Vitamin B Complex: Benefits, How to Take It and When You Really Need It

A vitamin B complex bundles all eight B vitamins in one supplement: thiamine (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), vitamin B6, biotin (B7), folate (B9) and vitamin B12. Your body needs them every day: they turn food into usable energy and keep your nerves and blood formation running. Most of them, though, already come from your plate. High-dose supplements, on the other hand, often deliver many times what's actually needed. For vitamin B6, the European Food Safety Authority (EFSA) even more than halved its upper limit in 2023, because too much of it can irritate the nerves over time.

So whether a B complex really does anything for you mainly comes down to two things: whether you're short on anything at all, and how much is in the tablet. For the second, a glance at the label is basically all it takes.

What is a vitamin B complex?

A vitamin B complex is a food supplement that contains all eight B vitamins together, usually as a tablet or capsule. The eight are grouped together because they're all water-soluble and work closely together in metabolism. For each one, the German Nutrition Society (DGE) gives its own reference value for daily intake from food and supplements combined. For some, it's an estimated value, because the data isn't yet enough for a precise recommendation:

Folate is the umbrella term for all forms of this vitamin, folic acid just the synthetic form found in most supplements. What methylfolate is all about is covered in the article folic acid and methylfolate. You'll find the other vitamins and the most important minerals in our overview of all vitamins and minerals.

What are B vitamins good for?

B vitamins are the helpers of the enzymes your cells use to get energy from carbohydrates, fat and protein. They're also needed so that nerves can pass on their signals and new blood is constantly made. If one of them is missing, this process stalls, and you often notice that first as tiredness. On the flip side, it doesn't run any faster with twice the amount, as long as nothing was actually missing before.

The health claims the EU allows for B vitamins are in a list of reviewed and authorized claims. For everyday life, these are the most important: thiamine, riboflavin, niacin, pantothenic acid, vitamin B6, vitamin B12 and biotin contribute to normal energy-yielding metabolism. Riboflavin, niacin, pantothenic acid, vitamin B6, folate and vitamin B12 contribute to the reduction of tiredness and fatigue. Thiamine, riboflavin, niacin, vitamin B6, vitamin B12 and biotin contribute to normal functioning of the nervous system, and folate contributes to normal blood formation. On top of that, there are claims about skin, hair, vision, psychological function and hormones. For instant energy at the push of a button, less stress or better sleep, on the other hand, there's no authorized claim. A few studies have asked exactly those questions, though.

Does a vitamin B complex help with tiredness and stress?

In studies with healthy adults, to some extent, though rather quietly and only after a few weeks of regular use. An analysis of eight controlled studies looked at people who took a supplement with vitamins and minerals for at least four weeks. They reported less stress and less tiredness than with a placebo, and the authors even suspect that supplements with high-dose B vitamins do more here. The differences were small to moderate, and some of the studies come from the manufacturers' orbit. The result is encouraging all the same.

In one of these studies, 215 working men between 30 and 55 took an effervescent tablet with high-dose B vitamins, vitamin C and minerals every day for 33 days. Afterwards they felt less stressed and less mentally fatigued after an hour of thinking tasks than the comparison group. It was funded by the supplement's manufacturer, and the amounts in it were anything but everyday. For thiamine, it was about twelve times what the DGE recommends for men per day. For vitamin B6, it was already almost as much as EFSA now sets as the upper limit for total intake. Whether smaller amounts around your daily needs do the same, this study didn't specifically test. One thing is clear, though: B vitamins work through regular intake, not like an espresso at the push of a button. And if the tiredness lasts for weeks, have it checked out by a doctor.

Who really needs a vitamin B complex?

According to the German Nutrition Society, if you're healthy and eat a balanced diet, you generally don't need a supplement. Among the B vitamins, the DGE specifically recommends only two: vitamin B12 on a vegan diet and folate when trying to conceive.

