Clinical Updates

Taking high-dose biotin can cause blood tests to show falsely high levels of testosterone and/or cortisol, as shown in recent cases. It can interfere with many other tests, as well. Get the details, in the Biotin section of our B Vitamin Supplements Review. Also see our Top Picks for biotin.

Also see: Which vitamins and supplements should be stopped before getting blood work and laboratory tests?

Can taking benfotiamine (a derivative of vitamin B-1) slow cognitive decline in people with mild cognitive impairment or Alzheimer’s disease? See what research suggests in our B Vitamins Supplements Review, which includes our Top Picks among B vitamins.

Also see: Do any supplements, foods or lifestyle modifications help with brain function, like memory and cognition?

Be aware of the risk of liver injury from use of very high dose niacin, as recently reported in an otherwise healthy, young woman who was taking niacin to manage anxiety and depression. Get the details in the Niacin (Nicotinic Acid) (B-3) section of our B Vitamin Supplements Review, which includes our Top Picks for B vitamins.

Also see: Is there a risk of liver toxicity with certain supplements?

Having bariatric surgery can lead to vitamin deficiencies in people who do not follow recommended supplementation. This was recently reported in three individuals who developed thiamin deficiency after gastric bypass surgery. Get the details in the Thiamin section of our B Vitamin Supplements Review.

Also see our Top Pick among multivitamins for people who have undergone bariatric surgery and our article about supplements to take or avoid after bariatric surgery.

Although rare, vitamin B-12 can cause allergic reactions, but so can “inactive” ingredients in B-12 and other supplements. For details see the Risks of B-12 section of our Vitamin B-12 Review, which includes our Top Picks for B-12.

Does biotin help nails to grow faster? Find out what research suggests, and also learn which topical treatment for hair growth may help nails to grow, in the Biotin section of our B Vitamin Supplements Review, which includes our Top Picks for biotin and other B vitamins.

Although rare, severe and life-threatening allergic reactions to folic acid from supplements have been reported. Get the details about this, as well as risks from too much folic acid, in the Folic Acid section of our B Vitamin Supplements Review, which includes our Top Picks for folic acid and folate, and other B vitamins.

Did supplementation with vitamin B-6 reduce antibiotic-related side effects in people treated for H. pylori infection (a common cause of peptic ulcers)? Find out in our B Vitamin Supplements Review, which includes our Top Picks for vitamin B-6 and other B vitamins.

Also see: 8 Supplements That May Help Treat Peptic Ulcers – And Some to Avoid

Be aware that vitamin B-12 deficiency can cause a range of side effects. Among these are low blood cell counts, as described in a recent case report. Get the details in the Symptoms of B-12 deficiency section of our B Vitamin Supplements Review.

Also see our Top Picks for B-12 and other B vitamins.

Low levels of B-12 have been linked with tinnitus (ringing in the ears) and other issues, but does taking B-12 reduce tinnitus? Find out in the B-12 section of our B Vitamin Supplements Review, which includes our Top Picks for B-12 and other B vitamins.

Also see our article about supplements that may improve or worsen tinnitus.

Walgreens has rebranded its "Finest Nutrition" supplements. Get the details in our B Vitamins Review.

Rarely, vitamin B-12 supplementation can cause an allergic reaction, as highlighted by a recent case. Be aware of the risks of B-12 as explained in our B Vitamin Supplements Review, which includes our Top Picks for vitamin B-12 and other B vitamins.

High doses of biotin from supplements can interfere with a wide range of laboratory and at-home tests, including those for pregnancy, doping, COVID, and heart attacks. Get the details in the Biotin section of our B Vitamin Supplements Review.

Also see: Which vitamins and supplements should be stopped before getting blood work and laboratory tests?

High doses of vitamin B-6 from supplements may cause adverse effects, even when doses do not exceed the established tolerable limit for B-6, as highlighted by a recently reported case. Learn about getting too much or too little vitamin B-6 in our B Vitamins Supplements Review, which includes our Top Picks among B-6 and other B vitamin supplements.

If you take metformin to treat diabetes, be aware that you are at higher risk of vitamin B12 deficiency. Recent laboratory research suggests a possible reason for this, as discussed in the ConsumerTips section of our B Vitamins Review. Also see our Top Picks among B12 supplements.

Is thiamin tetrahydrofurfuryl disulfide (TTFD), a derivative of thiamin, absorbed and used by the body better than thiamin itself? Find out, and learn about possible health effects, in the Thiamin (B-1) section of our B Vitamin Supplements Review.

Is nutritional yeast a good source of B-12 and other B vitamins? That depends on whether or not it is fortified. Get the details in the Getting B-12 from food section of our B Vitamin Supplements Review, which includes a list of foods containing B vitamins.

Vitamin B-12 deficiency can cause a wide range of adverse effects affecting the nervous system, cognition, blood and blood pressure, and more. Learn about the symptoms and recent cases, and find out who is most likely to be deficient in our B Vitamin Supplements Review.

