Important Message from ProHealth Founder, Rich Carson

Fatigue & Brain Fog: Could You Have a B-12 Deficiency?

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Is fatigue your ever-present companion? Despite the fact that you’re always tired, are you having trouble sleeping? Do you have difficulty focusing your thoughts? Is your memory getting worse? Do you have diarrhea, constipation or perhaps alternate between the two? These can all be indications that your body is not getting enough vitamin B-12.

Vitamin B-12 (cobalamin) is an essential nutrient, meaning it is required for normal body functioning but cannot be produced by the body. Therefore, it is necessary to obtain the B-12 your body needs through the food you eat and/or dietary supplements.

A B-12 vitamin deficiency is not uncommon. In fact, it’s thought to affect up to 15% of the general population. That percentage tends to be significantly higher in chronic illness populations.

Because so many people are deficient in B-12, particularly people with fibromyalgia and ME/CFS, and because many fibromyalgia and ME/CFS specialists recommend high doses of B-12 for their patients, ProHealth’s founder, Rich Carson, set out to develop a super-potent B-12 vitamin. The result was B-12 Extreme™ –– which contains the world’s most potent single dose of all four forms of vitamin B-12.

Symptoms of a B-12 Vitamin Deficiency

The symptoms of a vitamin B-12 deficiency are remarkably similar to many of the symptoms of fibromyalgia, ME/CFS, Lyme disease, multiple chemical sensitivities and Gulf War syndrome. While a B-12 deficiency is not thought to be the cause of these illnesses, it has been implicated as a possible factor in a number of different chronic illnesses. The symptoms of a vitamin B-12 deficiency may include:

Fatigue, Weakness

Memory loss




Shortness of breath

Poor sense of balance

Vision problems

Diarrhea or constipation

Loss of appetite

Cognitive functioning problems

Beefy, red, smooth and sore tongue

Sore mouth and/or bleeding gums

Numbness and tingling of hands and feet

Loss of hearing and tinnitus


Pale, possibly yellowish pallor in light-skinned individuals; blotchy pigmentation in dark-skinned individuals

The Connection Between B-12, Fibromyalgia and ME/CFS

Since a B-12 deficiency has so many symptoms in common with fibromyalgia and ME/CFS, researchers were naturally interested in whether or not low levels of B-12 could play a part in those illnesses.

A 1997 study of 12 patients with fibromyalgia and ME/CFS found that most had little or no detectable B-12 in their cerebrospinal fluid –– despite the fact that their B-12 blood tests were all normal. Conversely, they had high levels of homocysteine in their cerebrospinal fluid. Homocysteine is an amino acid, too much of which can be toxic to nerves and blood vessels, and may result in increased pain sensitivity and/or heart disease. When there is not enough vitamin B-12, homocysteine levels increase. As B-12 levels rise, homocysteine levels decrease.

Well-known and highly respected specialists like Drs. Mark Pellegrino, Paul Cheney, Charles Lapp, Kenny DeMeirleir, Jacob Teitelbaum, and Martin Pall all recommend vitamin B-12 for their fibromyalgia and ME/CFS patients.

Dietary Sources of Vitamin B-12

Vitamin B-12 is produced primarily in the digestive tracts of animals. The richest dietary sources of B-12 are beef liver and clams. Other good natural sources include meat, fish, eggs and dairy products. Some breakfast cereals and nutritional yeasts are fortified with B-12; however, they do not contain adequate amounts to be used as the sole dietary source.

Although a few plants like seaweed, algae and certain mushrooms contain some B-12, it doesn’t behave the same way in the body as the B-12 that comes from animal-based sources. Consuming plant-based sources of B-12 does not significantly increase vitamin B-12 levels in the body and should not be relied upon as the only source of B-12. Therefore, it’s particularly important for vegans to supplement vitamin B-12.

Are You Getting Enough B-12?

A better question might be “Are you absorbing enough B-12?

A deficiency of vitamin B12 is not usually caused by insufficient dietary intake but rather by a lack of intrinsic factor secretion. In order for the B-12 obtained from food to be absorbed by the body, it must attach itself to a protein called intrinsic factor, which is secreted in the stomach. Without intrinsic factor, vitamin B-12 cannot be absorbed.

Unfortunately, a number of things can inhibit the secretion of intrinsic factor, which in turn blocks the absorption of B-12 and results in a vitamin B-12 deficiency. High-risk factors for poor absorption include:

  • Digestive disorders such as celiac disease, Crohn’s disease, irritable bowel syndrome, bacterial overgrowth in the small intestine or a parasite.
  • Gastric bypass surgery.
  • Acid-reducing medications – Medications commonly prescribed for heartburn, GERD, acid reflux and peptic ulcers, such as proton pump inhibitors like Prilosec, Prevacid and Nexium, or H2 (histamine2) receptor antagonists like Pepcid and Zantac, suppress the secretion of stomach acids, also blocking the secretion of intrinsic factor.
  • Diabetes medications – Drugs like Metformin, used to treat diabetes, are known to impair intestinal absorption.
  • Aging – The older we get the more likely we are to be deficient in B-12. The Institute of Medicine (IOM) recommends that adults over 50 supplement their diets with vitamin B-12.
  • Vegetarian and vegan diets – Since B-12 is only found naturally in animal foods, it is important for people on these diets to supplement their diets with B-12.
  • Pernicious anemia – a blood disease that develops when the body lacks the intrinsic factor necessary to naturally absorb vitamin B12 from food.

