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Vitamin B complex is composed of eight B vitamins:

Each of these essential vitamins contributes to your overall bodily function. Read on to learn more about how these nutrients benefit you, how much you need, whether you should take supplements, and more.

B vitamins play a vital role in maintaining good health and well-being. As the building blocks of a healthy body, B vitamins have a direct impact on your energy levels, brain function, and cell metabolism.

Vitamin B complex may help prevent infections and help support or promote:

  • cell health
  • growth of red blood cells
  • energy levels
  • eyesight
  • brain function
  • digestion
  • appetite
  • proper nerve function
  • hormones and cholesterol production
  • cardiovascular health
  • muscle tone

For those who pregnant

B vitamins are especially important for those who are pregnant or breastfeeding. These vitamins aid in fetal brain development, and they reduce the risk of birth defects.

For people who are expecting, B vitamins may help manage energy levels, ease nausea, and lower the risk of developing preeclampsia.

For boosting testosterone

B vitamins are sometimes included in “testosterone-boosting” supplements and are thought to increase testosterone levels in men, which naturally decrease with age. However, human studies confirming these claims are lacking.

In spite of the lack of evidence for any testosterone-boosting effects, because B vitamins are helpful in hormone regulation, it’s possible that B vitamins may help regulate male hormones as well as female hormones.

The recommended daily amount of each B vitamin varies.

According to the National Institutes of Health (NIH), the recommended daily intake for women is:

  • B1: 1.1 milligrams (mg)
  • B2: 1.1 mg
  • B3: 14 mg NE
  • B5: 5 mg
  • B6: 1.3 mg
  • Biotin: 30 micrograms (mcg)
  • Folic acid: 400 mcg DFE
  • B12: 2.4 mcg

For men, the NIH recommends the following daily intake:

  • B1: 1.2 mg
  • B2: 1.3 mg
  • B3: 16 mg NE
  • B5: 5 mg
  • B6: 1.3 mg
  • Biotin: 30 mcg
  • Folic acid: 400 mcg DFE
  • B12: 2.4 mcg

Older adults and those who are pregnant may require higher amounts of B vitamins. Your doctor can provide dosage information tailored to your individual needs.

Certain underlying health conditions can prevent your body from properly absorbing vitamin B. You should also talk with your doctor about your vitamin B intake if you have:

Lots of foods contain B vitamins, making it easy to get enough from your diet. It’s best to get your B vitamins from a wide variety of food sources. This helps ensure you’re getting enough of each type.

You can find vitamin B in:

  • milk
  • cheese
  • eggs
  • liver and kidney
  • meat, such as chicken and red meat
  • fish, such as tuna, mackerel, and salmon
  • shellfish, such as oysters and clams
  • dark green vegetables, such as spinach and kale
  • vegetables, such as beets, avocados, and potatoes
  • whole grains and cereals
  • beans, such as kidney beans, black beans, and chickpeas
  • nuts and seeds
  • fruits, such as citrus, banana, and watermelon
  • soy products, such as soy milk and tempeh
  • blackstrap molasses
  • wheat germ
  • yeast and nutritional yeast

Most people get enough B vitamins by eating a balanced diet. However, it’s still possible to be deficient, especially if you’ve been taking certain medications for a while, such as proton pump inhibitors, or if you follow a very strict vegan or vegetarian diet.

The following symptoms may signal you’re not getting enough B vitamins:

  • skin rashes
  • cracks around the mouth
  • scaly skin on the lips
  • swollen tongue
  • fatigue
  • weakness
  • anemia
  • confusion
  • irritability or depression
  • nausea
  • abdominal cramps
  • diarrhea
  • constipation
  • numbness or tingling in the feet and hands

If you’re experiencing any of these symptoms and aren’t sure why, make an appointment to talk with your doctor.

Although it’s possible that you’re experiencing a vitamin B deficiency, these symptoms also overlap with many other underlying conditions. Your doctor can make a diagnosis and advise you on next steps.

If you’re deficient in B vitamins you may experience a range of symptoms, depending on which B vitamins you’re lacking.

If left untreated, a deficiency could increase your risk for:

Vitamin B12 deficiency, in particular, may increase your risk of neuropsychiatric disorders. Researchers are also investigating its role in hyperhomocysteinemia and atherosclerosis.

Babies born to individuals who were deficient in folic acid during pregnancy may be more likely to have certain birth defects.

Most people get enough B vitamins through their diet. Whole foods are also the best way for your body to absorb these vitamins.

It’s not necessary to take a supplement unless your doctor has confirmed that you’re deficient in a specific B vitamin. If they note a deficiency, they’ll most likely tell you whether you should take a specific B supplement or add a vitamin B complex supplement to your routine.

You may be more likely to need supplementation if you:

  • are age 50 or older
  • are pregnant
  • have certain chronic health conditions
  • take certain long-term medications
  • eat a strictly meat-free diet

One thing to keep in mind: Supplements aren’t regulated by the Food and Drug Administration (FDA), so you should only buy from a trusted, reputable brand. This helps ensure you’re taking a high quality product without any questionable additives.

If your doctor has noted a deficiency, they may be able to recommend a specific brand of supplements.

You should always read all labels carefully and follow any directions given by the manufacturer. If you have questions about the dosage, talk with your doctor.

You’re unlikely to get too much vitamin B complex from your diet. That’s because B complex vitamins are water soluble. That means they aren’t stored in your body but are excreted in your urine daily.

You’re also unlikely to get too much vitamin B if you’re taking any supplementation as directed.

That said, as with most supplements, it’s possible to consume too much at once — especially if you’re taking a supplement without receiving a deficiency diagnosis from your doctor.

When consumed in excess, a few different B vitamins can have specific side effects. For instance:

  • Vitamin B6. Too much B6 may lead to peripheral neuropathy, which is a loss of feeling in the arms and legs.
  • Folate or folic acid. Too much of this vitamin can cover up the symptoms of a vitamin B12 deficiency, which can eventually lead to nervous system damage.
  • Niacin. Too much niacin may cause skin flushes. Long-term excessive use may lead to liver damage.

While there isn’t enough research to say exactly what will happen if you consume too much B complex, more is not necessarily better, especially over the long term.

It’s always a good idea to talk with your doctor before you add any supplements to your routine.

You can discuss your desired health goal and why you think supplementation is necessary. Your doctor can help you determine if this is the best treatment option and advise you on any next steps.

Some supplements can interact with certain underlying conditions and medications, so it’s important to keep your doctor informed.

You should also see your doctor if you think you may be deficient in B vitamins. They can help determine what’s causing your symptoms and, if needed, recommend ways to increase your B vitamin intake.