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B Vitamins: Causes and Symptoms of Deficiency

Nutrition tip: make sure you’re getting enough B vitamins because they’re so important to many aspects of your health and well-being! (You can now check your vitamin B levels at home with EverlyWell’s B Vitamins Test.)

Read on to learn more about B vitamins: what they can mean for your health, symptoms and causes of deficiency, and more.

What is Vitamin B?

Vitamin B refers to several different types of vitamins that, together, are known as the B-complex vitamins.

There are 8 kinds of vitamins in the vitamin B complex: thiamine (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxine (B6), biotin (B7), folate (B9, also known as folic acid), and cobalamin (B12).

Each of these eight B vitamins play important roles in the body. B vitamins are needed to drive the chemical reactions that support your body’s many functions. For example, cells use B vitamins to generate energy from sugar, fatty acids, and other nutrients. So without B-complex vitamins, the human body could not function well at all.

B vitamins are water-soluble vitamins. In other words, they can dissolve in water – so excess B vitamins your body doesn’t use are washed out through urination, for example.

This means the body can’t easily store B vitamins for long periods of time. That’s why it’s especially important to regularly consume B vitamins – whether from your diet or from supplements – to avoid deficiency.

Benefits of B Vitamins

Benefits of Vitamin B6

  • Helps the body build neurotransmitters (like dopamine), which are special chemicals your brain needs to function
  • Helps your body make red blood cells
  • Helps immune system antibodies work correctly
  • May help lower the risk of lung cancer (though more research is needed to firmly establish this benefit of B6)

Benefits of Vitamin B9 (Folate or Folic Acid)

  • Helps the body make and repair DNA (genetic material)
  • Helps your body make red blood cells
  • Supplementing with high-enough levels of B9 before pregnancy (as well as during pregnancy) significantly lowers the risk of giving birth to a baby with neural tube defects like spina bifida

Benefits of Vitamin B12

  • Helps the body make and repair DNA (genetic material)
  • Helps your body make red blood cells – as well as nerve cells
  • Helps support healthy hair, skin, and nails

Think you might have low vitamin B levels? Take EverlyWell’s at-home B Vitamins Test to find out.

Or consider vitamin B9 (a.k.a. folate or folic acid): a deficiency in this vitamin and you might get sores on your mouth or a swollen tongue – among other possible symptoms.

Then there’s vitamin B6. If your levels of this key B vitamin are too low, then you could be looking at flaky, oily rashes on your upper body or face.

But these aren’t the only symptoms of B vitamin deficiency. So here’s a more complete list of vitamin B deficiency symptoms.


Vitamin B6 Deficiency

Signs of B6 deficiency include:

  • Getting sick from infections more often (because B6 helps support your immune system)
  • Getting cracks or sores in the skin around the corners of your mouth – or a swollen and sensitive tongue
  • Fatigue
  • A feeling of numbness or tingling in your hands and feet (this is known as “paresthesias”)
  • Depression, anxiety, and/or irritability
  • A red, itchy rash – often oily or flaky – that usually appears on the upper body or face. Small areas of your skin might also swell, resulting in white patches
  • Convulsions
  • Decreased alertness

Vitamin B9 Deficiency

Signs of B9 deficiency include:

  • Fatigue
  • More gray hair
  • Mouth sores
  • A swollen tongue
  • Weakness
  • Shortness of breath
  • Pale skin
  • Irritability

Vitamin B12 Deficiency

Signs of B12 deficiency include:

  • A feeling of numbness or tingling in your hands and feet (or “paresthesias”)
  • A smooth-appearing tongue
  • Fatigue
  • Weakness
  • Mouth sores
  • Mood changes
  • Blurry vision
  • Loss of breath
  • Dizziness
  • Pale skin

Are you deficient in key B vitamins? Check from the comfort of home with EverlyWell’s B Vitamins Test.

