B vitamins are a class of vitamins composed of several different vitamins that share several features. The most common B vitamins are found in a B-complex supplement that typically consists of vitamins B2, B3, B5, B6, and B12. There are, however, more than just these 5 and your B complex may contain all 8 current B vitamins. Despite the fact that throughout the history of B vitamins there have been almost 30 compounds that were considered B vitamins, only 8 are known to actually fit the definition of a B vitamin. All B vitamins must actually be vitamins. Being a vitamin means it is an organic compound essential for normal growth and functioning but that the organism, in this case, humans, is unable synthesize it via its own biological processes. Therefore, the essential nutrients known as vitamins can only be acquired in the appropriate amounts via diet or supplementation. The B class of vitamins specifically refers to vitamins that are, first, water-soluble and, second, involved in cellular metabolism. They can be involved in cell metabolism as either a co-factor for an enzyme or a precursor. A more in-depth discussion and explanation of vitamins and enzymes can be found here (coming soon). Because of B vitamins’ roles in cellular metabolism, often the production of adenosine triphosphate (ATP), B vitamins are associated with energy production. This is also why they are a common ingredient in energy drinks. Of the compounds now known to not actually be B vitamins, the most common are included here for completeness since you may still find them incorrectly advertised as a B vitamin.

B Vitamins

Vitamin B-Complex

The graph shows the number of articles about each component of a standard vitamin B-complex published each year as indexed by PubMed.gov. Click the graph to learn more about the publication history of the vitamins in standard B-complexes.

The components of a standard vitamin B-complex have been researched quite extensively. Commonly you will find at least five different B vitamins in a B complex. These are B2, B3, B5, B6, and B12. You can learn more about each one below.
Back to B Vitamins

Vitamin B2 (riboflavin)

Riboflavin, commonly known as vitamin B2, riboflavin is an essential vitamin. Cellular growth and development cannot occur without riboflavin and this is why certain periods of increased growth, such as pregnancy or extensive wound healing, require higher amounts of vitamin B2. Vegetarian diet or chronic use of alcohol are often associated with lower dietary intake of vitamin B2 and this is likely why these patient populations have lower vitamin B2 levels.

Early manifestations of B-2 deficiency are cheilosis, stomatitis, glossitis, vascularization of the cornea (resulting in photophobia, itching, burning and visual impairment), and nonspecific genital dermatitis. More severe deficiency may result in seborrheic dermatitis of nose, face, and scrotum. In deficiency, doses of 10 mg/day is adequate. Larger doses are not harmful but provide no added benefit.

The graph shows the number of articles about vitamin B2, also known as riboflavin, published each year as indexed by PubMed.gov. Click the graph to learn more about the publication history of vitamin B2.
Back to B Vitamins

Vitamin B3 (niacin)

Niacin, also called nicotinic acid or vitamin B3 or vitamin PP (“pellagra preventive”), is different from niacinamide or nicotinamide. Although they are equipotent vitamins and can be substituted in certain instances, niacin and niacinamide are not generally interchangeable. When administering niacin – especially for the first time and/or in a dose higher than 500mg – leads to vasodilation, an effect known as “blushing” or “hot flushes“. Its counterpart, niacinamide, does not cause a similar side effect and this has gained its popularity, especially among younger patients. Yet, if niacinamide could substitute niacin for treatment of vitamin B3 deficiencies, it is entirely ineffective in the treatment of cholesterol.

Niacin and niacinamide contribute to the formation of two essential coenzymes: NAD and NADP. However, niacin remains the only of the two that can effectively lower triglycerides and help increase high-density lipoprotein levels. High niacin doses have a positive effect on the lipid metabolism and have been shown to lower plasma cholesterol, especially triglycerides and free fatty acids. Niacinamide does not have this effect; thus, no matter how tempting lack of hot flushes may seem, be very reserved in pursuing cholesterol lowering with niacinamide.

Niacin deficiency involves nervous system, skin, and the gastrointestinal tract. A subclinical pellagra may produce mild symptoms such as indigestion, headache, insomnia or nervousness. Severe deficiency is characterized by dementia, dermatitis, and diarrhea. Replacement of niacin may require considerably high amounts, however, niacin supplementation should be approached slowly and ideally by using a liquid product that can be given as little as one drop at a time. If failed due to improperly planned replacement, patient compliance may become a lost cause due to intolerable side effects. Sudden, high doses of niacin can stimulate histamine release, aggravate gastritis, peptic ulcer disease, and asthma. Needless to say, discontinuation of supplementation may have subsequent severe consequences.

