![\"B12](\"https:\/\/ascensionkitchen.com\/wp-content\/uploads\/2016\/08\/B12-plant-based-diet-vegan.jpg\")
<\/p>\n<\/p>\n
This is the first of a series of posts I am sharing on plant based nutrition. I have personally enjoyed a plant based diet for close to ten years. Some of which have been as a vegetarian, and some as vegan. I have experienced numerous deficiencies during my journey, partly due to malabsorption, though I believe a lack of education was at the heart of it all. Yes, you can be healthy and well on a conscious and compassionate diet – but it takes careful planning and awareness of what your own unique body needs. <\/p>\n
[bctt tweet=\"B12 on a Plant Based Diet - what you need to know. Learn more here.\"]<\/p>\n
B12<\/sub> (cobalamin) is required for DNA synthesis and cell division, and is essential for maintaining the integrity of the protective sheath (myelin) surrounding nerve fibres. A deficiency can result in neurological manifestations.<\/em><\/span><\/p>\n B12 <\/sub>is produced by bacteria in the large intestines of animals. This is also true for us – however, since the absorption of B12<\/sub> occurs further up the colon (the terminal ileum), we are unable to make use of our own B12<\/sub> synthesis. It is simply excreted via a bowel movement [1, 2, 3]. <\/sub><\/em><\/span><\/p>\n B12<\/sub> for the most part, is found in animal products such as meat, poultry, seafood and dairy. It is not readily available in plant based foods, which makes it a nutrient of concern for those on a plant-based diet, particularly since a deficiency can cause serious health problems [1].<\/em><\/span><\/p>\n There are a lot of myths surrounding plant based sources of B12<\/sub><\/em>. Spirulina and blue-green algae contain a B12<\/sub> analogue that is not bioavailable to us. Nutritional yeast may provide adequate amounts, though often it has been fortified with a synthetic form. Chlorella may be a good source, but B12<\/sub> content varies widely<\/em>. One recent study has found nori to be a great source, however, the study was conducted on rats. Further studies are needed to validate whether it is a truly reliable source. To summarise - plant based sources are simply not reliable.<\/em><\/span><\/p>\n Strict vegetarians\/vegans may not notice a deficiency for years after starting a plant based diet, as the body readily stores B12<\/sub>. It is a good idea to be proactive and take a blood test to discern your B12<\/sub> status. The traditional serum B12<\/sub> blood test is controversial as it isn’t a very sensitive test – it measures the total sum of both active and inactive forms of B12<\/sub>. Better markers for B12 <\/sub>status may be homocysteine, methylmelonic acid and holotranscobalamin.<\/em><\/span><\/p>\n Supplementation may be required to meet needs after a while, methylcobalamin being the most active form. Absorption of B12<\/sub> depends on a healthy gut and adequate levels of hydrochloric acid.<\/em><\/span> <\/strong> <\/strong> <\/strong><\/p>\n 2.4 mcg\/day<\/strong> for adult men and women. <\/p>\n 2.6 mcg\/day<\/strong> during pregnancy.<\/span><\/p>\n 2.8 mcg\/day<\/strong> during lactation.<\/p>\n There is no set upper level of intake, with no evidence to suggest adverse effects associated with excess B12<\/sub> intake from food or supplements in healthy individuals [4].<\/span><\/p>\n The term ‘vitamin B12<\/sub>’ actually refers to a group of compounds with a central cobalt atom (known as “corrinoids”). Of the five forms, cyanocobalamin is the synthetic form you may be familiar with, as it is formulated in supplements. Hydroxycobalamin, aquacobalamin, methylcobalamin (methyl-B12) and 5-deoxyadenosylcobalamin are all natural sources, methyl-B12 being a highly active form [5].<\/span><\/p>\n [5, 6, 7].<\/span><\/p>\n Major signs of deficiency include megaloblastic anaemia and neurological manifestations [14].<\/span> Deficiency can cause an erosion of the protective sheath around nerve fibres in the periphery, spinal cord, optic and cranial nerves, and brain.<\/p>\n The neurological symptoms experienced may include;<\/strong><\/p>\n Damage caused may be irreversible if not detected early [1, 8].