Q: Does vitamin B6 boost mental health?
When it comes to the B vitamins, you’re probably most familiar with vitamin B12, which helps prevent anemia and maintain bone health, and B9 (folic acid), which is necessary for a healthy pregnancy.
But vitamin B6, in some ways, is “the forgotten vitamin,” said Dr. Reem Malouf, a neurologist at the University of Oxford who has studied B6’s effect on cognition. As with the other B vitamins, like B12 and B9, it is an essential nutrient, yet scientists don’t fully understand how it affects mental health, and it’s less well known than the others.
That doesn’t make it any less crucial for the body’s functioning, said Katherine Tucker, a nutritional epidemiologist at UMass Lowell. Vitamin B6 is involved in a number of chemical reactions that are important for nervous system and brain function, including the synthesis of proteins, amino acids and chemical messengers of the brain, as well as proper functioning of the immune system.
It’s also critical for pregnancy and postnatal care — helping to relieve morning sickness and necessary for fetal and infant brain development. And deficiencies in vitamin B6 have been linked with several neuropsychiatric conditions, including seizures, migraine, anxiety, depression and impaired memory.
What role does vitamin B6 play in mental health?
“Vitamin B6 affecting mental health is not a new concept,” said Jess Eastwood, a doctoral student in nutritional psychology at the University of Reading in Britain. In one study of nearly 500 university students published in July, for instance, Ms. Eastwood and her colleagues found that those who took high doses of vitamin B6 — 100 milligrams per day for about a month — reported feeling less anxious than those who took a placebo. Their findings also suggested that B6 might play a role in tamping down the increased brain activity that can occur with certain mood disorders.
But this study’s sample size was small, and there hasn’t been much research in general on how B6, whether supplemental or dietary, causes changes in mental health, Ms. Eastwood added. The conclusions of such studies, including this one, are often limited and don’t prove causation.
It can also be difficult to study what effect, if any, supplemental B6 has on mental health, in part because it’s challenging to measure how well vitamins are absorbed into the bloodstream.
Should we all be rushing out to buy B6 supplements?
Probably not, the experts said. For most healthy adults, the recommended daily intake of vitamin B6 is 1.3 to 1.7 milligrams.
As with the other essential vitamins, the body cannot produce B6 on its own, so you can get it only from foods or supplements. However, most healthy adults get more than enough vitamin B6 from their diets alone, Dr. Tucker said. “It’s widely available in whole foods,” she said, like tuna, salmon, fortified cereals, chickpeas, poultry, dark leafy greens, bananas, oranges, cantaloupe and nuts.
One cup of canned chickpeas, for instance, provides 1.1 milligrams of vitamin B6, while three ounces of roasted chicken breast supplies 0.5 milligrams.
Most dietary supplements also tend to contain more than what you need in a day — for some B6 supplements on the market, for example, it can be about 20 to 200 times as much. Taking such high doses of B6 supplements probably won’t cause any negative side effects in the short term, Dr. Tucker said, but the National Institutes of Health recommends that adults take no more than 100 milligrams per day. Taking much more than that, about 1,000 milligrams or more each day for long periods of time, could cause weakness, numbness and pain in the hands and feet; loss of muscle control; and nausea, though most symptoms subside once you stop taking such high doses.
Experts say that if you’re concerned you’re not getting enough vitamin B6 in your diet, ask your doctor for a blood test. If you are borderline or mildly deficient, you may have only minor symptoms, or none at all, and no complications. But if the deficiency becomes severe or prolonged, that could lead to more serious conditions, like microcytic anemia, depression, confusion, fatigue and weakened immunity, which can clear up after B6 levels are restored.
Certain medications or lifestyle habits may also contribute to a B6 deficiency. “The diabetes medication metformin, some hypertension medications, certainly alcohol, tend to cause loss of B6 in the body so that you end up retaining less B6 than you need,” Dr. Tucker said. Heavy drinkers, smokers and those who are taking certain medications should be much more mindful of their B6 levels, she added. People with kidney or malabsorption syndromes like chronic kidney disease, celiac disease, ulcerative colitis or Crohn’s disease may also be prone to B6 deficiency.
Keep in mind that those who are deficient in B6 also tend to be deficient in other B vitamins, Dr. Tucker said, so if you need to supplement your diet, you may be better served by taking a B-complex supplement, which usually contains all eight of the B vitamins in one dose.
But if you’re not deficient, Dr. Tucker added, you probably don’t need to take a supplement.
“I would always endorse a food-first approach,” Ms. Eastwood agreed. “If you are perhaps feeling more fatigued, you don’t feel quite yourself, and you’re aware that you maybe don’t eat a lot of food that contains B6,” then that might indicate you need to turn to more B6-rich foods.