Diagnosing a Vitamin B-12 Deficiency

A B-12 deficiency can be difficult to diagnose because serum blood levels of B-12 may test normal. Having circulating B-12 in the blood doesn’t mean it is being utilized properly by the body’s cells.

Some doctors suggest that a test measuring methyl-malonyl coenzyme A levels in the urine gives a more accurate reading of B-12’s availability in the body. However, because there are no known toxic effects, even at extremely high dosages, often doctors will prescribe vitamin B-12 based on symptoms and risk factors, rather than testing for a deficiency.

The Four Forms of B-12 and What Each Does

We tend to talk about vitamin B-12 as a single entity, but there are actually four different forms of B-12 in the cobalamin family –– each with its own distinct purpose.

  • Methylcobalamin
    Promotes improved memory, focus and concentration. Is important for the central nervous system, playing a vital role in cell growth and nerve cell regeneration. Supports healthy homocysteine levels. Helps regulate circadian rhythms, which contributes to improved sleep quality and refreshment.
  • Adensylcobalamin (Dibencozide)
    Promotes metabolism of essential fatty acids to produce more energy. Reacts with cells to provide muscles and nerves with bursts of energy.
  • Cyanocobalamin
    The most common form of B-12 found in oral supplements and injections. Becomes active in the liver, creating enzymes to help with blood formation, cell reproduction, iron utilization, and tissue synthesis. Promotes the digestion and absorption of foods.
  • Hydroxocobalamin
    Helps remove heavy metals from the system and supports overall detoxification. Is FDA-approved as an antidote for cyanide poisoning. Important for smokers because it removes the cyanide found in cigarette smoke. Also assists with methylation (gene regulation) and energy production.

How do you know which form(s) of B-12 you need? You don’t have to decide. By combining all four forms of the vitamin, B-12 Extreme provides you with the best of each.

Injections or Pills –– Is There a Difference?

Vitamin B-12 can be administered either orally or by injection. Since no one wants to get a shot unless they absolutely have to, it’s important to determine whether oral tablets are as effective as injections.

Two studies addressing that very issue concluded that oral supplementation with large doses of B-12 was as effective, if not more effective, than injections:

  • A 1997 study showed that oral supplementation with 2,000 mcg per day was three times as effective as injections in increasing B-12 levels in pernicious anemia patients.
  • A review of two clinical trials, published in 2006, concluded that 2,000 mcg doses of oral B-12 were as effective as intramuscular administration in vitamin B-12 deficient patients.

When it comes to oral supplementation of B-12, sublingual tablets are the best option because they are absorbed directly into the mucous membrane, by-passing the digestion process, which is often the cause of the deficiency to begin with.

Need-to-Know Information:

Safety: The IOM has not established any maximum dosage for vitamin B-12 because “no adverse effects have been associated with excess vitamin B-12 intake from food and supplements in healthy individuals.” Surplus B-12 is simply eliminated in the urine.

Dosage: The suggested dose of B-12 Extreme is one tablet once or twice a day, or as otherwise recommended by your healthcare professional.

How to Take: B-12 Extreme is a sublingual tablet. Place the tablet under your tongue and allow it to fully dissolve there. You should be aware that cobalamin, which is in all four forms of B-12, is an intense red color. As the tablet is dissolving, you may notice that your teeth, gums and sometimes even your lips appear to be red. Once the tablet has dissolved, the redness will begin to disappear on its own or you may want to brush your teeth to speed the process –– particularly if you are going out.

The original article, published September 28, 2012, was updated on September 23, 2019.

Karen Lee Richards is ProHealth’s Editor-in-Chief. A fibromyalgia patient herself, she co-founded the nonprofit organization now known as the National Fibromyalgia Association (NFA) in 1997 and served as its vice-president for eight years. She was also the executive editor of Fibromyalgia AWARE magazine. After leaving the NFA, Karen served as the Guide to Fibromyalgia and Chronic Fatigue Syndrome for the New York Times website About.com, then worked for eight years as the Chronic Pain Health Guide for The HealthCentral Network before coming to ProHealth. To learn more about Karen, see “Meet Karen Lee Richards.”


