What is the maximum dosage of B vitamins?

gay riley
Nutrition & Dietetics
Well this is a loaded question that is difficult to attempt in short answer but here it goes.

B vitamins are necessary for energy metabolism, immune function, neurological function, methylation and protection of DNA, red blood cell synthesis, cardiovascular health, skin and muscle and many other important biological functions.  B vitamins are water-soluble so in most cases you will not use what you don’t need from a supplement so unneeded Bs will spill out in the urine. The yellow color in your urine after taking your multi or a B vitamin comes from the Bs.  In my opinion, even healthy people in the United States should take a good multivitamin containing at least 100 percent of the RDA. Other folks that have heart disease, diabetes, an autoimmune disease or other medical conditions may require more than the daily recommendations. People taking hormone replacement, birth control, antacids, some antibiotics, arthritic medications or other medications can cause a malabsorption of some B vitamins, particularly B12 and folic acid. A deficiency of these B vitamins can cause serious health problems. So it is important to determine with your doctor or nutritionist your need for therapeutic doses. Vitamin B6 is the only B vitamin that has shown to have the potential to cause nerve damage in doses over or around 500 mg daily so the Nutrition Board of the Institutes of Medicine has set the upper limit at 100 mg daily.

Finally to answer your question. Take a good full spectrum multivitamin with at least 100% of vitamin B1 (thiamine), vitamin B2 (riboflavin), vitamin B3 (niacin or niacin amide), vitamin B5 (pantothenic acid), vitamin B6 (pyridoxine, pyridoxal, or pyridoxamine, or pyridoxine hydrochloride), vitamin B7 (biotin), vitamin B9 (folic acid), vitamin B12 (methyl or cynocobalamin). The only B vitamin you may see that is never over the RDA is B6 so don't worry if your multi is a little higher in other Bs. Google the food sources for B vitamins found in lean meats, whole grains, green leafy vegetables, brewer's yeast, molasses and liver. I don't recommend the energy drinks for your source of Bs that usually comes with caffeine and sugar. The caffeine and sugar may be the source of energy!

The B vitamins include B1 (thiamine), B2 (riboflavin), B3 (niacin), B5 (Pantothenic acid), B6 (pyridoxamine), B7 (biotin) B9 (folic acid), and B12. They are together or separately involved in most of the body's metabolic processes. The maximum dosage is often scientifically referred to as The Tolerable Upper Intake Level (UL) or the highest level of daily nutrient intake that is likely to pose no risk of adverse health effects most healthy individuals. Intake above the UL increases risk of adverse events. There are not many ULs set for B vitamins because they are water soluble, meaning the body excretes most of what it doesn't use making overdoing on B vitamins difficult but possible with some. Below is what is known about the maximum dose of some of the B vitamins.

  • Thiamin: There are no reports available of adverse effects from consumption of excess thiamin by ingestion of food and supplements. Because the data are inadequate for a quantitative risk assessment, no Tolerable Upper Intake Level (UL) can be derived for thiamin but stay below 25mgs unless advised by a doctor.
  • Riboflavin: No adverse effects were reported in humans after single oral doses of up to 60 mg of supplemental riboflavin and there is no UL at this time.
  • Niacin: Although the UL is set at 35mgs because niacin can cause harmless flushing, niacin in the form of niacinamide can be taken in far larger doses but stay below 100mgs.
  • Vitamin B6 (Pyridoxine): 100mgs/day is the UL but stay below 50mgs unless advised by a qualified physician
  • Folate: the UL for adults is 1 mg/day or 1,000 µg/day
  • Vitamin B12: No adverse effects have been associated with excess B12 intake from food or supplements in healthy individuals.
  • Pantothenic acid: No reports of adverse effects of oral pantothenic acid in humans or animals were found and therefore no UL has been set.

The goal is to make sure you get proper daily amounts of all necessary B vitamins. This goal is accomplished by eating a healthy diet (as found in the Sharecare Fitness application) and taking a daily multivitamin and mineral formula that contains the necessary B vitamins within the amounts shown below (upper portion of range for active people and/or dieters unless otherwise noted):

  • B1: 2-10mg/day
  • B2: 5-10mg/day
  • B3 (Niacinamide – this form will not cause flushing): 15-30mg/day
  • B5: 0-15mgs (women and over 50)
  • B6: 6-12mg/day
  • B7 (biotin): 100-300mcgs
  • Folic acid: 200-400mcg/day
  • B12: 12-100mcg

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.