What everyday life actually looks like was surveyed by the Max Rubner Institute (MRI) in Germany's National Nutrition Survey II with more than 15,000 people. For niacin, almost everyone reached the amount recommended back then, for vitamin B6 about nine in ten. For thiamine, on the other hand, almost one in three women fell short, and for folate as many as four in five adults, measured, though, against the higher recommendation of the time. That isn't the same as a deficiency, but it shows pretty well which B vitamins are most likely to run short in everyday life. A supplement with B vitamins is worth it above all in these cases:

• Vegan diet: Vitamin B12 can't be reliably covered from plants. That's why the DGE calls a supplement “absolutely necessary”, more in the article vegan and multivitamins.
• Certain medications: If you take stomach acid blockers or the diabetes drug metformin for years, low B12 levels are more common. Then a check with your doctor is worth it, more on that in the article on B12 deficiency and daily needs.
• Trying to conceive: Women who want to get pregnant should take an extra 400 µg of folic acid or an equivalent amount of folate a day. They should start no later than four weeks before conception and only stop after the 12th week of pregnancy. There are specially formulated supplements for that. Supplements containing vitamin A should only be taken during pregnancy after consulting your doctor.
• The pill: For vitamin B6, there are hints that the pill can lower levels, for folate and B12 no relevant effect, more in the article what women really need.
• Lots of exercise: The DGE links the requirement for thiamine, riboflavin and niacin to energy intake. That doesn't prove a general extra need for B vitamins, though, more in the article vitamins for athletes.

What are the signs of a vitamin B deficiency?

From the outside, you can hardly tell, the signs are too nonspecific: tiredness, exhaustion, and with vitamin B12 also tingling or numbness in the hands and feet. Only a lab value reliably shows a deficiency.

Because tiredness can have so many causes, according to the German clinical guideline on fatigue, your family doctor will first measure a few basic values. Vitamin tests aren't automatically part of that, they only come when there are hints. With vitamin B12, the usual blood value also reacts late, holotranscobalamin and methylmalonic acid show a deficiency earlier. An overview of which sign fits what can be found in getting tested for a vitamin deficiency.

For women with persistent tiredness, it's worth looking at iron first. Iron deficiency is the most common nutrient deficiency of all, and women of childbearing age in particular are often affected, about one in five. And tingling in the hands and feet can come not only from a B12 deficiency but also from too much vitamin B6. So bring the list of your supplements to the doctor's office too.

When is the best time to take a vitamin B complex?

Ideally in the morning with breakfast. No study has compared different times of day yet. But taking it with your morning meal is the easiest way to make it a habit, and with vitamins the body constantly excretes, that's what matters most.

The German consumer advice centers (Verbraucherzentrale) generally recommend taking food supplements “in the middle of a completely normal meal”. B vitamins don't need fat for that, they're water-soluble and in the blood within a few hours. A small side finding from Australia also speaks for the morning. In a study with 100 participants, everyone took vitamin B6 or a B complex before bed for five nights. Those on the B complex said they slept worse and were more tired when they woke up. It was only a side observation. Still, we wouldn't exactly put a B complex on the nightstand. How B vitamins fit into a routine with other supplements is covered in the article when to take a multivitamin.

What are the side effects of a vitamin B complex?

In amounts around your daily needs, B vitamins are well tolerated. Side effects almost always come down to high amounts. The most important topic here is vitamin B6, because too much of it can irritate the nerves over time, up to tingling or nerve pain in the hands and feet.

In 2023, EFSA lowered its upper limit for vitamin B6 from 25 to 12 mg a day, and it applies to food and supplements combined. According to EFSA, it's practically only exceeded by people who regularly take high-dose B6 supplements. Complaints were also reported at smaller amounts, though. Australia's medicines regulator, the TGA, saw nerve problems from vitamin B6 mainly in people who combined several supplements. Often they didn't even know their magnesium also contained B6.

In the Netherlands, 238 reports of nerve pain came in for B6 products, 79 of them at 12 mg a day or less. A third of those affected recovered after stopping. Reports like these don't prove the cause, but the everyday advice is quick to give. Add up the B6 from all your supplements, including your magnesium, and if you get tingling, stop B6-containing supplements and have it checked by a doctor.

The other B vitamins cause far fewer problems. Niacin in the form of nicotinic acid can trigger a so-called flush, hot, reddened skin. Nicotinamide, on the other hand, doesn't trigger this flush. Biotin can skew some lab tests, such as thyroid or heart values. That's been shown for milligram amounts like 10 mg a day. Still, let them know before a blood draw if you take biotin, which is also what Germany's Federal Institute for Risk Assessment (BfR) recommends. What else can become too much with a multivitamin is covered in the article multivitamin side effects and interactions.