<\/span><\/p>\n Other signs and symptoms include;<\/strong><\/p>\n [8, 9].<\/span><\/p>\n In actuality, of the known cases of B12<\/sub> deficiency in the wider population, 95% are due to inadequate absorption or impaired utilisation. Inadequate dietary intake, increased requirements (such as pregnancy and lactation), and increased excretion due to alcoholism make up the remainder. However, in regards to vegetarian and vegan populations, inadequate dietary intake does account for the major cause [1].<\/span><\/p>\n The digestion and absorption of B12 <\/sub>is a little bit like ‘pass the parcel’ – with numerous protein transporters taking turns at escorting it along the digestive tract.<\/p>\n When vitamin B12<\/sub> is consumed from dietary sources, it is bound to protein and must be released in order to be absorbed. Once it reaches the stomach, gastric acid – also known as hydrochloric acid (HCl), with the help of enzymes, detaches the B12<\/sub> from the protein. From here, another protein (R-factor) attaches to the B12<\/sub> and transports it to the small intestine [1].<\/span><\/p>\n Meanwhile, intrinsic factor (a glycoprotein) is being produced by parietal cells within glands located in the fundus and body of the stomach [10].<\/span> Its secretion is stimulated by pathways that also stimulate gastric acid secretion [11].<\/span> It travels from the stomach to the small intestine and forms a complex with B12<\/sub> after the R-factor has delivered it and been enzymatically degraded. The new B12<\/sub>-intrinsic factor complex protects the B12<\/sub> from the environment in the gut, and transports it to the terminal ileum (the very end section of the small intestine) where it is finally absorbed by intestinal cells with the help of yet another protein transporter [1, 8].<\/span><\/p>\n A B12<\/sub> deficiency may be caused by a lack of production or function of intrinsic factor, leading to malabsorption. This is known as pernicious anaemia. Deficiency may also occur due to genetic defects resulting in malabsorption despite adequate, functioning intrinsic factor [12].<\/span> It is worth noting that medications that reduce gastric acidity (such as those taken for stomach ulcers) will consequently impact B12<\/sub> absorption. Any resection (removal) of the ileum will decrease absorption, as will conditions such as irritable bowel syndrome, ulcerative colitis and Crohn’s disease. Finally, bacteria and intestinal parasites may compete for B12<\/sub> [5].<\/span><\/p>\n Naturopathically speaking, it’s important to maintain stomach acid (hydrochloric acid - HCl), given its role in liberating the vitamin from food. Things that may adversely affect stomach acid are infections such as H. pylori<\/em>, chronic overeating, chronic stress, excess intake of processed foods and carbohydrates, caffeine and alcohol (sorry!) [10].<\/span> A microbial imbalance in the small intestine, also known as intestinal dysbiosis or Small Intestinal Bacterial Overgrowth (SIBO), often occurring after antibiotics, may also contribute to a decrease in HCl [13].<\/span><\/p>\n A whole foods diet that includes plenty of bitter foods is a great way to keep gastric acid stimulated. Anecdotal evidence suggests apple cider vinegar before a meal is also helpful, and, in some cases, a Naturopath or Herbalist may see it appropriate to prescribe digestive bitters such as gentian, dandelion and wormwood.<\/p>\n Vegans have a greater risk of developing a B12<\/sub> deficiency, relative to non-vegetarians [14].<\/span> However – it may take years to notice deficiency symptoms as the body can store B12<\/sub> for a very long time.<\/p>\n As mentioned, Vitamin B12<\/sub> is synthesized by certain types of bacteria, and concentrated in the bodies of predators higher in the food chain [15].