With most foods and supplements, you kind of just swallow them and hope for the best. You have to be patient to see if they make a difference, and sometimes you’re still not sure. If you’re low on B vitamins, however, supplementing with them tends to yield results you can feel quickly. Your mind starts firing on all cylinders again and you may even find that you have the motivation to get more done—and better handle the stress that comes from doing.

Find out the many roles B vitamins play in an optimized body with our comprehensive guide below.

What Are B Vitamins?

B vitamins are water-soluble and act as either cofactors or precursors for metabolic processes. In other words, they allow a protein to do its job in the body or help cause chemical reactions. B vitamins are known for the role they play in boosting energy, mood, memory, and skin health. There are eight B vitamins in all: B1 (thiamine), B2 (riboflavin), B3 (niacin), B5, B6, B7, B9 (folate), and B12. Supplements that contain all eight B vitamins are known as B complexes.

Benefits of B Vitamins

B Vitamins have been shown to help performance and health in the following ways.

Boost Energy

B vitamins help power your body’s critical systems. From mental support in the conversion of neurotransmitters, to energy support, to detoxification of sugar end products, a good B vitamin can make a huge difference in your day.

In the U.S., it’s long been thought that most people get enough B vitamins through their food, and many foods are already fortified with them (cereals and non-dairy milks, for example).

But research is beginning to call into question whether the current Recommended Dietary Allowances (RDA) are enough.

Data from Tufts University shows that 40% of people between the ages of 26 and 83 have B12 levels on the low end of what is currently considered the normal range, bordering on deficiency.

The researchers said that the levels shown were low enough for the subjects to exhibit altered neurological function, which is known to be fatigue, weakness, and lack of focus.

Boosting B12 levels helps explain why athletes and celebrities who get B12 injections often claim that they feel an almost immediate jump in energy and focus.

Apart from assisting in the metabolic reactions that make you feel alert, B12 is thought to protect the sheaths that cover nerves, so having inadequate levels is like letting the wires that run from the computer in your brain get frayed—the signals they carry won’t get relayed efficiently.

Promote Performance

There’s evidence that B vitamins can help you hit your targets—literally. Two studies published in the International Journal for Vitamin and Nutrition Research looked at how amateur pentathletes performed when given supplemental vitamins B1, B6, and B12. The subjects in both trials improved their accuracy over the course of eight weeks.

What exactly happened? Researchers believe the vitamins had a calming effect that assisted in mediating the quality of the shooters’ sensory-motor control. In other words, being in a calmer state aided their fine motor skills, allowing them to hit more bullseyes. This is in line with an article from Medical Hypotheses that determined B6 is necessary for the production of serotonin and GABA, neurotransmitters that control mood, pain sensation, and anxiety.

In addition, several B vitamins help form the hemoglobin in red blood cells, which carry oxygen to the muscles during exercise. This has the potential to promote more efficient aerobic performance.

Maintain Mood

B vitamins seem to have a strong influence on how you feel mentally. A study in The Journal of the Royal College of General Practitioners looked at women with moderate to severe pre-menstrual characteristics who supplemented with B6. After three months, the subjects reported feeling less fatigued and irritable.

A study in Psychopharmacology also showed mood-boosting benefits for vitamin B6. Researchers found a correlation between blood levels of the vitamin and the subjects’ attitude: the higher the B6, the more positive their outlook.

Regulate Stress

B vitamins may help you perform better on the job, or at least handle your workload with a healthier attitude. A 2011 study in Human Psychopharmacology had 60 people take a B complex for three months. The subjects reported significantly lower stress, less confusion in the workplace, and reduction of a “dejected mood.”

Support Memory

If you have trouble remembering to take your supplements, you might want to make a note to self to take B vitamins first. An Australian trial had 211 women, middle-aged and older, take B6, folate (B9), and B12 daily for 35 days. When given various tests, the subjects saw significant boosts in memory performance. This is one reason why B6 is a key ingredient in Alpha Brain.

Interestingly, the youngest women in the study started with folate and B12 levels that were below 70% of the RDA. As they restored B vitamin levels, there was a direct association with cognitive performance.

In the same Psychopharmacology study mentioned above, vitamin B6 promoted long-term memory performance in subjects (men aged 70–79) after three months of supplementation.

