Updated November 29, 2023. Medically reviewed by Neka Miller, PhD. Written by Jordana White. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.
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Nutrition tip: make sure you’re getting enough B vitamins because they’re so important to many aspects of your health and well-being. Vitamin B benefits the body by maintaining the health of cells and nerves as well as aiding in the production of DNA.
Read on to learn more about B vitamins: what they can mean for your health, symptoms and causes of deficiency, and more.
Vitamin B refers to several different types of vitamins that, together, are known as the B-complex vitamins. Vitamin B benefits the nerves and cells within the body and also helps with the production of DNA (the chemical substance that genes are made from).
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). Deficiencies in these B vitamins can lead to a number of different symptoms over time (if the deficiency isn’t reversed).
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.
Vitamin B12 can affect your red blood cell count, and can even lead to neurological symptoms in severe cases.  If someone’s vitamin B12 status isn’t at a normal level, their healthcare provider may recommend a high-dosage B12 supplement or even—in some cases—B12 injections.
When it comes to vitamins needed for both a sound body and mind, the B vitamins aren’t something you want to ignore. Take, for example, vitamin B12: don’t get enough of this vitamin, and your energy levels throughout the day might sag – with your mind constantly turning, perhaps, to thoughts of sleep in your warm cozy bed.
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.
Signs of B6 deficiency include:
Signs of B9 deficiency include:
Signs of B12 deficiency include:
Vitamin B deficiency can increase the risk of various diseases and conditions which can affect your heart health, brain health, mental well-being, and more. For example, both B9 and B12 deficiency causes anemia in some cases – a condition in which your body lacks healthy red blood cells (which makes it hard for different parts of your body to get the oxygen they need). Anemia can also lead to fatigue, dizziness, shortness of breath, and even numbness and tingling in some cases.
Other conditions linked with vitamin B deficiency include:
Here’s a roundup of 4 of the top causes of vitamin B deficiency: a non-balanced diet, excessive alcohol consumption, various medications (such as proton-pump inhibitors, or PPIs), and gut malabsorption conditions.
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. If you follow a well-balanced diet that provides your body with the right level of nutrients, you can help avoid symptoms of vitamin B deficiencies.
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 or vegetarian diet, then you might not get enough vitamin B12 – because vitamin B12 is found almost exclusively in animal-based foods and dairy products. )
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 [4-6]:
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.
Several types of prescription medicines can bump up the likelihood of a 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.
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).
It’s recommended that older adults who have deficient levels of vitamin B talk with their healthcare provider as soon as possible to come up with a treatment plan. If you are showing vitamin B deficiency symptoms, it may be because you do not have enough vitamin B in your diet. If you're showing signs of tiredness, lightheadedness, shortness of breath, or other deficiency symptoms, consider checking your B vitamins level. For those looking to improve their vitamin B levels, Everlywell offers vegan, non-GMO vitamin B12 and B6 supplements.
Originally published February 6, 2019.
Neka Miller, PhD holds a PhD in Molecular Pharmacology and is an experienced technical writer covering topics including pharmacology, cancer initiation, neuroscience, and traumatic brain injury. Miller has also created manuals and custom reports featuring data visualizations, protocols, method sections, and manuscripts, as well as authoring published works in scientific journals.