Some clinicians advise that doses higher than 1 g per day may interfere with liver function and cause jaundice. Others state they never saw toxicity associated with niacin supplementation. I have to say that, provided a slow and careful initiation and proper dose-escalation, I never saw a niacin intoxication myself. However, depending on the reason for supplementation, a shorter niacin supplementation course may be better than longer. If taken for lowering triglycerides and it proves to be effective (and well-tolerated), then – by all the means – keep going!

I recommend patients to start as low as 20mg niacin daily and increase slowly all the way to 750mg daily divided among three meals or until an effect is noticed (whichever occurs first). I would add here that triglyceride improvement may only occur 3 months later, so be patient and consistent following clinician advise as prescribed. To learn more about the vitamin B supplements that I tried and recommend, please visit Dr Alice’s Shop.

The graph shows the number of articles about vitamin B3, also known as niacin, published each year as indexed by PubMed.gov. Click the graph to learn more about the publication history of vitamin B3.
Back to B Vitamins

Vitamin B5 (pantothenic acid)

Pantothenic acid is a precursor to coenzyme A and is involved in many biological processes. Despite argued benefits, pantothenic acid is not an effective antistress medicine and does not prevent graying of the hair either. Deficiency states are rare and not easily detectable. They may manifest nonspecific, including abdominal cramps, nausea, vomiting, headache, fatigue, insomnia, weakness and paresthesia. Toxicity is minimal (diarrhea is a side effect) and most B-complex daily supplements provide up to 30mg pantothenic acid, amount sufficient to prevent deficiency.
The graph shows the number of articles about vitamin B5, also known as pantothenic acid, published each year as indexed by PubMed.gov. Click the graph to learn more about the publication history of vitamin B5.
Back to B Vitamins

Vitamin B6 (pyridoxine)

The graph shows the number of articles about vitamin B6, also known as pyridoxine, published each year as indexed by PubMed.gov. Click the graph to learn more about the publication history of vitamin B6.

Pyridoxine, better known as vitamin B6, is involved in both protein and amino acid metabolism, specifically tryptophan synthesis. Clinicians got used to informing the public that B-6 deficiency is rare but we have little proof to support this statement. The best way to put it is that we believe that B-6 deficiencies are rare. However, the truth is tha, t we have limited evidence to say either way.

Infants with severe B-6 deficiency are irritable and may present with convulsive disorders. Adult deficiency, on the other hand, is similar to niacin or riboflavin deficiency. Increased pyridoxine requirements should be expected during pregnancy and lactation. However, contrary to many popular beliefs, B-6 does not prevent pregnancy-associated nausea and vomiting. Other instances of adult deficiency may be instances of certain drug treatments. One should expect lower B-6 levels if treated with isoniazid, cycloserine, hydralazine, estrogen (hormone replacement therapy and birth control users!), phenytoin and folic acid. Patients receiving any of the therapies mentioned above should be advised to supplement 10-20mg pyridoxine daily.

Regarding the use of hormone replacement therapy or of certain estrogen-containing oral contraceptives, if symptoms of the depressive syndrome are noticed, the patient may respond to pyridoxine supplementation and doses up to 100mg daily are recommended. Some less expected uses of pyridoxine are relief from carpal tunnel paresthesias and pain in hands (doses up to 100mg twice or three times daily), and amelioration of penicillamine-induced neurotoxicity.

Patients diagnosed with Parkinson’s disease should avoid vitamin B-6 supplementation due to the fact that pyridoxine is a cofactor for DOPA carboxylase – the enzyme that inactivates levodopa in the peripheral circulation. Since it facilitates the conversion of levodopa to dopamine outside the central nervous system, pyridoxine antagonizes the therapeutic action of levodopa. However, patients receiving drugs such as Sinemet or other forms of carbidopa-levodopa combination can take standard doses of B-6.B-6 will not affect adversely the carbidopa-levodopa effect, as carbidopa is a peripheral dopa carboxylase inhibitor.

Very high daily doses of B-6 (200-600mg) may inhibit prolactin, while doses of 1 gram daily used for pre-menstrual syndrome treatment may cause sensory neuropathy. For such instances, clinical advise should be followed closely.
Back to B Vitamins

Vitamin B12 (cyancobalamin)

The graph shows the number of articles about vitamin B12, commonly used to refer to cobalamin, published each year as indexed by PubMed.gov. Click the graph to learn more about the publication history of vitamin B12.

