B Complex supplement health benefit, review of studies, dosage and side effects
October 22 2016 by
Ray Sahelian, M.D.


How much of a vitamin B complex do you need? Nobody really knows the answer to this, but my personal opinion is that for the majority of people, there is no need to take more than one, two, or three times the RDA on a long term basis, although higher amounts can be taken on a short term basis. The amount of supplemental B vitamins that a person could benefit from depends on one's diet.

For an excellent daily multivitamin with vitamin B complex, consider MultiVit Rx, a supplement that I formulated, a daily comprehensive multivitamin for more energy and vitality.




Vitamin B coenzyme complex supplements are the cheapest, safest, and most reliable way to improve your wellbeing and overall mental abilities. I recommend a Vitamin B complex to those who wish to improve their mood, mental clarity, and energy. The effects are subtle, especially in the young who normally have adequate dietary intake of these nutrients. Improvements in cognitive functions from vitamin B are particularly noticeable in middle age individuals and the elderly.

B vitamin products sold online
Doctor's Best, Best Fully Active B Complex, 30 Veggie Caps
Now Foods, B-50, 100 Veggie Caps


Most Vitamin B Complex supplements have the following:
B 1 -- Thiamine Cocarboxylase
B 2 -- Riboflavin Flavin Mono Nucleotide
B 3 -- Niacin, Nicotinamide and NADH
B 5 -- Pantothenic acid, Pantethine
B 6 -- Pyridoxine Pyridoxal Phosphate
B12 -- Cyanocobalamin Dibencozide or Methylcobalamin
Folic acid


Oral or sublingual B complex, there seems to be no difference in overall benefit
It is important to take a B complex sublingually or is an oral pill good enough?

A single-center, double-blinded, randomized controlled study to evaluate the relative efficacy of sublingual and oral vitamin B-complex administration in reducing total serum homocysteine levels.
J Altern Complement Med. 2006. College of Naturopathic Medicine, University of Bridgeport, Bridgeport, CT.
Forty-one subjects, between the ages of 50 and 80 years with total serum homocysteine concentrations exceeding 11 micromol/L, were treated with a six-week regimen of vitamin B complex. Each B complex consisted of 1000 microg vitamin B12 (as methylcobalamin), 400 microgram folate (as folic acid), and 5 mg vitamin B6 (as pyridoxine HCl). Participants in the study were randomized into two groups designated, retrospectively, as sublingual and PO. Members of group sublingual were given a sublingually delivered vitamin B complex and a matching orally delivered placebo. Members of group PO were given an orally delivered vitamin complex and a matching sublingually delivered placebo. A significant reduction in homocysteine values was observed in both groups upon completion of the 6-week protocol. There was no significant difference in serum homocysteine concentrations between sublingual vitamin B and oral vitamin B groups either before or after treatment.


Side effects, safety, toxicity, danger
High doses of B vitamins can speed heart rate and cause insomnia.

I just had blood work done and the results indicate my liver enzyme ALT level elevated to 46, which I know is borderline. It will be checked again in three months. I am very particular about my diet so am perplexed at why it isn't normal. I do take b-complex injections once a week so was wondering if this could be the reason?
    There are many causes for an elevated ALT level and it is difficult to know in any one individual what the cause is without more testing. I have not heard of B complex injections causing this issue but I cannot rule it out, either.

Benefit for eye health
Klin Oczna. 2014. Nutritional optic neuropathy (aka deficiency optic neuropathy) is a dysfunction of the optic nerve resulting from improper dietary content of certain nutrients essential for normal functioning of the nerve fibers. Most commonly, it results from folic acid and vitamin B complex deficiency associated with malnutrition or poor dietary habits, incorrectly applied vegetarian diet, or chronic alcohol abuse. Obese patients after bariatric surgery constitute another risk group of optic neuropathy. Nutritional optic neuropathy is characterized by painless, gradually progressing, bilateral and symmetrical decrease in visual acuity, which can be accompanied by the color vision dysfunction. Progression of the neuropathy is associated with optic nerve atrophy, manifesting as complete disc pallor. Treatment of nutritional neuropathy includes dietary supplementation, aimed at compensating for the deficient nutrients. The treatment is mostly based on folic acid, vitamin B complex, and protein replacement, as well as eliminating risk factors of neuropathy.

