mechanism of homocysteine. Elevated levels of homocysteine, in combination with low B12, have been associated with poor bone health. The results of a meta-analysis examining B12 and bone health confirm a decreased risk for bone fractures with an increase in B12 levels and a decrease in homocysteine blood concentrations.
B12 is also required for the conversion of folate into a form the body can use, and the two depend on one another for proper function in the body; thus, it is best to supplement with both to avoid precipitating imbalance and exacerbating symptoms of deficiency. In pregnancy, B12 works closely with folate in the production and delivery of genetic material, cell division, proper fetal development, and the manufacture of red blood cells. And, like folate, the need for B12 is increased during pregnancy. Even marginally low levels of B12 may increase risk of postpartum depression.
Like folate deficiency, B12 deficiency can develop in an infant if the mother was deficient throughout her pregnancy or while breastfeeding. This can have drastic effects on childhood growth and development, including abnormal brain development, hypotonia (a state of low muscle tone), feeding difficulties, lethargy, tremors, hyperirritability, and even coma. While these manifestations can often be resolved by adding B12 to the diet or taking supplements, deficiencies that persist may result in irreversible damage. Therefore, adequate maternal intake of B12 is essential for a healthy baby. If a soon-to-be mother is vegetarian, it may be advisable for her to consume dairy products, and she should consider supplementation.
An additional factor that may contribute to the development of B12 deficiency symptoms is the fact that the ranges deemed adequate for vitamin B12 blood levels in the U.S. are among the lowest worldwide. B12 deficiency in the U.S. is generally characterized by a blood level lower than 200 pg/mL – far beneath the lower limit of normalcy, 500-550 pg/mL, used by Japan and European nations. The scientific literature shows that people with blood serum levels between 200 and 350 pg/mL have clear deficiency symptoms. Data suggests that 40 percent of the population between the ages of 26 and 83 have levels in the low normal range, according to U.S. standards, and this range may be associated with neurological problems. Moreover, research indicates that some individuals who fall within the low end of the normal range exhibit markers of B12 deficiency – namely, high levels of homocysteine and methylmalonic acid (MMA), and suppression of deoxyuridine, which is involved in DNA synthesis.
Some experts state that elevated homocysteine and MMA are more sensitive markers for deficiency than serum B12 levels, and recommend that tests for these two markers be used when patients exhibit symptoms of deficiency despite having normal serum levels. Moreover, the MMA test is often deemed more reliable than homocysteine, which may be elevated due to other factors, such as low folate or B6 levels. Naturopath David Getoff, CCN, CTN, FAAIM, explains that a serum B12 test only tells how much of the vitamin is circulating in the blood serum, not how much is getting into the cells. He recommends the MMA test, noting that high levels indicate that the cells are not getting enough B12, due to either an intake or absorption issue.
When deficiency is present, a combination of B12-containing foods (such as beef liver, sardines, raw cheeses, and cottage cheese) and oral supplementation is usually enough to correct it. Most B12 supplements are in the form of cyanocobalamin, a synthetic form of the vitamin. Although this form includes a cyanide molecule, the cyanide is normally excreted through the urine and is generally considered safe for most people. Those with kidney failure, however, would be advised to use methylcobalamin or hydroxycobalamin. The methylcobalamin form, which contains a methyl group (consisting of carbon and hydrogen) instead of cyanide, is gaining popularity. One of the active forms of B12 found naturally in the body, methylcobalamin appears, on the basis of some studies, to be more easily absorbed. In cases of severe deficiency, or when deficiency is related to impaired absorption, B12 may be administered via injection. However, nasal gel preparations and high-dose, easily absorbable oral supplements, such as drops, sprays, or lozenges, can be equally effective – and are less expensive.
Sources of the B-complex vitamins
- Many people can achieve a healthy B-vitamin status through the use of diet alone. Focusing on the following whole, unprocessed foods will help you get the B vitamins you need for optimal health:
- Meat, fish, poultry, and eggs provide varying amounts of all of the B vitamins except folate. Although lacking niacin (B3), eggs contain the amino acid tryptophan, which is used to make niacin. Choose organic, pasture-raised, and grassfed animal products.
- Organ meats, especially liver, are good sources of all the B vitamins, particularly B12.
- Fresh vegetables and some fruits contain various B vitamins, other than B12. Dark green, leafy vegetables are great sources of folate, especially when eaten raw.
- Brewer’s and nutritional yeasts are good sources of most of the B vitamins, particularly thiamine (B1) and riboflavin (B2). The only missing vitamin is B12, but this is often added to nutritional yeast, making it a source of B12 for vegetarians.