Aid In Detox

Your body burns carbs for fuel during exercise (unless you’ve gone keto, which you can read about HERE). An unavoidable byproduct of this process is the creation of toxic compounds called glyoxals, which can damage cells and cause disease. An article in Biochemical Society Transactions reported that B1 (thiamine) helps break down glyoxals. It goes on to say that Western diets are low in B1 and high in sugar, which could result in high levels of glyoxals in the body.

Assist in Reduction of Intense Headaches

Research from the journal Headache put 49 headache-suffering (but otherwise healthy) people on riboflavin for three months. The subjects were divided into two groups—one that took a high dose of the vitamin and one that took a low dose, intended as a placebo. Impressively, the subjects in both groups saw a 50% or greater reduction in headache frequency.

Another study in the Journal of Headache and Pain that followed children and adolescents on riboflavin found that 68% of subjects cut their headache frequency in half. In addition, the intensity of the headaches reduced by 21%.

Promote Skin Health

Man, do we wish we knew about this stuff in high school. A 2014 study in Dermatology and Therapy had 41 subjects with mild to moderate facial acne take vitamin B5 for 12 weeks. The result? The men and women enjoyed a significant reduction in blemishes—by as much as 68%.

What B Vitamin Should I Take?

B Ready: How B Vitamins Can Optimize You

As you can see, each B vitamin offers special benefits, so aiming for one without the others would cause you to miss out on a lot of great nutrition. According to the University of Maryland Medical Center, getting only one of any of the B vitamins long-term can create an imbalance, so you may want to take a B-vitamin complex to cover all your B needs in one shot and in balanced amounts.

Because most Americans follow a diet that’s lower in B1 (thiamine) and higher in sugar than is optimal, it’s wise to make sure your supplement offers a hefty dose of B1—and in a form that it can absorb effectively. A study in the International Journal of Clinical Pharmacology and Therapeutics examined the different types of vitamin B1 to determine which absorbed the quickest in the body and was most easily put to use. Researchers found that one of these—benfotiamine—peaked B1 levels five times more than the other B derivatives and the bioavailability was more than 3.5 times greater.

Another shopping tip: look for B vitamins that are methylated. Many supplements offer folic acid in synthetic form. A review from the journal Xenobiotica shows that 5-methyltetrahydrofolate, which is how folate appears in nature, is more readily absorbed by the body for immediate use.

How Do Vegans Get B Vitamins?

In 2014, a giant review of 40 studies in the European Journal of Clinical Nutrition looked at vitamin B levels in plant-based dieters, finding that as much as 86.5% of vegetarians—and even more vegans—were at risk for deficiency. As B12 is only available in animal foods, choosing not to consume them means supplementation is critical.

Can B Vitamins Cause Cancer?

Last summer, a study from Ohio State University made headlines with findings that men who took high doses of B6 and B12 were at a greater risk of lung cancer. What a lot of people failed to pay attention to (before retweeting it) is that the at-risk subjects in the study were also smokers. They were between the ages of 50 and 76, and taking extreme amounts—20mg of B6 and 55 micrograms of B12, when the RDA is a mere 1.3mg and 2.4 micrograms, respectively. The study’s lead researcher, Theodore Brasky, also stated that the risk developed with high B intakes “over a very long period of time” (the study looked at the previous 10 years). Furthermore, lung cancer risk was not found to increase among the women studied.

“If they are men and they are smoking and taking B vitamin supplements,” Brasky told Medical Daily, “they really need to quit smoking. Smoking is the number one cause of lung cancer.”

In reaction to the study, Ross Walker, M.D., an Australian cardiologist and author, summed it up well in a blog post for Medium. “The bottom line is very straightforward—don’t smoke and don’t accept a one-line sensationalist headline.”

As usual, there’s a counterargument to be made as well. Another study by the International Agency for Research on Cancer (IARC) found that people—including smokers—who had high levels of B6 and the amino acid methionine in their blood for five years were 60% LESS likely to develop lung cancer. Methionine is common in lean meats such as chicken breast.

Ultimately, don’t look to B vitamins to prevent diseases, but supplementing with them as directed isn’t cause for alarm.