Also see our article: Top 8 Supplements for Vegetarians and Vegans.

Biotin has been promoted for reducing wrinkles, but does clinical research support this? Find out in the Biotin (B-7) section of our B Vitamin Supplements Review, which also discusses the evidence for biotin for treating brittle nails and hair loss.

Also, see our CL Answer about supplements for reducing wrinkles and tightening the skin.

Vitamin B-6 deficiency can cause nerve pain and weakness, even resulting in inability to walk, as shown in a recent case. However, getting too much B-6 from supplements can also cause these symptoms. Find out how much B6 you should be getting in the Vitamin B-6 section of our B Vitamins Supplements Review.

For information about supplements that may help with other forms of nerve pain, see our answer to the question: Do any supplements, like Nervive, help with nerve pain, like sciatica or diabetic neuropathy?

Can taking folic acid (vitamin B-9) reduce the risk of self-harm and suicide? Find out what a recent study found in the Depression section of our B Vitamin Supplements Review.

A baby was recently born with severe riboflavin deficiency due to a lack of riboflavin in the mother's vegan diet and supplements. Learn more about riboflavin requirements in our B Vitamin Supplements Review.

A CL Member had trouble sleeping when taking high dose B-12 to correct a deficiency and asked us if this is common. Find out in the B-12 section of our B Vitamin Supplements Review.

Also see: Supplements That May Help or Worsen Insomnia.

If you take metformin for diabetes, be aware that you are at risk for vitamin B-12 deficiency. See the latest guidelines to monitor for this in the B-12 section of our B Vitamin Supplements Review.

Beans and peas are great dietary sources of folate (vitamin B-9), but the right preparation can more than double their folate levels, according to a recent study. Find out how in the Folate section of our B Vitamin Supplements Review.

Also see our table of Foods Containing B Vitamins to find out other foods that are good sources of folate and other B vitamins.

Can taking high-dose vitamin B-6 or B-12 improve self-reported anxiety? Find out what a recent study showed in the Anxiety section of our B Vitamin Supplements Review.

Also see our answer to the question: What are the best supplements for depression and anxiety?

Can supplementing with vitamin B-6 or zinc improve psychiatric conditions associated with pyrrole disorder? Find out by using the links.

People with Parkinson's disease tend to have lower levels of vitamin B-6 and B-12. Find out if supplementing with B-6 or B-12 is beneficial and whether B-6 can interfere with drugs for Parkinson's.

Can vitamin B-5 supplementation improve symptoms of rheumatoid arthritis or osteoarthritis? Find out what research suggests in the B-5 (Pantothenic Acid) section of our B Vitamins Supplements Review.

Many people who have had bariatric (stomach-reducing) surgery need to supplement with B-12 and other B vitamins. Find out what happened to such a person who discontinued supplementation in the Vitamin B-12 section of our B Vitamin Supplements Review.

Taking very high doses of niacin can cause symptoms resembling anaphylactic shock, as was recently reported. Get the details in the Niacin section of our B Vitamin Supplements Review.

B-12 deficiency can cause severe symptoms, even when B-12 levels in the blood are not low, as shown in a recent case. Find out why, and which tests can help, in the B-12 section of our B Vitamin Supplements Review.

People with a certain MTHFR gene mutation (C677T) may be more likely to develop B vitamin deficiencies. But what about those with a less common MTHFR mutation – A1298C? Find out what research suggests in the MTHFR gene mutation and B vitamin metabolism section of our B Vitamin Supplements Review.

Raising lower blood levels of vitamin B-12 may help with nighttime leg cramps according to some reports. Get the details in the B-12 section of our B Vitamin Supplements Review.

For information about other supplements that may help, see our answer to the question: Do any supplements, foods, or oils help reduce muscle pain, muscle cramps, or nighttime leg cramps?

Correcting B-12 deficiency may improve cognition in people with dementia, according to a recent study and case reports. Get the details in the Memory, Cognition, and Alzheimer’s Disease section of our B Vitamin Supplements Review.

Although not common, B-12 deficiency can occur in infants. A recent study showed common symptoms and risk factors. Learn about B-12 deficiency in infants as well as in men and women in the B-12 section of our B Vitamin Supplements Review.

Two studies this week showed the risk of high blood pressure to be lowest among people with adequate, but not excessive, dietary intakes of magnesium and niacin.

Also, see which foods are good sources of magnesium and, separately, good sources of niacin.

The death of a woman from acute liver failure highlights the risk of a particular formulation of high-dose niacin. For details, see the Niacin section of the B Vitamin Supplements Review. (Also see our Top Picks for niacin and other B vitamins.)

For more information, see ConsumerLab's answer to the question, I take omeprazole (Prilosec), a proton pump inhibitor, to reduce stomach acid. Are there supplements I should avoid, or be taking, due to this drug?.