- Whole grains provide the full complement of B vitamins except for vitamin B12. In grains, much of the vitamin content is contained in the germ and bran, which are removed in the milling process (up to 90 percent in the case of niacin). Soak and sprout whole grains to make them more easily digestible and to promote increased absorption of B vitamins.
- Legumes, nuts, and seeds also contain varying amounts of all the B vitamins except for B12. As with grains, it is best to soak and sprout these foods to improve their digestibility and absorption of their B vitamin content.
A diverse diet comprised of fresh, unprocessed foods can help prevent B vitamin deficiency, although certain circumstances may require supplementation. An adequate supply of all the B vitamins (not just folate and B12) is particularly important for those considering pregnancy and those already pregnant; in addition to a sizable intake of foods containing B vitamins, including dark green vegetables and a wide range of animal products, supplementation up to one year prior to conception and throughout pregnancy may be the best course of action.
While each B vitamin has its own distinct purpose in the body, it is important to recognize that they work together as a team. If you do need supplementation, choose a high-quality B-complex supplement, rather than relying on any one single B vitamin.
Price-Pottenger members can read hundreds of additional articles on our website.
To become a member, click here.
About the Author
Stephanie Cold is the communications specialist for the College of Agriculture, Food and Environmental Sciences at the University of Wisconsin-River Falls. She has previously worked with multiple local food cooperatives in the areas of marketing and communications and has taught community education classes on the topics of fermentation, raw milk, and more.
Selected foods high in B vitamins
|Chickpeas, cooked, ¾ cup||0.84 mg|
|Beef liver, cooked, 2 ½ oz||0.66-0.76 mg|
|Chicken liver, cooked, 2 ½ oz||0.57-0.63 mg|
|Venison, cooked, 2 ½ oz||0.46-0.57 mg|
|Banana, 1 medium||0.43 mg|
|Potato, cooked, 1 medium||0.37-0.60 mg|
|Salmon, Chinook, 2 ½ oz||0.35-0.36 mg|
|Pistachios, without shell, ¼ cup||0.35 mg|
|Sweet potato, cooked, 1 medium||0.33 mg|
|Sunflower seeds, w/o shell, ¼ cup||0.27-0.48 mg|
|Avocado, ½ fruit||0.26 mg|
|Beef, various cuts, cooked, 2 ½ oz||0.20-0.30 mg|
|Chicken liver, cooked, 2 ½ oz||420-518 mcg|
|Yeast extract spread, 2 Tbsp||360 mcg|
|Lentils, cooked, ¾ cup||265 mcg|
|Adzuki beans, cooked, ¾ cup||234-238 mcg|
|Asparagus, cooked, 4 spears||128-141 mcg|
|Beef liver, cooked, 2 ½ oz||122-195 mcg|
|Spinach, cooked, ½ cup||121-139 mcg|
|Broccoli, cooked, ½ cup||89 mcg|
|Brussels sprouts, cooked, 6 sprouts||83 mcg|
|Artichoke, cooked, ½ cup||79-106 mcg|
|Turnip greens, cooked, ½ cup||68-93 mcg|
|Spinach, raw, 1 cup||61 mcg|
|Lamb kidney, cooked, 2 ½||59.2 mcg|
|Beef or lamb liver, cooked, 2 ½ oz||52.9-66.0 mcg|
|Mussels, cooked, 2 ½ oz||18.0 mcg|
|Clams, cooked, 2 ½ oz||14.6 mcg|
|Herring, Atlantic, kippered, 2 ½ oz||14.0 mcg|
|Oysters, cooked, 2 ½ oz||13.2-21.6 mcg|
|Chicken liver, cooked, 2 ½ oz||12.6-23.4 mcg|
|Ground beef, cooked, 2 ½ oz||2.4-2.7 mcg|
|Swiss cheese, 1 ½ oz||1.7 mcg|
|Egg, cooked, 2 large||1.5-1.6 mcg|
|Milk, 1 cup||1.2-1.4 mcg|
|Cottage cheese, 1 cup||1.1-1.5 mcg|
Source: Dietitians of Canada. Vitamins. www.dietitians.ca/Your-Health/Nutrition-A-Z/Vitamins.aspx.
- Weintraub PW . All about B vitamins. Experience Life. September 2010. https://experiencelife.com/article/all-about-b-vitamins/. Accessed May 22, 2017.
- Hvas AM, Juul S, Bech P, Nexø E. Vitamin B6 level is associated with symptoms of depression. Psychother Psychosom. 2004; 73(6):340-343. doi: 10.1159/000080386.
- Busch F. The New Nutrition: From Antioxidants to Zucchini. New York: John W iley & Sons, Inc; 2000.
