What Happens To Your Body If You Take Too Many B Vitamins?

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An old saying that still rings true today is “too much of anything is bad for you”. This applies to the things we eat, our habits, and even the “healthy choices” we make – taking vitamins included.

Vitamin C has been taken in much higher doses than the Recommended Daily Amount and this seems to be well tolerated by the body, possibly conferring benefits. However that is not the case for other vitamins and overuse of vitamins A, B and D in particular can cause problems. B vitamins are good for health but overuse can cause an array of surprising symptoms. A useful rule of thumb is that B vitamins should be taken as B complex, not separately unless under medical supervision.

Vitamin B: The Pros

B Vitamins are very popular because of their ability to generally improve your health. B-complex, made up of a variety of different B-vitamins, is believed to help with acne, wound healing, and even anxiety and stress. People also take these vitamins separately to deal with different health concerns. ^[1] According to the Office of Dietary Supplements (under the National Institutes of Health), Vitamin B-12 helps form red blood cells (to help with anemia), improves neurological function, and protects DNA. ^[2] Another popular vitamin supplement is B-6, which helps with protein metabolism. Proteins are essential in the building and repair of the body’s cells and taking B vitamins can help with that. ^[3]

Vitamin B: The Cons

Vitamin B1

Vitamin B1, also known as thiamin, is one of the 8 known B-vitamins. While this vitamin is known to help reduce stress and boost the immune system, it can build up in the body and cause unwanted side effects. Thiamin is excreted primarily in the urine and after intakes of 5mg, there is a sudden decrease in absorption by the body — this is why there is very rarely any reports of vitamin B1 toxicity. However, an excess of this vitamin has been reported to cause an upset stomach, dry and itchy skin, nausea, dizziness — symptoms similar to an allergic reaction, although more research is needed to prove these claims. ^[4]

Vitamin B2

Vitamin B2 or riboflavin helps with energy production and acts as an antioxidant, getting rid the body’s free radicals which can damage the body’s cells and DNA. While this vitamin is generally considered as safe, excessive intake or cumulative high doses can cause itching, numbness, burning or prickling sensations, urine discoloration (yellow or orange) an increased sensitivity to light ^[5] and even anaphylaxis – severe/dangerous allergic reaction.

Vitamin B3

Like other B vitamins, Vitamin B3 or niacin helps with the conversion of food into glucose, the body’s useable form of energy. Niacin in particular also helps in the production of different sex and stress-related hormones in the body, as well as helping improve circulation and suppressing inflammation. To an extent, it is also famous for helping lower LDL levels. LDL is also known as “bad cholesterol” or the kind of cholesterol that damages blood vessel and ends up being stored as fat. ^[6]

However, high doses of Vitamin B3 can also cause unpleasant to dangerous side effects such as skin flushing, upset stomach, severe headaches and dizziness, blurred vision, and the worst – liver damage. According to the University of Maryland Medical Center, long term use of niacin supplements has been associated with hepatic damage. Similarly, a case study on a man who overdosed on niacin presented with impaired mental functions, kidney failure, and severe anemia. ^[6][7]

Vitamin B6

Vitamin B6 or pyridoxine was previously mentioned to help with protein metabolism, but the Mayo Clinic warns against high doses of this vitamin. The clinic reports that Vitamin B6 in high doses can cause abnormal heart rhythms, acne, severe allergic reactions, breast enargement and/or soreness, decreased muscle tone, drowsiness, headaches and nausea, heartburn and loss of appetite, and stomach upset or worse, ulcerative colitis (a type of inflammatory bowel disorder). A study on 2015 focused on the effects of Vitamin B6 on the nervous system, found that it increased the risk for peripheral sensory neuropathy, or loss of sensation in peripheral areas of the body like the hands and feet. They found that this vitamin could have teratogenic effects on a growing embryo, which causes the loss of sensation and eventual neuropathy. ^[8][9]

Vitamin B12

Excess – numbness or tingling in the arm, hands and face.. headache, dizziness, diarrhea, indigestion, upset stomach, vomiting, nausea, back pain, swelling, arthritis, anxiety, nervousness and lack of coordination, skin problems, improper heart functioning, increases the risk of getting cancer. ^[10][11]