The shelf is full of "B complex," "B12 forte" and "energy support" jars, and the marketing promises you more energy in big letters. It is understandable to think: it cannot hurt to try. Yet the honest question is not which jar to grab, but whether you are short of anything at all.
My view: taking a broad B complex on a hunch is wasted money for most people. Of the eight B vitamins, only two deficiencies show up often in practice: vitamin B12 and folate. Targeted testing tells you more than a broad supplement.
Which B vitamins are in the B complex?
The B complex includes eight water-soluble vitamins. They often work together, but each has its own role.
| B vitamin | Main role | Deficiency often relevant? |
|---|---|---|
| B1 (thiamine) | Energy from carbohydrates, nerve function | Sometimes (heavy alcohol use) |
| B2 (riboflavin) | Energy metabolism, skin and eyes | Rarely |
| B3 (niacin) | Energy and cell repair | Rarely |
| B5 (pantothenic acid) | Hormone and fatty-acid production | Rarely |
| B6 (pyridoxine) | Protein metabolism, neurotransmitters | Sometimes |
| B7 (biotin) | Skin, hair and metabolism | Rarely |
| B11 (folate) | Cell division and blood formation | Yes, around pregnancy |
| B12 (cobalamin) | Nervous system and red blood cells | Yes, vegans and older adults |
What does the B complex do together?
The B vitamins play a central role in your energy metabolism: they help your body extract energy from food. They are also needed for your nervous system, blood formation and cell repair. A good intake supports your energy level, but it does not resolve fatigue on its own if another cause is at play. That is exactly why targeted testing is smarter than blind supplementing.
Where do you actually see a deficiency?
Most B vitamins come amply from a varied diet. Two stand out:
- A vitamin B12 deficiency occurs in vegans, older adults and with gastrointestinal problems.
- A folate deficiency mainly plays a role around pregnancy and with a one-sided diet.
Because B12 and folate can mask each other in symptoms and in the blood picture, they are often assessed together. A high folate intake, for example, can hide a B12 deficiency while nerve damage quietly continues.
Which complaints fit a B12 or folate deficiency?
The complaints overlap heavily, which is exactly why you cannot tell them apart without a blood test. What you may see:
- Persistent fatigue and a sense of weakness
- Paleness and breathlessness on exertion, because both deficiencies can cause anaemia
- Tingling or numbness in hands and feet, especially with a B12 deficiency
- Concentration and memory problems or low mood
- An inflamed or smooth tongue
The difference that matters: a folate deficiency mainly causes anaemia, while a B12 deficiency can also damage the nervous system. That nerve damage is not always fully reversible after prolonged delay, which is exactly why you do not want to hide a B12 deficiency behind a broad supplement.
Who should test?
Not everyone needs their B vitamins measured, but for some groups it is genuinely wise. The NHG and the Voedingscentrum point mainly to:
- Vegans and strict vegetarians: without animal products or supplementation, B12 runs out over time.
- Older adults: absorption of B12 from food declines with age.
- People with gastrointestinal conditions or after stomach surgery: absorption is disrupted.
- Women planning a pregnancy or in early pregnancy: there is a specific folate recommendation around conception.
Is a broad B-complex supplement worth it?
For most people on a varied diet, a general B complex is not needed. It can be useful with a plant-based diet, a confirmed deficiency or on a doctor's advice. If you supplement on a hunch, you do not know whether you really need it, and with a hidden B12 deficiency a broad supplement high in folate may even mask the problem.
Where do you find B vitamins?
- Meat, fish, eggs and dairy: rich in B12 and other B vitamins
- Wholegrain products and legumes: B1, B3, B6, folate
- Green leafy vegetables: folate
- Nuts and seeds: B5, B6, biotin
Frequently asked questions
Does a B complex give more energy?
Only if you were deficient. With a normal level, extra B vitamins add nothing to your energy. The surplus of water-soluble B vitamins is passed in urine.
Which B vitamins should I test?
In practice mainly B12 and folate, since that is where the relevant deficiencies sit. With specific complaints or heavy alcohol use, your doctor may also weigh B1 or B6.
Can you get too many B vitamins?
Most B vitamins are water-soluble, so you pass much of a surplus in urine. That does not mean unlimited supplementing is useful. Vitamin B6 is known to cause nerve complaints with prolonged very high doses, so stay within the recommended amounts for supplements and consult your doctor if in doubt.
Want to know whether your B12 and folate are sufficient? A B vitamins panel measures the key values, or build a custom blood test. Read our overview of vitamin deficiency too. Every result at Vitalcheck is reviewed by a registered doctor. A blood value is not a diagnosis: discuss symptoms and treatment with your GP.
Sources
- Gezondheidsraad (Health Council of the Netherlands). Dietary reference values for vitamins and minerals. 2018.
- Voedingscentrum (Netherlands Nutrition Centre). Vitamin B12 and folate. Accessed 2026.
- Thuisarts.nl / NHG. Vitamin B12. Accessed 2026.
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