- Lee M, Hong KS, Chang SC, Saver JL. Efficacy of homocysteine-lowering therapy with folic acid in stroke prevention: a meta-analysis. Stroke. 2010; 41(6):1205-1212. doi: 10.1161/STROKEAHA.109.573410.
- Consumer Lab. Product review: B vitamin supplements (B complexes, B6, B12, biotin, folate, niacin, riboflavin & more). https://www.consumerlab.com/reviews/Review_Best_B_Vitamins_and_Complexes…. Updated April 18, 2017. Accessed May 15, 2017.
- National Center for Environmental Health. Second National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population. 2012. http://www.cdc.gov/nutritionreport/pdf/Nutrition_Book_complete508_final.pdf.
- Low Dog T. Fortify Your Life: Your Guide to Vitamins, Minerals & More. Washington, DC: National Geographic Society, 2016.
- University of Maryland Medical Center (UMMC). Vitamin B9 (folic acid). http://umm.edu/health/medical/altmed/supplement/vitamin-b9-folic-acid. Updated June 21, 2013. Accessed August 12, 2015.
- Kresser C. The little known (but crucial) difference between folate and folic acid. http://chriskresser.com/folate-vs-folic-acid. Published March 9, 2012. Accessed August 12, 2015.
- Doscherholmen A, McMahon J, Ripley D. Inhibitory effect of eggs on vitamin B12 absorption: description of a simple ovalbumin 57Co-vitamin B12 absorption test. Br J Haematol.1976; 33(2):261-272. PMID: 944587.
- Pawlak R, Parrott SJ, Raj S, et al. How prevalent is vitamin B12 deficiency among vegetarians? Nutr Rev. 2013; 71(2):110-117. doi: 10.1111/nure.12001.
- Hattersley JG. High-dose vitamin B12 for at-home prevention and reversal of Alzheimer’s disease (AD) – and much more. PPNF Journal of Health and Healing. 2005; 29(2).
- Lieberman S, Bruning N. Real Vitamin & Mineral Book. New York: Avery; 2007.
- Choi SW. Vitamin B12 deficiency: a new risk factor for breast cancer? Nutr Rev. 1999; 57(8):250-253. PMID: 10518411.
- Wu K, Helzlsouer KJ, Comstock GW, et al. A prospective study on folate, B12, and pyridoxal 5’-phosphate (B6) and breast cancer. Cancer Epidemiol Biomarkers Prev. 1999; 8(3):209-217. PMID: 10090298.
- Lajous M, Lazcano-Ponce E, Hernandez-Avila M, et al. Folate, vitamin B(6), and vitamin B(12) intake and the risk of breast cancer among Mexican women. Cancer Epidemiol Biomarkers Prev. 2006; 15(3):443-448. DOI: 10.1158/1055-9965.EPI-05-0532.
- Hernandez BY, McDuffie K, Wilkens LR, Kamemoto L, Goodman MT. 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):859-870. DOI: 10.1158/1055-9965.EPI-05-0532.
- Mercola J. Vitamin B12 deficiency and bone health. http://articles.mercola.com/sites/articles/archive/2014/09/15/vitamin-b1…. Published September 15, 2014. Accessed August 17, 2015.
- van Wijngaarden JP, Doets EL, Szczecinska A, et al. Vitamin B12, folate, homocysteine, and bone health in adults and elderly people: a systematic review with meta-analysis. J Nutr Metab. 2013. doi: 10.1155/2013/486186.
- Stabler SP. Vitamin B12 deficiency. N Engl J Med. 2013; 368(2):149–159. doi: 10.1056/NEJMc1304350.
- Fallon S, Enig MG. Vitamin B12: vital nutrient for good health. www.westonaprice.org/health-topics/abcs-of-nutrition/vitamin-b12-vital-n…. Published July 28, 2005. Accessed August 12, 2015.
- Kresser C. B12 deficiency: a silent epidemic with serious consequences. http://chriskresser.com/b12 -deficiency-a-silent-epidemic-with-serious-consequences. Published May 6, 2011. Accessed May 24, 2017.
- Moore EM, Watters DAK, Ames D, Mander AG. Vitamin B12 and cognitive impairment. In: Martin CR, Preedy VR, eds. Diet and Nutrition in Dementia and Cognitive Decline. Burlington, VT: Elsevier Science; 2014;637-648.
- Getoff D. Attaining optimal health in the 21st century [online course transcript]. Price-Pottenger Nutrition Foundation. 2012.
Published in the Price-Pottenger Journal of Health and Healing
Spring 2017 | Volume 41, Number 1
Copyright © 2017 Price-Pottenger Nutrition Foundation, Inc.®
All Rights Reserved Worldwide