Vitamin B12, often referred to cyancobalamin, is a vitamin involved in numerous physiological processes. It is essential for normal growth, lipid metabolism, hematopoiesis, and maintenance of myelin throughout the entire central nervous system. Lack of vitamin B12 may only be noticed many weeks to months beyond its occurrence and, to a similar extent, the results of its effective supplementation take a very long time to show. Pernicious anemia (a type of macrocytic anemia) may occur due to inadequate dietary intake but also due to the lack of intrinsic factor – a protein essential for the absorption of B12 vitamin into the body.

Among the most well-known symptoms of vitamin B12 deficiency are, of course, anemia-related symptoms, such as fatigue, tiredness, pale skin etc. However, other clinical manifestations are also important: paresthesias of hand and feet, weakness, mental confusion, bizarre behavior, hallucinations, optic atrophy, weight loss, and shortness of breath. Accurate and early diagnosis is critical. Awareness of the fact that folic acid together with suboptimal B-12 will improve anemia but will not be sufficient to improve any neurological manifestations, is essential. In fact, the folic acid used to treat anemia may accelerate the neurological damage caused by B12 deficiency if insufficient B12 is supplied.

It is important to note that a majority of patients with chronic anemia are thought to be B12 deficient due to malfunctioning intrinsic factor. This includes patients with gastroesophageal reflux disease, peptic ulcer disease, diabetes mellitus (especially metformin users), and pre-diabetes. In these patients, oral supplementation of vitamin B-12 will likely be ineffective or suboptimal. Thus, parenteral supplementation (vitamin B12 shots) or sublingual formulations are highly recommended. To learn more about the vitamin B supplements that I tried and recommend, please visit Dr Alice’s Shop.
Back to B Vitamins

Other B Vitamins


In addition to B2, B3, B5, B6, and B12 these other B vitamins may also be found in your B complex and are members of the B class of vitamins. They consist of B1, B7, and B9. You can learn more about each one below. The B vitamins that fill in the gaps between B1-B12 are no longer B vitamins but can be found below in former B vitamins.

Vitamin B1 (thiamine)

Thiamine, commonly known as vitamin B1, is an essential co-factor for the carbohydrate metabolism. The higher the carbohydrate, sugar or alcohol intake, the higher the thiamine requirements will be. If the patient goes through withdrawal, low thiamine levels may not be noted until 2-3 weeks after the withdrawal. In addition, heightened requirements are reported in pregnancy, untreated hyperthyroidism, and instances of high fever.

Thiamine deficiency symptoms range from edema, tachycardia, ECG abnormalities, and epigastric pain, to actual cardiac failure. Neurological manifestations may include paresthesia of extremities, weakness, fatigue, mental confusion, ataxia, and muscle atrophy. Severe deficiency (beri-beri) is rare in the developed countries but worth investigating.

Heart failure due to profound B-1 deficiency requires 5-10 mg of thiamine up to 3 times daily for several days. Neurological symptoms are more refractory, requiring parenteral thiamine between 30 and 100 mg daily for several days. The extreme alcoholic cases are at high risk due to the ability of alcohol to impair thiamine transport across the intestine. Prompt and aggressive replacement of thiamine is indicated in chronic alcohol users and also to prevent or minimize severe neurological manifestations of Wernicke’s encephalopathy and Korsakoff’s psychosis.

For fun fact: use of thiamine as an insect repellent has been advocated, however, no repellant effect has been confirmed up to 300 mg doses. Yet, the odor of the raw chemical is surely offensive.

The graph shows the number of articles about vitamin B1, also known as thiamine, published each year as indexed by PubMed.gov. Click the graph to learn more about the publication history of vitamin B1.
Back to B Vitamins

Vitamin B7 (biotin)

The graph shows the number of articles about vitamin B7, also known as biotin, published each year as indexed by PubMed.gov. Click the graph to learn more about the publication history of vitamin B7.

Biotin, also known as vitamin B7, ….
Back to B Vitamins

Vitamin B9 (folic acid)

The graph shows the number of articles about vitamin B9, also known as folic acid or folate, published each year as indexed by PubMed.gov. Click the graph to learn more about the publication history of vitamin B9.