High-dose B complex or multivitamin: which makes more sense?

Our take: for everyday life, a multivitamin that contains all eight B vitamins close to your daily needs and also brings along the other vitamins and trace elements is enough. A high-dose B complex is more for a specific, diagnosed need, and then in consultation with your doctor.

With B complexes, “high-dose” quickly means many times your daily needs in a single tablet. Why they're dosed so high, we don't know, but we suspect it has more to do with the store shelf than with your body. More only helps up to a point. Whatever the body doesn't need of water-soluble vitamins right now, it excretes again, and with B6 it eventually becomes a risk. How big the difference can be is shown by the supplement from the stress study with the 215 men next to BASE by Fifty Five, our multivitamin. The amounts stand side by side here, the study results belong to the study supplement:

We chose the smaller numbers on the right very deliberately, because BASE is meant to complement what's already coming in through your diet. All eight B vitamins sit between 100 and 200% of the NRV (nutrient reference value). That's the reference for the percentages on the label. Measured against the DGE, seven of them are at or above the reference value for women and men, with only thiamine for men just below it or right on it, depending on age. Vitamin B6 comes as pyridoxal 5'-phosphate, the form in which B6 works in the body, and niacin as nicotinamide, which doesn't cause a flush.

Apart from BASE, the only other product of ours with vitamin B6 is CALM, our magnesium, also with 2.0 mg, which adds up to 4 mg together and so a third of EFSA's upper limit of 12 mg. If you take both, the easiest way is this: BASE in the morning, CALM in the evening. Spacing them out isn't required, but this way two products become a clear routine. When a single supplement is still the better choice is covered in the article single vitamin or multivitamin. What belongs in a multivitamin and what deliberately doesn't, you'll find in the multivitamin guide.

FAQ

How fast does a vitamin B complex work?

B vitamins reach the blood within hours. But it takes weeks for your levels there to shift measurably. In 80 healthy adults between 50 and 87, it took eight weeks with a multivitamin close to daily needs until the active form of vitamin B6 in the blood had risen by about 37% and folate by about 42%. So feel free to give a new routine a month or two before you judge it.

Can I take a B complex on top of my multivitamin?

You can, but it's rarely necessary. If your multivitamin already contains all eight B vitamins, you're simply taking them twice. With several supplements, the German consumer advice centers expressly advise making sure they don't contain the same nutrients. With vitamin B6, it's the total that counts anyway.

Why does urine turn yellow after B vitamins?

The culprit is riboflavin, vitamin B2. It's naturally a strong yellow color, and whatever the body doesn't need right now ends up in your urine. Completely harmless, in other words.

Do I need a B complex with or without folic acid?

For most people, a supplement with folate is a good fit, because folate is one of the B vitamins where many people don't reach the recommendation through food. Do watch the amount: folic acid and 5-MTHF from supplements share a combined tolerable upper intake level (UL) of 1,000 µg a day. That's because a lot of it can mask a vitamin B12 deficiency. It then no longer shows up in the blood, but it keeps progressing in the nerves. For us, a supplement with folate therefore also includes vitamin B12.

Which foods are high in B vitamins?

B vitamins are found in many staple foods: whole grains, legumes, nuts, green vegetables, dairy, eggs, meat and fish. So a varied diet brings enough of most of them. The big exception is vitamin B12, which according to the DGE only occurs in relevant amounts in animal foods.

Which vitamin B complex is the best?

The one that fits your needs, and for most people that's not the one with the highest percentages. Good signs are all eight B vitamins in amounts close to your daily needs, vitamin B6 without a megadose, niacin as nicotinamide and every single amount openly declared. Test winner lists only help if you know what they were rated on. How to recognize a good supplement on the label yourself is something we've pulled together in the article how to spot a good multivitamin.

Disclaimer:

This article is for informational purposes only and does not replace medical advice, diagnosis, or treatment by a physician or pharmacist. The information provided here should not be used for self-diagnosis or self-treatment. Food supplements are no substitute for a balanced, varied diet and a healthy lifestyle. For any health questions or complaints, please always consult a doctor you trust. Fifty Five accepts no liability for any inconvenience or harm resulting from the use of the information presented here.

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