<\/span> Sources include;<\/p>\n Of the above, the bioavailability (the amount of B12<\/sub> that is absorbed into systemic circulation and hence available for use) of fish, lamb and chicken ranges from 42%-66%. Less than 9% of vitamin B12<\/sub> from eggs is absorbed [14],<\/span> and furthermore, up to 10% is lost in cooking [5]. <\/strong><\/span><\/p>\n Generally speaking, B12 <\/sub>is not readily available on a plant based diet. However, there are a few foods in which it is found, in varying amounts. This is an incredibly grey area however, and while it is true that a few isolated studies have found good amounts of B12<\/sub> in plant foods (such as nori), they need to be repeated on a larger scale, in humans, before anyone can safely recommend them as a truly reliable source without the need for supplementation.<\/p>\n Additionally, a common trap many fall in to, is thinking a food has appreciable amounts of B12<\/sub>, when in actual fact, the amount per serving<\/em> of that food is just not significant.<\/p>\n ***<\/p>\n Tempeh, <\/strong>fermented soy bean, was shown in one study to be a great source of B12<\/sub>, however, the amount of B12<\/sub> per 100g can vary so widely that it is simply not a reliable source [14]. <\/strong><\/span><\/p>\n Nori <\/strong>– the research on B12<\/sub> content in nori (purple laver) – the dried and toasted seaweed you make sushi with, is probably the most promising. Animal studies have shown it to be in a bioavailable form, with a 4g serving meeting the RDI for adults [14, 16].<\/span> Again, it is risky to bet all your B12<\/sub> just on nori – there could well be huge variations in B12<\/sub> content within regions, and human studies are needed to validate findings.<\/p>\n Chlorella, <\/strong>a microalgae that is often sold as a supplemental powder or tablets, contains biologically active B12<\/sub>. A recent study found that that B12<\/sub> content however widely varied – from zero to several micrograms per 100g dry weight [15].<\/span> It would be a good idea to check the nutritional panel on chlorella products to see what it is you are really getting.<\/p>\n Shiitake mushrooms <\/strong>have been shown to contain high levels of B12<\/sub> in a bioavailable form. About 50g of dried shiitake mushroom would meet the RDI for adults, however this just doesn’t seem practical on a day to day basis [15].<\/span><\/p>\n Nutritional yeast <\/strong>is another source of B12. <\/sub>I have not come across any studies yet that determine whether this is in the bioavailable or analogue form. Some brands fortify their nutritional yeast with B vitamins. I believe the Braggs brand however contains B12<\/sub> due to a natural fermentation. <\/p>\n In addition to the few plant based sources, many cereals, soy products and vegetarian ‘meats’ are fortified with B12<\/sub>. <\/strong><\/p>\n Spirulina <\/strong>and edible algae other than those mentioned do not provide active B12<\/sub>. They contain an analogue that is not bioavailable to humans. There is a blue-green algae<\/strong> (Aphanizomenon flos-aquae<\/em>) on the market advertised as having one of the highest percentages of B12<\/sub> on the planet – however, in actual fact, it contains only pseudovitamin B12<\/sub> – which is biologically inactive in humans [14].<\/span><\/p>\n [bctt tweet=\"B12 myth busting: spirulina and blue-green algae are NOT sources of B12 for humans!\"]<\/p>\n Spirulina and blue-green algae are not sources of B12! They contain analogues that are biologically inactive.<\/span><\/p>\n A B12 <\/sub>or<\/strong> folate deficiency can result in megaloblastic anaemia – a term used to describe large, immature red blood cells that can’t divide, or carry oxygen efficiently. It is important to discern which nutrient is deficient, as giving folate to someone who is in fact B12<\/sub> deficient will correct the anaemia but not the neurologic damage, which may become irreversible [9]. <\/span><\/p>\n This is how folate can ‘mask’ a B12<\/sub> deficiency, and, as vegetarians\/vegans typically have (or should have!) a diet rich in leafy greens (folate), it is a good idea to be proactive and get blood tests to discern B12<\/sub> status.<\/p>\n Typically, a blood test is taken to assess serum B12<\/sub> status. However, there are some controversies around this. It is thought that this method is inaccurate as it does not discern whether the B12<\/sub> in the blood is the active or biologically inactive form [17].