Other conditions linked with vitamin B deficiency include:

  • Paresthesias – A “pins-and-needles” feeling often experienced around the arms, hands, legs, or feet
  • Peripheral neuropathy – A nervous system condition that is often felt as a stabbing or burning pain
  • Psychosis – A mental condition in which one’s thoughts and perceptions are significantly altered, resulting in delusions, hallucinations, nonsense speech, or other symptoms
  • Heart attack and stroke – A deficiency in vitamin B12 may heighten the risk of getting a heart attack or stroke


Your body can’t directly make B vitamins (unlike proteins, for example – which the body manufactures out of many smaller building blocks).

But that’s usually not a problem because your body gets B vitamins from the food you eat. However, for a variety of reasons, sometimes we don’t eat the right balance of food necessary to get enough of the vitamins we need. (For example, if you follow a vegan diet, then you might not get enough vitamin B12 – because vitamin B12 is found almost exclusively in animal-based foods.)

photo-1518912006-3761723e528a Your body gets B vitamins from the food you eat.

That’s when vitamin deficiencies – like vitamin B deficiency – can crop up. As such, dietary inadequacies are one of the key causes of vitamin B deficiency.

So, obvious follow-up question here: what foods contain a lot of B vitamins? Well, that depends on which B vitamin is under consideration – vitamin B6, B9, or B12. Here’s a quick rundown of foods you can eat to boost your levels of each of these B vitamins (source):

  • Vitamin B6 – Meat, fish, legumes, nuts, bananas, potatoes
  • Vitamin B9 – Leafy vegetables, legumes, citrus fruits
  • Vitamin B12 – Meat, fish, and other animal products


Whether your drink of choice is shaken and not stirred, includes a barrel-aged spirit, or is a humble mug of beer, there’s nothing especially harmful about (safely) having a drink every now and then.

Needless to say, though, excessive alcohol consumption can have its downsides – one of which is vitamin B deficiency. Alcohol, in short, makes your kidneys flush B vitamins out of your system much more quickly than usual. That means your body doesn’t have all the time it needs to make use of these B vitamins – so they, quite literally, go to waste.

photo-1532634745-d438fed1a87e Alcohol makes your kidneys flush B vitamins out of your system much more quickly than usual, which can lead to vitamin B deficiency.


Several types of prescription medicines can bump up the likelihood of a vitamin B deficiency:

  • Increased likelihood of vitamin B6 deficiency – anticonvulsants, isoniazid, hydralazine, corticosteroids, and penicillamine (common brand name: Cuprimine)
  • Increased likelihood of vitamin B9 deficiency – phenytoin (common brand name: Dilantin), trimethoprim-sulfamethoxazole, methotrexate (common brand names: Rheumatrex, Trexall), and sulfasalazine (common brand name: Azulfidine)
  • Increased likelihood of vitamin B12 deficiency – metformin, proton pump inhibitors (PPIs), antacids, long-term antibiotics, and antidepressants

photo-1512069843211-ff3b764416be Some prescription medications can bump up the likelihood of vitamin B deficiency.


Under healthy conditions, B vitamins are absorbed by the gut and into your bloodstream. The bloodstream then transports these much-needed vitamins throughout your body. So what happens if B vitamins don’t make it into the bloodstream? It’s simple: they can’t be put to good use by the body!

And that’s exactly what can go wrong if you have a gut malabsorption condition – like Crohn’s, for example, or ulcerative colitis or Celiac disease. These conditions prevent B vitamins from entering the bloodstream, significantly dropping your blood’s vitamin B levels – and potentially harming your well-being.

abdominal-pain-2821941 960 720 If you have a gut malabsorption condition – like Crohn’s, for example, or ulcerative colitis or Celiac disease – B vitamins are prevented from entering your bloodstream.


Since vitamin B deficiency is relatively common – some have even declared it a “worldwide problem” – it’s helpful to know some of its main causes (like the 4 described above).

There's more you can do to reduce the health risks related to a vitamin B deficiency. For starters, consider checking your vitamin B levels with EverlyWell’s easy-to-take B Vitamins Test. Then, if you are indeed deficient, you can consult with your healthcare provider on the next steps you can take.

Learn More About Vitamin B

B Vitamins For Energy: Myth or Science?

At-Home B Vitamins Test