Fletcher RH, Fairfield KM. Vitamins for chronic disease prevention in adults. JAMA. 2002;287(23):3127-3129. doi: 10.1001/jama.287.23.3127

Regland B, Andersson M, Abrahamsson L, Bagby J, Dyrehag LE, Gottfries CG. Increased concentrations of homocysteine in the cerebrospinal fluid in patients with fibromyalgia and chronic fatigue syndrome. Scand J Rheumatol. 1997;26(4):301-7. doi: 10.3109/03009749709105320

Stott DJ, Langhorne P, Hendry A, et al. Prevalence and haemopoietic effects of low serum vitamin B12 levels in geriatric medical patients. Br J Nutr. 1997 Jul;78(1):57-63. doi: 10.1079/bjn19970118

Institute of Medicine. Food and Nutrition Board. Dietary Reference Intakes: Thiamin, riboflavin, niacin, vitamin B6, folate, vitamin B12, pantothenic acid, biotin, and choline. National Academy Press. Washington, DC, 1998. https://www.nap.edu/read/6015/chapter/1

Mayer G, Kroger M, Meier-Ewert K. Effects of vitamin B12 on performance and circadian rhythm in normal subjects. Neuropsychopharmacology. 1996 Nov;15(5):456-64. DOI: 10.1016/S0893-133X(96)00055-3

Verhaeverbeke I, Mets T, Mulkens K, Vandewoude M. Normalization of low vitamin B12 serum levels in older people by oral treatment. Journal of the American Geriatrics Society. January, 1997; 45(1):124. doi: 10.1111/j.1532-5415.1997.tb01000.x

Butler CC1, Vidal-Alaball J, Cannings-John R, et al. Oral vitamin B12 versus intramuscular vitamin B12 for vitamin B12 deficiency: a systematic review of randomized controlled trials. Fam Pract. 2006 Jun;23(3):279-85. doi: 10.1093/fampra/cml008

Note: This information has not been reviewed by the FDA. It is general information, not intended to diagnose, prevent, treat or cure any illness, condition or disease, and should not replace the personal attention of a qualified healthcare professional. It is very important that you make no change in your healthcare plan or health support regimen without researching and discussing it in collaboration with your professional healthcare team.

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5 thoughts on “Fatigue & Brain Fog: Could You Have a B-12 Deficiency?”

  1. njwph says:

    Cyanocobalamin is a synthetic form of B-12 and does not occur naturally in nature. The body cannot use it as is and has to convert it a useable form of B12.
    There is no benefit in Cyanocobalamin over the other forms and it actaully releases cyanide (albeit a very small amount) as the body converts it to a useable form of B12.
    If you are serious about your health, I would avoid cyanocobalamin forms of B12 all together.
    I think this article is misleading, and I would be very interested to see any scientific evidence of cyanocobalamin having any benefit to the body that is not provided by the other forms of B12

  2. herenow23 says:


    The ProHealth teaser to the article is: “A combination of magnesium and malic acid tops the list of recommendations for easing pain and fatigue, especially for those with fibromyalgia or ME/CFS. Magnesium (Mg) is one of the most important nutrients required by our bodies.” When I click – “Read more” I get: “Fatigue & Fibro Fog: Could You Have a B-12 Deficiency?” So I’m a little confused as usual :/ I may have clicked the wrong thing, I will recheck.

    Regardless, I used to use a particular brand of Magnesium and Malic acid with “sustained release” that is supposed to be easiest on the stomach. The product I used also has 5-MTHF, or folate an active form of Vitamin B-9, folic acid as you know 1,000 times better than I do. However, even using just half a tablet with an evening meal I wake with a burning gut that doesn’t go away, therefore I stopped using it.

    Now thanks to your advice I’m using Epson salt and a Epson salt lotion. However, the directions say 2 cups for every gallon of water. Maybe I need to buy it in 55 gallon drums 😉

    I will read more on your site. Do you have any suggestions regarding Magnesium and Malic acid and my stomach issue?

    You folks are doing an incredible job! The amount of medical and/or research content and naturally the quality supplements are really impressive! Keep up the great work!

    Mahalos to everyone at ProHealth and have a great day :)))

  3. Jen123456 says:

    It’s all about nutrition. I have been completely free of my FM symptoms for nearly a year and it has been down to nutrition. I was diagnosed by a consultant rheumatologist and the condition was disabling for me. A friend suggested I watch Joe Cross’ movie Fat Sick & Nearly Dead (it’s on youtube and he has made a 2nd one since), he cured his auto-immune disease by going on a 60 day fast of home made veg & fruit juice, and then following Dr Joel Fuhrman’s nutrition diet. I got his reboot juice diet book and a juicer, then juiced for 60 days and been careful with my diet since. Joe has a free website with all the info and a community for support. I was pain free at 3 weeks but continued for the full 60 days as I ached still if I cheated on the fast. I can have gluten, dairy etc now and I’m fine but I try not to, and I still have a juice or 2 every day. Dr Fuhrman has had success with FM on his nutrition diet too, his book is Eat to Live. I hope this helps others to break free.

  4. Deadinbed1 says:

    My B-12 level was TOO high as i learned from the dr. years ago yet it did NOTHING for me! i believe lots of people tried everything from diet to supplements WITHOUT improvement at all! Severe sufferers need SERIOUS HELP!!!

  5. GeekyGranny says:

    Vitamin B12 is in the soil… not in animals. Animals get it from the soil. This flagrant error makes me doubt the writers intelligence.

    You can get B12 in mushrooms, nutritional yeast, black strap molasses, etc. root veggies that you grow will have it.

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