<\/span> This means analogues in foods such as sea vegetables and green powders (spirulina, blue green algae, barley grass) could give a person a falsely high reading.<\/p>\n There are other blood tests that can be helpful in detecting both B12<\/sub> and folate deficiencies. These include homocysteine and methylmelonic acid (MMA). In a B12<\/sub> deficiency, Homocysteine and MMA will be elevated, while only homocysteine (not MMA) will be elevated with a folate deficiency [18].<\/span> Raised plasma homocysteine levels are associated with long-term cardiovascular risk, and risk of neurodegenerative diseases such as Alzheimer’s [19].<\/span><\/p>\n Holotranscobalamin II (TC2) is another way to assess B12<\/sub>. It is a protein that transports B12<\/sub> in the blood, falling with a deficiency [1].<\/span> It is thought to be a far more sensitive test than the standard serum B12 <\/sub>blood test [20].<\/span><\/p>\n Vegetarians consuming dairy and eggs will still be receiving B12<\/sub> in the diet, however vegans need to rely on supplement or conscious consumption of fortified foods, as natural plant based sources do not provide significant or reliable amounts [1].<\/span> The body can only absorb a little B12<\/sub> at a time. Studies suggest small and frequent doses are advantageous [21].<\/span><\/p>\n This is part of a series on plant based nutrition. If you enjoyed the article and learnt something new, please feel free to share. Sign up to my newsletter below to get the series in your inbox as they come. My plan is to post these fortnightly.<\/em><\/span><\/p>\n Lauren.<\/em><\/span><\/p>\nB12 RDI:
\n<\/strong><\/h2>\nIntroduction<\/h2>\n
What does vitamin B12<\/sub> do? <\/strong><\/h2>\n
\n
B12<\/sub> Deficiency<\/h2>\n
\n
\n
What causes a B12<\/sub> deficiency?<\/h2>\n
\n
Gut health matters: Digestion and absorption of B12<\/sub><\/h2>\n
Vegetarian \/ Vegan Needs<\/h2>\n
Food sources<\/h2>\n
\n
Plant based sources<\/h2>\n
Myth busting<\/h2>\n
![\"B12](\"https:\/\/ascensionkitchen.com\/wp-content\/uploads\/2016\/08\/Spirulina-B12-vegan.jpg\" "\\"B12")
<\/p>\nFolate can ‘mask’ a B12<\/sub> deficiency<\/h2>\n
Testing for B12<\/sub><\/h2>\n
Supplements<\/h2>\n
In the series:<\/h3>\n
![\"Iron](\"https:\/\/ascensionkitchen.com\/wp-content\/uploads\/2016\/09\/Iron-plant-based-diet-vegan-1.jpg\")
<\/a>![\"Protein](\"https:\/\/ascensionkitchen.com\/wp-content\/uploads\/2016\/10\/Protein-plant-based-diet-vegan.jpg\")
<\/a>![\"Calcium](\"https:\/\/ascensionkitchen.com\/wp-content\/uploads\/2016\/09\/Calcium-plant-based-diet-vegan.jpg\")
<\/a>![\"Zinc](\"https:\/\/ascensionkitchen.com\/wp-content\/uploads\/2016\/10\/Zinc-plant-based-diet-zinc-vegan-diet.jpg\")
<\/a><\/p>\nReferences:<\/strong><\/h5>\n
\n
Zeuschner, C.L., Hokin, B.D., Marsh, K.A., Saunders, A.V., Reid, M.A., & Ramsay, M.R. (2012). Vitamin B12<\/sub> and vegetarian diets. MJA Open, 1<\/em>(2), 27-32. Doi: 10.5694\/mjao11.11509<\/span><\/h5>\n<\/li>\n
Kau, A.L., Ahern, P.P., Griffin, N.W., Goodman, A.L., & Gordon, J.I. (2011). Human nutrition, the gut microbiome, and immune system: envisioning the future. Nature, 474<\/em>(7351), 327-336. Doi: 10.1038\/nature10213<\/span><\/h5>\n<\/li>\n
Allen, R.H., & Stabler, S.P. (2008). Identification and quantitation of cobalamin and cobalamin analogues in human feces 1’2’3. American Society for Clinical Nutrition, 87<\/em>(5), 1324-1335. Retrieved from http:\/\/ajcn.nutrition.org\/content\/87\/5\/1324.long<\/a><\/span><\/h5>\n<\/li>\n
Nutrient Reference Values for Australia and New Zealand. (2014). Vitamin B12<\/sub>. Retrieved from https:\/\/www.nrv.gov.au\/nutrients\/vitamin-b12<\/a><\/span><\/h5>\n<\/li>\n
Braun, L, & Cohen, M. (2015). Herbs & natural supplements. An evidence-based guide <\/em>(4th ed., Vol. 2). Sydney, Australia: Churchill Livingstone<\/span><\/h5>\n<\/li>\n
Harvard Medical School. (2009). Retrieved from: http:\/\/www.health.harvard.edu\/staying-healthy\/listing_of_vitamins<\/a><\/span><\/h5>\n<\/li>\n
Coppen, A., & Bolander-Gouaille, C. (2005). Treatment of depression: Time to consider folic acid and vitamin B12. Journal of Psychopharmacology, 19<\/em>(1), 59-65<\/span><\/h5>\n<\/li>\n