Folic acid, also known as vitamin B9, is a substance responsible to form tetrahydrofolate – a precursor of purine, pyrimidine, serine, methionine, and choline. Both DNA and RNA are formed as a result of the folic acid conversion to tetrahydrofolate. This is the reason for heightened requirements during growth and pregnancy. Vitamin B12 is required for the metabolism of folate, and folate deficiency may result from B12 deficiency. Poor diet or alcoholism may both contribute to folic acid deficiency, subsequently leading to macrocytic or megaloblastic anemia. Other less specific symptoms include a sore throat, diarrhea, irritability, and forgetfulness.

If considering to increase folic acid intake, remember that folates are heat labile. Canning, long exposure to heat or excessive refining may destroy 50-100% of the folic acid content. Thus, dietary supplementation with 0.5 or 0.8mg is recommended. In addition to pregnancy, the following conditions have increased folic acid requirements: hemolytic anemia, blood loss, hyperthyroidism, rheumatoid arthritis (due to methotrexate treatment) and certain hematopoietic malignancies.

Medications known to lower folic acid levels are: methotrexate, pemetrexed, phenytoin, and trimethoprim. Conversely, folic acid supplementation may lower phenytoin efficacy and lower convulsive threshold in phenytoin users.

The therapeutic dose of folic acid to correct the deficiency is 1 mg/day for 1-3 months. Toxicity occurs very rarely, usually with doses above 15 mg daily. Continuous supplementation may be needed in cases of chronic malabsorption.
Back to B Vitamins

Former B Vitamins


These former B vitamins, adenine, inositol, aminobenzoic acid, and salicylic acid are often still advertised either with the old vitamin B name or the currently accepted name. Most of these lost their status as a B vitamin because they were found to not actually be vitamins, meaning that the body has a way of synthesizing these compounds on its own. You can learn more about each one below.

Adenine (formerly vitamin B4)

The graph shows the number of articles about adenine, formerly known as vitamin B4, published each year as indexed by PubMed.gov. Click the graph to learn more about the publication history of adenine.

Historically, vitamin B4 actually referred to three different organic compounds. They were adenine, choline, and carnitine. The choice here to focus on adenine is as follows. Choline, while synthesized by the human body, is not synthesized in sufficient amounts and so must still be acquired through diet or supplementation and, thus, has its own section in supplements which can be found here. Carnitine is not an essential nutrient for humans and so we are left with adenine, which the human body can synthesize in adequate quantities. Also, if you are looking at a supplement labeled vitamin B4, check to see what compounds are actually in it and if you cannot find them specifically listed DO NOT BUY IT.
Back to B Vitamins

Inositol (formerly vitamin B8)

The graph shows the number of articles about inositol, formerly known as vitamin B8, published each year as indexed by PubMed.gov. Click the graph to learn more about the publication history of inositol.

Inositol, formerly known as vitamin B8, lost its status as a B vitamin when it was discovered that it could be synthesized, primarily in the kidney, from glucose-6-phosphate. The substrate, glucose-6-phosphate, is a molecule that is readily synthesized in nearly every cell of the body from glucose and is readily available.
Back to B Vitamins

Aminobenzoic Acid(formerly vitamin B10)

The graph shows the number of articles about aminobenzoic acid, formerly known as vitamin B10, published each year as indexed by PubMed.gov. Click the graph to learn more about the publication history of aminobenzoic acid.

Aminobenzoic acid, formerly known as vitamin B10, is not actually synthesized by the human body, but is nonetheless no longer considered an essential nutrient and, thus, lost its status as a vitamin. The reason for this is that even though the human body does not synthesize aminobenzoic acid the bacteria in our intestines does, a lot. The bacteria in our gut is able to make enough aminobenzoic acid that the only known instances of a deficiency are in people that do not have the bacteria necessary to make it.
Back to B Vitamins

Salicylic Acid (formerly vitamin B11)

The graph shows the number of articles about salicylic acid, formerly known as vitamin B11, published each year as indexed by PubMed.gov. Click the graph to learn more about the publication history of salicylic acid.

Whether salicylic acid or another compound pteryl-hepta-glutamic acid (PHGA) was what vitamin B11 was used most often to refer to is still debatable. However, PHGA is just a modified form of vitmain B9 and is not currently available on its own as a supplement, unlike salicylic acid. Salicylic acid, the active form of asprin and the popular acne treatment, is occasionally marketed as vitamin B11, hence the choice to discuss vitamin B11 as salicylic acid.Also, if you are looking at a supplement labelled vitamin B11, check to see what compounds are actually in it and if you cannot find them specifically listed DO NOT BUY IT.
Back to B Vitamins

Advertisements