Weight gain or loss
Could you please tell me if you are aware of any times when someone takes vitamin b complex that they also experience weight gain?
   We have not heard this before, but that does not mean it is not possible.


Dosage and daily dose, how much to take
I recently found a b-complex vitamin which has reasonable amounts of each vitamin. It is B-Right by Jarrow Formulas. This product comes in a capsule. I would like to take about half of the dose daily. Do you think that if I open the capsule and only take half of the contents that i can be reasonably sure that I am getting around half the dose of each vitamin? I want to keep the ratio of each vitamin the same as to not create an imbalance.
   Just because a company has put together a group of vitamins together as a B complex formula -- such as the B-Right by Jarrow Formulas -- does not mean that this combination is what your body needs. As a rule I think most B complex formulas have too high amounts and therefore it is a good idea to take less. It is impossible to know for sure what the ideal B complex combination would be for your body since your diet is different than other people's diet and the type of foods you consume are likely to change over time. Hence, for practical purposes, it is irrelevant whether taking half of the capsule will provide the exact ratio in the formula.

I noticed that all the daily values were not too much like many other b-vitamin products, but vitamin b-12 is 5,000 of the DV%. Is this amount necessary and healthy to take on a daily basis? Also I noticed it contains coenzyme-q-10, and I am 28 years of age, is it necessary for me to start taking it?
    The decision whether to take supplements is done case by case in consultation with a health care provider. Only a small amount of oral vitamin B 12 is absorbed. It is a good idea to take breaks from the use of most supplements, including B complex pills. Some people may decide to take a B complex supplement only 2 or 3 times a week.


Combining with dietary supplements
I am a medical doctor. You mentioned on your site that you think that perhaps 1-3 times RDA of B complex should generally be enough. My question: When taking a high dose of SAMe, e.g. 800mg, how much B complex do you think one should take, in order to avoid homocysteine buildup, without unnecessarily aggravating possible side-effects such as insomnia. I started looking at this up on pubmed, but cannot easily get a clear answer. Further, do you think that taking B complex once every several days would be effective, or is it too rapidly metabolized? How concerned should I be about the homocysteine buildup? Is ALL of the B complex significant, or can one take selective treatment (B12?). A patient of mine is experiencing insomnia following SAMe and B-complex, and I would like to taper the latter down, but want to do so responsibly. I also thought that clarifying this would be of interest to many others.
   These are difficult questions to answer since little research is available and there could be enormous differences between individuals depending on their diet, activity level, metabolism, age, etc. As a general rule I am not concerned about the homocysteine aspect. I think 800 mg of SAM-e is too high and I would rather focus on lowering the amount and taking small amounts of the Bs a few times a week.


Use by pets, dogs, cats

We raise and show Chinese Shar-Pei. My husband is the head trainer for PetSmart. He fell in love with some tiny dogs in his classes, so I bought a Lhasa. He came by a transport truck instead of flying, the breeder did not believe in flying dogs-which we do all the time. He was in the truck 4 days. When we met the truck driver and picked up the puppy, I did not even think to quarantine him or even check for fleas. And at 9 weeks old, he already had a profuse coat. My husband took him to a groomer at PetSmart and was mortified to find out he had fleas. And before we knew it, they were all over the house. None on the outside dogs. You just cannot have fleas if you have show dogs, and we use NO chemicals on our dogs. I did have some diatomaceous earth which I sprinkled all over the house. Then got on the internet. One site said that B 50 would get rid of fleas. I did think seriously about this since I have taken it for 40 some years now and bugs donít bite me. In South Carolina that is quite something, and something my friends all had noted. So I gave a B 50 to every dog in the house every day, even down to our Pom [we donít breed anything but Shar-Pei but we both bring home everything-both rescuers!] This would be from a 50 lb. Shar-Pei to the Pom who maybe weighs 5 lbs. In 3 days I could tell a difference. In 10 days there were no fleas on anyone. Knowing the eggs would hatch, we did not give it for 10 days, then gave it 10 days again, and repeated that once more. No fleas. Strange but true!